Agenda — Desert Hot Springs City Council, April 21, 2026 (part 7 of 19)

16 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 55.000 to Point/Station 55.000 **** SUBAREA FLOW ADDITION ****
______________________________________________________________________ COMMERCIAL subarea type
Runoff Coefficient = 0.866
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 32.00
Pervious area fraction = 0.100; Impervious fraction = 0.900 Time of concentration = 10.68 min.

Rainfall intensity = 4.598(In/Hr) for a 100.0 year storm Subarea runoff = 11.941(CFS) for 3.000(Ac.)
Total runoff = 66.288(CFS) Total area = 13.700(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 55.000 to Point/Station 56.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 640.500(Ft.)
Downstream point/station elevation = 640.000(Ft.)
Pipe length = 360.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 66.288(CFS)
Nearest computed pipe diameter = 51.00(In.)
Calculated individual pipe flow = 66.288(CFS)
Normal flow depth in pipe = 44.81(In.)
Flow top width inside pipe = 33.30(In.)
Critical Depth = 28.97(In.)
Pipe flow velocity = 5.02(Ft/s)
Travel time through pipe = 1.20 min.

Time of concentration (TC) = 11.88 min.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 56.000 to Point/Station 56.000 **** SUBAREA FLOW ADDITION ****
______________________________________________________________________ COMMERCIAL subarea type
Runoff Coefficient = 0.864
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 32.00
Pervious area fraction = 0.100; Impervious fraction = 0.900 Time of concentration = 11.88 min.

Rainfall intensity = 4.323(In/Hr) for a 100.0 year storm Subarea runoff = 23.544(CFS) for 6.300(Ac.)
Total runoff = 89.831(CFS) Total area = 20.000(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 56.000 to Point/Station 56.000 **** SUBAREA FLOW ADDITION ****
______________________________________________________________________ COMMERCIAL subarea type
Runoff Coefficient = 0.864
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 32.00
Pervious area fraction = 0.100; Impervious fraction = 0.900 Time of concentration = 11.88 min.

Rainfall intensity = 4.323(In/Hr) for a 100.0 year storm Subarea runoff = 6.727(CFS) for 1.800(Ac.)
Total runoff = 96.558(CFS) Total area = 21.800(Ac.)
Item Number: 1.

Page 867 of 2902 ends

17 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 56.000 to Point/Station 57.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 640.000(Ft.)
Downstream point/station elevation = 638.000(Ft.)
Pipe length = 970.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 96.558(CFS)
Nearest computed pipe diameter = 57.00(In.)
Calculated individual pipe flow = 96.558(CFS)
Normal flow depth in pipe = 43.78(In.)
Flow top width inside pipe = 48.11(In.)
Critical Depth = 34.07(In.)
Pipe flow velocity = 6.62(Ft/s)
Travel time through pipe = 2.44 min.

Time of concentration (TC) = 14.32 min.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 57.000 to Point/Station 57.000 **** SUBAREA FLOW ADDITION ****
______________________________________________________________________ COMMERCIAL subarea type
Runoff Coefficient = 0.862
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 32.00
Pervious area fraction = 0.100; Impervious fraction = 0.900 Time of concentration = 14.32 min.

Rainfall intensity = 3.879(In/Hr) for a 100.0 year storm Subarea runoff = 4.347(CFS) for 1.300(Ac.)
Total runoff = 100.905(CFS) Total area = 23.100(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 57.000 to Point/Station 58.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 638.000(Ft.)
Downstream point/station elevation = 637.500(Ft.)
Pipe length = 50.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 100.905(CFS)
Nearest computed pipe diameter = 42.00(In.)
Calculated individual pipe flow = 100.905(CFS)
Normal flow depth in pipe = 34.50(In.)
Flow top width inside pipe = 32.17(In.)
Critical Depth = 36.95(In.)
Pipe flow velocity = 11.92(Ft/s)
Travel time through pipe = 0.07 min.

Time of concentration (TC) = 14.39 min.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 58.000 to Point/Station 58.000 **** SUBAREA FLOW ADDITION ****
______________________________________________________________________ COMMERCIAL subarea type
Runoff Coefficient = 0.862
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 32.00
Pervious area fraction = 0.100; Impervious fraction = 0.900 Time of concentration = 14.39 min.

Rainfall intensity = 3.868(In/Hr) for a 100.0 year storm Subarea runoff = 2.000(CFS) for 0.600(Ac.)
Item Number: 1.

Page 868 of 2902 ends

18 Total runoff = 102.905(CFS) Total area = 23.700(Ac.) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 58.000 to Point/Station 58.000 **** SUBAREA FLOW ADDITION ****
______________________________________________________________________ COMMERCIAL subarea type
Runoff Coefficient = 0.862
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 32.00
Pervious area fraction = 0.100; Impervious fraction = 0.900 Time of concentration = 14.39 min.

Rainfall intensity = 3.868(In/Hr) for a 100.0 year storm Subarea runoff = 0.667(CFS) for 0.200(Ac.)
Total runoff = 103.572(CFS) Total area = 23.900(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 58.000 to Point/Station 59.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 637.500(Ft.)
Downstream point/station elevation = 637.000(Ft.)
Pipe length = 110.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 103.572(CFS)
Nearest computed pipe diameter = 51.00(In.)
Calculated individual pipe flow = 103.572(CFS)
Normal flow depth in pipe = 38.16(In.)
Flow top width inside pipe = 44.28(In.)
Critical Depth = 36.46(In.)
Pipe flow velocity = 9.09(Ft/s)
Travel time through pipe = 0.20 min.

Time of concentration (TC) = 14.59 min.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 59.000 to Point/Station 59.000 **** SUBAREA FLOW ADDITION ****
______________________________________________________________________ COMMERCIAL subarea type
Runoff Coefficient = 0.862
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 32.00
Pervious area fraction = 0.100; Impervious fraction = 0.900 Time of concentration = 14.59 min.

Rainfall intensity = 3.837(In/Hr) for a 100.0 year storm Subarea runoff = 52.574(CFS) for 15.900(Ac.)
Total runoff = 156.146(CFS) Total area = 39.800(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 59.000 to Point/Station 60.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 637.000(Ft.)
Downstream point/station elevation = 620.000(Ft.)
Pipe length = 220.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 156.146(CFS)
Nearest computed pipe diameter = 33.00(In.)
Calculated individual pipe flow = 156.146(CFS)
Normal flow depth in pipe = 29.44(In.)
Flow top width inside pipe = 20.48(In.)
Critical depth could not be calculated.

Pipe flow velocity = 27.90(Ft/s)
Item Number: 1.

Page 869 of 2902 ends

19 Travel time through pipe = 0.13 min.

Time of concentration (TC) = 14.73 min.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 60.000 to Point/Station 60.000 **** CONFLUENCE OF MINOR STREAMS ****
______________________________________________________________________ Along Main Stream number: 2 in normal stream number 2
Stream flow area = 39.800(Ac.)
Runoff from this stream = 156.146(CFS)
Time of concentration = 14.73 min.

Rainfall intensity = 3.817(In/Hr)
Summary of stream data:

Stream Flow rate TC Rainfall Intensity
No. (CFS) (min) (In/Hr)
1 14.922 22.27 3.003
2 156.146 14.73 3.817
Largest stream flow has longer or shorter time of concentration Qp = 156.146 + sum of
Qa Tb/Ta

14.922 * 0.661 = 9.869
Qp = 166.015
Total of 2 streams to confluence:

Flow rates before confluence point:

14.922 156.146
Area of streams before confluence:

5.900 39.800
Results of confluence:

Total flow rate = 166.015(CFS)
Time of concentration = 14.726 min.

Effective stream area after confluence = 45.700(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 60.000 to Point/Station 61.000 **** IMPROVED CHANNEL TRAVEL TIME ****
______________________________________________________________________ Upstream point elevation = 620.000(Ft.)
Downstream point elevation = 619.000(Ft.)
Channel length thru subarea = 260.000(Ft.)
Channel base width = 50.000(Ft.)
Slope or 'Z' of left channel bank = 4.000
Slope or 'Z' of right channel bank = 4.000
Estimated mean flow rate at midpoint of channel = 168.068(CFS) Manning's 'N' = 0.030
Maximum depth of channel = 5.000(Ft.)
Flow(q) thru subarea = 168.068(CFS)
Depth of flow = 1.038(Ft.), Average velocity = 2.989(Ft/s) Channel flow top width = 58.305(Ft.)
Flow Velocity = 2.99(Ft/s)
Travel time = 1.45 min.

Time of concentration = 16.18 min.

Sub-Channel No. 1 Critical depth = 0.695(Ft.)
' ' ' Critical flow top width = 55.563(Ft.)
' ' ' Critical flow velocity= 4.580(Ft/s)
' ' ' Critical flow area = 36.699(Sq.Ft)
Adding area flow to channel
UNDEVELOPED (fair cover) subarea
Runoff Coefficient = 0.657
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 50.00
Item Number: 1.

Page 870 of 2902 ends

20 Pervious area fraction = 1.000; Impervious fraction = 0.000 Rainfall intensity = 3.615(In/Hr) for a 100.0 year storm Subarea runoff = 4.040(CFS) for 1.700(Ac.)
Total runoff = 170.055(CFS) Total area = 47.400(Ac.)
Depth of flow = 1.045(Ft.), Average velocity = 3.002(Ft/s) Sub-Channel No. 1 Critical depth = 0.695(Ft.)
' ' ' Critical flow top width = 55.563(Ft.)
' ' ' Critical flow velocity= 4.634(Ft/s)
' ' ' Critical flow area = 36.699(Sq.Ft)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 61.000 to Point/Station 62.000 **** IMPROVED CHANNEL TRAVEL TIME ****
______________________________________________________________________ Upstream point elevation = 619.000(Ft.)
Downstream point elevation = 618.000(Ft.)
Channel length thru subarea = 120.000(Ft.)
Channel base width = 50.000(Ft.)
Slope or 'Z' of left channel bank = 4.000
Slope or 'Z' of right channel bank = 4.000
Estimated mean flow rate at midpoint of channel = 176.233(CFS) Manning's 'N' = 0.015
Maximum depth of channel = 5.000(Ft.)
Flow(q) thru subarea = 176.233(CFS)
Depth of flow = 0.563(Ft.), Average velocity = 5.987(Ft/s) Channel flow top width = 54.507(Ft.)
Flow Velocity = 5.99(Ft/s)
Travel time = 0.33 min.

Time of concentration = 16.51 min.

Sub-Channel No. 1 Critical depth = 0.711(Ft.)
' ' ' Critical flow top width = 55.688(Ft.)
' ' ' Critical flow velocity= 4.691(Ft/s)
' ' ' Critical flow area = 37.569(Sq.Ft)
Adding area flow to channel
COMMERCIAL subarea type
Runoff Coefficient = 0.860
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 32.00
Pervious area fraction = 0.100; Impervious fraction = 0.900 Rainfall intensity = 3.572(In/Hr) for a 100.0 year storm Subarea runoff = 12.291(CFS) for 4.000(Ac.)
Total runoff = 182.346(CFS) Total area = 51.400(Ac.)
Depth of flow = 0.575(Ft.), Average velocity = 6.065(Ft/s) Sub-Channel No. 1 Critical depth = 0.734(Ft.)
' ' ' Critical flow top width = 55.875(Ft.)
' ' ' Critical flow velocity= 4.690(Ft/s)
' ' ' Critical flow area = 38.876(Sq.Ft)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 62.000 to Point/Station 63.000 **** IMPROVED CHANNEL TRAVEL TIME ****
______________________________________________________________________ Upstream point elevation = 618.000(Ft.)
Downstream point elevation = 610.000(Ft.)
Channel length thru subarea = 630.000(Ft.)
Channel base width = 100.000(Ft.)
Slope or 'Z' of left channel bank = 4.000
Slope or 'Z' of right channel bank = 4.000
Estimated mean flow rate at midpoint of channel = 189.013(CFS) Manning's 'N' = 0.030
Item Number: 1.

Page 871 of 2902 ends

21 Maximum depth of channel = 5.000(Ft.)
Flow(q) thru subarea = 189.013(CFS)
Depth of flow = 0.520(Ft.), Average velocity = 3.559(Ft/s) Channel flow top width = 104.162(Ft.)
Flow Velocity = 3.56(Ft/s)
Travel time = 2.95 min.

Time of concentration = 19.46 min.

Sub-Channel No. 1 Critical depth = 0.477(Ft.)
' ' ' Critical flow top width = 103.813(Ft.)
' ' ' Critical flow velocity= 3.892(Ft/s)
' ' ' Critical flow area = 48.565(Sq.Ft)
Adding area flow to channel
UNDEVELOPED (fair cover) subarea
Runoff Coefficient = 0.638
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 50.00
Pervious area fraction = 1.000; Impervious fraction = 0.000 Rainfall intensity = 3.247(In/Hr) for a 100.0 year storm Subarea runoff = 13.260(CFS) for 6.400(Ac.)
Total runoff = 195.606(CFS) Total area = 57.800(Ac.)
Depth of flow = 0.531(Ft.), Average velocity = 3.607(Ft/s) Sub-Channel No. 1 Critical depth = 0.488(Ft.)
' ' ' Critical flow top width = 103.906(Ft.)
' ' ' Critical flow velocity= 3.929(Ft/s)
' ' ' Critical flow area = 49.782(Sq.Ft)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 63.000 to Point/Station 63.000 **** SUBAREA FLOW ADDITION ****
______________________________________________________________________ COMMERCIAL subarea type
Runoff Coefficient = 0.858
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 32.00
Pervious area fraction = 0.100; Impervious fraction = 0.900 Time of concentration = 19.46 min.

Rainfall intensity = 3.247(In/Hr) for a 100.0 year storm Subarea runoff = 47.925(CFS) for 17.200(Ac.)
Total runoff = 243.531(CFS) Total area = 75.000(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 63.000 to Point/Station 63.000 **** SUBAREA FLOW ADDITION ****
______________________________________________________________________ COMMERCIAL subarea type
Runoff Coefficient = 0.858
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 32.00
Pervious area fraction = 0.100; Impervious fraction = 0.900 Time of concentration = 19.46 min.

Rainfall intensity = 3.247(In/Hr) for a 100.0 year storm Subarea runoff = 3.622(CFS) for 1.300(Ac.)
Total runoff = 247.153(CFS) Total area = 76.300(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Item Number: 1.

Page 872 of 2902 ends

22 Process from Point/Station 63.000 to Point/Station 70.000 **** IMPROVED CHANNEL TRAVEL TIME ****
______________________________________________________________________ Upstream point elevation = 610.000(Ft.)
Downstream point elevation = 609.500(Ft.)
Channel length thru subarea = 100.000(Ft.)
Channel base width = 50.000(Ft.)
Slope or 'Z' of left channel bank = 4.000
Slope or 'Z' of right channel bank = 4.000
Manning's 'N' = 0.015
Maximum depth of channel = 5.000(Ft.)
Flow(q) thru subarea = 247.153(CFS)
Depth of flow = 0.801(Ft.), Average velocity = 5.798(Ft/s) Channel flow top width = 56.409(Ft.)
Flow Velocity = 5.80(Ft/s)
Travel time = 0.29 min.

Time of concentration = 19.75 min.

Sub-Channel No. 1 Critical depth = 0.891(Ft.)
' ' ' Critical flow top width = 57.125(Ft.)
' ' ' Critical flow velocity= 5.181(Ft/s)
' ' ' Critical flow area = 47.704(Sq.Ft)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 70.000 to Point/Station 70.000 **** CONFLUENCE OF MAIN STREAMS ****
______________________________________________________________________ The following data inside Main Stream is listed:

In Main Stream number: 2
Stream flow area = 76.300(Ac.)
Runoff from this stream = 247.153(CFS)
Time of concentration = 19.75 min.

Rainfall intensity = 3.220(In/Hr)
Summary of stream data:

Stream Flow rate TC Rainfall Intensity
No. (CFS) (min) (In/Hr)
1 48.490 28.77 2.588
2 247.153 19.75 3.220
Largest stream flow has longer or shorter time of concentration Qp = 247.153 + sum of
Qa Tb/Ta

48.490 * 0.686 = 33.278
Qp = 280.431
Total of 2 main streams to confluence:

Flow rates before confluence point:

48.490 247.153
Area of streams before confluence:

16.700 76.300
Results of confluence:

Total flow rate = 280.431(CFS)
Time of concentration = 19.747 min.

Effective stream area after confluence = 93.000(Ac.)
End of computations, total study area = 93.00 (Ac.)
The following figures may
be used for a unit hydrograph study of the same area.

Area averaged pervious area fraction(Ap) = 0.290
Area averaged RI index number = 37.5
Item Number: 1.

Page 873 of 2902 ends

SECTION 5

UNIT HYDROGRAPH

CALCULATIONS
Item Number: 1.

Page 874 of 2902 ends

1 U n i t H y d r o g r a p h A n a l y s i s
Copyright (c) CIVILCADD/CIVILDESIGN, 1989 - 2014, Version 9.0 Study date 02/11/25 File: 39143BC1100.out
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ------------------------------------------------------------------------ Riverside County Synthetic Unit Hydrology Method
RCFC & WCD Manual date - April 1978
Program License Serial Number 6406
--------------------------------------------------------------------- English (in-lb) Input Units Used
English Rainfall Data (Inches) Input Values Used
English Units used in output format
--------------------------------------------------------------------- Hydrology Study for TPM 39143
In the City of Desert Hot Springs
Onsite areas to Basin "C" & Basin "D"
100-year 1-hour Storm
-------------------------------------------------------------------- Drainage Area = 76.30(Ac.) = 0.119 Sq. Mi.

Drainage Area for Depth-Area Areal Adjustment = 76.30(Ac.) = 0.119 Sq. Mi.

Length along longest watercourse = 2975.00(Ft.)
Length along longest watercourse measured to centroid = 1500.00(Ft.) Length along longest watercourse = 0.563 Mi.

Length along longest watercourse measured to centroid = 0.284 Mi.

Difference in elevation = 46.50(Ft.)
Slope along watercourse = 82.5277 Ft./Mi.

Average Manning's 'N' = 0.030
Lag time = 0.153 Hr.

Lag time = 9.20 Min.
25% of lag time = 2.30 Min.
40% of lag time = 3.68 Min.

Unit time = 5.00 Min.

Duration of storm = 1 Hour(s)
User Entered Base Flow = 0.00(CFS)
2 YEAR Area rainfall data:

Area(Ac.)[1] Rainfall(In)[2] Weighting[1*2]

76.30 0.45 34.64
100 YEAR Area rainfall data:

Area(Ac.)[1] Rainfall(In)[2] Weighting[1*2]

76.30 1.69 128.95
STORM EVENT (YEAR) = 100.00
Area Averaged 2-Year Rainfall = 0.454(In)
Area Averaged 100-Year Rainfall = 1.690(In)
Point rain (area averaged) = 1.690(In)
Areal adjustment factor = 99.93 %
Adjusted average point rain = 1.689(In)
Sub-Area Data:

Area(Ac.) Runoff Index Impervious %

76.300 34.40 0.780
Total Area Entered = 76.30(Ac.)
Item Number: 1.

Page 875 of 2902 ends

2 RI RI Infil. Rate Impervious Adj. Infil. Rate Area% F AMC2 AMC-2 (In/Hr) (Dec.%) (In/Hr) (Dec.) (In/Hr)

34.4 34.4 0.720 0.780 0.215 1.000 0.215
Sum (F) = 0.215
Area averaged mean soil loss (F) (In/Hr) = 0.215
Minimum soil loss rate ((In/Hr)) = 0.107
(for 24 hour storm duration)
Soil low loss rate (decimal) = 0.276
--------------------------------------------------------------------- Slope of intensity-duration curve for a 1 hour storm =0.5800 ---------------------------------------------------------------------- U n i t H y d r o g r a p h
DESERT S-Curve
-------------------------------------------------------------------- Unit Hydrograph Data
--------------------------------------------------------------------- Unit time period Time % of lag Distribution Unit Hydrograph (hrs) Graph % (CFS)
--------------------------------------------------------------------- 1 0.083 54.374 4.601 3.538
2 0.167 108.748 30.910 23.769
3 0.250 163.122 28.680 22.054
4 0.333 217.496 12.304 9.462
5 0.417 271.870 7.165 5.509
6 0.500 326.244 4.836 3.719
7 0.583 380.619 3.226 2.480
8 0.667 434.993 2.409 1.852
9 0.750 489.367 1.769 1.360
10 0.833 543.741 1.290 0.992
11 0.917 598.115 0.817 0.628
12 1.000 652.489 0.597 0.459
13 1.083 706.863 0.650 0.500
14 1.167 761.237 0.459 0.353
15 1.250 815.611 0.287 0.221
Sum = 100.000 Sum= 76.896
----------------------------------------------------------------------- The following loss rate calculations reflect use of the minimum calculated loss rate subtracted from the Storm Rain to produce the maximum Effective Rain value Unit Time Pattern Storm Rain Loss rate(In./Hr) Effective (Hr.) Percent (In/Hr) Max | Low (In/Hr)
1 0.08 3.60 0.730 ( 0.215) 0.201 0.528
2 0.17 4.20 0.851 0.215 ( 0.235) 0.636
3 0.25 4.40 0.892 0.215 ( 0.246) 0.677
4 0.33 4.60 0.932 0.215 ( 0.257) 0.718
5 0.42 5.00 1.013 0.215 ( 0.280) 0.799
6 0.50 5.60 1.135 0.215 ( 0.313) 0.920
7 0.58 6.40 1.297 0.215 ( 0.358) 1.082
8 0.67 8.10 1.642 0.215 ( 0.453) 1.427
9 0.75 13.10 2.655 0.215 ( 0.733) 2.440
10 0.83 34.50 6.992 0.215 ( 1.930) 6.777
11 0.92 6.70 1.358 0.215 ( 0.375) 1.143
12 1.00 3.80 0.770 ( 0.215) 0.213 0.558
(Loss Rate Not Used)
Sum = 100.0 Sum = 17.7
Flood volume = Effective rainfall 1.48(In)
times area 76.3(Ac.)/[(In)/(Ft.)] = 9.4(Ac.Ft)
Total soil loss = 0.21(In)
Total soil loss = 1.357(Ac.Ft)
Total rainfall = 1.69(In)
Flood volume = 408651.0 Cubic Feet
Total soil loss = 59103.0 Cubic Feet
-------------------------------------------------------------------- Peak flow rate of this hydrograph = 247.149(CFS)
-------------------------------------------------------------------- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Item Number: 1.

Page 876 of 2902 ends

3 1 - H O U R S T O R M
R u n o f f H y d r o g r a p h
-------------------------------------------------------------------- Hydrograph in 5 Minute intervals ((CFS))
-------------------------------------------------------------------- Time(h+m) Volume Ac.Ft Q(CFS) 0 75.0 150.0 225.0 300.0
----------------------------------------------------------------------- 0+ 5 0.0129 1.87 Q | | | |
0+10 0.1149 14.81 VQ | | | |
0+15 0.3159 29.19 |V Q | | | |
0+20 0.5755 37.69 | V Q | | | |
0+25 0.8769 43.77 | V Q | | | |
0+30 1.2210 49.97 | VQ | | | |
0+35 1.6173 57.54 | VQ | | | |
0+40 2.0835 67.69 | VQ| | | |
0+45 2.6745 85.81 | |Q | | |
0+50 3.6126 136.22 | | V Q | | |
0+55 5.3147 247.15 | | | V | Q |
1+ 0 6.8281 219.74 | | | Q| |
1+ 5 7.7136 128.57 | | Q | | V |
1+10 8.2537 78.42 | Q | | V |
1+15 8.5938 49.39 | Q | | | V |
1+20 8.8236 33.37 | Q | | | V |
1+25 8.9897 24.11 | Q | | | V |
1+30 9.1098 17.44 | Q | | | V |
1+35 9.1962 12.54 |Q | | | V|
1+40 9.2553 8.57 |Q | | | V|
1+45 9.2990 6.35 Q | | | V|
1+50 9.3365 5.44 Q | | | V|
1+55 9.3624 3.76 Q | | | V|
2+ 0 9.3774 2.18 Q | | | V|
2+ 5 9.3805 0.45 Q | | | V|
2+10 9.3813 0.12 Q | | | V
----------------------------------------------------------------------- Item Number: 1.

Page 877 of 2902 ends

1 U n i t H y d r o g r a p h A n a l y s i s
Copyright (c) CIVILCADD/CIVILDESIGN, 1989 - 2014, Version 9.0 Study date 02/11/25 File: 39143BC24100.out
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ------------------------------------------------------------------------ Riverside County Synthetic Unit Hydrology Method
RCFC & WCD Manual date - April 1978
Program License Serial Number 6406
--------------------------------------------------------------------- English (in-lb) Input Units Used
English Rainfall Data (Inches) Input Values Used
English Units used in output format
--------------------------------------------------------------------- Hydrology Study for TPM 39143
In the City of Desert Hot Springs
Onsite areas to Basin "C" & Basin "D"
100-year 1-hour Storm
-------------------------------------------------------------------- Drainage Area = 76.30(Ac.) = 0.119 Sq. Mi.

Drainage Area for Depth-Area Areal Adjustment = 76.30(Ac.) = 0.119 Sq. Mi.

Length along longest watercourse = 2975.00(Ft.)
Length along longest watercourse measured to centroid = 1500.00(Ft.) Length along longest watercourse = 0.563 Mi.

Length along longest watercourse measured to centroid = 0.284 Mi.

Difference in elevation = 46.50(Ft.)
Slope along watercourse = 82.5277 Ft./Mi.

Average Manning's 'N' = 0.030
Lag time = 0.153 Hr.

Lag time = 9.20 Min.
25% of lag time = 2.30 Min.
40% of lag time = 3.68 Min.

Unit time = 15.00 Min.

Duration of storm = 24 Hour(s)
User Entered Base Flow = 0.00(CFS)
2 YEAR Area rainfall data:

Area(Ac.)[1] Rainfall(In)[2] Weighting[1*2]

76.30 1.47 112.16
100 YEAR Area rainfall data:

Area(Ac.)[1] Rainfall(In)[2] Weighting[1*2]

76.30 5.12 390.66
STORM EVENT (YEAR) = 100.00
Area Averaged 2-Year Rainfall = 1.470(In)
Area Averaged 100-Year Rainfall = 5.120(In)
Point rain (area averaged) = 5.120(In)
Areal adjustment factor = 99.99 %
Adjusted average point rain = 5.119(In)
Sub-Area Data:

Area(Ac.) Runoff Index Impervious %

76.300 34.40 0.780
Total Area Entered = 76.30(Ac.)
Item Number: 1.

Page 878 of 2902 ends

2 RI RI Infil. Rate Impervious Adj. Infil. Rate Area% F AMC2 AMC-2 (In/Hr) (Dec.%) (In/Hr) (Dec.) (In/Hr)

34.4 34.4 0.720 0.780 0.215 1.000 0.215
Sum (F) = 0.215
Area averaged mean soil loss (F) (In/Hr) = 0.215
Minimum soil loss rate ((In/Hr)) = 0.107
(for 24 hour storm duration)
Soil low loss rate (decimal) = 0.276
--------------------------------------------------------------------- U n i t H y d r o g r a p h
DESERT S-Curve
-------------------------------------------------------------------- Unit Hydrograph Data
--------------------------------------------------------------------- Unit time period Time % of lag Distribution Unit Hydrograph (hrs) Graph % (CFS)
--------------------------------------------------------------------- 1 0.250 163.122 34.768 26.735
2 0.500 326.244 48.116 37.000
3 0.750 489.367 11.033 8.484
4 1.000 652.489 4.016 3.088
5 1.250 815.611 2.067 1.589
Sum = 100.000 Sum= 76.896
----------------------------------------------------------------------- The following loss rate calculations reflect use of the minimum calculated loss rate subtracted from the Storm Rain to produce the maximum Effective Rain value Unit Time Pattern Storm Rain Loss rate(In./Hr) Effective (Hr.) Percent (In/Hr) Max | Low (In/Hr)
1 0.25 0.20 0.041 ( 0.379) 0.011 0.030
2 0.50 0.30 0.061 ( 0.375) 0.017 0.044
3 0.75 0.30 0.061 ( 0.370) 0.017 0.044
4 1.00 0.40 0.082 ( 0.366) 0.023 0.059
5 1.25 0.30 0.061 ( 0.362) 0.017 0.044
6 1.50 0.30 0.061 ( 0.357) 0.017 0.044
7 1.75 0.30 0.061 ( 0.353) 0.017 0.044
8 2.00 0.40 0.082 ( 0.349) 0.023 0.059
9 2.25 0.40 0.082 ( 0.345) 0.023 0.059
10 2.50 0.40 0.082 ( 0.340) 0.023 0.059
11 2.75 0.50 0.102 ( 0.336) 0.028 0.074
12 3.00 0.50 0.102 ( 0.332) 0.028 0.074
13 3.25 0.50 0.102 ( 0.328) 0.028 0.074
14 3.50 0.50 0.102 ( 0.324) 0.028 0.074
15 3.75 0.50 0.102 ( 0.320) 0.028 0.074
16 4.00 0.60 0.123 ( 0.316) 0.034 0.089
17 4.25 0.60 0.123 ( 0.312) 0.034 0.089
18 4.50 0.70 0.143 ( 0.308) 0.040 0.104
19 4.75 0.70 0.143 ( 0.304) 0.040 0.104
20 5.00 0.80 0.164 ( 0.300) 0.045 0.119
21 5.25 0.60 0.123 ( 0.296) 0.034 0.089
22 5.50 0.70 0.143 ( 0.292) 0.040 0.104
23 5.75 0.80 0.164 ( 0.288) 0.045 0.119
24 6.00 0.80 0.164 ( 0.285) 0.045 0.119
25 6.25 0.90 0.184 ( 0.281) 0.051 0.133
26 6.50 0.90 0.184 ( 0.277) 0.051 0.133
27 6.75 1.00 0.205 ( 0.273) 0.057 0.148
28 7.00 1.00 0.205 ( 0.270) 0.057 0.148
29 7.25 1.00 0.205 ( 0.266) 0.057 0.148
30 7.50 1.10 0.225 ( 0.262) 0.062 0.163
31 7.75 1.20 0.246 ( 0.259) 0.068 0.178
32 8.00 1.30 0.266 ( 0.255) 0.073 0.193
33 8.25 1.50 0.307 ( 0.252) 0.085 0.222
34 8.50 1.50 0.307 ( 0.248) 0.085 0.222
35 8.75 1.60 0.328 ( 0.245) 0.090 0.237
36 9.00 1.70 0.348 ( 0.241) 0.096 0.252
37 9.25 1.90 0.389 ( 0.238) 0.107 0.282
Item Number: 1.

Page 879 of 2902 ends

3 38 9.50 2.00 0.410 ( 0.234) 0.113 0.297
39 9.75 2.10 0.430 ( 0.231) 0.119 0.311
40 10.00 2.20 0.450 ( 0.228) 0.124 0.326
41 10.25 1.50 0.307 ( 0.225) 0.085 0.222
42 10.50 1.50 0.307 ( 0.221) 0.085 0.222
43 10.75 2.00 0.410 ( 0.218) 0.113 0.297
44 11.00 2.00 0.410 ( 0.215) 0.113 0.297
45 11.25 1.90 0.389 ( 0.212) 0.107 0.282
46 11.50 1.90 0.389 ( 0.209) 0.107 0.282
47 11.75 1.70 0.348 ( 0.205) 0.096 0.252
48 12.00 1.80 0.369 ( 0.202) 0.102 0.267
49 12.25 2.50 0.512 ( 0.199) 0.141 0.371
50 12.50 2.60 0.532 ( 0.196) 0.147 0.385
51 12.75 2.80 0.573 ( 0.193) 0.158 0.415
52 13.00 2.90 0.594 ( 0.191) 0.164 0.430
53 13.25 3.40 0.696 0.188 ( 0.192) 0.509
54 13.50 3.40 0.696 0.185 ( 0.192) 0.511
55 13.75 2.30 0.471 ( 0.182) 0.130 0.341
56 14.00 2.30 0.471 ( 0.179) 0.130 0.341
57 14.25 2.70 0.553 ( 0.177) 0.153 0.400
58 14.50 2.60 0.532 ( 0.174) 0.147 0.385
59 14.75 2.60 0.532 ( 0.171) 0.147 0.385
60 15.00 2.50 0.512 ( 0.169) 0.141 0.371
61 15.25 2.40 0.491 ( 0.166) 0.136 0.356
62 15.50 2.30 0.471 ( 0.163) 0.130 0.341
63 15.75 1.90 0.389 ( 0.161) 0.107 0.282
64 16.00 1.90 0.389 ( 0.158) 0.107 0.282
65 16.25 0.40 0.082 ( 0.156) 0.023 0.059
66 16.50 0.40 0.082 ( 0.154) 0.023 0.059
67 16.75 0.30 0.061 ( 0.151) 0.017 0.044
68 17.00 0.30 0.061 ( 0.149) 0.017 0.044
69 17.25 0.50 0.102 ( 0.147) 0.028 0.074
70 17.50 0.50 0.102 ( 0.145) 0.028 0.074
71 17.75 0.50 0.102 ( 0.142) 0.028 0.074
72 18.00 0.40 0.082 ( 0.140) 0.023 0.059
73 18.25 0.40 0.082 ( 0.138) 0.023 0.059
74 18.50 0.40 0.082 ( 0.136) 0.023 0.059
75 18.75 0.30 0.061 ( 0.134) 0.017 0.044
76 19.00 0.20 0.041 ( 0.132) 0.011 0.030
77 19.25 0.30 0.061 ( 0.130) 0.017 0.044
78 19.50 0.40 0.082 ( 0.129) 0.023 0.059
79 19.75 0.30 0.061 ( 0.127) 0.017 0.044
80 20.00 0.20 0.041 ( 0.125) 0.011 0.030
81 20.25 0.30 0.061 ( 0.124) 0.017 0.044
82 20.50 0.30 0.061 ( 0.122) 0.017 0.044
83 20.75 0.30 0.061 ( 0.120) 0.017 0.044
84 21.00 0.20 0.041 ( 0.119) 0.011 0.030
85 21.25 0.30 0.061 ( 0.118) 0.017 0.044
86 21.50 0.20 0.041 ( 0.116) 0.011 0.030
87 21.75 0.30 0.061 ( 0.115) 0.017 0.044
88 22.00 0.20 0.041 ( 0.114) 0.011 0.030
89 22.25 0.30 0.061 ( 0.113) 0.017 0.044
90 22.50 0.20 0.041 ( 0.112) 0.011 0.030
91 22.75 0.20 0.041 ( 0.111) 0.011 0.030
92 23.00 0.20 0.041 ( 0.110) 0.011 0.030
93 23.25 0.20 0.041 ( 0.109) 0.011 0.030
94 23.50 0.20 0.041 ( 0.108) 0.011 0.030
95 23.75 0.20 0.041 ( 0.108) 0.011 0.030
96 24.00 0.20 0.041 ( 0.107) 0.011 0.030
(Loss Rate Not Used)
Sum = 100.0 Sum = 14.8
Flood volume = Effective rainfall 3.71(In)
times area 76.3(Ac.)/[(In)/(Ft.)] = 23.6(Ac.Ft)
Total soil loss = 1.41(In)
Total soil loss = 8.965(Ac.Ft)
Total rainfall = 5.12(In)
Flood volume = 1027357.2 Cubic Feet
Total soil loss = 390512.8 Cubic Feet
-------------------------------------------------------------------- Peak flow rate of this hydrograph = 38.050(CFS)
-------------------------------------------------------------------- Item Number: 1.

Page 880 of 2902 ends

4 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 24 - H O U R S T O R M
R u n o f f H y d r o g r a p h
-------------------------------------------------------------------- Hydrograph in 15 Minute intervals ((CFS))
-------------------------------------------------------------------- Time(h+m) Volume Ac.Ft Q(CFS) 0 10.0 20.0 30.0 40.0
----------------------------------------------------------------------- 0+15 0.0164 0.79 Q | | | |
0+30 0.0636 2.29 V Q | | | |
0+45 0.1274 3.09 V Q | | | |
1+ 0 0.2039 3.70 V Q | | | |
1+15 0.2855 3.95 V Q | | | |
1+30 0.3588 3.55 V Q | | | |
1+45 0.4304 3.47 V Q | | | |
2+ 0 0.5098 3.84 V Q | | | |
2+15 0.6000 4.37 V Q | | | |
2+30 0.6929 4.49 |V Q | | | |
2+45 0.7948 4.94 |V Q | | | |
3+ 0 0.9086 5.51 |V Q | | | |
3+15 1.0250 5.63 |V Q | | | |
3+30 1.1424 5.68 |V Q | | | |
3+45 1.2602 5.70 | V Q | | | |
4+ 0 1.3862 6.10 | V Q | | | |
4+15 1.5236 6.65 | V Q | | | |
4+30 1.6717 7.17 | V Q | | | |
4+45 1.8322 7.77 | V Q | | | |
5+ 0 2.0039 8.31 | V Q | | | |
5+15 2.1715 8.11 | V Q | | | |
5+30 2.3278 7.56 | V Q | | | |
5+45 2.4993 8.30 | V Q | | | |
6+ 0 2.6833 8.91 | V Q | | | |
6+15 2.8781 9.43 | V Q| | | |
6+30 3.0857 10.05 | V Q | | |
6+45 3.3045 10.59 | V Q | | |
7+ 0 3.5357 11.19 | V |Q | | |
7+15 3.7699 11.34 | V |Q | | |
7+30 4.0133 11.78 | V |Q | | |
7+45 4.2766 12.75 | V | Q | | |
8+ 0 4.5622 13.82 | V | Q | | |
8+15 4.8790 15.33 | V | Q | | |
8+30 5.2225 16.63 | V | Q | | |
8+45 5.5808 17.34 | V| Q | | |
9+ 0 5.9610 18.40 | V Q | | |
9+15 6.3726 19.92 | V Q| | |
9+30 6.8185 21.58 | |V |Q | |
9+45 7.2907 22.85 | | V | Q | |
10+ 0 7.7873 24.04 | | V | Q | |
10+15 8.2424 22.03 | | V | Q | |
10+30 8.6223 18.38 | | V Q | | |
10+45 9.0263 19.55 | | V Q| | |
11+ 0 9.4808 22.00 | | V | Q | |
11+15 9.9368 22.07 | | V | Q | |
11+30 10.3861 21.75 | | V |Q | |
11+45 10.8189 20.95 | | V Q | |
12+ 0 11.2363 20.20 | | VQ | |
12+15 11.7167 23.25 | | V| Q | |
12+30 12.2853 27.52 | | V Q | |
12+45 12.8999 29.74 | | |V Q| |
13+ 0 13.5550 31.71 | | | V |Q |
13+15 14.2745 34.82 | | | V | Q |
13+30 15.0607 38.05 | | | V | Q |
13+45 15.7705 34.36 | | | V | Q |
14+ 0 16.3561 28.34 | | | VQ | |
14+15 16.9472 28.61 | | | Q | |
14+30 17.5648 29.89 | | | Q| |
14+45 18.1758 29.57 | | | QV |
15+ 0 18.7798 29.23 | | | Q|V |
15+15 19.3653 28.34 | | | Q | V |
15+30 19.9282 27.24 | | | Q | V |
Item Number: 1.

Page 881 of 2902 ends

5 15+45 20.4434 24.94 | | | Q | V |
16+ 0 20.9092 22.55 | | | Q | V |
16+15 21.2402 16.02 | | Q | | V |
16+30 21.3969 7.59 | Q | | | V |
16+45 21.5045 5.21 | Q | | | V |
17+ 0 21.5866 3.97 | Q | | | V |
17+15 21.6751 4.28 | Q | | | V |
17+30 21.7853 5.34 | Q | | | V |
17+45 21.9003 5.56 | Q | | | V |
18+ 0 22.0090 5.26 | Q | | | V |
18+15 22.1073 4.76 | Q | | | V |
18+30 22.2029 4.63 | Q | | | V |
18+45 22.2895 4.19 | Q | | | V |
19+ 0 22.3560 3.22 | Q | | | V |
19+15 22.4168 2.94 | Q | | | V |
19+30 22.4936 3.72 | Q | | | V |
19+45 22.5747 3.92 | Q | | | V |
20+ 0 22.6393 3.13 | Q | | | V |
20+15 22.6996 2.92 | Q | | | V |
20+30 22.7682 3.32 | Q | | | V |
20+45 22.8380 3.38 | Q | | | V |
21+ 0 22.9000 3.00 | Q | | | V |
21+15 22.9593 2.87 | Q | | | V |
21+30 23.0192 2.90 | Q | | | V|
21+45 23.0777 2.83 | Q | | | V|
22+ 0 23.1371 2.88 | Q | | | V|
22+15 23.1955 2.83 | Q | | | V|
22+30 23.2549 2.88 | Q | | | V|
22+45 23.3051 2.43 | Q | | | V|
23+ 0 23.3532 2.33 | Q | | | V|
23+15 23.4008 2.30 | Q | | | V|
23+30 23.4480 2.28 | Q | | | V|
23+45 23.4951 2.28 | Q | | | V|
24+ 0 23.5422 2.28 | Q | | | V|
24+15 23.5730 1.49 |Q | | | V|
24+30 23.5810 0.39 Q | | | V|
24+45 23.5839 0.14 Q | | | V|
25+ 0 23.5849 0.05 Q | | | V|
----------------------------------------------------------------------- Item Number: 1.

Page 882 of 2902 ends

1 U n i t H y d r o g r a p h A n a l y s i s
Copyright (c) CIVILCADD/CIVILDESIGN, 1989 - 2014, Version 9.0 Study date 02/11/25 File: 39143d1100.out
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ------------------------------------------------------------------------ Riverside County Synthetic Unit Hydrology Method
RCFC & WCD Manual date - April 1978
Program License Serial Number 6406
--------------------------------------------------------------------- English (in-lb) Input Units Used
English Rainfall Data (Inches) Input Values Used
English Units used in output format
--------------------------------------------------------------------- Hydrology Study for TPM 39143
In the City of Desert Hot Springs
Onsite areas to Basin "D"
100-year 1-hour Storm
-------------------------------------------------------------------- Drainage Area = 12.60(Ac.) = 0.020 Sq. Mi.

Drainage Area for Depth-Area Areal Adjustment = 12.60(Ac.) = 0.020 Sq. Mi.

Length along longest watercourse = 1665.00(Ft.)
Length along longest watercourse measured to centroid = 800.00(Ft.) Length along longest watercourse = 0.315 Mi.

Length along longest watercourse measured to centroid = 0.152 Mi.

Difference in elevation = 11.00(Ft.)
Slope along watercourse = 34.8829 Ft./Mi.

Average Manning's 'N' = 0.040
Lag time = 0.154 Hr.

Lag time = 9.23 Min.
25% of lag time = 2.31 Min.
40% of lag time = 3.69 Min.

Unit time = 5.00 Min.

Duration of storm = 1 Hour(s)
User Entered Base Flow = 0.00(CFS)
2 YEAR Area rainfall data:

Area(Ac.)[1] Rainfall(In)[2] Weighting[1*2]

12.60 0.45 5.72
100 YEAR Area rainfall data:

Area(Ac.)[1] Rainfall(In)[2] Weighting[1*2]

12.60 1.69 21.29
STORM EVENT (YEAR) = 100.00
Area Averaged 2-Year Rainfall = 0.454(In)
Area Averaged 100-Year Rainfall = 1.690(In)
Point rain (area averaged) = 1.690(In)
Areal adjustment factor = 99.99 %
Adjusted average point rain = 1.690(In)
Sub-Area Data:

Area(Ac.) Runoff Index Impervious %

12.600 46.70 0.521
Total Area Entered = 12.60(Ac.)
Item Number: 1.

Page 883 of 2902 ends

2 RI RI Infil. Rate Impervious Adj. Infil. Rate Area% F AMC2 AMC-2 (In/Hr) (Dec.%) (In/Hr) (Dec.) (In/Hr)

46.7 46.7 0.604 0.521 0.321 1.000 0.321
Sum (F) = 0.321
Area averaged mean soil loss (F) (In/Hr) = 0.321
Minimum soil loss rate ((In/Hr)) = 0.160
(for 24 hour storm duration)
Soil low loss rate (decimal) = 0.483
--------------------------------------------------------------------- Slope of intensity-duration curve for a 1 hour storm =0.5800 ---------------------------------------------------------------------- U n i t H y d r o g r a p h
DESERT S-Curve
-------------------------------------------------------------------- Unit Hydrograph Data
--------------------------------------------------------------------- Unit time period Time % of lag Distribution Unit Hydrograph (hrs) Graph % (CFS)
--------------------------------------------------------------------- 1 0.083 54.142 4.564 0.580
2 0.167 108.284 30.689 3.897
3 0.250 162.426 28.760 3.652
4 0.333 216.568 12.350 1.568
5 0.417 270.710 7.187 0.913
6 0.500 324.852 4.856 0.617
7 0.583 378.994 3.239 0.411
8 0.667 433.136 2.420 0.307
9 0.750 487.278 1.779 0.226
10 0.833 541.420 1.302 0.165
11 0.917 595.562 0.833 0.106
12 1.000 649.704 0.592 0.075
13 1.083 703.846 0.649 0.082
14 1.167 757.988 0.473 0.060
15 1.250 812.130 0.307 0.039
Sum = 100.000 Sum= 12.698
----------------------------------------------------------------------- The following loss rate calculations reflect use of the minimum calculated loss rate subtracted from the Storm Rain to produce the maximum Effective Rain value Unit Time Pattern Storm Rain Loss rate(In./Hr) Effective (Hr.) Percent (In/Hr) Max | Low (In/Hr)
1 0.08 3.60 0.730 0.321 ( 0.353) 0.409
2 0.17 4.20 0.852 0.321 ( 0.412) 0.531
3 0.25 4.40 0.892 0.321 ( 0.431) 0.571
4 0.33 4.60 0.933 0.321 ( 0.451) 0.612
5 0.42 5.00 1.014 0.321 ( 0.490) 0.693
6 0.50 5.60 1.136 0.321 ( 0.549) 0.815
7 0.58 6.40 1.298 0.321 ( 0.627) 0.977
8 0.67 8.10 1.642 0.321 ( 0.794) 1.322
9 0.75 13.10 2.656 0.321 ( 1.284) 2.335
10 0.83 34.50 6.996 0.321 ( 3.380) 6.675
11 0.92 6.70 1.359 0.321 ( 0.656) 1.038
12 1.00 3.80 0.771 0.321 ( 0.372) 0.450
(Loss Rate Not Used)
Sum = 100.0 Sum = 16.4
Flood volume = Effective rainfall 1.37(In)
times area 12.6(Ac.)/[(In)/(Ft.)] = 1.4(Ac.Ft)
Total soil loss = 0.32(In)
Total soil loss = 0.337(Ac.Ft)
Total rainfall = 1.69(In)
Flood volume = 62608.1 Cubic Feet
Total soil loss = 14680.3 Cubic Feet
-------------------------------------------------------------------- Peak flow rate of this hydrograph = 39.362(CFS)
-------------------------------------------------------------------- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Item Number: 1.

Page 884 of 2902 ends

3 1 - H O U R S T O R M
R u n o f f H y d r o g r a p h
-------------------------------------------------------------------- Hydrograph in 5 Minute intervals ((CFS))
-------------------------------------------------------------------- Time(h+m) Volume Ac.Ft Q(CFS) 0 10.0 20.0 30.0 40.0
----------------------------------------------------------------------- 0+ 5 0.0016 0.24 Q | | | |
0+10 0.0147 1.90 VQ | | | |
0+15 0.0416 3.90 |V Q | | | |
0+20 0.0771 5.16 | V Q | | | |
0+25 0.1190 6.08 | V Q | | | |
0+30 0.1675 7.04 | V Q | | | |
0+35 0.2243 8.25 | V Q | | | |
0+40 0.2925 9.89 | VQ| | | |
0+45 0.3810 12.86 | V Q | | |
0+50 0.5265 21.12 | | V |Q | |
0+55 0.7976 39.36 | | | V | Q|
1+ 0 1.0389 35.04 | | | V | Q |
1+ 5 1.1767 20.01 | | Q | V |
1+10 1.2602 12.13 | | Q | | V |
1+15 1.3133 7.71 | Q | | | V |
1+20 1.3492 5.22 | Q | | | V |
1+25 1.3753 3.78 | Q | | | V |
1+30 1.3942 2.75 | Q | | | V |
1+35 1.4078 1.98 |Q | | | V|
1+40 1.4172 1.35 |Q | | | V|
1+45 1.4240 1.00 Q | | | V|
1+50 1.4300 0.87 Q | | | V|
1+55 1.4342 0.61 Q | | | V|
2+ 0 1.4367 0.36 Q | | | V|
2+ 5 1.4372 0.07 Q | | | V|
2+10 1.4373 0.02 Q | | | V|
----------------------------------------------------------------------- Item Number: 1.

Page 885 of 2902 ends

1 U n i t H y d r o g r a p h A n a l y s i s
Copyright (c) CIVILCADD/CIVILDESIGN, 1989 - 2014, Version 9.0 Study date 02/11/25 File: 39143d24100.out
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ------------------------------------------------------------------------ Riverside County Synthetic Unit Hydrology Method
RCFC & WCD Manual date - April 1978
Program License Serial Number 6406
--------------------------------------------------------------------- English (in-lb) Input Units Used
English Rainfall Data (Inches) Input Values Used
English Units used in output format
--------------------------------------------------------------------- Hydrology Study for TPM 39143
In the City of Desert Hot Springs
Onsite areas to Basin "D"
100-year 24-hour Storm
-------------------------------------------------------------------- Drainage Area = 12.60(Ac.) = 0.020 Sq. Mi.

Drainage Area for Depth-Area Areal Adjustment = 12.60(Ac.) = 0.020 Sq. Mi.

Length along longest watercourse = 1665.00(Ft.)
Length along longest watercourse measured to centroid = 800.00(Ft.) Length along longest watercourse = 0.315 Mi.

Length along longest watercourse measured to centroid = 0.152 Mi.

Difference in elevation = 11.00(Ft.)
Slope along watercourse = 34.8829 Ft./Mi.

Average Manning's 'N' = 0.040
Lag time = 0.154 Hr.

Lag time = 9.23 Min.
25% of lag time = 2.31 Min.
40% of lag time = 3.69 Min.

Unit time = 15.00 Min.

Duration of storm = 24 Hour(s)
User Entered Base Flow = 0.00(CFS)
2 YEAR Area rainfall data:

Area(Ac.)[1] Rainfall(In)[2] Weighting[1*2]

12.60 1.47 18.52
100 YEAR Area rainfall data:

Area(Ac.)[1] Rainfall(In)[2] Weighting[1*2]

12.60 5.12 64.51
STORM EVENT (YEAR) = 100.00
Area Averaged 2-Year Rainfall = 1.470(In)
Area Averaged 100-Year Rainfall = 5.120(In)
Point rain (area averaged) = 5.120(In)
Areal adjustment factor = 100.00 %
Adjusted average point rain = 5.120(In)
Sub-Area Data:

Area(Ac.) Runoff Index Impervious %

12.600 46.70 0.521
Total Area Entered = 12.60(Ac.)
Item Number: 1.

Page 886 of 2902 ends

2 RI RI Infil. Rate Impervious Adj. Infil. Rate Area% F AMC2 AMC-2 (In/Hr) (Dec.%) (In/Hr) (Dec.) (In/Hr)

46.7 46.7 0.604 0.521 0.321 1.000 0.321
Sum (F) = 0.321
Area averaged mean soil loss (F) (In/Hr) = 0.321
Minimum soil loss rate ((In/Hr)) = 0.160
(for 24 hour storm duration)
Soil low loss rate (decimal) = 0.483
--------------------------------------------------------------------- U n i t H y d r o g r a p h
DESERT S-Curve
-------------------------------------------------------------------- Unit Hydrograph Data
--------------------------------------------------------------------- Unit time period Time % of lag Distribution Unit Hydrograph (hrs) Graph % (CFS)
--------------------------------------------------------------------- 1 0.250 162.426 34.610 4.395
2 0.500 324.852 48.163 6.116
3 0.750 487.278 11.079 1.407
4 1.000 649.704 4.048 0.514
5 1.250 812.130 2.101 0.267
Sum = 100.000 Sum= 12.698
----------------------------------------------------------------------- The following loss rate calculations reflect use of the minimum calculated loss rate subtracted from the Storm Rain to produce the maximum Effective Rain value Unit Time Pattern Storm Rain Loss rate(In./Hr) Effective (Hr.) Percent (In/Hr) Max | Low (In/Hr)
1 0.25 0.20 0.041 ( 0.567) 0.020 0.021
2 0.50 0.30 0.061 ( 0.560) 0.030 0.032
3 0.75 0.30 0.061 ( 0.554) 0.030 0.032
4 1.00 0.40 0.082 ( 0.547) 0.040 0.042
5 1.25 0.30 0.061 ( 0.541) 0.030 0.032
6 1.50 0.30 0.061 ( 0.534) 0.030 0.032
7 1.75 0.30 0.061 ( 0.528) 0.030 0.032
8 2.00 0.40 0.082 ( 0.522) 0.040 0.042
9 2.25 0.40 0.082 ( 0.515) 0.040 0.042
10 2.50 0.40 0.082 ( 0.509) 0.040 0.042
11 2.75 0.50 0.102 ( 0.503) 0.049 0.053
12 3.00 0.50 0.102 ( 0.497) 0.049 0.053
13 3.25 0.50 0.102 ( 0.490) 0.049 0.053
14 3.50 0.50 0.102 ( 0.484) 0.049 0.053
15 3.75 0.50 0.102 ( 0.478) 0.049 0.053
16 4.00 0.60 0.123 ( 0.472) 0.059 0.064
17 4.25 0.60 0.123 ( 0.466) 0.059 0.064
18 4.50 0.70 0.143 ( 0.460) 0.069 0.074
19 4.75 0.70 0.143 ( 0.454) 0.069 0.074
20 5.00 0.80 0.164 ( 0.449) 0.079 0.085
21 5.25 0.60 0.123 ( 0.443) 0.059 0.064
22 5.50 0.70 0.143 ( 0.437) 0.069 0.074
23 5.75 0.80 0.164 ( 0.431) 0.079 0.085
24 6.00 0.80 0.164 ( 0.426) 0.079 0.085
25 6.25 0.90 0.184 ( 0.420) 0.089 0.095
26 6.50 0.90 0.184 ( 0.414) 0.089 0.095
27 6.75 1.00 0.205 ( 0.409) 0.099 0.106
28 7.00 1.00 0.205 ( 0.403) 0.099 0.106
29 7.25 1.00 0.205 ( 0.398) 0.099 0.106
30 7.50 1.10 0.225 ( 0.392) 0.109 0.116
31 7.75 1.20 0.246 ( 0.387) 0.119 0.127
32 8.00 1.30 0.266 ( 0.382) 0.129 0.138
33 8.25 1.50 0.307 ( 0.376) 0.148 0.159
34 8.50 1.50 0.307 ( 0.371) 0.148 0.159
35 8.75 1.60 0.328 ( 0.366) 0.158 0.169
36 9.00 1.70 0.348 ( 0.361) 0.168 0.180
37 9.25 1.90 0.389 ( 0.356) 0.188 0.201
Item Number: 1.

Page 887 of 2902 ends

3 38 9.50 2.00 0.410 ( 0.351) 0.198 0.212
39 9.75 2.10 0.430 ( 0.346) 0.208 0.222
40 10.00 2.20 0.451 ( 0.341) 0.218 0.233
41 10.25 1.50 0.307 ( 0.336) 0.148 0.159
42 10.50 1.50 0.307 ( 0.331) 0.148 0.159
43 10.75 2.00 0.410 ( 0.326) 0.198 0.212
44 11.00 2.00 0.410 ( 0.321) 0.198 0.212
45 11.25 1.90 0.389 ( 0.316) 0.188 0.201
46 11.50 1.90 0.389 ( 0.312) 0.188 0.201
47 11.75 1.70 0.348 ( 0.307) 0.168 0.180
48 12.00 1.80 0.369 ( 0.303) 0.178 0.191
49 12.25 2.50 0.512 ( 0.298) 0.247 0.265
50 12.50 2.60 0.532 ( 0.294) 0.257 0.275
51 12.75 2.80 0.573 ( 0.289) 0.277 0.296
52 13.00 2.90 0.594 0.285 ( 0.287) 0.309
53 13.25 3.40 0.696 0.281 ( 0.336) 0.416
54 13.50 3.40 0.696 0.276 ( 0.336) 0.420
55 13.75 2.30 0.471 ( 0.272) 0.228 0.243
56 14.00 2.30 0.471 ( 0.268) 0.228 0.243
57 14.25 2.70 0.553 0.264 ( 0.267) 0.289
58 14.50 2.60 0.532 ( 0.260) 0.257 0.275
59 14.75 2.60 0.532 0.256 ( 0.257) 0.277
60 15.00 2.50 0.512 ( 0.252) 0.247 0.265
61 15.25 2.40 0.492 ( 0.248) 0.237 0.254
62 15.50 2.30 0.471 ( 0.244) 0.228 0.243
63 15.75 1.90 0.389 ( 0.241) 0.188 0.201
64 16.00 1.90 0.389 ( 0.237) 0.188 0.201
65 16.25 0.40 0.082 ( 0.233) 0.040 0.042
66 16.50 0.40 0.082 ( 0.230) 0.040 0.042
67 16.75 0.30 0.061 ( 0.226) 0.030 0.032
68 17.00 0.30 0.061 ( 0.223) 0.030 0.032
69 17.25 0.50 0.102 ( 0.219) 0.049 0.053
70 17.50 0.50 0.102 ( 0.216) 0.049 0.053
71 17.75 0.50 0.102 ( 0.213) 0.049 0.053
72 18.00 0.40 0.082 ( 0.210) 0.040 0.042
73 18.25 0.40 0.082 ( 0.207) 0.040 0.042
74 18.50 0.40 0.082 ( 0.204) 0.040 0.042
75 18.75 0.30 0.061 ( 0.201) 0.030 0.032
76 19.00 0.20 0.041 ( 0.198) 0.020 0.021
77 19.25 0.30 0.061 ( 0.195) 0.030 0.032
78 19.50 0.40 0.082 ( 0.192) 0.040 0.042
79 19.75 0.30 0.061 ( 0.190) 0.030 0.032
80 20.00 0.20 0.041 ( 0.187) 0.020 0.021
81 20.25 0.30 0.061 ( 0.185) 0.030 0.032
82 20.50 0.30 0.061 ( 0.182) 0.030 0.032
83 20.75 0.30 0.061 ( 0.180) 0.030 0.032
84 21.00 0.20 0.041 ( 0.178) 0.020 0.021
85 21.25 0.30 0.061 ( 0.176) 0.030 0.032
86 21.50 0.20 0.041 ( 0.174) 0.020 0.021
87 21.75 0.30 0.061 ( 0.172) 0.030 0.032
88 22.00 0.20 0.041 ( 0.170) 0.020 0.021
89 22.25 0.30 0.061 ( 0.168) 0.030 0.032
90 22.50 0.20 0.041 ( 0.167) 0.020 0.021
91 22.75 0.20 0.041 ( 0.165) 0.020 0.021
92 23.00 0.20 0.041 ( 0.164) 0.020 0.021
93 23.25 0.20 0.041 ( 0.163) 0.020 0.021
94 23.50 0.20 0.041 ( 0.162) 0.020 0.021
95 23.75 0.20 0.041 ( 0.161) 0.020 0.021
96 24.00 0.20 0.041 ( 0.161) 0.020 0.021
(Loss Rate Not Used)
Sum = 100.0 Sum = 10.7
Flood volume = Effective rainfall 2.68(In)
times area 12.6(Ac.)/[(In)/(Ft.)] = 2.8(Ac.Ft)
Total soil loss = 2.44(In)
Total soil loss = 2.565(Ac.Ft)
Total rainfall = 5.12(In)
Flood volume = 122424.7 Cubic Feet
Total soil loss = 111748.1 Cubic Feet
-------------------------------------------------------------------- Peak flow rate of this hydrograph = 5.051(CFS)
-------------------------------------------------------------------- Item Number: 1.

Page 888 of 2902 ends

4 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 24 - H O U R S T O R M
R u n o f f H y d r o g r a p h
-------------------------------------------------------------------- Hydrograph in 15 Minute intervals ((CFS))
-------------------------------------------------------------------- Time(h+m) Volume Ac.Ft Q(CFS) 0 2.5 5.0 7.5 10.0
----------------------------------------------------------------------- 0+15 0.0019 0.09 Q | | | |
0+30 0.0075 0.27 VQ | | | |
0+45 0.0150 0.36 VQ | | | |
1+ 0 0.0240 0.44 VQ | | | |
1+15 0.0336 0.47 VQ | | | |
1+30 0.0423 0.42 VQ | | | |
1+45 0.0507 0.41 VQ | | | |
2+ 0 0.0601 0.45 VQ | | | |
2+15 0.0707 0.51 VQ | | | |
2+30 0.0816 0.53 |VQ | | | |
2+45 0.0937 0.58 |VQ | | | |
3+ 0 0.1071 0.65 |VQ | | | |
3+15 0.1208 0.66 |VQ | | | |
3+30 0.1346 0.67 |VQ | | | |
3+45 0.1485 0.67 | Q | | | |
4+ 0 0.1634 0.72 | Q | | | |
4+15 0.1796 0.78 | VQ | | | |
4+30 0.1970 0.85 | VQ | | | |
4+45 0.2159 0.92 | Q | | | |
5+ 0 0.2362 0.98 | Q | | | |
5+15 0.2559 0.96 | Q | | | |
5+30 0.2744 0.89 | Q | | | |
5+45 0.2946 0.98 | QV | | | |
6+ 0 0.3163 1.05 | Q | | | |
6+15 0.3392 1.11 | Q | | | |
6+30 0.3637 1.18 | QV | | | |
6+45 0.3895 1.25 | QV | | | |
7+ 0 0.4167 1.32 | Q | | | |
7+15 0.4443 1.34 | QV | | | |
7+30 0.4730 1.39 | QV | | | |
7+45 0.5041 1.50 | QV | | | |
8+ 0 0.5377 1.63 | QV | | | |
8+15 0.5751 1.81 | QV | | | |
8+30 0.6155 1.96 | QV | | | |
8+45 0.6578 2.04 | QV| | | |
9+ 0 0.7026 2.17 | QV| | | |
9+15 0.7511 2.35 | QV | | |
9+30 0.8037 2.54 | QV | | |
9+45 0.8593 2.69 | Q V | | |
10+ 0 0.9178 2.83 | |Q V | | |
10+15 0.9715 2.60 | Q V | | |
10+30 1.0163 2.17 | Q | V | | |
10+45 1.0639 2.30 | Q| V | | |
11+ 0 1.1175 2.59 | Q V | | |
11+15 1.1713 2.60 | Q V | | |
11+30 1.2242 2.56 | Q V | | |
11+45 1.2753 2.47 | Q| V | | |
12+ 0 1.3245 2.38 | Q| V | | |
12+15 1.3811 2.74 | Q V| | |
12+30 1.4481 3.24 | | Q V | |
12+45 1.5205 3.51 | | Q V | |
13+ 0 1.5979 3.75 | | Q | V | |
13+15 1.6878 4.35 | | Q | V | |
13+30 1.7921 5.05 | | Q V | |
13+45 1.8844 4.46 | | Q | V | |
14+ 0 1.9556 3.45 | | Q | V | |
14+15 2.0265 3.43 | | Q | V | |
14+30 2.1000 3.56 | | Q | V| |
14+45 2.1722 3.50 | | Q | V |
15+ 0 2.2437 3.46 | | Q | |V |
15+15 2.3128 3.34 | | Q | | V |
15+30 2.3791 3.21 | | Q | | V |
Item Number: 1.

Page 889 of 2902 ends

5 15+45 2.4399 2.94 | |Q | | V |
16+ 0 2.4948 2.66 | Q | | V |
16+15 2.5339 1.89 | Q | | | V |
16+30 2.5525 0.90 | Q | | | V |
16+45 2.5652 0.62 | Q | | | V |
17+ 0 2.5749 0.47 |Q | | | V |
17+15 2.5853 0.50 | Q | | | V |
17+30 2.5983 0.63 | Q | | | V |
17+45 2.6118 0.66 | Q | | | V |
18+ 0 2.6246 0.62 | Q | | | V |
18+15 2.6362 0.56 | Q | | | V |
18+30 2.6475 0.55 | Q | | | V |
18+45 2.6577 0.49 |Q | | | V |
19+ 0 2.6656 0.38 |Q | | | V |
19+15 2.6728 0.35 |Q | | | V |
19+30 2.6818 0.44 |Q | | | V |
19+45 2.6914 0.46 |Q | | | V |
20+ 0 2.6990 0.37 |Q | | | V |
20+15 2.7061 0.34 |Q | | | V |
20+30 2.7142 0.39 |Q | | | V |
20+45 2.7224 0.40 |Q | | | V |
21+ 0 2.7297 0.35 |Q | | | V |
21+15 2.7367 0.34 |Q | | | V |
21+30 2.7438 0.34 |Q | | | V|
21+45 2.7507 0.33 |Q | | | V|
22+ 0 2.7577 0.34 |Q | | | V|
22+15 2.7646 0.33 |Q | | | V|
22+30 2.7716 0.34 |Q | | | V|
22+45 2.7775 0.29 |Q | | | V|
23+ 0 2.7832 0.27 |Q | | | V|
23+15 2.7888 0.27 |Q | | | V|
23+30 2.7943 0.27 |Q | | | V|
23+45 2.7999 0.27 |Q | | | V|
24+ 0 2.8054 0.27 |Q | | | V|
24+15 2.8091 0.18 Q | | | V|
24+30 2.8100 0.05 Q | | | V|
24+45 2.8104 0.02 Q | | | V|
25+ 0 2.8105 0.01 Q | | | V
----------------------------------------------------------------------- Item Number: 1.

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SECTION 6

INFILTRATION BASIN SIZING

CALCULATIONS
Item Number: 1.

Page 891 of 2902 ends

Area 10-year 100-year Area 10-year 100-year Area 10-year 100-year (ac) (cfs) (cfs) (ac) (cfs) (cfs) (ac) (cfs) (cfs)
A 93.0 100.1 212.1 A 93.0 146.5 280.4 0.0 46.4 68.3
Total 93.0 100.1 212.1 Total 93.0 146.5 280.4 0.0 46.4 68.3 Note:

The proposed onsite basins will be proposed to collect and infiltrate the 100-year 24-hour storm volumes TPM 39143 in City of Desert Hot Springs, Riverside County TABLE 3 SUMMARY OF HYDROLOGY ANALYSIS
Drainage
Area Drainage Area
Existing (1) Proposed (2) Difference (3) = (2) - (1)
Item Number: 1.

Page 892 of 2902 ends

(ac) (ac-ft) (ac-ft) (ac-ft)
B & C 76.3 9.3813 23.5849 40.37
D 12.6 1.4373 2.8105 3.16
Infiltration
Basin
1-HR Unit
Hydrograph
24-HR Unit
Hydrograph
Basin
VolumeProvided Area
TABLE 4 SUMMARY OF UNIT HYDROGRAPH ANALYSIS AND INFILTRATION BASINS TPM 39143 in City of Desert Hot Springs, Riverside County Item Number: 1.

Page 893 of 2902 ends

F:\1376\Engineering\SY_Hydrology\ Page 1
Provided Volume for Basin "B"
Designer: G. Guan
Project: TPM 39143
Location: City of Desert Hot Springs, Riverside County
Date: 2/17/2025
Elevation Depthincremental Depthcumulative Area Areaaverage (ft) (ft) (ft) (ft2
) (ft2) (ft3) (ac-ft) (ft3) (ac-ft)
620.00 15700 0 0

5.00 23350 116750 2.680
625.00 5.00 31000 116750 2.68

3.00 36000 108000 2.479
628.00 8.00 41000 224750 5.16
(Spillway to Basin "C")
Note:

Basin "B" and Basin "C" will be used for onsite tributary infiltration.

Volumeincremental Volumecumulative
2/17/2025
Item Number: 1.

Page 894 of 2902 ends

F:\1376\Engineering\SY_Hydrology\ Page 1
Provided Volume for Basin "C"
Designer: G. Guan
Project: TPM 39143
Location: City of Desert Hot Springs, Riverside County
Date: 2/17/2025
Elevation Depthincremental Depthcumulative Area Areaaverage (ft) (ft) (ft) (ft2
) (ft2) (ft3) (ac-ft) (ft3) (ac-ft)
610.00 97700 0 0

5.00 116300 581500 13.349
615.00 5.00 134900 581500 13.35

5.00 154700 773500 17.757
620.00 10.00 174500 1355000 31.11

1.00 178600 178600 4.100
621.00 11.00 182700 1533600 35.21
(Spillway to downstream channel)
Note:

Basin "B" and Basin "C" will be used for onsite tributary infiltration.

Total proivided volume: 40.37 ac-ft
Volumeincremental Volumecumulative
2/17/2025
Item Number: 1.

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F:\1376\Engineering\SY_Hydrology\ Page 1
Provided Volume for Basin "D"
Designer: G. Guan
Project: TPM 39143
Location: City of Desert Hot Springs, Riverside County
Date: 2/17/2025
Elevation Depthincremental Depthcumulative Area Areaaverage (ft) (ft) (ft) (ft2
) (ft2) (ft3) (ac-ft) (ft3) (ac-ft)
645.50 0 0 0

0.50 7900 3950 0.091
646.00 0.50 15800 3950 0.09

4.00 33400 133600 3.067
650.00 4.50 51000 137550 3.16
(Spillway)
Volumeincremental Volumecumulative
2/17/2025
Item Number: 1.

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SECTION 7

OFF-SITE DRAINAGE ANALYSIS

PREPARED BY JE FULLER
Please See
Appendix E of the DHS Varner Road EIR Addendum
Item Number: 1.

Page 897 of 2902 ends

G
Appendix G
Water Supply Assessment
Item Number: 1.

Page 898 of 2902 ends

1 Water Supply Assessment
for the Proposed
Desert Hot Springs Newland Project
Prepared for:

Coachella Valley Water District
P.O. Box 1058
Coachella, CA 92236
Prepared by:

Terra Nova Planning and Research, Inc. ®
42635 Melanie Place, Suit 101
Palm Desert, CA 92211
760-341-4800
March 2025
Item Number: 1.

Page 899 of 2902 ends

2 Table of Contents
List of Figures............................................................................................................................................... 4 List of Tables................................................................................................................................................ 4 1 Summary and Requirements............................................................................................................... 5

1.1 Regulatory Requirements.................................................................................................................. 6

1.1.1 Senate Bill 610 ............................................................................................................................ 6

1.1.2 Senate Bill 1262 .......................................................................................................................... 7

1.2 Water Management Planning Documents........................................................................................ 7

1.2.1 Urban Water Management Planning Act................................................................................... 7

1.2.2 Sustainable Groundwater Management Act ............................................................................. 8

1.2.3 Groundwater Replenishment..................................................................................................... 9 2 Public Water System..........................................................................................................................10

2.1 Coachella Valley Water District.......................................................................................................10

2.1.2 Coachella Valley Water District – Potable Water Distribution Systems................................. 11

2.2 Coachella Valley Hydrology.............................................................................................................12 3 Public Water System – Existing Supply and Demand .......................................................................14

3.1 Groundwater....................................................................................................................................14

3.1.1 Coachella Valley Groundwater Basin.......................................................................................14

3.1.2 Groundwater Demand..............................................................................................................16

3.1.3 Groundwater Sustainability .....................................................................................................16

3.2 Imported Water...............................................................................................................................22

3.2.1 Colorado River Water...............................................................................................................22

3.2.2 State Water Project ..................................................................................................................25

3.2.3 Other SWP Water .....................................................................................................................26

3.3 Surface Water..................................................................................................................................27

3.3.1 River/Stream Diversion ............................................................................................................27

3.3.2 Stormwater Capture.................................................................................................................27

3.4 Wastewater and Recycled Water....................................................................................................28

3.5 Conservation....................................................................................................................................29

3.6 Landscape Ordinance.......................................................................................................................29

3.7 Water Shortage Contingency Planning ...........................................................................................32 4 Public Water System – Projected Supply and Demand ....................................................................33

4.1 Projected Urban Demand and Supply.............................................................................................33 Item Number: 1.

Page 900 of 2902 ends

3 4.2 Normal, Single-Dry, Multiple-Dry Year Comparison.......................................................................34 5 Project Description ............................................................................................................................37 6 Project Water Demands ....................................................................................................................41

6.1 Projected Indoor Residential Water Demand.................................................................................41

6.2 Projected Indoor Commercial and Industrial Water Demand........................................................41

6.3 Projected Outdoor Irrigation Water Demand.................................................................................41

6.4 Projected Outdoor Water Features Demand..................................................................................42

6.5 Projected Total Water Demand.......................................................................................................42

6.6 Projected Water Sources.................................................................................................................42

6.7 Conservation Measures...................................................................................................................43 7 Availability of Sufficient Supplies......................................................................................................44

7.1 Water Supply Assessment...............................................................................................................44

7.2 Requirement for Written Verification of Water Supply Availability..............................................45 8 References .........................................................................................................................................46 Item Number: 1.

Page 901 of 2902 ends

4 List of Figures
Figure 2-1: Coachella Valley Water District Boundary and Coachella Valley Cities....................................11 Figure 2-2: Coachella Valley Water District Domestic Water Service Areas ..............................................12 Figure 3-1: Coachella Valley Groundwater Basin and Subbasins ...............................................................15 Figure 3-2: Water Level Monitoring Wells in the Indio Subbasin...............................................................17 Figure 3-3: Historical Annual Change in Groundwater Storage in the Indio Subbasin...............................18 Figure 3-4: Change in Groundwater Elevation from Water Year 2008-2009 through Water Year 2022- 2023 in the Indio Subbasin.........................................................................................................................19 Figure 3-5: Water Level Monitoring Wells in the Mission Creek Subbasin ................................................20 Figure 3-6: Historical Annual Change in Groundwater Storage in the Mission Creek Subbasin.................21 Figure 3-7: Change in Groundwater Elevation from Water Year 2008-2009 through Water Year 2022- 2023 in the Mission Creek Subbasin ..........................................................................................................22 Figure 5-1: Project Regional Location Map ................................................................................................38 Figure 5-2: Project Vicinity Map.................................................................................................................39 Figure 5-3: Conceptual Project Site Plan ....................................................................................................39 List of Tables
Table 2-1: Current and Projected Population for CVWD’s Service Area ....................................................12 Table 2-2: Monthly Average Climate Data for Palm Springs......................................................................13 Table 2-3: Monthly Average Climate Data for Thermal..............................................................................13 Table 3-1: Groundwater Storage in the Coachella Valley Groundwater Basin...........................................16 Table 3-2: CVWD Groundwater Demand in the Coachella Valley Groundwater Basin ..............................16 Table 3-3: CVWD Colorado River Entitlements (AFY).................................................................................24 Table 3-4: Colorado River Deliveries to CVWD at the Imperial Dam/Coachella Canal...............................25 Table 3-5: CVWD Groundwater Recharge of Colorado River Water..........................................................25 Table 3-6: State Water Project Table A Allocations....................................................................................26 Table 4-1: CVWD Projected Urban Retail Potable Demands......................................................................33 Table 4-2: CVWD Projected Urban Water Supplies....................................................................................34 Table 4-3: Normal Year Supply and Demand Comparison .........................................................................34 Table 5-1: Project Land Use Summary .......................................................................................................40 Table 6-1: Projected Indoor Residential Water Demand .............................. Error! Bookmark not defined.

Table 6-2: Projected Indoor Commercial and Industrial Water Demand...................................................41 Table 6-3: Projected Outdoor Irrigation Water Demand ...........................................................................41 Table 6-4: Projected Outdoor Recreational Water Demand......................... Error! Bookmark not defined.

Table 6-5: Projected Total Water Demand................................................................................................. 42 Table 6-6: Projected Water Sources...........................................................................................................42 Item Number: 1.

Page 902 of 2902 ends

5 1 Summary and Requirements
The environmental review of the Newland Project (Project) is being prepared in compliance with the California Environmental Quality Act (CEQA) process. The City of Desert Hot Springs is the Lead Agency for the planning and environmental review of the proposed Project. The City of Desert Hot Springs has identified the Coachella Valley Water District (CVWD) as the Public Water System (PWS) that will supply water for the proposed Project, and has requested that CVWD assist in preparing a Water Supply Assessment (WSA) as part of the environmental review for the Project.

The Project is located in the northwest portion of the Coachella Valley within the City of Desert Hot Springs, Riverside County. The Newland Project (Project) encompasses approximately 123.4 acres of vacant land in the Coachella Valley to include up to 1,500,000 square feet of distribution warehouse space, as well as 384,199.20 sf of irrigated landscape area, 38.7 acres (1,685,772 ± sf) of open space/habitat conservation, and 21.7 acres (945,252 ± sf) of roadway improvements with an additional 44,388.42 sf irrigated landscape area. This WSA determined that the total projected water demand for the Project is 72.96 AFY, or 0.591 acre-feet per acre. This WSA demonstrates that sufficient water supplies exist, or will exist based on current water planning assumptions, to meet the projected demands of the Project, in addition to current and future projected water demands within CVWD’s service area in normal, single-dry, and multiple-dry years over a 20-year projection. This WSA will be reviewed every five years, or in the event that the water planning assumptions have changed, until the Project begins construction on Planning Area 1 and associated off-site improvements to ensure it remains accurate and no significant changes to either the Project or available water supply has occurred. Consistent with the provisions of SB 610, neither this WSA nor its approval shall be construed to create a right or entitlement to water service or any specific level of water service, and shall not impose, expand, or limit any duty concerning the obligation of CVWD to provide certain service to its existing customers or to any future potential customers.

This WSA does not constitute an agreement to provide water service to the Project, and does not entitle the Project, Project Applicant, or any other person or entity to any right, priority or allocation in any supply, capacity, or facility. To receive water service, the Project will be subject to an agreement with CVWD, together with any and all applicable fees, charges, plans and specifications, conditions, and any and all other applicable CVWD requirements in place and as amended from time to time. Nor does anything in this WSA prevent or otherwise interfere with CVWD’s discretionary authority to declare a water shortage emergency in accordance with the Water Code.

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6 1.1 Regulatory Requirements
This WSA provides an assessment of the availability of sufficient water supplies during normal, single-dry, and multiple-dry years over a 20-year projection to meet the projected demands of the Project, in addition to existing and planned future water demands of CVWD, as required by Senate Bill (SB) 610 and SB 1262. This WSA also includes identification of existing water supply entitlements, water rights, water service contracts, or agreements relevant to the identified water supply for the Project and quantities of water received in prior years pursuant to those entitlements, rights, contracts, and agreements.

This WSA has been prepared in compliance with the requirements under SB 610 and SB 1262 by Terra Nova Planning and Research, Inc. in consultation with CVWD and the City of Desert Hot Springs. This WSA does not relieve the Project from complying with all applicable state, county, city, and local ordinances or regulations, including the CVWD Landscape Ordinance and indoor water use performance standards provided in the California Water Code (CWC). This WSA will be reviewed every five years, or in the event that the water planning assumptions have changed, until the Project begins construction Planning Area 1 and associated off-site improvements, to ensure it remains accurate and no significant changes to either the Project or available water supply has occurred. The Project applicant shall notify CVWD when construction of Planning Area 1 and associated off-site improvements begins.

1.1.1 Senate Bill 610
On January 1, 2002, Senate Bill 610 (SB 610) was enacted and codified in CWC Section 10910 et seq., requiring the preparation of a Water Supply Assessment (WSA) for certain new development projects. As stated in SB 610, the purpose of a WSA is to determine whether the PWS’s “total projected water supplies available during normal, single-dry, and multiple-dry water years during a 20-year projection will meet the projected water demand associated with the proposed project, in addition to the PWS’s existing and planned future uses, including agricultural and manufacturing uses.”
CWC Section 10912 defines a “project” as any of the following:
• A proposed residential development of more than 500 dwelling units; • A proposed shopping center or business establishment employing more than 1,000 persons or having more than 500,000 square feet of floor space; • A proposed commercial office building employing more than 1,000 persons or having more than 250,000 square feet of floor space;
• A proposed hotel or motel, or both, having more than 500 rooms; • A proposed industrial, manufacturing, or processing plant, or industrial park, planned to house more than 1,000 persons, occupying more than 40 acres of land, or having more than 650,000 square feet of floor space;
• A mixed-use project that includes one or more of the projects specified in this subdivision; or
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7 • A project that would demand an amount of water equivalent to, or greater than, the amount of water required by a 500 dwelling unit project (about 250 acre-feet per year).

The intent of SB 610 is to improve the link between information on water supply availability and certain land-use decisions made by cities and counties.

1.1.2 Senate Bill 1262
On January 1, 2017, Senate Bill 1262 (SB 1262) was enacted and amended CWC Section 10910, requiring that information regarding the Sustainable Groundwater Management Act (SGMA) be included in a WSA if the water supply for a proposed project includes groundwater from a basin that is not adjudicated and was designated medium- or high-priority by the California Department of Water Resources (DWR).

1.2 Water Management Planning Documents
CVWD has prepared long-term planning documents to project future was use and manage the water supplies within its service area. These planning documents can be used for compliance with SB 610 and SB 1262 and are discussed in further detail in the following sections.

1.2.1 Urban Water Management Planning Act
The Urban Water Management Planning Act (UWMPA) was established by Assembly Bill 797 (AB 797) on September 21, 1983, and passage of this law recognized that water is a limited resource and that efficient water use and conservation would be actively pursued throughout the State.

The UWMPA requires that municipal water suppliers providing either directly or indirectly to more than 3,000 customers, or supplying more the 3,000 acre-feet per year (AFY), prepare and adopt an Urban Water Management Plan (UWMP) every five years which defines their current and future water use, source of supply, source reliability, and existing conservation measures.

1.2.1.1 Coachella Valley Water District Urban Water Management Plan CVWD prepared and adopted its 2005, 2010, and 2015 UWMPs to document CVWD’s projected water demands and plans for delivering water supplies to its water service area during normal, single-dry, and multiple-dry years over a 20-year projection.

The six urban water suppliers in the Coachella Valley (CVWD, Coachella Water Authority, Desert Water Agency (DWA), Indio Water Authority (IWA), Mission Springs Water District (MSWD), and Myoma Dunes Mutual Water Company) collaboratively prepared the 2020 Coachella Valley Regional UWMP, including regional and individual agency content and other necessary elements as set forth in DWR’s 2020 UWMP Guidebook. The 2020 Coachella Valley Regional UWMP was submitted to DWR on July 1, 2021. DWR accepted CVWD’s portion of the Regional UWMP on May 17, 2022.

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8 1.2.2 Sustainable Groundwater Management Act
In September 2014, Governor Brown signed three bills into law: Assembly Bill 1739, Senate Bill 1319, and Senate Bill 1168, which became collectively known as the Sustainable Groundwater Management Act (SGMA), creating a framework for sustainable, local groundwater management for the first time in California history. DWR evaluated and prioritized the 515 groundwater basins identified in Bulletin 118, and 94 of these groundwater basins were designated as high- or medium-priority basins, as of December 2019, requiring them to be sustainably managed within 20 years. SGMA required local authorities to form local Groundwater Sustainability Agencies (GSAs) by June 30, 2017 to evaluate conditions in their local groundwater basins and adopt locally-based Groundwater Sustainability Plans (GSPs), or Alternatives to a GSP (Alternative Plans), tailored to their regional economic and environmental needs.

As defined by DWR, the subbasins of the Coachella Valley Groundwater Basin are the Indio, Mission Creek, San Gorgonio Pass, and Desert Hot Springs Subbasins. CVWD’s service area overlies the Indio, Mission Creek, and Desert Hot Springs Subbasins. The Indio and Mission Creek Subbasins have been designated medium-priority by DWR and are subject to the requirements of SGMA. The Desert Hot Springs Subbasin has been designated very low-priority by DWR and is not subject to the requirements of SGMA. The Project is located within the Indio Subbasin, which has been designated as a medium priority groundwater basin by DWR under SGMA.

1.2.2.1 Alternative Plan for the Indio Subbasin
Twenty years before the adoption of SGMA, CVWD began the development of the initial water management plan for the Coachella Valley in 1994 after recognizing the need to sustainably manage the Coachella Valley Groundwater Basin. The original planning document is the 2002 Coachella Valley Water Management Plan (CVWMP). The 2002 CVWMP was updated in 2010 and adopted in 2012.

CVWD, DWA, CWA, and IWA, are the Indio Subbasin GSAs designated by DWR for their respective service areas. On December 29, 2016, CVWD, DWA, CWA, and IWA collaboratively submitted the 2010 CVWMP Update as an Alternative Plan for the Indio Subbasin, with an associated Bridge Document and supporting documents, to DWR for review and evaluation. On July 17, 2019, DWR determined that the Alternative Plan for the Indio Subbasin satisfies the objectives of SGMA and notified the Indio Subbasin GSAs that the Alternative Plan was approved, and that they would be required to submit an assessment and update of the Alternative Plan pursuant to the SGMA by January 1, 2022 and every five years thereafter. The 2022 Alternative Plan Update for the Indio Subbasin was submitted to DWR on December 29, 2021. On June 27, 2024 DWR approved the 2022 Alternative Plan Update for the Indio Subbasin finding that it continues to satisfy the objectives of SGMA.

On February 1, 2018, DWR notified all GSAs who submitted Alternative Plans that they would be required to submit annual reports pursuant to SGMA by April 1, 2018 and every year thereafter.

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9 CVWD, DWA, CWA, and IWA have collaboratively prepared and submitted the Indio Subbasin Annual Reports for Water Years 2016-2017 through 2022-2023.

1.2.2.2 Alternative Plan for the Mission Creek Subbasin In 2004, CVWD, DWA, and MSWD reached an agreement and created the Mission Creek Subbasin Management Committee (Management Committee). The Management Committee jointly prepared the 2013 Mission Creek-Garnet Hill Subbasin Water Management Plan (2013 MC-GH WMP).

On December 29, 2016, CVWD, DWA, and MSWD collaboratively submitted the 2013 MC-GH WMP as an Alternative Plan for the Mission Creek Subbasin, with an associated Bridge Document and supporting documents, to DWR for review and evaluation. On July 17, 2019, DWR determined that the Alternative Plan for the Mission Creek Subbasin satisfies the objectives of SGMA and notified the Management Committee that the Alternative Plan was approved, and that they would be required to submit an assessment and update of the Alternative Plan pursuant to SGMA by January 1, 2022 and every five years thereafter. The 2022 Alternative Plan Update for the Mission Creek Subbasin was submitted to DWR on December 30, 2021. On June 27, 2024 DWR approved the 2022 Alternative Plan Update for the Mission Creek Subbasin finding that it continues to satisfy the objectives of SGMA.

On February 1, 2018, DWR notified all GSAs who submitted Alternative Plans that they would be required to submit annual reports pursuant to SGMA by April 1, 2018 and every year thereafter.

CVWD, DWA, and MSWD have collaboratively prepared and submitted the Mission Creek Subbasin Annual Reports for Water Years 2016-2017 through 2022-2023.

1.2.3 Groundwater Replenishment
State Water Code (SWC) 31630-31639 provides CVWD with the authority to levy and collect water replenishment assessments to implement groundwater replenishment programs (GRPs) within its jurisdictional boundary. Groundwater replenishment is necessary to mitigate overdraft of the groundwater basin and associated undesirable results. The jurisdictional areas that benefit from the GRPs, and where CVWD levies replenishment assessments on groundwater production, are termed Areas of Benefit (AOBs). There are three AOBs within CVWD’s boundary: the Mission Creek Subbasin AOB, the West Whitewater River Subbasin AOB, and the East Whitewater River Subbasin AOB. The GRP for the West Whitewater River Subbasin AOB was formed in 1976, the GRP for the Mission Creek Subbasin AOB was formed in 2003, and the GRP for the East Whitewater River Subbasin AOB was formed in 2004. The Project is located within the West Whitewater River Subbasin AOB.

1.2.3.1 Annual Engineer’s Reports
CVWD is required to prepare and present to its Board of Directors annually an Engineer’s Report on Water Supply and Replenishment Assessment reporting on the conditions of the groundwater supplies and recommend Replenishment Assessment Charges (RACs) to be levied upon groundwater production greater than 25 AFY within each AOB in accordance with SWC 31630- Item Number: 1.

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10 31639. The Engineer’s Report must include the following information: a summary of the conditions of groundwater supplies; the need for replenishment; a description of the replenishment programs, including the source and amount of replenishment waters, the costs associated with the GRP, the areas directly and indirectly benefited by the GRP, and the amount of groundwater produced in each area during the prior year; and a recommendation for the RAC to be levied on each AOB. The 2024-2025 Engineer’s Report on Water Supply and Replenishment Assessment was prepared and presented to CVWD’s Board of Directors on April 23, 2024. 2 Public Water System
The City of Desert Hot Springs is the Lead Agency for the planning and environmental review of the proposed Newland Project (Project). The City of Desert Hot Springs has identified the Coachella Valley Water District (CVWD) as the Public Water System (PWS) that will supply water for the proposed Project, and has requested that CVWD assist in preparing a Water Supply Assessment/ (WSA) as part of the environmental review for the Project.

2.1 Coachella Valley Water District
CVWD was established in 1918 under the County Water District Act provisions of the California Water Code. CVWD provides water related services for domestic water, wastewater collection and treatment, recycled water, agricultural irrigation water, drainage management, imported water supply, groundwater replenishment, stormwater management, flood control, and water conservation. CVWD’s boundary encompasses approximately 640,000 acres as shown in Figure 2-1, mostly within Riverside County, but also extending into northern Imperial and San Diego Counties.

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11 Figure 2-1: Coachella Valley Water District Boundary and Coachella Valley Cities

2.1.2 Coachella Valley Water District – Potable Water Distribution Systems CVWD has two domestic water service areas that serve potable water to its local communities:
the Cove Communities system and Improvement District No. 8 (ID-8) as shown in Figure 2-2.

CVWD previously had three water systems, but ID-11 was consolidated into the Cove Communities system in March 2021. CVWD had approximately 114,196 domestic water connections and served 85,014 acre-feet (AF) of water in 2023. CVWD serves all of the Cities of Rancho Mirage, Thousand Palms, Palm Desert, Indian Wells, and La Quinta, and a portion of Indio, Coachella, and Cathedral City. Other areas served with domestic water by CVWD include a portion of lands near Desert Hot Springs and the Indio Hills. CVWD also serves other unincorporated communities including Thermal, Mecca, Oasis, Desert Shores, Salton Sea Beach, Salton City, North Shore, Bombay Beach, Hot Mineral Springs, and other portions of unincorporated Riverside and Imperial Counties. The Project is located within CVWD’s Cove Communities domestic water distribution system.

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12 Figure 2-2: Coachella Valley Water District Domestic Water Service Areas The 2020 Regional UMWP projected that population in CVWD’s urban water service area would increase as shown in Table 2-1.

Table 2-1: Current and Projected Population for CVWD’s Service Area Population
Served
2020 2025 2030 2035 2040 2045
268,952 292,077 315,202 338,274 360,813 383,300
Source: 2020 Coachella Valley Regional Urban Water Management Plan

2.2 Coachella Valley Hydrology
The bulk of natural groundwater replenishment comes from runoff from the adjacent mountains.

Climate in the Coachella Valley is characterized by low humidity, high summer temperatures, and mild dry winters. Average annual precipitation varies from 3 to 6 inches of rain on the Coachella Valley floor to more than 30 inches in the surrounding mountains. Most of the precipitation occurs between December and February, except for summer thundershowers. Prevailing winds in the area are usually gentle, but occasionally increase to velocities as high as 30 miles per hour or more. Mid-summer temperatures commonly exceed 100 degrees Fahrenheit (oF), frequently Item Number: 1.

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13 reach 110 oF, and periodically reach or exceed 120 oF, and the average winter temperature is approximately 60 oF as shown in Table 2-2 and Table 2-3.

Table 2-2: Monthly Average Climate Data for Palm Springs Source: 2020 Coachella Valley Regional Urban Water Management Plan 1 National Weather Service Forecast, Station Palm Springs Airport, 1998-2020 2 CIMIS Station 208 – La Quinta II, 2007-2020
Table 2-3: Monthly Average Climate Data for Thermal
Source: 2020 Coachella Valley Regional Urban Water Management Plan 1 National Weather Service Forecast, Station Desert Resorts Regional Airport, 1990-2020 2 CIMIS Station 218 – Thermal South, 2010-2020
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Max (oF)1 71 73 80 86 94 104 108 107 102 90 78 69 89
Min (oF)1 47 49 54 59 65 73 80 79 74 64 53 46 62
Rain (in)1 0.95 0.92 0.36 0.10 0.02 0.00 0.25 0.14 0.20 0.20 0.26 0.70 3.80 ETo (in)2 2.5 3.4 5.6 7.1 8.3 8.7 8.1 7.5 6.2 4.7 2.9 2.2 67.2 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Max (oF) 1 71 74 81 87 95 103 107 106 101 91 79 69 89
Min (oF) 1 39 43 49 55 63 69 76 75 68 57 45 38 56
Rain (in)1 0.64 0.61 0.34 0.08 0.01 0.01 0.13 0.12 0.32 0.19 0.17 0.34 2.96 ETo (in) 2 2.7 3.9 6.4 8.0 9.3 9.3 9.6 9.1 7.1 5.3 3.2 2.4 70.2 Item Number: 1.

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14 3 Public Water System – Existing Supply and Demand
Currently, all of Coachella Valley Water District’s (CVWD’s) urban potable water uses are supplied using groundwater. In addition to groundwater, CVWD has imported water supplies from the State Water Project (SWP) and the Colorado River, and recycled water from water reclamation plants. These imported and recycled water supplies are used to meet CVWD’s non-potable water demands and to replenish the groundwater basin.

3.1 Groundwater
Groundwater is the principal source of potable supply in the Coachella Valley and CVWD obtains groundwater from both the Indio and Mission Creek Subbasins of the Coachella Valley Groundwater Basin. CVWD has the legal authority to manage the groundwater basin within its boundaries under the County Water District Law (California Water Code section 30000, et seq.) and as a Groundwater Sustainability Agency (GSA) under the Sustainable Groundwater Management Act (SGMA).

Groundwater, to be supplied to the Project, is also used by other domestic water suppliers and private pumpers for crop irrigation, fish farms, duck clubs, golf course irrigation, greenhouses, and industrial uses in the Coachella Valley.

3.1.1 Coachella Valley Groundwater Basin
The Coachella Valley Groundwater Basin is bounded on the north and east by the San Bernardino and Little San Bernardino Mountains, on the south and west by the Santa Rosa and San Jacinto Mountains, and on the south by the Salton Sea. At the west end of the San Gorgonio Pass, between Beaumont and Banning, the basin boundary is defined by a surface drainage divide separating the Coachella Valley Groundwater Basin from the Beaumont Groundwater Basin of the Upper Santa Ana Drainage Area.

The southern boundary is formed primarily by the watershed of the Mecca Hills and by the northwest shoreline of the Salton Sea running between the Santa Rosa Mountains and Mortmar.

Between the Salton Sea and Travertine Rock, at the base of the Santa Rosa Mountains, the southern boundary crosses the Riverside County Line into Imperial and San Diego Counties.

Although there is interflow of groundwater throughout the Coachella Valley Groundwater Basin, fault barriers, constrictions in the basin profile, and areas of low permeability limit and control movement of groundwater. Based on these factors, the Coachella Valley Groundwater Basin has been divided into subbasins and subareas as described by DWR in 1964 and 2003, and by the United States Geological Survey (USGS) in 1974.

3.1.1.1 Coachella Valley Groundwater Basin – Subbasins
As shown on Figure 3-1, the subbasins of the Coachella Valley Groundwater Basin are the Indio, Mission Creek, San Gorgonio Pass, and Desert Hot Springs Subbasins. The subbasins are defined Item Number: 1.

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15 without regard to water quantity or quality. They delineate areas underlain by formations which readily yield stored groundwater through water wells and offer natural reservoirs for the regulation of water supplies.

The boundaries between subbasins within the Coachella Valley Groundwater Basin are generally defined by faults that impede the lateral movement of groundwater. Minor subareas have also been delineated based on one or more of the following geologic or hydrologic characteristics:
types of water-bearing formations, water quality, areas of confined groundwater, forebay areas, groundwater divides, and surface drainage divides.

Figure 3-1: Coachella Valley Groundwater Basin and Subbasins Source: Indio Subbasin Annual Report for Water Year 2022-2023 The following is a list of the subbasins in the Coachella Valley Groundwater Basin as designated by DWR in Bulletin 118:
• Indio Subbasin (Subbasin 7-21.01)
• Mission Creek Subbasin (Subbasin 7-21.02)
• San Gorgonio Pass Subbasin (Subbasin 7-21.03)
• Desert Hot Springs Subbasin (Subbasin 7-21.04)
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16 DWR designated the Indio, Mission Creek, and San Gorgonio Pass Subbasins as medium-priority, and the Desert Hot Springs Subbasin as very low priority. None of the subbasins are adjudicated or in a state of overdraft.

In 1964, DWR estimated that the subbasins in the Coachella Valley Groundwater Basin contained approximately 39,200,000 acre-feet (AF) of water in the first 1,000 feet below the groundwater surface. The capacities of the subbasins are shown in Table 3-1.

Table 3-1: Groundwater Storage in the Coachella Valley Groundwater Basin Subbasin/Subarea Storage (AF) 1
Indio Subbasin
Palm Springs Subarea 4,600,000
Thousand Palms Subarea 1,800,000
Oasis Subarea 3,000,000
Garnet Hill Subarea 1,000,000
Thermal Subarea 19,400,000
Indio Subbasin Subtotal 29,800,000
Mission Creek Subbasin 2,600,000
San Gorgonio Subbasin 2,700,000
Desert Hot Springs Subbasin 4,100,000
Total 39,200,000
Source: DWR Bulletin 108 (1964)
1 First 1,000 feet below ground surface. (DWR, 1964)

3.1.2 Groundwater Demand
Groundwater is the principal source of potable supply in the Coachella Valley and CVWD obtains groundwater from both the Indio and Mission Creek Subbasins of the Coachella Valley Groundwater Basin. CVWD‘s groundwater demand in the Coachella Valley Groundwater Basin for 2018 through 2023 is shown in Table 3-2.

Table 3-2: CVWD Groundwater Demand in the Coachella Valley Groundwater Basin Groundwater Production (AF) 2018 2019 2020 2021 2022 2023 Indio Subbasin 96,176 93,130 96,661 98,484 97,106 90,374 Mission Creek Subbasin 2,786 2,642 3,182 3,062 2,960 2,687 Total 98,962 95,772 99,843 101,546 100,066 93,061

3.1.3 Groundwater Sustainability
Long-term sustainability is typically assessed based on changes in groundwater storage over a period on the order of ten to twenty years that includes wet and dry periods.

3.1.3.1 Indio Subbasin
The 2022 Indio Subbasin Alternative Plan Update identified 57 Key Wells across the subbasin to represent local groundwater levels, shown in Figure 3-2. The plan set metrics to demonstrate sustainability, including a Minimum Threshold (MT) at each Key Well. MTs are numeric values Item Number: 1.

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17 used to define undesirable results under SGMA. In WY 2022-2023, water levels in all 57 Key Wells remained above their respective MTs. This confirms that the significant undesirable results of chronic lowering of groundwater levels, depletion of groundwater storage, and potential subsidence are not occurring in the Indio Subbasin.

Figure 3-2: Water Level Monitoring Wells in the Indio Subbasin Source: Indio Subbasin Annual Report for Water Year 2022-2023 Figure 3-3 shows the historical annual change in groundwater storage from 1970 through Water Year (WY) 2022-2023 in the Indio Subbasin. The figure also shows annual inflows, outflows, groundwater production, and 10-year and 20-year running-average change in groundwater storage. During periods of high artificial recharge, the change in storage tends to be positive. In dry years or periods of high groundwater pumping, the change in storage can be negative.

As shown in Figure 3-3, annual inflows to the Indio Subbasin are highly variable with years of high inflows corresponding to wet years when SWP delivery volumes were greater. Higher inflows in the mid-1980s occurred when the Metropolitan Water District of Southern California (MWD) commenced large-scale advanced water deliveries to the Indio Subbasin. After period of decline, both the 10-year and 20-year running-average change in storage have shown positive trends Item Number: 1.

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18 since 2009. The 10-year and 20-year running-averages have been positive since 2017 and 2023 respectively.

Figure 3-3: Historical Annual Change in Groundwater Storage in the Indio Subbasin Source: Indio Subbasin Annual Report for Water Year 2022-2023 As shown in Figure 3-4, groundwater levels have increased significantly in the Indio Subbasin from WY 2008-2009 to WY 2022-2023. The Indio Subbasin Annual Report uses 2009 water levels as a metric of sustainability because historical low groundwater levels occurred in the years around 2009 throughout most of the Indio Subbasin. The Indio Subbasin shows a long-term positive trend in sustainability resulting from implementation of the Indio Subbasin Alternative Plan.

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19 Figure 3-4: Change in Groundwater Elevation from Water Year 2008-2009 through Water Year 2022-2023 in the Indio Subbasin
Source: Indio Subbasin Annual Report for Water Year 2022-2023

3.1.3.2 Mission Creek Subbasin
The 2022 Mission Creek Subbasin Alternative Plan Update identified nine Key Wells across the subbasin to represent local groundwater levels, as shown in Figure 3-5. The plan set MTs at each Key Well to demonstrate sustainability. In WY 2022-2023, water levels in all nine Key Wells remained above their respective MTs, as shown in the hydrographs in Figure 3-5. This confirms that the significant undesirable results of chronic lowering of groundwater levels, depletion of groundwater storage, and potential subsidence are not occurring in the Mission Creek Subbasin.

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20 Figure 3-5: Water Level Monitoring Wells in the Mission Creek Subbasin Source: Mission Creek Annual Report for Water Year 2022-2023 Figure 3-6 shows the historical annual change in groundwater storage from 1978 through WY 2022-2023 in the Mission Creek Subbasin. The figure also shows annual inflows, outflows, groundwater production, and 10-year and 20-year running-average change in groundwater storage. During periods of high artificial recharge, the change in storage tends to be positive. In dry years or periods of high groundwater pumping, the change in storage can be negative.

As shown in Figure 3-6, after a period of decline, starting in 2004 both the 10-year and 20-year running-average change in groundwater storage have shown positive trends. Annual inflows to the Mission Creek Subbasin are highly variable with years of high inflows corresponding to years when SWP delivery volumes were greater. The 20-year running-average change in storage shows that the Mission Creek Subbasin has been in balance since 2012.

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21 Figure 3-6: Historical Annual Change in Groundwater Storage in the Mission Creek Subbasin Source: Mission Creek Subbasin Annual Report for Water Year 2022-2023 Groundwater levels have increased significantly in the Mission Creek Subbasin over the past 10 years from WY 2008-2009 to WY 2022-2023 as shown in Figure 3-7. The Mission Creek Subbasin Annual Report uses 2009 water levels as a metric of sustainability because historical low groundwater levels occurred in the years around 2009 throughout most of the Mission Creek Subbasin. The Mission Creek Subbasin shows a long-term positive trend in sustainability resulting from implementation of the Mission Creek Subbasin Alternative Plan.

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22 Figure 3-7: Change in Groundwater Elevation from Water Year 2008-2009 through Water Year 2022-2023 in the Mission Creek Subbasin
Source: Mission Creek Subbasin Annual Report for Water Year 2022-2023

3.2 Imported Water
CVWD has two sources of imported water available: Colorado River water delivered via the Coachella Canal and SWP water exchanged for Colorado River water delivered through the Colorado River Aqueduct. These imported water sources are used to recharge the groundwater basin and as an alternative source to meet non-potable demands from irrigation of agriculture, golf, and urban uses that would have otherwise been met by pumping groundwater. In the future, if urban demand significantly increases relative to non-potable uses, Colorado River water may be treated and delivered directly to customers through CVWD’s potable water distribution system.

3.2.1 Colorado River Water
Colorado River water has been a significant water supply source for the Indio Subbasin since the Coachella Canal was completed in 1949. CVWD is the only agency in the Indio Subbasin that receives Colorado River water allocations. The Colorado River is managed and operated in accordance with the Law of the River, a collection of interstate compacts, federal and state legislation, various agreements and contracts, an international treaty, a U.S. Supreme Court decree, and federal administrative actions that govern the rights to use Colorado River water within the seven Colorado River Basin states. The 1922 Colorado River Compact apportioned the Item Number: 1.

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23 waters of the Colorado River Basin between the Upper Colorado River Basin (i.e., Colorado, Wyoming, Utah, and New Mexico) and the Lower Basin (i.e., Nevada, Arizona, and California).

The 1922 Colorado River Compact allocates 15 million AFY of Colorado River water as follows:

7.5 million AFY to the Upper Basin and 7.5 million AFY to the Lower Basin, plus up to 1 million AFY of surplus supplies. The Lower Basin’s water was further apportioned among the three Lower Basin states by the 1928 Boulder Canyon Project Act and the 1931 Boulder Canyon Project Agreement, typically called the 1931 Seven Party Agreement, which allocates California’s apportionment of Colorado River water among Palo Verde Irrigation District, Imperial Irrigation District (IID), CVWD, Metropolitan Water District of Southern California (MWD), City of Los Angeles, City of San Diego, and County of San Diego. The 1964 U.S. Supreme Court decree in Arizona v. California established Arizona’s basic annual apportionment at 2.8 million AFY, California’s at 4.4 million AFY, and Nevada’s at 0.3 million AFY. Mexico is entitled to 1.5 million AFY of the Colorado River under the 1944 United States-Mexico Treaty for Utilization of Waters of the Colorado and Tijuana Rivers and of the Rio Grande. However, this treaty did not specify a required quality for water entering Mexico. In 1973, the United States and Mexico signed Minute No. 242 of the International Boundary and Water Commission requiring certain water quality standards for water entering Mexico. California’s Colorado River supply is protected by the 1968 Colorado River Basin Project Act, which provides that in years of insufficient supply on the main stem of the Colorado River, supplies to the Central Arizona Project shall be reduced to zero before California will be reduced below 4.4 million AF in any year. This assures full supplies to the Coachella Valley, except in periods of extreme drought.

The Coachella Canal is a branch of the All-American Canal that brings Colorado River water into the Imperial and Coachella Valleys. Under the 1931 Seven Party Agreement, CVWD receives 330,000 AFY of Priority 3A Colorado River water diverted from the All-American Canal at the Imperial Dam. The Coachella Canal originates at Drop 1 on the All-American Canal and extends approximately 123 miles, terminating in CVWD’s Lake Cahuilla. The service area for Colorado River water delivery under CVWD’s contract with the U.S. Bureau of Reclamation (USBR) is defined as Improvement District No. 1 (ID-1), which encompasses 136,400 acres covering most of the East Valley and a portion of the West Valley north of Interstate 10. Under the 1931 Seven Party Agreement, CVWD has water rights to Colorado River water as part of the first 3.85 million AFY allocated to California. CVWD is in the third priority position along with IID.

In 2003, CVWD, IID, and MWD successfully negotiated the 2003 Quantification Settlement Agreement (2003 QSA), which quantifies Colorado River allocations through 2077 and supports the transfer of water between agencies. Under the 2003 QSA, CVWD has a base entitlement of 330,000 AFY. CVWD negotiated water transfer agreements with MWD and IID that increased CVWD supplies by an additional 123,000 AFY. CVWD’s net QSA supply will increase to 424,000 AFY by 2026 and remain at that level until 2047, decreasing to 421,000 AFY until 2077, when the agreement terminates. As of 2021, CVWD’s available Colorado River water diversions at Imperial Dam under the QSA were 399,000 AFY. This includes the base entitlement of 330,000 AFY, the MWD/IID Transfer of 20,000 AFY, IID/CVWD First Transfer of 50,000 AFY, and IID/CVWD Second Transfer of 28,000 AFY. CVWD’s QSA diversions also deducts the -26,000 AFY transferred to San Diego County Water Authority (SDCWA) as part of the Coachella Canal Lining Project and the - Item Number: 1.

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24 3,000 AFY transfer to Indian Present Perfected Rights. Additionally, under the 2003 QSA, MWD transferred 35,000 AFY of its State Water Project (SWP) Table A Amount to CVWD. This SWP water is exchanged for Colorado River water and can be delivered at Imperial Dam for delivery via the Coachella Canal to the eastern portion of the Indio Subbasin or at Lake Havasu for delivery via the Colorado River Aqueduct to the western portion of the Indio Subbasin at the Whitewater River Groundwater Replenishment Facility (WWR-GRF). The 2019 Second Amendment guaranteed delivery of the 35,000 AFY from 2019 to 2026, for a total of 280,000 AFY of water to the WWR-GRF during that timeframe. MWD can deliver the water through CVWD’s Whitewater Service Connections (for recharge at WWR-GRF) or via the Advance Delivery account.

The MWD/IID Transfer originated in a 1989 agreement with MWD to receive 20,000 AF of its Colorado River supply. The 2019 Amended and Restated Agreement for Exchange and Advance Delivery of Water defined the exchange and delivery terms between MWD, CVWD, and DWA.

The 2019 Second Amendment to Delivery and Exchange Agreement reduced CVWD’s annual delivery of the MWD/IID Transfer to 15,000 AFY, for a total of 105,000 AF, if taken at the Whitewater Service Connections (for recharge at WWR-GRF) between 2020 and 2026. For those seven years, MWD keeps the remaining 5,000 AFY, after which CVWD’s allocation increases back up to 20,000 AFY. CVWD’s total allocations under the QSA, including MWD’s transfer of 35,000 AFY and the MWD/IID Transfer, will increase from 424,000 AFY in 2020 to 459,000 AFY by 2026 and remain at that level for the remainder of the 75-year term of the QSA. Table 3-3 lists total Colorado River entitlements under existing agreements.

Table 3-3: CVWD Colorado River Entitlements (AFY)
Source: 2022 Alternative Plan Update for the Indio Subbasin 1 The Second IID/CVWD Transfer began in 2018 with 13,000 AF of water. This amount increases annually by 5,000 AFY for a total of 53,000 AFY in 2026.
2 The 35,000 AFY MWD/CVWD SWP Transfer may be delivered at either Imperial Dam or Whitewater River and is not subject to SWP or Colorado River reliability.
3 Accounts for -5,000 AFY reduction in MWD/IID Approval Agreement deliveries from 2020-2026 per the 2019 Amendments with MWD.

The Colorado River deliveries to CVWD at the Imperial Dam/Coachella Canal from 2018 through 2023 are shown in Table 3-4.

Diversion 2020 2025 2030 2035 2040 2045
Base Entitlement 330,000 330,000 330,000 330,000 330,000 330,000 1988 MWD/IID Approval Agreement 20,000 20,000 20,000 20,000 20,000 20,000 IID/CVWD First Transfer 50,000 50,000 50,000 50,000 50,000 50,000 IID/CVWD Second Transfer1 23,000 48,000 53,000 53,000 53,000 53,000 Coachella Canal Lining -26,000 -26,000 -26,000 -26,000 -26,000 -26,000 Indian Present Perfected Rights Transfer -3,000 -3,000 -3,000 -3,000 -3,000 -3,000 QSA Diversions 394,000 419,000 424,000 424,000 424,000 424,000 MWD SWP Transfer2 35,000 35,000 35,000 35,000 35,000 35,000 Total Diversions 429,000 454,000 459,000 459,000 459,000 459,000 Assumed Conveyance Losses (5%) -21,200 -22,700 -22,950 -22,950 -22,950 -22,950 MWD/IID Approval Agreement Transfer3 -5,000 -5,000 0 0 0 0 Total Available Deliveries 402,800 426,300 436,050 436,050 436,050 436,050 Item Number: 1.

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25 Table 3-4: Colorado River Deliveries to CVWD at the Imperial Dam/Coachella Canal Diversions (AF) 2018 2019 20201 20211 20221 20231
Imperial Dam/Coachella Canal 338,035 343,971 350,618 351,904 330,387 286,506 Source: U.S. Bureau of Reclamation, Lower Colorado Region, Colorado River Accounting and Water Use Reports for Arizona, California, and Nevada.
1 15,000 AFY of 1988 MWD/IID Approval Agreement water was delivered at WWR-GRF from 2020 to 2023.

CVWD’s recharge volumes of Colorado River water from 2018 through 2023 are shown in Table 3-5.

Table 3-5: CVWD Groundwater Recharge of Colorado River Water Groundwater Recharge (AF) 2018 2019 2020 2021 2022 2023 Thomas E. Levy GRF 33,348 36,143 37,536 37,971 27,993 2,076 Palm Desert GRF 0 7,757 9,700 10,633 10,949 11,179
Total 33,348 43,900 47,236 48,604 38,942 13,255
Source: 2024-2025 CVWD Annual Engineer’s Reports on Water Supply and Replenishment Assessment

3.2.2 State Water Project
The SWP is managed by DWR and includes 705 miles of aqueduct and conveyance facilities extending from Lake Oroville in Northern California to Lake Perris in Southern California. The SWP has contracts to deliver 4.172 million AFY to the State Water Contractors. The State Water Contractors consist of 29 public entities with long-term contracts with DWR for all, or a portion of, their water supply needs. In 1962 and 1963, DWA and CVWD, respectively, entered contracts with the State of California for a total of 61,200 AFY of SWP water. SWP water has been an important component of the region’s water supply mix since CVWD and DWA began receiving and recharging SWP exchange water at the WWR-GRF. Starting in 1973, CVWD and DWA began exchanging their SWP water with MWD for Colorado River water delivered via MWD’s Colorado River Aqueduct. Because CVWD and DWA do not have a physical connection to SWP conveyance facilities, MWD takes delivery of CVWD’s and DWA’s SWP water, and in exchange, delivers an equal amount of Colorado River water to the Whitewater Service Connections (for recharge at WWR-GRF and Mission Creek Groundwater Replenishment Facility). The exchange agreement was most recently re-established in the 2019 Amended and Restated Agreement for Exchange and Advance Delivery of Water.

Each SWP contract contains a “Table A” exhibit that defines the maximum annual amount of water each contractor can receive excluding certain interruptible deliveries. DWR uses Table A amounts to allocate available SWP supplies and some SWP project costs among the contractors.

Each year, DWR determines the amount of water available for delivery to SWP contractors based on hydrology, reservoir storage, the requirements of water rights licenses and permits, water quality, and environmental requirements for protected species in the Sacramento-San Joaquin River Delta (Delta). The available supply is then allocated according to each SWP contractor’s Table A amount.

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26 CVWD’s and DWA’s collective increments of Table A water are listed in Table 3-6. Original Table A SWP water allocations for CVWD and DWA were 23,100 AFY and 38,100 AFY, respectively, for a combined amount of 61,200 AFY. CVWD and DWA obtained a combined 100,000 AFY transfer from MWD under the 2003 Exchange Agreement. In 2004, CVWD purchased an additional 9,900 AFY of SWP Table A water from the Tulare Lake Basin Water Storage District (Tulare Lake Basin) in Kings County. In 2007, CVWD and DWA made a second purchase of Table A SWP water from Tulare Lake Basin totaling 7,000 AFY. In 2007, CVWD and DWA also completed the transfer of 16,000 AFY of Table A Amounts from the Berrenda Mesa Water District in Kern County. These latter two transfers became effective in January 2010. With these additional transfers, the total SWP Table A Amount for CVWD and DWA is 194,100 AFY. Table 3-7 shows the percent allocation of SWP Table A allocations from 2018 through 2022. Table 3-8 shows the recharge of SWP Exchange Water from 2018 through 2023.

Table 3-6: State Water Project Table A Allocations
Original SWP
Table A
(AFY)
Tulare Lake
Basin 2004
Transfer
(AFY)
Metropolitan
Water District
2003 Transfer
(AFY)
Tulare Lake
Basin 2007
Transfer
(AFY)
Berrenda
Mesa 2007
Transfer
(AFY)
Total
(AFY)
CVWD 23,100 9,900 88,100 5,250 12,000 138,350
DWA 38,100 0 11,900 1,750 4,000 55,750
Total 61,200 9,900 100,000 7,000 16,000 194,100
Source: 2020 Coachella Valley Regional Urban Water Management Plan Table 3-7: State Water Project Table A Percent Allocations 2018 2019 2020 2021 2022 2023
Table A Allocation 35% 75% 20% 5% 5% 100%
Source: CA Department of Water Resources Historical Table A Allocations for Years 1996-2024 Table 3-8: CVWD and DWA Groundwater Recharge
Groundwater Recharge (AF) 2018 2019 2020 2021 2022 2023 Whitewater River GRF 129,725 235,600 126,4871 15,0061 15,0111 219,7451 Mission Creek GRF 2,027 3,688 1,768 0 0 5,275
Total 131,752 239,288 128,255 15,006 15,011 225,020
Source: CVWD 2024-2025 Annual Engineer’s Reports on Water Supply and Replenishment Assessment 1 Between 2020 and 2023, 15,000 AFY of 1988 MWD/IID Approval Agreement water was delivered at Whitewater River GRF.

3.2.3 Other SWP Water
There are other types of SWP water that can be purchased, such as individual water purchase opportunities and transfers/exchanges. These may be conveyed to CVWD and DWA as available, but no commitments exist.

In 2008, CVWD and DWA entered into separate agreements with DWR for the purchase and conveyance of supplemental SWP water under the Yuba River Accord Dry Year Water Purchase Item Number: 1.

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27 Program (Yuba Accord). This program provides dry year supplies through a water purchase agreement between DWR and Yuba County Water Agency, which settled long-standing operational and environmental issues over instream flow requirements for the lower Yuba River.

The amount of water available for purchase varies annually and is allocated among participating SWP contractors based on their Table A amounts. CVWD and DWA may purchase up to 1.72 percent and 0.69 percent, respectively, of available Yuba Accord water, in years it is made available. Yuba Accord deliveries have varied from zero in multiple years to a total of 2,664 AFY to CVWD and DWA in 2013.

Article 21 water (described in Article 21 of the SWP water contracts), “Interruptible Water,” is water that State Water Contractors may receive on a short-term basis in addition to their Table A water if they request it in years when it is available. Article 21 water is used by many contractors to help meet demands in low allocation years. Article 21 water is not available every year, amounts vary when it is available, and is proportionately allocated among participating Contractors. The availability and delivery of Article 21 water cannot interfere with normal SWP operations and cannot be carried over for delivery in a subsequent year.

3.3 Surface Water
CVWD does not currently use or intend to use any local surface water as part of its urban potable water supply. Local runoff is captured and used for groundwater recharge.

3.3.1 River/Stream Diversion
Surface water supplies come from several local rivers and streams including the Whitewater River, Snow Creek, Falls Creek, and Chino Creek, as well as a number of smaller creeks and washes. Because surface water supplies are affected by variations in annual precipitation, the annual supply is highly variable. The 50-year hydrologic period from 1970 to 2019 had an annual average watershed runoff of 52,506 AFY, with approximately 43,300 AFY in natural infiltration.

Runoff during the 25-year period from 1995 to 2019 was below average, with 39,196 AFY in watershed runoff and 29,200 AFY in natural infiltration. CVWD does not currently use or intend to use any local surface water as part of its urban potable water supply. Local runoff is captured or infiltrates naturally for groundwater recharge.

3.3.2 Stormwater Capture
The Coachella Valley drainage area is approximately 65 percent mountainous and 35 percent typical desert valley with alluvial fan topography buffering the valley floor from the steep mountain slopes. The mean annual precipitation ranges from 30 inches or more in the San Bernardino Mountains to less than 3 inches at the Salton Sea. Three types of storms produce precipitation in the drainage area: general winter storms, general thunderstorms, and local thunderstorms. Longer duration, lower intensity rainfall events tend to have higher recharge rates, but runoff from flash flooding can result from all three types of storms. Otherwise, there is little to no flow in most of the streams in the drainage area.

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28 Significant amounts of local runoff are currently captured at the Whitewater River GRF and in the debris basins and unlined channels of the western Coachella Valley. Additional stormwater will be captured when the Thousand Palms Flood Control Project is completed and when flood control is constructed in the Oasis area. However, limited data exists to estimate the amount of additional stormwater that could be captured by new facilities in the Coachella Valley.

Nonetheless, large-scale stormwater capture is not expected to yield sufficient water to be worth the investment as a single purpose project. Small-scale stormwater retention systems located in areas of suitable geology to allow percolation could capture small intensity storms as well as street runoff. The potential yield of these systems is not known at this time, but stormwater capture should be considered in conjunction with projects that construct stormwater and flood control facilities.

3.4 Wastewater and Recycled Water
Wastewater that has been highly treated and disinfected can be reused for landscape irrigation and other purposes. Recycled wastewater has historically been used for irrigation of golf courses and municipal landscaping in the Coachella Valley since as early as the 1960s. As growth occurs in the eastern Coachella Valley, the supply of recycled water is expected to increase, creating an additional opportunity to maximize local water supply.

CVWD operates five water reclamation plants (WRPs), two of them (WRP-7 and WRP-10) generate recycled water for irrigation of golf courses and large landscaped areas. WRP-4 became operational in 1986 and serves the communities from La Quinta to Mecca. WRP-4 effluent is not currently recycled, however, it will be in the future when the demand for recycled water is developed and tertiary treatment is constructed. The other two WRPs serve communities near the Salton Sea. A sixth WRP (WRP-9) was decommissioned in July 2015. The wastewater treated by CVWD from 2018 through 2023 is shown in Table 3-9. Table 3-10 shows the recycled water produced by CVWD from 2018 through 2023. CVWD will continue to expand its recycled water program by connecting additional recycled water customers to meet the non-potable water demands in the western and eastern portions of the Coachella Valley.

Table 3-9: Wastewater Treated by CVWD
Wastewater (AF) 2018 2019 2020 2021 2022 2023
WRP-1 19 16 18 24 22 21
WRP-2 12 16 13 15 16 17
WRP-4 5,900 6,065 6,353 6,452 6,440 6,117
WRP-7 3,275 3,246 3,236 3,287 3,375 3,420
WRP-10 10,124 9,663 9,238 8,980 9,235 9,309
Total 19,330 19,006 18,858 18,758 19,088 18,884
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29 Table 3-10: Recycled Water Produced by CVWD

3.5 Conservation
Water conservation, and the reduced groundwater production associated with water conservation, benefits the groundwater basin and is an important element of the Alternative Plans and the 2020 Regional UWMP.

CVWD has utilized several programs to ensure water conservation within its service area. CVWD has implemented allocation-based conservation water pricing (i.e. tiered rates) to prevent water waste or unreasonable use of water. In addition, CVWD’s indoor rebate programs are designed to assist homeowners and commercial customers reduce water usage by upgrading toilets, replacing inefficient devices, and installing new technology to improve efficiency. CVWD also has outdoor rebate programs that are designed to assist homeowners, homeowners associations, and commercial customers reduce outdoor water usage by converting turf to desert landscaping, installing smart irrigation controllers, and improving the efficiency of irrigation systems. CVWD offers seminars, workshops, and classes to help educate the public regarding the need for water conservation and the conservation programs that are available.

3.6 Landscape Ordinance
CVWD Landscape Ordinance 1302.5 requires a series of reduction methods in conjunction with the Model Water Efficient Landscape Ordinance (MWELO) set forth by the Department of Water Resources. Reduction methods include requirements that new developments install weatherbased irrigation controllers that automatically adjust watering. Additional requirements include setbacks of spray emitters from impervious surfaces, as well as use of porous rock and gravel buffers between grass and curbs to eliminate run-off onto streets. With the exception of turf, all landscaping including groundcover and shrubbery must be irrigated with a drip system. Also, the maximum water allowance for landscaped areas through the CVWD service area has been reduced. This reduction goal requires that developers maximize the use of native and other drought-tolerant landscape materials and minimize use of more water-intensive landscape features, including turf and fountains. Projects that will be served by CVWD’s Domestic Water System are subject to the current CVWD Landscape Ordinance or any future updates in effect at the time that landscape plans are approved.

Recycled Water
(AF) 2018 2019 2020 2021 2022 2023
WRP-7 2,246 1,657 1,936 2,136 2,170 2,167
WRP-10 7,857 7,100 7,521 7,285 7,371 7,111
Total 10,103 8,757 9,457 9,421 9,541 9,278
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30 3.7 Other Demand Management Regulations
California recognizes the need for regulations that encourage efficient water management practices and has developed policies that emphasize water use efficiency and conservation.

CVWD will continue to foster efficient water use by engaging customers and supporting programs that focus on water conservation to meet the requirements of these regulations.

3.7.1 Making Conservation A California Way of Life
Making Conservation a California Way of Life aims to increase water efficiency across the State.

Two bills (Senate Bill 606 and Assembly Bill 1668) were passed in 2018 directing the Department of Water Resources and the State Water Resources Control Board (State Water Board) to develop regulations for the next generation of California water savings requirements.

On July 3, 2024, the State Water Board adopted the Making Conservation a California Way of Life regulation. The adopted regulation holds urban retail water suppliers responsible for meeting individualized water use objectives calculated for each service area. The water use objective (or water budget) is calculated from the five components shown below in Figure 3-7.

Individual residents will not be regulated — only urban water suppliers will be responsible for meeting the water use objective for the service area.

Figure 3-7: Components of Water Use Objective Calculation Indoor Residential Objective
The indoor residential standard applies to both existing and new construction of single family and multi-family housing units within an urban water supplier’s service area. The indoor residential standard is based on a gallons per capita per day (gpcd) metric that will decrease over time. The state will not enforce indoor budgets for individual residential parcels. Suppliers multiply population served by the indoor residential standard by 365 days to calculate the annual indoor water use budget for the service area.

The indoor residential standard will decrease from 55 gpcd to 42 gpcd by 2030 to as shown in Table 3-11.

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31 Table 3-11: Indoor Residential Water Use Standard
Year Standard
2020-2024 55 gpcd
2025-2029 47 gpcd
2030 onward 42 gpcd
Outdoor Residential Objective
In addition to the indoor residential water use objective, outdoor residential water use objectives were also adopted through the regulation. The outdoor residential objective applies to both existing and new construction of single family and multiple family housing units within an urban water supplier’s service area. The state provided each supplier with residential landscape area (based on aerial imagery). Total residential landscape area (in square feet) will be used to calculate an individualized residential landscape budget based on local conditions like evapotranspiration (Eto) and precipitation. The State will not enforce outdoor water budgets for individual residential parcels.

Some special landscaped areas (SLAs) are assigned a higher landscape efficiency factor of 1.0 allowing a higher water budget for these irrigated areas. SLAs include areas dedicated to edible plants, serving a recreational function, irrigated with recycled water, and water features that use recycled water.

Commercial Industrial Institutional with Dedicated Irrigation Meters (CII-DIM) The Making Conservation a California Way of Life regulation also sets outdoor water budgets for commercial, industrial, and institutional outdoor landscapes with dedicated irrigation meters (CII-DIM). For CII-DIM landscape irrigation, the total irrigated area will be used to calculate individualized outdoor water budgets based on local conditions like Eto and precipitation. Urban water suppliers will make annual progress in measuring the irrigated area of CII landscapes with DIMs, with all subject landscapes being measured by 2028. The State will not enforce outdoor water budgets for individual CII-DIM customers.

Similar to the outdoor residential objective, the regulation identified SLAs for CII-DIMs which include areas dedicated to edible plants, serving a recreational function, irrigated with recycled water, and water features that use recycled water, as well as bioengineered slopes; ponds for recreation or for sustaining wildlife; public swimming pools; existing plant collections, botanical gardens, and arboretums; and cemeteries built before 2015.

3.7.2 Non-Functional Turf Ban
In October 2023, California passed AB 1572 (Friedman), a statewide legislation prohibiting the use of potable water to irrigate non-functional turf on commercial, industrial, and institutional properties with potable water. Non-functional turf means any turf areas that are decorative and have no other functions, such as recreation. The prohibition includes turf located within street rights-of-way, including road medians, and parking lots. The legislation exempts Item Number: 1.

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32 functional turf, such as sports fields, picnic areas, and cemeteries, or areas irrigated with recycled water. The legislation does not apply to residential turf but does prohibit the use of potable water to irrigate common areas within homeowners’ associations.

The ban takes effect as of the following dates:
1) 2027 – Properties owned by local governments
2) 2028 – Commercial and industrial properties
3) 2029 – Common areas of homeowners’ associations
4) 2031 – Properties owned by local governments in disadvantaged communities or when state funding for turf replacement is available

3.8 Water Shortage Contingency Planning
Based on the experiences from the 2013-2015 drought, CVWD’s domestic Water Shortage Contingency Plan provides the shortage levels summarized in Table 3-11. The trigger levels used to determine the water shortage level depend on the local water situation or applicable State mandates. CVWD has a diverse mix of water supplies and benefits from a large groundwater basin providing storage. CVWD’s groundwater replenishment program replenishes the basin to increase groundwater storage during wet years and that supply is available for use during dry years.

Table 3-12: Urban Water Shortage Contingency Plan Shortage Levels Shortage Level Shortage Range Water Supply Condition
1 Up to 10% Normal water supplies
2 Up to 20% Slightly limited water supplies
3 Up to 30% Moderately limited water supplies
4 Up to 40% Limited water supplies
5 Up to 50% Significantly limited water supplies
6 Up to 60% Severe shortage or catastrophic incident
Source: 2020 CVWD Water Shortage Contingency Plan
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33 4 Public Water System – Projected Supply and Demand
Coachella Valley Water District (CVWD) projects that a majority of its urban potable water uses will continue to be supplied from local groundwater. In addition to groundwater, CVWD has secured imported water supplies from the State Water Project (SWP) and the Colorado River, and recycled water from water reclamation plants. These imported and recycled water supplies are used to meet CVWD’s non-potable water demands and to replenish the groundwater basin.

4.1 Projected Urban Demand and Supply
The following tables from the 2020 Regional Urban Water Management Plan (Regional UWMP) provide the CVWD’s projected water supplies and demands. Potable water demand projections for the CVWD service area are summarized in Table 4-1.

Table 4-1: CVWD Projected Urban Retail Potable Demands
Projected Water Use
Use Type 2025 2030 2035 2040 2045
Single Family 60,142 63,824 67,331 69,816 71,695
Multi-Family 6,873 7,245 7,742 8,267 9,045
CII 7,060 7,244 7,438 7,709 7,985
Landscape 34,193 36,205 38,226 39,865 41,516
Other 1,457 1,563 1,670 1,755 1,840
Losses 13,736 14,501 15,222 15,670 16,085
Total 123,461 130,582 137,629 143,081 148,166
Source: 2020 Coachella Valley Regional Urban Water Management Plan A summary of existing and planned urban water supply volumes by source are presented in Table 4-2. It should be noted that the supplies and demands presented in the tables below include recycled water delivered to CVWD’s non-potable customers based on the DWR standardized tables and 2020 UWMP Guidebook. DWR requires the supply reliability table to include both potable and recycled water, however, CVWD’s recycled water is not a potable water supply and is not delivered to CVWD’s potable water customers. Instead, recycled water is used to offset the groundwater pumping of private well owners (mainly for golf course and landscape irrigation) to eliminate overdraft.

These projections were based on 2010 U.S. Census Data, DWR’s Population Tool, the Southern California Association of Governments’ (SCAG) 2020 Connect SoCal Regional Transportation Plan, and seasonal occupancy data from the Greater Palm Springs Convention and Visitors Bureau.

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34 Table 4-2: CVWD Projected Urban Water Supplies
Projected Water Supply (AFY)
Water Supply 2025 2030 2035 2040 2045
Groundwater 123,461 130,582 137,629 143,081 148,166
Recycled Water 13,600 14,400 15,100 15,900 16,800
Total 137,061 144,982 152,729 158,981 164,966
Source: 2020 Coachella Valley Regional Urban Water Management Plan

4.2 Normal, Single-Dry, Multiple-Dry Year Comparison
The following tables from the 2020 Regional UWMP provide CVWD’s projected water supplies and demands in a normal year, single-dry year, and multiple-dry years.

During normal years, CVWD will be able to meet current and future urban water demand needs projected in the 2020 Regional UWMP through groundwater pumping and recycled water as shown in Table 4-3.

Table 4-3: Normal Year Supply and Demand Comparison
2025 2030 2035 2040 2045
Supply Totals (AFY) 137,061 144,982 152,729 158,981 164,966 Groundwater 123,461 130,582 137,629 143,081 148,166
Recycled Water 13,600 14,400 15,100 15,900 16,800
Demand Totals (AFY) 137,061 144,982 152,729 158,981 164,966 Potable Water Demand 123,461 130,582 137,629 143,081 148,166 Recycled Water Demand 13,600 14,400 15,100 15,900 16,800 Difference 0 0 0 0 0
Source: 2020 Regional Urban Water Management Plan
Note: CVWD and the other Regional UWMP agencies collaborate on groundwater management plans for long-term sustainability. During a normal year, single-dry year, or five-dry year period, the agencies could produce additional groundwater if demands exceeded the estimates shown here.

During single-dry years, CVWD will be able to meet current and future urban water demand needs through groundwater pumping and recycled water as shown in Table 4-4. Water supplies during the single-dry year are 100 percent reliable. CVWD’s groundwater replenishment program replenishes the basin to increase groundwater storage during wet years and that supply is available for use during dry years. Thus, the supply and demand comparison for the single-dry year is the same as the normal year.

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35 Table 4-4: Single-Dry Year Supply and Demand Comparison 2025 2030 2035 2040 2045
Supply Totals (AFY) 137,061 144,982 152,729 158,981 164,966 Groundwater 123,461 130,582 137,629 143,081 148,166
Recycled Water 13,600 14,400 15,100 15,900 16,800
Demand Totals (AFY) 137,061 144,982 152,729 158,981 164,966 Potable Water Demand 123,461 130,582 137,629 143,081 148,166 Recycled Water Demand 13,600 14,400 15,100 15,900 16,800 Difference 0 0 0 0 0
Source: 2020 Regional Urban Water Management Plan
Note: CVWD and the other Regional UWMP agencies collaborate on groundwater management plans for long-term sustainability. During a normal year, single-dry year, or five-dry year period, the agencies could produce additional groundwater if demands exceeded the estimates shown here.

During multiple-dry years, CVWD will be able to meet current and future urban water demand needs through groundwater pumping and recycled water as shown in Table 4-5. Similar to the single-dry year, the multiple-dry year water supply reliability is 100 percent. Thus, the supply and demand comparison for the multiple-dry years is the same as the normal year. CVWD and the other Regional UWMP agencies collaborate on groundwater management plans for long-term sustainability. During a normal year, single-dry year, or five-dry year period, the agencies could produce additional groundwater if demands exceeded the estimates shown here.

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36 Table 4-5: Multiple-Dry Years Supply and Demand Comparison 2025 2030 2035 2040 2045
First Year
Supply Totals (AFY) 137,061 144,982 152,729 158,981 164,966 Groundwater 123,461 130,582 137,629 143,081 148,166
Recycled Water 13,600 14,400 15,100 15,900 16,800
Demand Totals (AFY) 137,061 144,982 152,729 158,981 164,966 Potable Water Demand 123,461 130,582 137,629 143,081 148,166 Recycled Water Demand 13,600 14,400 15,100 15,900 16,800 Difference 0 0 0 0 0
Second Year
Supply Totals (AFY) 137,061 144,982 152,729 158,981 164,966 Groundwater 123,461 130,582 137,629 143,081 148,166
Recycled Water 13,600 14,400 15,100 15,900 16,800
Demand Totals (AFY) 137,061 144,982 152,729 158,981 164,966 Potable Water Demand 123,461 130,582 137,629 143,081 148,166 Recycled Water Demand 13,600 14,400 15,100 15,900 16,800 Difference 0 0 0 0 0
Third Year
Supply Totals (AFY) 137,061 144,982 152,729 158,981 164,966 Groundwater 123,461 130,582 137,629 143,081 148,166
Recycled Water 13,600 14,400 15,100 15,900 16,800
Demand Totals (AFY) 137,061 144,982 152,729 158,981 164,966 Potable Water Demand 123,461 130,582 137,629 143,081 148,166 Recycled Water Demand 13,600 14,400 15,100 15,900 16,800 Difference 0 0 0 0 0
Fourth Year
Supply Totals (AFY) 137,061 144,982 152,729 158,981 164,966 Groundwater 123,461 130,582 137,629 143,081 148,166
Recycled Water 13,600 14,400 15,100 15,900 16,800
Demand Totals (AFY) 137,061 144,982 152,729 158,981 164,966 Potable Water Demand 123,461 130,582 137,629 143,081 148,166 Recycled Water Demand 13,600 14,400 15,100 15,900 16,800 Difference 0 0 0 0 0
Fifth Year
Supply Totals (AFY) 137,061 144,982 152,729 158,981 164,966 Groundwater 123,461 130,582 137,629 143,081 148,166
Recycled Water 13,600 14,400 15,100 15,900 16,800
Demand Totals (AFY) 137,061 144,982 152,729 158,981 164,966 Potable Water Demand 123,461 130,582 137,629 143,081 148,166 Recycled Water Demand 13,600 14,400 15,100 15,900 16,800 Difference 0 0 0 0 0
Source: 2020 Regional Urban Water Management Plan
Note: CVWD and the other Regional UWMP agencies collaborate on groundwater management plans for long-term sustainability. During a normal year, single-dry year, or five-dry year period, the agencies could produce additional groundwater if demands exceeded the estimates shown here.

CVWD’s total current urban water demand was 102,339 acre-feet (AF) for 2023, including 93,061 AF of groundwater and 9,278 AF of recycled water.

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37 5 Project Description
The Newland Project (Project) is located in the northwest portion of the Coachella Valley within the incorporated limits of the City of Desert Hot Springs, Riverside County as shown in Figure 5-

1. The Project will be accessible from Varner Road and West Drive and is bounded by Varner Road to the north, West Drive to the east, and Interstate-10 Freeway to the south and west, as shown in Figure 5-2. The Project encompasses approximately 123.4 acres of vacant land designated for industrial and open space use within two (2) distinct planning areas as proposed by the Desert Hot Springs Varner Road Specific Plan and shown in Figure 5-3 and Table 5-1.

Planning Area 1: Planning Area 1 (PA-1, Distribution Warehouse) is 63 acres and zoned “Industrial”. Pursuant to the Specific Plan development standards, the Project is allowed to build up to 1,500,000 sf of industrial space. The Project is expected to buildout at a lower scale but for analysis purposes, the most conservative approach will be taken. Therefore, this WSA assumes the maximum buildout potential of 1,500,000 sf of industrial space, specifically distribution warehouse with office and storage space. The facility will reach a maximum height of 50 feet.

There is no prospective user and therefore, exact building square footage for distribution, storage, and office space is unknown. The typical distribution warehouse has a storage capacity that covers 70 to 80 percent of the building’s square footage.1 However, this analysis assumes a 50 percent storage use and 50 percent distribution and office use to account for the possibility of larger percentage of space dedicated to distribution and office square footage. In addition, the water demand for storage space is much lower than that of distribution and office space; therefore, reducing the assumed storage space from 70-80 percent to 50 percent would yield higher water demand estimates for a more conservative analysis. The distribution warehouse would accommodate 750,000 square feet of storage space and 750,000 feet of distribution and office space. Landscaping is assumed to cover 14 percent of Planning Area 1 total acreage, equating to 384,199.20 sf of landscaping which will primarily consist of non-invasive drought tolerant vegetation dispersed throughout the site including but not limited to the site’s parking lot, detention basin, and roadway frontage. Water demand will consist of indoor water use, primarily from the distribution and office space, and outdoor water use for landscape irrigation.

Planning Area 2: Planning Area 2 (PA-2, Conservation Area) is 38.7 acres and zoned “Open Space”. PA-2 consists of two separate but contiguous areas, the larger area located north of Varner Road is comprised by 35.6 acres, and the smaller area, south of Varner Road in the northwestern region of the Specific Planning Area, is comprised of 3.1 acres. No development or modifications related to the site’s industrial use is permitted, except for supporting infrastructure intended for drainage and flood control. Apart from this, the site will remain unoccupied, desert land. And as such, the Specific Plan intends to preserve the existing biological resources and 1 KPI of the Day – Logistics: # Warehouse storage space. (2021, June 29). Performancemagazine.org. https://www.performancemagazine.org/kpi-logistics-warehouse-storage-space/ Item Number: 1.

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38 native habitat by incorporating Planning Area 2 with the Willow Hole Conservation Area, which abuts the site immediately to the north. The property will be managed according to the Coachella Valley Multiple Species Habitat Conservation Plan (CVMSHCP), administered by the Coachella Valley Conservation Commission. Planning Area 2 will not generate any water demands considering no structures or landscaping are proposed.

Roadway Improvements: Currently, Varner Road is partially paved, and West Drive is a dirt road.

For this reason, the Specific Plan proposes roadway improvements along Varner Road and West Drive, in compliance with the City of Desert Hot Springs General Plan development standards for their respective roadway classification. At buildout, Varner Road would be built to the ultimate width of a Secondary II roadway and include roadway paving, landscaping, curb and gutter, a 12- foot wide pedestrian sidewalk to the south side, and a 10-foot wide multipurpose trail along the north side only. In conjunction, the portion of Varner Road between the Project’s east boundary and Palm Drive will be improved with roadway paving. West Drive will be built to the ultimate width of a Local Collector and include roadway paving, landscaping, curb and gutter, and a 10- foot wide pedestrian sidewalk on the west side only. The segment of Varner Road and West Drive located immediately adjacent to Planning Area 1 will be landscaped. Therefore, assuming the maximum mixed-used pedestrian sidewalk and landscape area for a Secondary II and Local Collector roadway is reserved for landscape only, then Varner Road has a landscape area of 27,973.92 sf and West Drive has a landscape area of 16,414.50 sf. Water demand from these roadway improvements will be limited to outdoor water use for landscape irrigation.

Figure 5-1: Project Regional Location Map
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39 Figure 5-2: Project Vicinity Map
Figure 5-3: Conceptual Project Site Plan
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40 Table 5-1: Project Land Use Summary
Planning Area Specific Plan/Land Use
Designation
Land Area
(Acres)
Non-Residential Building
Area (ft2)
Planning Area 1 Industrial 63.0 1,500,000
Planning Area 2 Open Space 38.7 N/A
Roadway Improvements Roadway 21.7 N/A
Total 123.4 1,500,000
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41 6 Project Water Demands
The Newland Project (Project) encompasses approximately 123.4 acres of vacant land in the Coachella Valley to include up to 1,500,000 square foot distribution warehouse, as well as 384,199.20 sf of irrigated landscape area, 38.7 acres (1,685,772± sf) of open space/habitat conservation, and 21.7 acres (945,252± sf) of roadway improvements with an additional 44,388.42 sf irrigated landscape area.

6.1 Projected Indoor Residential Water Demand
The projected indoor water usage would not include residential use. Land uses within the Specific Planning area are nonresidential and limited to industrial and open space. No residential development would be permitted and therefore, indoor residential water demand would not contribute to the Project’s total water usage.

6.2 Projected Indoor Commercial and Industrial Water Demand The projected indoor commercial and industrial unit usage for this WSA is based on the American Water Works Association Research Foundations (AWWARF’s) Commercial and Industrial End Uses of Water and the U.S. Energy Information Administration. The projected indoor commercial and industrial water demand for the Project totals 42.35 AFY as shown in Table 6-2 below.

Table 6-1: Projected Indoor Commercial and Industrial Water Demand Planning Area Indoor
Area (ft2)
Water
Demand
Factor
(gal/ ft2)
1-2
Water
Demand
(gpd)
Water
Demand
(AFY)
Planning Area 1:Distribution/Office Space 750,000 15 30,821.92 34.52 Planning Area 1: Storage Space 750,000 3.4 6,986.30 7.83 Total 1,500,000 37,808.22 42.35 1 AWWARF Commercial and Industrial End Uses of Water, 2000. 2 Storage Space Water Demand: CBECS 2012 Water Consumption in Large Buildings Summary, February 2017.

See Appendix A.

6.3 Projected Outdoor Irrigation Water Demand
The projected outdoor irrigation water usage is based on the Maximum Applied Water Allowance (MAWA) equation from Appendix D of Coachella Valley Water District’s (CVWD’s) Landscape Ordinance No. 1302.5, which meets the water conservation goals of the California Department of Water Resources (DWR) Model Efficient Landscape Ordinance (MWELO). The projected outdoor irrigation water demand for the Project is 30.59 AFY as shown in Table 6-3 below.

Table 6-2: Projected Outdoor Irrigation Water Demand
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42 Planning Area Landscaped
Area (ft2)
ETo
(in/yr) 1 ETAF 2
Conversion
Factor
(gal/ft2) 3
Water
Demand
(gpd)
Water
Demand
(AFY)
Planning Area 1 384,199.20 83.34 0.45 0.62 24,474.92 27.42 Roadway
Improvement
44,388.42 83.34 0.45 0.62 2,827.71 3.17
Total 428,587.62 27,302.63 30.59 1 Reference Evapotranspiration (ETo) for ETo Zone 5 from CVWD Landscape Ordinance 1302.5, Appendix C 2 Evapotranspiration Adjustment Factor (ETAF) from CVWD Landscape Ordinance 1302.5, Appendix D 3 Conversion Factor from CVWD Landscape Ordinance 1302.5, Appendix D

6.4 Projected Outdoor Water Features Demand
The projected outdoor water use does not include water features for recreational use. No water feature including but not limited to swimming pools, fountains, or ponds are proposed within the developable area of the Project site. Water use from projected outdoor water features are not applicable to this Project.

6.5 Projected Total Water Demand
The total projected water demand for the Project is 72.96 AFY, or 0.591 acre-feet per acre, as shown in Table 6-5 below.

Table 6-3: Projected Total Water Demand
Planning Area Land Area
(Acres)
Indoor
Residential
Demand
(AFY)
Indoor
Commercial
and
Industrial
Demand
(AFY)
Outdoor
Irrigation
Demand
(AFY)
Outdoor
Recreational
Demand
(AFY)
Total
Water
Demand
(AFY)
Planning Area 1 63.0 N/A 42.37 27.42 N/A 69.79
Planning Area 2 38.7 N/A N/A N/A N/A N/A
Roadway
Improvements 21.7 N/A N/A 3.17 N/A 3.17
Total 123.40 N/A 42.37 30.59 N/A 72.96

6.6 Projected Water Sources
The only source of portable water for the Project will be supplied by CVWD’s domestic system, which extracts groundwater from the local aquifer. This source will service indoor water industrial use, as well as outdoor water use for landscape irrigation. There is no private well located within the Specific Planning area nor is there a plan for the construction of private wells.

The Project will depend on CVWD’s domestic water system for all water uses.

Table 6-4: Projected Water Sources
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43 Planning Area
Land
Area
(Acres)
Indoor
Residential
Demand
Indoor
Commercial
and Industrial
Demand
Outdoor
Irrigation
Demand
Outdoor
Water
Feature
Demand
Planning Area 1 63.0 N/A CVWD Domestic
Water System
CVWD Domestic
Water System N/A
Planning Area 2 38.7 N/A N/A N/A N/A
Roadway
Improvements

21.7 N/A N/A CVWD Domestic
Water System N/A

6.7 Conservation Measures
The landscape guidelines in the Desert Hot Springs Newland Specific Plan emphasizes noninvasive drought tolerant vegetation that are climate-appropriate, water efficient, and sustainable. At this time, no landscape plan has been proposed for Planning Area 2. Therefore, Planning Area 2 would not contribute to the Project’s total water demand as it relates to outdoor water use for irrigation.

All plant palette throughout the Project area shall utilize a low maintenance and low water palette. The landscaping and irrigation plan and system shall comply with all CVWD and the City ordinance relating to water efficiency, and the Project shall use automated irrigation systems with irrigation timers, and two drip or bubble heads per tree to provide efficient deep-root irrigation.

The Project’s adherence to the CVWD conservation programs, most notably in CVWD Landscape Ordinance 1302.5, will guide development of the Project landscape plan and will further enforce the necessary water conservation ethic and strategy.

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44 7 Availability of Sufficient Supplies

7.1 Water Supply Assessment
Based on the analysis in this Water Supply Assessment (WSA), the projected total water demand for the Newland Project (Project) will be 72.96 acre-feet per year (AFY), or 0.59 acre-feet per acre. CVWD’s long-term water management planning ensures that adequate water supplies are available to meet existing and future water needs within its service area. CVWD’s 5-year average urban water demand from 2019 to 2023 was 98,058 AFY, and the projected urban water demand by 2045 is 148,166 AFY. This Project’s water demand of 72.96 AFY accounts for approximately

0.14 percent of the total planned increases by 2045 based on the current conditions as represented by the average urban water demand of 98,058 AFY from 2019 to 2023.

This WSA provides an assessment of the availability of sufficient water supplies during normal, single-dry, and multiple-dry years over a 20-year projection to meet the projected demands of the Project, in addition to existing and planned future water demands of CVWD, as required by Senate Bill (SB) 610 and SB 1262. This WSA also includes identification of existing water supply entitlements, water rights, water service contracts, and agreements relevant to the identified water supply for the Project and quantities of water received in prior years pursuant to those entitlements, rights, contracts, and agreements.

This WSA has been prepared in compliance with the requirements of SB 610 and SB 1262 by Terra Nova Planning & Research in consultation with CVWD and the City of Desert Hot Springs. This WSA does not relieve the Project from complying with all applicable state, county, city, and local ordinances or regulations including the CVWD Landscape Ordinance, and indoor water use performance standards provided in the California Water Code now or in the future.

Consistent with the provisions of SB 610, neither this WSA nor its approval shall be construed to create a right or entitlement to water service or any specific level of water service, and shall not impose, expand, or limit any duty concerning the obligation of CVWD to provide certain service to its existing customers or to any future potential customers.

This WSA does not constitute an agreement to provide water service to the Project, and does not entitle the Project, Project applicant, or any other person or entity to any right, priority, or allocation in any supply, capacity, or facility. To receive water service, the Project will be subject to an agreement with CVWD, together with any and all applicable fees, charges, plans and specifications, conditions, and any and all other applicable CVWD requirements in place and as amended from time to time. Nor does anything in this WSA prevent or otherwise interfere with CVWD’s discretionary authority to declare a water shortage emergency in accordance with the Water Code.

This WSA will be reviewed every five years, or in the event that the water planning assumptions have changed, until the Project begins construction on all planning areas to ensure it remains Item Number: 1.

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45 accurate and no significant changes to either the Project or available water supply has occurred.

The Project applicant shall notify CVWD when construction of the projects in all planning areas begin.

7.2 Requirement for Written Verification of Water Supply Availability Government Code §66473.7 requires that a Written Verification of Water Supply (WV) be prepared in connection with the approval of a development agreement or tentative map that includes a subdivision. A subdivision is defined as a proposed residential development of more than 500 units, except that for a water agency with fewer than 5,000 service connections, a subdivision includes a residential development project that would account for an increase of 10 percent or more in the number of the agency’s existing service connections.

This WSA is not a WV. If the City of Desert Hot Springs determines that the Project or any planning area meets the definition of a subdivision and therefore requires preparation of a WV, the City of Desert Hot Springs must request a WV prepared by CVWD in compliance with the requirements of SB 221. This WSA may be used to support the WV. Depending on circumstances including but not limited to new water efficiency regulations or changes in water supply availability, CVWD may recommend preparation of an updated supply and demand assessment to support the WV.

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46 8 References
American Water Works Association Research Foundation, Commercial and Institutional End Uses of Water, 2000
California Department of Water Resources, Final State Water Project Delivery Capability Report 2019, August 2020
California Department of Water Resources, Results of the Indoor Residential Water Use Study, November 2021
California Department of Water Resources, State Water Project Historical Table A Allocations, Water Years 1996-2024, April 2024
Coachella Valley Water District, Coachella Water Authority, Desert Water Agency, Indio Water Authority, Mission Springs Water District, Myoma Dunes Mutual Water Company, 2020 Coachella Valley Regional Urban Water Management Plan, Water Systems Consulting, Inc., June 2021
Coachella Valley Water District, 2024-2025 Engineer’s Report on Water Supply and Replenishment Assessment, April 2023
Coachella Valley Water District, Landscape Ordinance 1302.5, July 2020 Coachella Valley Water District, Coachella Water Authority, Desert Water Agency, and Indio Water Authority, Indio Subbasin Annual Report for Water Year 2022-2023, Todd Groundwater Inc., March 2024
Coachella Valley Water District, Coachella Water Authority, Desert Water Agency, and Indio Water Authority, 2022 Indio Subbasin Water Management Plan Update/Alternative Plan Update, Todd Groundwater Inc., December 2021
Coachella Valley Water District, Desert Water Agency, and Mission Springs Water District, Mission Creek Subbasin Annual Report for Water Year 2022-2023, Wood Environment & Infrastructure Solutions Inc., February 2024
United States Bureau of Reclamation, Colorado River Accounting and Water Use Reports for Arizona, California, and Nevada

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H
Appendix H
Noise and Vibration Analysis
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Reference Number
16328-02 NA
Agency
City of Desert Hot Springs
Date
March 13, 2025

VARNER ROAD / WEST DRIVE

LOGISTICS

NOISE AND VIBRATION ANALYSIS
Prepared By:

Bill Lawson | [email protected]
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16328
-02 NA ii Varner Road / West Drive Logistics
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16328-02 NA iii Varner Road / West Drive Logistics

TABLE OF CONTENTS
EXECUTIVE SUMMARY .......................................................................................................................1 1 INTRODUCTION..........................................................................................................................3

1.1 Site Location .......................................................................................................................................... 3

1.2 Project Description................................................................................................................................. 3 2 FUNDAMENTALS ........................................................................................................................7

2.1 Range of Noise ....................................................................................................................................... 7

2.2 Noise Descriptors ...................................................................................................................................8

2.3 Sound Propagation.................................................................................................................................8

2.4 Noise Control..........................................................................................................................................9

2.5 Noise Barrier Attenuation .......................................................................................................................9

2.6 Land Use Compatibility With Noise....................................................................................................... 10

2.7 Community Response to Noise............................................................................................................. 10

2.8 Vibration .............................................................................................................................................. 11 3 REGULATORY SETTING............................................................................................................... 13

3.1 State of California Noise Requirements ................................................................................................ 13

3.2 City of Desert Hot Springs General Plan Noise Element ........................................................................ 13

3.3 Operational Noise Standards (Absolute)............................................................................................... 15

3.4 Construction Noise Standards (Absolute) ............................................................................................. 15

3.5 Construction Vibration Standards ......................................................................................................... 16 4 SIGNIFICANCE CRITERIA ............................................................................................................. 17

4.1 Noise Level Increases (Threshold A)...................................................................................................... 17

4.2 Vibration (Threshold B)......................................................................................................................... 19

4.3 CEQA Guidelines Not Further Analyzed (Threshold C) .......................................................................... 19

4.4 Significance Criteria Summary.............................................................................................................. 20 5 EXISTING NOISE LEVEL MEASUREMENTS........................................................................................ 21

5.1 Measurement Procedure and Criteria ................................................................................................... 21

5.2 Noise Measurement Locations ............................................................................................................. 21

5.3 Noise Measurement Results ................................................................................................................. 23 6 TRAFFIC NOISE METHODS AND PROCEDURES................................................................................... 25

6.1 FHWA Traffic Noise Prediction Model ................................................................................................... 25

6.2 Off-Site Traffic Noise Prediction Model Inputs ...................................................................................... 25 7 OFF-SITE TRAFFIC NOISE ANALYSIS............................................................................................... 31

7.1 Traffic Noise Contours .......................................................................................................................... 31

7.2 Existing Project Traffic Noise Level Increases ........................................................................................ 31

7.3 EACP (2027) Project Traffic Noise Level Increases ................................................................................. 35

7.4 HY (2045) Project Traffic Noise Level Increases ..................................................................................... 35 8 RECEIVER LOCATIONS................................................................................................................ 39 9 OPERATIONAL NOISE ANALYSIS ................................................................................................... 41

9.1 Operational Noise Sources ................................................................................................................... 41

9.2 Reference Noise Levels......................................................................................................................... 41

9.3 CadnaA Noise Prediction Model ........................................................................................................... 44

9.4 Project Operational Noise Levels .......................................................................................................... 45

9.5 Project Operational Noise Level Compliance ........................................................................................46

9.6 Project Operational Noise Level Increases ............................................................................................ 47 Item Number: 1.

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16328-02 NA iv Varner Road / West Drive Logistics
10 CONSTRUCTION IMPACTS ...........................................................................................................49

10.1 Construction Noise Levels ....................................................................................................................49

10.2 Construction Reference Noise Levels....................................................................................................49

10.3 Construction Noise Analysis ................................................................................................................. 51

10.4 Project Site Construction Noise Level Compliance ................................................................................ 52

10.5 Temporary Construction Noise Level Increases ..................................................................................... 53

10.6 Nighttime Concrete Pour Noise Analysis............................................................................................... 53

10.7 Construction Vibration Analysis ............................................................................................................ 55 11 REFERENCES ........................................................................................................................... 57 12 CERTIFICATION ........................................................................................................................ 59

APPENDICES
APPENDIX 3.1: CITY OF DESERT HOT SPRINGS MUNICIPAL CODE APPENDIX 5.1: STUDY AREA PHOTOS
APPENDIX 5.2: NOISE LEVEL MEASUREMENT WORKSHEETS
APPENDIX 7.1: OFF-SITE TRAFFIC NOISE LEVEL CALCULATIONS APPENDIX 9.1: CADNAA OPERATIONAL NOISE CALCULATIONS
APPENDIX 10.1: CONSTRUCTION NOISE CALCULATIONS
APPENDIX 10.2: NIGHTTIME CONCRETE POUR NOISE CALCULATIONS

LIST OF EXHIBITS
EXHIBIT 1-1: PROJECT LOCATION.........................................................................................................4 EXHIBIT 1-2: PRELIMINARY SITE PLAN ..................................................................................................5 EXHIBIT 2-1: TYPICAL NOISE LEVELS ....................................................................................................7 EXHIBIT 2-2: NOISE LEVEL INCREASE PERCEPTION................................................................................. 10 EXHIBIT 2-3: TYPICAL LEVELS OF GROUND-BORNE VIBRATION ................................................................. 12 EXHIBIT 3-1: NOISE AND LAND USE COMPATIBILITY GUIDELINES ............................................................... 14 EXHIBIT 5-1: NOISE MEASUREMENT LOCATIONS ................................................................................... 22 EXHIBIT 8-1: RECEIVER LOCATIONS....................................................................................................40 EXHIBIT 9-1: OPERATIONAL NOISE SOURCE LOCATIONS..........................................................................42 EXHIBIT 10-1: CONSTRUCTION NOISE SOURCE LOCATIONS ...................................................................... 50 Item Number: 1.

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16328-02 NA v Varner Road / West Drive Logistics

LIST OF TABLES
TABLE ES-1: SUMMARY OF CEQA SIGNIFICANCE FINDINGS........................................................................1 TABLE 4-1: SIGNIFICANCE CRITERIA SUMMARY .....................................................................................20 TABLE 5-1: AMBIENT NOISE LEVEL MEASUREMENTS .............................................................................. 23 TABLE 6-1: OFF-SITE ROADWAY PARAMETERS .....................................................................................26 TABLE 6-2: AVERAGE DAILY TRAFFIC VOLUMES .................................................................................... 27 TABLE 6-3: TIME OF DAY VEHICLE SPLITS ............................................................................................28 TABLE 6-4: EXISTING WITH PROJECT VEHICLE MIX ................................................................................28 TABLE 6-5: EACP (2027) WITH PROJECT VEHICLE MIX ...........................................................................28 TABLE 6-6: HY (2045) WITH PROJECT VEHICLE MIX ..............................................................................29 TABLE 7-1: EXISTING WITHOUT PROJECT CONTOURS ............................................................................. 32 TABLE 7-2: EXISTING WITH PROJECT CONTOURS................................................................................... 32 TABLE 7-3: EAC (2027) WITHOUT PROJECT CONTOURS .......................................................................... 32 TABLE 7-4: EACP (2027) WITH PROJECT CONTOURS ............................................................................. 33 TABLE 7-5: HY (2045) WITHOUT PROJECT CONTOURS ........................................................................... 33 TABLE 7-6: HY (2045) WITH PROJECT CONTOURS................................................................................. 33 TABLE 7-7: EXISTING WITH PROJECT TRAFFIC NOISE LEVEL INCREASES....................................................... 34 TABLE 7-8: EACP (2027) WITH PROJECT TRAFFIC NOISE LEVEL INCREASES................................................. 36 TABLE 7-9: HY (2045) WITH PROJECT TRAFFIC NOISE LEVEL INCREASES .................................................... 37 TABLE 9-1: REFERENCE NOISE LEVEL MEASUREMENTS........................................................................... 43 TABLE 9-2:DAYTIME PROJECT OPERATIONAL NOISE LEVELS .................................................................... 45 TABLE 9-3: NIGHTTIME PROJECT OPERATIONAL NOISE LEVELS .................................................................46 TABLE 9-4: OPERATIONAL NOISE LEVEL COMPLIANCE............................................................................46 TABLE 9-5: DAYTIME PROJECT OPERATIONAL NOISE LEVEL INCREASES ...................................................... 47 TABLE 9-6: NIGHTTIME OPERATIONAL NOISE LEVEL INCREASES ...............................................................48 TABLE 10-1: CONSTRUCTION REFERENCE NOISE LEVELS......................................................................... 51 TABLE 10-2: CONSTRUCTION EQUIPMENT NOISE LEVEL SUMMARY............................................................ 52 TABLE 10-3: CONSTRUCTION NOISE LEVEL COMPLIANCE......................................................................... 52 TABLE 10-4: DAYTIME CONSTRUCTION NOISE LEVEL INCREASES............................................................... 53 TABLE 10-5: NIGHTTIME CONCRETE POUR NOISE LEVEL COMPLIANCE........................................................ 54 TABLE 10-6: VIBRATION SOURCE LEVELS FOR CONSTRUCTION EQUIPMENT ................................................. 55 TABLE 10-7: PROJECT CONSTRUCTION VIBRATION LEVELS....................................................................... 56 Item Number: 1.

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LIST OF ABBREVIATED TERMS
(1) Reference
ANSI American National Standards Institute
Calveno California Vehicle Noise
CEQA California Environmental Quality Act
CNEL Community Noise Equivalent Level
dBA A-weighted decibels
EIR Environmental Impact Report
EPA Environmental Protection Agency
FHWA Federal Highway Administration
FTA Federal Transit Administration
INCE Institute of Noise Control Engineering
Leq Equivalent continuous (average) sound level
Lmax Maximum level measured over the time interval
mph Miles per hour
PPV Peak Particle Velocity
Project Varner Road / West Drive Logistics
REMEL Reference Energy Mean Emission Level
RMS Root-mean-square
VdB Vibration Decibels
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16328-02 NA 1 Varner Road / West Drive Logistics

EXECUTIVE SUMMARY
Urban Crossroads, Inc. has prepared this noise study to determine the noise exposure and the necessary noise mitigation measures for the proposed Varner Road / West Drive Logistics (Project) in the City of Desert Hot Springs. The Project consists of the development of up to 1,500,000 square feet (SF) of high cube warehouse. This noise study has been prepared to satisfy applicable City of Desert Hot Springs noise standards and significance criteria based on Appendix G of the California Environmental Quality Act (CEQA) Guidelines. (1)
The results of this Noise and Vibration Analysis are summarized below based on the significance criteria in Section 4 of this report consistent with Appendix G of the California Environmental Quality Act (CEQA) Guidelines. (1) Table ES-1 shows the findings of significance for each potential noise and/or vibration impact under CEQA before and after any required mitigation measures.

TABLE ES-1: SUMMARY OF CEQA SIGNIFICANCE FINDINGS
Analysis Report
Section
Significance Findings
Unmitigated Mitigated
Off-Site Traffic Noise 7 Less Than Significant -
Operational Noise 9 Less Than Significant -
Project Construction Noise 10 Less Than Significant -
Nighttime Concrete Pour 10 Less Than Significant -
Construction Vibration 10 Less Than Significant -
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16328-02 NA 3 Varner Road / West Drive Logistics
1 INTRODUCTION
This Noise and Vibration Analysis has been completed to determine the noise impacts associated with the development of the proposed Varner Road / West Drive Logistics (Project). This noise and vibration analysis briefly describes the Project, provides information regarding noise fundamentals, sets out the local regulatory setting, presents the study methods and procedures for noise analysis, evaluates the future exterior noise environment, potential off-site traffic impacts, the Projectrelated long-term stationary-source operational noise, and Project-related short-term construction noise and vibration impacts.

1.1 SITE LOCATION
The Project site is located south of Varner Road and west of West Drive in the City of Desert Hot Springs. The Project is bounded by the I-10 Freeway to the west, with vacant land to the north and east as shown in Exhibit 1-1. The nearest existing noise-sensitive residential use is located south of the Project site.

1.2 PROJECT DESCRIPTION
A preliminary site plan for the proposed Project is shown in Exhibit 1-1. Although the site plan shows a building size of 1,209,230 square feet, up to 1,500,000 square feet of high cube warehouse could occur at the site based on the Project description. The activity levels associated with 1,500,000 square feet of high cube warehouse are therefore used as the basis of this analysis.

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EXHIBIT 1-1: PROJECT LOCATION
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EXHIBIT 1-2: PRELIMINARY SITE PLAN
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2 FUNDAMENTALS
Noise is simply defined as "unwanted sound." Sound becomes unwanted when it interferes with normal activities, when it causes actual physical harm, or when it has adverse effects on health.

Noise is measured on a logarithmic scale of sound pressure level known as a decibel (dB). Aweighted decibels (dBA) approximate the subjective response of the human ear to broad frequency noise source by discriminating against very low and very high frequencies of the audible spectrum.

They are adjusted to reflect only those frequencies which are audible to the human ear. Exhibit 2-1 presents a summary of the typical noise levels and their subjective loudness and effects that are described in more detail below.

EXHIBIT 2-1: TYPICAL NOISE LEVELS
Source: Environmental Protection Agency Office of Noise Abatement and Control, Information on Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an Adequate Margin of Safety (EPA/ONAC 550/9-74-004) March 1974.

2.1 RANGE OF NOISE
Since the range of intensities that the human ear can detect is so large, the scale frequently used to measure intensity is a scale based on multiples of 10, the logarithmic scale. The scale for measuring intensity is the decibel scale. Each interval of 10 decibels indicates a sound energy ten times greater than before, which is perceived by the human ear as being roughly twice as loud. (2) The most common sounds vary between 40 dBA (very quiet) to 100 dBA (very loud). Normal conversation at three feet is roughly at 60 dBA, while loud jet engine noises equate to 110 dBA at approximately 1,000 feet, which can cause serious discomfort. (3) Another important aspect of noise is the duration of the sound and the way it is described and distributed in time.

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2.2 NOISE DESCRIPTORS
Environmental noise descriptors are generally based on averages, rather than instantaneous, noise levels. The most used metric is the equivalent level (Leq). Equivalent sound levels are not measured directly but are calculated from sound pressure levels typically measured in A-weighted decibels (dBA). The equivalent sound level (Leq) represents a steady state sound level containing the same total energy as a time varying signal over a given sample period and is commonly used to describe the “average” noise levels within the environment.

Peak hour or average noise levels, while useful, do not completely describe a given noise environment. Noise levels lower than peak hour may be disturbing if they occur during times when quiet is most desirable, namely evening and nighttime (sleeping) hours. To account for this, the Community Noise Equivalent Level (CNEL), representing a composite 24-hour noise level is utilized.

The CNEL is the weighted average of the intensity of a sound, with corrections for time of day, and averaged over 24 hours. The time-of-day corrections require the addition of 5 decibels to dBA Leq sound levels in the evening from 7:00 p.m. to 10:00 p.m., and the addition of 10 decibels to dBA Leq sound levels at night between 10:00 p.m. and 7:00 a.m. These additions are made to account for the noise sensitive time periods during the evening and night hours when noise can become more intrusive. CNEL does not represent the actual sound level heard at any time, but rather represents the total sound exposure. The City of Desert Hot Springs relies on the 24-hour CNEL level to assess land use compatibility with transportation related noise sources.

2.3 SOUND PROPAGATION
When sound propagates over a distance, it changes in level and frequency content. The way noise reduces with distance depends on the following factors.

2.3.1 Geometric Spreading
Sound from a localized source (i.e., a stationary point source) propagates uniformly outward in a spherical pattern. The sound level attenuates (or decreases) at a rate of 6 dB for each doubling of distance from a point source. Highways consist of several localized noise sources on a defined path and hence can be treated as a line source, which approximates the effect of several point sources.

Noise from a line source propagates outward in a cylindrical pattern, often referred to as cylindrical spreading. Sound levels attenuate at a rate of 3 dB for each doubling of distance from a line source. (2)

2.3.2 Ground Absorption
The propagation path of noise from a highway to a receiver is usually very close to the ground. Noise attenuation from ground absorption and reflective wave canceling adds to the attenuation associated with geometric spreading. Traditionally, the excess attenuation has also been expressed in terms of attenuation per doubling of distance. This approximation is usually sufficiently accurate for distances of less than 200 ft. For acoustically hard sites (i.e., sites with a reflective surface between the source and the receiver, such as a parking lot or body of water), no excess ground attenuation is assumed. For acoustically absorptive or soft sites (i.e., those sites with an absorptive ground surface between the source and the receiver such as soft dirt, grass, or scattered bushes and trees), an excess ground attenuation value of 1.5 dB per doubling of distance is normally assumed.

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When added to the cylindrical spreading, the excess ground attenuation results in an overall dropoff rate of 4.5 dB per doubling of distance from a line source. (4)

2.3.3 Atmospheric Effects
Receivers located downwind from a source can be exposed to increased noise levels relative to calm conditions, whereas locations upwind can have lowered noise levels. Sound levels can be increased at large distances (e.g., more than 500 feet) due to atmospheric temperature inversion (i.e., increasing temperature with elevation). Other factors such as air temperature, humidity, and turbulence can also have significant effects. (2)

2.3.4 Shielding
A large object or barrier in the path between a noise source and a receiver can substantially attenuate noise levels at the receiver. The amount of attenuation provided by shielding depends on the size of the object and the frequency content of the noise source. Shielding by trees and other such vegetation typically only has an “out of sight, out of mind” effect. That is, the perception of noise impact tends to decrease when vegetation blocks the line-of-sight to nearby residents. However, for vegetation to provide a substantial, or even noticeable, noise reduction, the vegetation area must be at least 15 feet in height, 100 feet wide and dense enough to completely obstruct the line-of-sight between the source and the receiver. This size of vegetation may provide up to 5 dBA of noise reduction. The Federal Highway Administration (FHWA) does not consider the planting of vegetation to be a noise abatement measure. (5)

2.4 NOISE CONTROL
Noise control is the process of obtaining an acceptable noise environment for an observation point or receiver by controlling the noise source, transmission path, receiver, or all three. This concept is known as the source-path-receiver concept. In general, noise control measures can be applied to these three elements.

2.5 NOISE BARRIER ATTENUATION
Effective noise barriers can reduce noise levels by 10 to 15 dBA, cutting the loudness of traffic noise in half. A noise barrier is most effective when placed close to the noise source or receiver. Noise barriers, however, do have limitations. For a noise barrier to work, it must block the line-of-sight path of sound from the noise source.

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2.6 LAND USE COMPATIBILITY WITH NOISE
Some land uses are more tolerant of noise than others. For example, schools, hospitals, churches, and residences are more sensitive to noise intrusion than commercial or industrial developments and related activities. As ambient noise levels affect the perceived amenity or livability of a development, so too can the mismanagement of noise impacts impair the economic health and growth potential of a community by reducing the area’s desirability as a place to live, shop and work.

For this reason, land use compatibility with the noise environment is an important consideration in the planning and design process. The FHWA encourages State and Local government to regulate land development in such a way that noise-sensitive land uses are either prohibited from being located adjacent to a highway, or that the developments are planned, designed, and constructed in such a way that noise impacts are minimized. (6)

2.7 COMMUNITY RESPONSE TO NOISE
Approximately sixteen percent of the population has a very low tolerance for noise and will object to any noise not of their making. Consequently, even in the quietest environment, some complaints may occur. Twenty to thirty percent of the population will not complain even in very severe noise environments. (7 pp. 8-6) Thus, a variety of reactions can be expected from people exposed to any given noise environment.

Surveys have shown that community response to noise varies from no reaction to vigorous action for newly introduced noises averaging from 10 dB below existing to 25 dB above existing. (8) According to research originally published in the Noise Effects Handbook (7), the percentage of high annoyance ranges from approximately 0 percent at 45 dB or less, 10 percent are highly annoyed around 60 dB, and increases rapidly to approximately 70 percent being highly annoyed at approximately 85 dB or greater. Despite this variability in behavior on an individual level, the population can be expected to exhibit the following responses to changes in noise levels as shown on Exhibit 2-2. A change of 3 dBA is considered barely perceptible, and changes of 5 dBA are considered readily perceptible. (4)
EXHIBIT 2-2: NOISE LEVEL INCREASE PERCEPTION
0 1 2 3 4 5 6 7 8 9 10
Just Perceptible
Barely Perceptible
Readily Perceptible
Twice as Loud
Noise Level Increase (dBA)
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2.8 VIBRATION
Per the Federal Transit Administration (FTA) Transit Noise and Vibration Impact Assessment Manual, vibration is the periodic oscillation of a medium or object. The rumbling sound caused by the vibration of room surfaces is called structure-borne noise. Sources of ground-borne vibrations include natural phenomena (e.g., earthquakes, volcanic eruptions, sea waves, landslides) or humanmade causes (e.g., explosions, machinery, traffic, trains, construction equipment). Vibration sources may be continuous, such as factory machinery, or transient, such as explosions. As is the case with airborne sound, ground-borne vibrations may be described by amplitude and frequency.

Additionally, in contrast to airborne noise, ground-borne vibration outdoors is not a common environmental problem and annoyance from ground-borne vibration is almost exclusively an indoor phenomenon )8(. Therefore, the effects of vibrations should only be evaluated at a structure and the effects of the building structure on the vibration should be considered. Wood-frame buildings, such as typical residential structures, are more easily excited by ground vibration than heavier buildings.

In contrast, large masonry buildings with spread footings have a low response to ground vibration (8). In general, the heavier a building is, the lower the response will be to the incident vibration energy. However, all structurers reduce vibration levels due to the coupling of the building to the soil.

There are several different methods that are used to quantify vibration. The peak particle velocity (PPV) is defined as the maximum instantaneous peak of the vibration signal (8). The PPV is most frequently used to describe vibration impacts to buildings but is not always suitable for evaluating human response (annoyance) because it takes some time for the human body to respond to vibration signals. Instead, the human body responds to average vibration amplitude often described as the root mean square (RMS). The RMS amplitude is defined as the average of the squared amplitude of the signal and is most frequently used to describe the effect of vibration on the human body (8).

However, the RMS amplitude and PPV are related mathematically, and the RMS amplitude of equipment is typically calculated from the PPV reference level. The RMS amplitude is approximately 70% of the PPV (9). Thus, either can be used in the description of vibration impacts.

While not universally accepted, vibration decibel notation (VdB) is another vibration notation developed and used by the FTA in their guidance manual to describe vibration levels and provide a background of common vibration levels and set vibration limits. (8) Decibel notation (VdB) serves to reduce the range of numbers used to describe vibration levels and is used in this report to describe vibration levels. As stated in the FTA guidance manual, the background vibration-velocity level in residential areas is generally 50 VdB. Ground-borne vibration is normally perceptible to humans at approximately 65 VdB. For most people, a vibration-velocity level of 75 VdB is the approximate dividing line between barely perceptible and distinctly perceptible levels. Typical outdoor sources of perceptible ground-borne vibration are construction equipment, steel-wheeled trains, and traffic on rough roads. If a roadway is smooth, the ground-borne vibration is rarely perceptible. The range of interest is from approximately 50 VdB, which is the typical background vibration-velocity level, to 100 VdB, which is the general threshold where minor damage can occur in fragile buildings. Exhibit 2-3 illustrates common vibration sources and the human and structural response to ground-borne vibration.

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EXHIBIT 2-3: TYPICAL LEVELS OF GROUND-BORNE VIBRATION
Source: Federal Transit Administration (FTA) Transit Noise and Vibration Impact Assessment Manual.

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3 REGULATORY SETTING
To limit population exposure to physically and/or psychologically damaging as well as intrusive noise levels, the federal government, the State of California, various county governments, and most municipalities in the state have established standards and ordinances to control noise. In most areas, automobile and truck traffic is the major source of environmental noise. Traffic activity generally produces an average sound level that remains constant with time. Air and rail traffic, and commercial and industrial activities are also major sources of noise in some areas. Federal, state, and local agencies regulate different aspects of environmental noise. Federal and state agencies generally set noise standards for mobile sources such as aircraft and motor vehicles, while regulation of stationary sources is left to local agencies.

3.1 STATE OF CALIFORNIA NOISE REQUIREMENTS
The State of California regulates freeway noise, sets standards for sound transmission, provides occupational noise control criteria, identifies noise standards, and provides guidance for local land use compatibility. State law requires that each county and city adopt a General Plan that includes a Noise Element which is to be prepared per guidelines adopted by the Governor’s Office of Planning and Research (OPR). (10) The purpose of the Noise Element is to limit the exposure of the community to excessive noise levels. In addition, the California Environmental Quality Act (CEQA) requires that all known environmental effects of a project be analyzed, including environmental noise impacts.

3.2 CITY OF DESERT HOT SPRINGSGENERAL PLAN NOISE ELEMENT The purpose of the City of Desert Hot SpringsGeneral Plan Safety and Noise Element is to coordinate the City’s land uses with the existing and future noise environment. (11) To protect City of Desert Hot Springs residents from excessive noise levels, the Noise Element contains the following project related goal and policies:

Goal A noise environment that provides peace and quiet that compliments the city’s spa resort character
SN-8.1 Sensitive Land Uses. Protect noise-sensitive land uses from high noise levels from both existing and future noise sources. Sensitive uses include residences, resorts and community open space, schools, libraries, churches, hospitals, and convalescent homes.

SN-8.2 Noise Impacts. Assess proposed development and associated traffic for the potential to generate adverse and incompatible noise impacts. Require mitigation for identified impacts.

SN-8.5 Land Use Compatibility. Designate land uses that are compatible with higher noise levels adjacent to major arterial roads and highways, the Interstate10 corridor, or designated industrial lands.

SN-8.10 Noise-Generating Uses. Require specific design for noise-generating uses such as restaurants, bars, and industrial business located near sensitive uses such as residential.

SN-8.11 Noise-Level Compliance. Require new development to monitor and document compliance with all applicable noise level limits in areas subject to potentially significant noise impacts.

SN-8.13 Noise-reducing Pavement. Encourage the use of noise-reducing paving materials such as rubberized asphalt for road surfacing projects near sensitive land uses.

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The noise policies and programs specified in the City of Desert Hot Springs Noise Element provide the guidelines necessary to satisfy this goal. Further, the noise criteria identified in the City of Desert Hot Springs General Plan Noise Element (Table SN-2) are guidelines to evaluate the land use compatibility of transportation-related noise. The compatibility criteria, shown in Exhibit 3-1, provides the City with a planning tool to gauge the compatibility of land uses relative to existing and future exterior noise levels.

The Noise and Land Use Compatibility Guidelines indicates that industrial land uses, such as the Project site, are considered normally acceptable with exterior noise levels below 70 dBA CNEL, and conditionally acceptable with noise levels above 70 dBA CNEL. Noise-sensitive residential land uses are considered normally acceptable with exterior noise levels below 60 dBA CNEL, and conditionally acceptable with noise levels below 65 dBA CNEL. For conditionally acceptable land uses, new construction or development should be undertaken only after a detailed analysis of the noise reduction requirement is made and needed noise insulation features included in the design. (11) EXHIBIT 3-1: NOISE AND LAND USE COMPATIBILITYGUIDELINES Source: City of Desert Hot SpringsGeneral Plan Safety and Noise Element, Table SN-2.

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3.3 OPERATIONAL NOISE STANDARDS (ABSOLUTE)
To analyze noise impacts originating from a designated fixed location or private property such as the Varner Road / West Drive Logistics Project, operational source noise is typically evaluated against standards established under a City’s Municipal Code. While the City of Desert Hot Springs maintains several policies in the Municipal Code to control the negative effects of nuisance noise, it does not identify specific exterior noise level limits. Therefore, the County of Riverside General Plan Noise Element Policy N 4.1 exterior noise standards are used in this analysis to assess the potential impacts due to the operation of the Project. Policy N 4.1 of the County of Riverside General Plan Noise Element sets a stationary-source average Leq exterior noise limit not to be exceeded for a cumulative period of more than ten minutes in any hour of 65 dBA Leq for daytime hours of 7:00 a.m. to 10:00 p.m., and 45 dBA Leq during the noise-sensitive nighttime hours of 10:00 p.m. to 7:00 a.m. (12)

3.4 CONSTRUCTION NOISE STANDARDS (ABSOLUTE)
To control noise impacts associated with the construction of the proposed Project, the City has established limits to the hours of work permitted. Section 9.04.030 of the City’s Code of Ordinances, provided in Appendix 3.1, indicates that construction activity is not permitted between the hours of 5:00 p.m. each day and 7:00 a.m. of the next day, except when daylight savings time is in effect.

During such time as daylight savings time is in effect in the City, no such activities shall be permitted between the hours of 6:00 p.m. of each day and 6:00 a.m. of the next day and no construction activities are permitted on Sundays. (13) However, neither the City of Desert Hot Springs General Plan nor Municipal Code establish numeric maximum acceptable construction source noise levels at potentially affected receivers, which would allow for a quantified determination of what CEQA constitutes a substantial temporary or permanent increase in ambient noise levels.

According to Caltrans guidance, construction noise impacts shall not exceed 86 dBA Lmax at 50 feet from the job site activities between the hours of 9:00 p.m. to 6:00 a.m. (14) Equipment and operations are usually at or less than that level, except for blasting, pile drivers (impact or vibratory), hoe rams, pavement breakers for crack-and-seat operations, and other impact equipment. (2) The Caltrans guidance also suggests that detailed discussions of typical construction equipment noise levels are probably not necessary unless the project involves unusually sensitive receptors or nighttime work or if the project is controversial. (2) Since this limitation is only associated with nighttime activities and does not address the noise level at the point of concern, e.g., a residence, Caltrans construction criteria were similarly not considered as the appropriate threshold for environmental review.

Further research indicated U.S. Department of Transportation guidance for construction published by the Federal Transit Administration (FTA) is appropriate and based on well documented studies of the effects of construction noise. According to the FTA Transit Noise and Vibration Impact Assessment Manual, local noise ordinances are typically not very useful in evaluating construction noise impacts.

They usually relate to nuisance and hours of allowed activity, and sometimes specify limits in terms of maximum levels, but are generally not practical for assessing the impact of a construction project.

Project construction noise criteria should account for the existing noise environment, the absolute noise levels during construction activities, the duration of the construction, and the adjacent land use. (8 p. 172)
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Due to the lack of standardized construction noise thresholds, the FTA provides guidelines that can be considered reasonable criteria for construction noise assessments. The FTA identifies two types of construction noise assessment criteria, general and detailed. For general construction noise assessments, the analysis is limited to the two noisiest pieces of equipment with an hourly daytime exterior noise level threshold for residential land use of 90 dBA Leq(1hr). (8 p. 179) However, for longterm construction projects that would expose sensitive receivers to noise for extended periods of time, the FTA considers a daytime 8-hour average exterior construction noise level of 80 dBA Leq(8hr).

The absolute FTA thresholds are intended to account for reasonable expectations regarding construction noise during the daytime hours and are intended to protect human health.

Therefore, to evaluate whether the Project will generate potentially significant short-term noise levels at nearby noise sensitive residential receiver locations, a daytime exterior construction noise level of 80 dBA Leq is used as a reasonable threshold to assess construction noise level impacts based on the FTA detailed analysis construction noise criteria with a nighttime exterior construction noise level of 70 dBA Leq. (8 p. 179)

3.5 CONSTRUCTION VIBRATION STANDARDS
Construction activity can result in varying degrees of ground-borne vibration, depending on the equipment and methods used, distance to the affected structures and soil type. Construction vibration is generally associated with pile driving and rock blasting. Other construction equipment such as air compressors, light trucks, hydraulic loaders, etc., generates little or no ground vibration. (8) To analyze vibration impacts originating from the operation and construction of the Varner Road / West Drive Logistics, vibration-generating activities are appropriately evaluated against standards established under the Municipal Code if such standards exist. However, the City of Desert Hot Springs does not identify specific construction vibration level limits. Therefore, for analysis purposes, the Caltrans Transportation and Construction Vibration Guidance Manual, (9 p. 38)Table 19, vibration damage is used in this noise study to assess potential temporary construction-related impacts at adjacent building locations. The nearest noise sensitive buildings adjacent to the Project site can best be described as “older residential structures” with a maximum acceptable continuous vibration threshold of 0.3 PPV (in/sec).

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4 SIGNIFICANCE CRITERIA
The following significance criteria are based on currently adopted guidance provided by Appendix G of the California Environmental Quality Act (CEQA) Guidelines. (1) For the purposes of this report, impacts would be potentially significant if the Project results in or causes:

A. Generation of a substantial temporary or permanent increase in ambient noise levels in the vicinity of the project in excess of standards established in the local general plan or noise ordinance, or applicable standards of other agencies?
B. Generation of excessive ground-borne vibration or ground-borne noise levels? C. For a project located within the vicinity of a private airstrip or an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project expose people residing or working in the project area to excessive noise levels?

4.1 NOISE LEVEL INCREASES (THRESHOLD A)
Noise level increases resulting from the Project are evaluated based on the Appendix G CEQA Guidelines. Under CEQA, consideration must be given to the magnitude of the increase, the existing baseline ambient noise levels, and the location of receivers to determine if a noise increase represents a significant adverse environmental impact. This approach recognizes that there is no single noise increase that renders the noise impact significant. (15) This is primarily because of the wide variation in individual thresholds of annoyance and differing individual experiences with noise.

Thus, an important way of determining a person’s subjective reaction to a new noise is the comparison of it to the existing environment to which one has adapted—the so-called ambient environment.

4.1.1 Noise Sensitive Receivers (Substantial Permanent Noise Level Increase) The Federal Interagency Committee on Noise (FICON) (16) developed guidance to be used for the assessment of project-generated increases in noise levels that consider the ambient noise level. The FICON recommendations are based on studies that relate aircraft noise levels to the percentage of persons highly annoyed by aircraft noise. Although the FICON recommendations were specifically developed to assess aircraft noise impacts, these recommendations are often used in environmental noise impact assessments involving the use of cumulative noise exposure metrics, such as the average-daily noise level (CNEL) and equivalent continuous noise level (Leq). In general, the more a new noise level exceeds the previously existing ambient noise level, the less acceptable the new noise level will typically be judged.

As previously stated, the approach used in this noise study recognizes that there is no single noise increase that renders a noise impact significant, based on a 2008 California Court of Appeal ruling on Gray v. County of Madera. (15) For example, if the ambient noise environment is quiet (<60 dBA) and the new noise source greatly increases the noise levels, an impact may occur if the noise criteria may be exceeded. Therefore, for this analysis, a readily perceptible 5 dBA or greater project-related noise level increase is considered a significant impact when the without project noise levels are below 60 dBA. Per the FICON, in areas where the without project noise levels range from 60 to 65 dBA, a 3 dBA barely perceptible noise level increase appears to be appropriate for most people.

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louder than 1.5 dBA or greater is considered a significant impact if the noise criteria for a given land use is exceeded, since it likely contributes to an existing noise exposure exceedance.

The FICON guidance provides an established source of criteria to assess the impacts of substantial temporary or permanent increase in baseline ambient noise levels. Based on the FICON criteria, the amount to which a given noise level increase is considered acceptable is reduced when the without Project (baseline) noise levels are already shown to exceed certain land-use specific exterior noise level criteria. The specific levels are based on typical responses to noise level increases of 5 dBA or readily perceptible, 3 dBA or barely perceptible, and 1.5 dBA depending on the underlying without Project noise levels for noise-sensitive uses. These levels of increases and their perceived acceptance are consistent with guidance provided by both the Federal Highway Administration (4 p. 9) and Caltrans (17 p. 2_48).

4.1.2 Non-Noise Sensitive Receivers (Substantial Permanent Noise Level Increase) The City of Desert Hot Springs General Plan Noise Element, Table SN-2, Noise and Land Use Compatibility Guidelines were used to establish the satisfactory noise levels of significance for nonnoise-sensitive land uses in the Project study area. As previously shown on Exhibit 3-1, the normally acceptable exterior noise level for non-noise-sensitive industrial land uses are 70 dBA CNEL. Noise levels greater than 70 dBA CNEL are considered conditionally acceptable per the Noise and Land Use Compatibility Guidelines. (11) To determine if Project-related traffic noise increases are significant at off-site non-noise-sensitive land uses, a barely perceptible 3 dBA criteria is used. When the without Project noise levels are greater than the normally acceptable 70 dBA CNEL land use compatibility criteria, a barely perceptible 3 dBA or greater noise level increase is considered a significant impact since the noise level criteria is already exceeded. The noise increases used to determine significant impacts for non-noise-sensitive land uses is generally consistent with the FICON noise level increase thresholds for noise-sensitive land uses but instead rely on the City of Desert Hot Springs General Plan Noise Element, Table SN-2, Noise and Land Use Compatibility Guidelines normally acceptable 70 dBA CNEL exterior noise level criteria.

4.1.3 Construction Noise (Substantial Temporary Noise Level Increase) To control the noise-generating construction activities, the temporary noise level increases over the existing ambient conditions must be considered under CEQA Significance Threshold A. Although noise ordinances vary across jurisdictions, many cities and counties in California, including Los Angeles, San Diego, and San Francisco, set construction noise limits between 75 and 80 dBA Leq and typically restrict construction activities to the daytime hours. In contrast, everyday noise regulations are more stringent because they apply to continuous, long-term noise sources that can significantly impact the quality of life. As a result, many jurisdictions establish daytime residential noise limits around 55 dBA Leq. This suggests that a reasonable 20 dBA increase over the daytime noise limit can be tolerated without significant adverse effects. This is also illustrated in the adoption of many CEQA documents statewide that use an 80 dBA Leq limit for assessing construction impacts while using everyday noise level limits of local noise ordinances in assessing on-site operational impacts.

Therefore, if the Project-related construction noise levels generate a temporary noise level increase over the existing daytime ambient noise levels more than 20 dBA Leq then the Project construction noise increases will be considered a significant impact.

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4.2 VIBRATION (THRESHOLD B)
As described in Section 3.4, the vibration impacts originating from the construction of the Varner Road / West Drive Logistics, vibration-generating activities are appropriately evaluated using standards established by the Caltrans Transportation and Construction Vibration Guidance Manual, Table 19. Caltrans’ vibration thresholds for building damage are used in this noise study to assess potential operational and temporary construction-related impacts at adjacent building locations. A maximum acceptable continuous vibration threshold of 0.3 PPV (in/sec) is used to describe the nearest residential buildings adjacent to the Project site.

4.3 CEQAGUIDELINES NOT FURTHER ANALYZED (THRESHOLD C)
CEQA Noise Threshold C applies when there are nearby public and private airports and/or airstrips and focuses on land use compatibility of the Project to nearby airports and airstrips. The Project site is not located within two miles of an airport or airstrip. The closest major airport is the Palm Springs International Airport, located over 3 miles south of the Project site. As such, the Project site would not be exposed to excessive noise levels from airport operations, and therefore, impacts are considered less than significant, and no further noise analysis is conducted in relation to Appendix G to the CEQA Guidelines, Noise Threshold C.

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4.4 SIGNIFICANCE CRITERIA SUMMARY
Noise impacts shall be considered significant if any of the following occur as a direct result of the proposed development. Table 4-1 shows the significance criteria summary matrix that includes the allowable criteria used to identify potentially significant incremental noise level increases.

TABLE 4-1: SIGNIFICANCE CRITERIA SUMMARY
Analysis Receiving
Land Use Condition(s)
Significance Criteria
Daytime Nighttime
Off-Site
Traffic Noise-Sensitive
If ambient is < 60 dBA CNEL1 ≥ 5 dBA CNEL Project increase If ambient is 60 - 65 dBA CNEL1 ≥ 3 dBA CNEL Project increase If ambient is > 65 dBA CNEL1 ≥ 1.5 dBA CNEL Project increase Off-Site
Traffic Non-Noise-Sensitive If ambient is > 70 dBA CNEL2 ≥ 3 dBA CNEL Project increase Operational Noise-Sensitive
Residential Exterior Noise Level3 65 dBA Leq 45 dBA Leq If ambient is < 60 dBA Leq
1 ≥ 5 dBA Leq Project increase
If ambient is 60 - 65 dBA Leq
1 ≥ 3 dBA Leq Project increase
If ambient is > 65 dBA Leq
1 ≥ 1.5 dBA Leq Project increase
Construction Noise-Sensitive
Noise Level Threshold4 80 dBA Leq 70 dBA Leq
Exterior Noise Level Increase5 20 dBA Leq
Vibration Level Threshold6 0.3 PPV (in/sec)
1 FICON, 1992.
2 City of Desert Hot Springs Noise and Land Use Compatibility Guidelines (Exhibit 3-1). 3 County of Riverside General Plan Noise Element, Policy N 4.1. 4 Federal Transit Administration, Transit Noise and Vibration Impact Assessment Manual. 5 Temporary construction noise increases that can be tolerated without significant adverse effects. 6 Caltrans Transportation and Construction Vibration Manual, April 2020 Table 19 "Daytime" = 7:00 a.m. to 10:00 p.m.; "Nighttime" = 10:00 p.m. to 7:00 a.m.

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16328-02 NA 21 Varner Road / West Drive Logistics
5 EXISTING NOISE LEVEL MEASUREMENTS
To assess the existing noise level environment, 24-hour noise level measurements were taken at six locations in the Project study area. The receiver locations were selected to describe and document the existing noise environment within the Project study area. Exhibit 5-1 provides the boundaries of the Project study area and the noise level measurement locations. To fully describe the existing noise conditions, long-term noise level measurements were collected by Urban Crossroads, Inc. on Thursday, February 20, 2025. Appendix 5.1 includes study area photos.

5.1 MEASUREMENT PROCEDURE AND CRITERIA
To describe the existing noise environment, the hourly noise levels were measured during typical weekday conditions over a 24-hour period. By collecting individual hourly noise level measurements, it is possible to describe the equivalent daytime and nighttime hourly noise levels.

The long-term noise readings were recorded using Piccolo Type 2 integrating sound level meter and dataloggers. The Piccolo sound level meters were calibrated using a Larson-Davis calibrator, Model CAL 150. All noise meters were programmed in "slow" mode to record noise levels in "A" weighted form. The sound level meters and microphones were equipped with a windscreen during all measurements. All noise level measurement equipment satisfies the American National Standards Institute (ANSI) standard specifications for sound level meters ANSI S1.4-2014/IEC 61672-1:2013. (18)

5.2 NOISE MEASUREMENT LOCATIONS
The long-term noise level measurements were positioned as close to the nearest sensitive receiver locations as possible to assess the existing equivalent hourly noise levels surrounding the Project site. Both Caltrans and the FTA recognize that it is not reasonable to collect noise level measurements that can fully represent every part of a private yard, patio, deck, or balcony normally used for human activity when estimating impacts for new development projects. This is demonstrated in the Caltrans general site location guidelines which indicate that, sites must be free of noise contamination by sources other than sources of interest. Avoid sites located near sources such as barking dogs, lawnmowers, pool pumps, and air conditioners unless it is the express intent of the analyst to measure these sources. (2) Further, FTA guidance states, that it is not necessary nor recommended that existing noise exposure be determined by measuring at every noise-sensitive location in the project area. Rather, the recommended approach is to characterize the noise environment for clusters of sites based on measurements or estimates at representative locations in the community. (8)
Based on recommendations of Caltrans and the FTA, it is not necessary to collect measurements at each individual building or residence, because each receiver measurement represents a group of buildings that share acoustical equivalence. (8) In other words, the area represented by the receiver shares similar shielding, terrain, and geometric relationship to the reference noise source. Receivers represent a location of noise sensitive areas and are used to estimate the future noise level impacts.

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16328-02 NA 22 Varner Road / West Drive Logistics
EXHIBIT 5-1: NOISE MEASUREMENT LOCATIONS
Collecting noise level measurements at the nearby sensitive receiver locations allows for a comparison of the before and after Project noise levels and is necessary to assess potential noise increase due to the Project’s contribution to the ambient noise levels. This approach is necessary to calculate the temporary or permanent increase in ambient noise levels as required by the CEQA Guidelines Environmental Checklist.

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16328-02 NA 23 Varner Road / West Drive Logistics

5.3 NOISE MEASUREMENT RESULTS
The noise measurements presented below focus on the equivalent or the hourly energy average sound levels (Leq) to describe the existing ambient conditions. Table 5-1 provides the (energy average) noise levels used to describe the hourly daytime (7:00 a.m. to 10:00 p.m.) and nighttime (10:00 p.m. to 7:00 a.m.) noise levels at each noise level measurement location. The equivalent sound level (Leq) represents a steady state sound level containing the same total energy as a time varying signal over a given sample period. The daytime and nighttime equivalent noise levels represent the average of all hourly noise levels observed during these time periods expressed as a single number.

TABLE 5-1: AMBIENT NOISE LEVEL MEASUREMENTS
Location1 Description
Energy Average
Noise Level
(dBA Leq)
2 CNEL
Daytime Nighttime
L1 Located northeast of the site near the residence
at 66625 20th Ave. 51.9 48.6 55.9
L2 Located northeast of the site near the residence
at 20600 Circle B Dr. 44.2 38.9 46.8
L3 Located east of the site near the residence at
65900 Thornton Rd. 57.4 51.4 59.7
L4 Located south of the site near the residence at
3301 Salvia Rd. 73.7 68.2 76.4
L5 Located south of the site near the residence at
65995 Thornton Rd. 56.5 51.2 59.3
L6 Located southwest of the site near the residence
at 1810 Fan Palm Way 45.8 40.5 48.6
1 See Exhibit 5-A for the noise level measurement locations. 2 Energy (logarithmic) average levels. The long-term 24-hour measurement worksheets are included in Appendix 5.2. "Daytime" = 7:00 a.m. to 10:00 p.m.; "Nighttime" = 10:00 p.m. to 7:00 a.m.

Table 5-1 provides the equivalent noise levels used to describe the daytime and nighttime ambient conditions for each of the measurements. Appendix 5.2 provides summary worksheets of the noise levels for each hour as well as the minimum, maximum, L1, L2, L5, L8, L25, L50, L90, L95, and L99 percentile noise levels observed during the daytime and nighttime periods.

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16328-02 NA 25 Varner Road / West Drive Logistics
6 TRAFFIC NOISE METHODS AND PROCEDURES
The following section outlines the methods and procedures used to estimate and analyze the future traffic noise environment. Consistent with the City of Desert Hot Springs General Plan, Noise and Land Use Compatibility Guidelines(Table SN-2), all transportation-related noise levels for the outdoor activity areas are presented in terms of the 24-hour CNEL’s. Unlike a simple arithmetic average noise level, CNEL represents the logarithmic summation of the equivalent hourly noise levels with evening and nighttime noise penalties recognizing that noise may have different impacts on people depending on when it occurs.

6.1 FHWA TRAFFIC NOISE PREDICTION MODEL
The expected roadway noise level increases from vehicular traffic were calculated by Urban Crossroads, Inc. using a computer program that replicates the Federal Highway Administration (FHWA) Traffic Noise Prediction Model- FHWA-RD-77-108. (19) This methodology is commonly used to describe the off-site traffic noise levels throughout southern California. The FHWA Model arrives at a predicted noise level through a series of adjustments to the Reference Energy Mean Emission Level (REMEL) by vehicle type. REMEL represents the maximum sound level (Lmax) of individual vehicle “pass by” events by vehicle type when measured at a “reference distance” of 50 feet from the center of the travel lane. This is the same methodology and approach used for the City of Desert Hot Springs General Plan. (11) In California the national REMELs are substituted with the California Vehicle Noise (Calveno) Emission Levels. (17) Adjustments are then made to the REMEL to account for: the roadway classification (e.g., collector, secondary, major or arterial), the roadway active width (i.e., the distance between the center of the outermost travel lanes on each side of the roadway), the total average daily traffic (ADT), the travel speed, the percentages of automobiles, medium trucks, and heavy trucks in the traffic volume, the roadway grade, the angle of view (e.g., whether the roadway view is blocked), the site conditions ("hard" or"soft" relates to the absorption of the ground, pavement, or landscaping), and the percentage of total ADT which flows each hour throughout a 24- hour period. Research conducted by Caltrans has shown that the use of soft site conditions is appropriate for the application of the FHWA traffic noise prediction model used in this analysis. (20)

6.2 OFF-SITE TRAFFIC NOISE PREDICTION MODEL INPUTS
Table 6-1 presents the roadway parameters used to assess the Project’s off-site dBA CNEL transportation noise impacts. Table 6-1 identifies the 6 off-site study area roadway segments, the distance from the centerline to adjacent land use based on the functional roadway classifications per the City of Desert Hot Springs General Plan Circulation Element, and the vehicle speeds. The ADT volumes used in this study area presented on Table 6-2 are based on the Varner Road / West Drive LogisticsTraffic Analysis prepared by Urban Crossroads, Inc. for the following traffic scenarios (21):
• Existing without Project (E)
• Existing with Project (EP)
• Existing plus Ambient plus Cumulative (EAC) 2027 without Project • Existing plus Ambient plus Cumulative (EACP) 2027 with Project • Horizon Year 2045 (HY) without Project
• Horizon Year 2045 (HYP) with Project
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16328-02 NA 26 Varner Road / West Drive Logistics
The ADT volumes vary for each roadway segment based on the existing traffic volumes and the combination of project traffic distributions. This analysis relies on a comparative evaluation of the off-site traffic noise impacts at the boundary of the right-of-way of the receiving adjacent land use, without and with project ADT traffic volumes from the Project traffic analysis. Consistent with the Varner Road / West Drive Logistics Traffic Analysis, the Project is anticipated to generate a net total of 3,194 two-way trips per day (actual vehicles) that includes 960 truck trips.

To quantify the off-site noise levels, Project-related truck trips were added to the heavy truck category in the FHWA noise prediction model. The addition of the Project related truck trips increases the percentage of heavy trucks in the vehicle mix. This approach recognizes that the FHWA noise prediction model is significantly influenced by the number of heavy trucks in the vehicle mix.

The unadjusted daily Project truck trip-ends were assigned to the individual off-site study area roadway segments based on the Project truck trip distribution percentages documented in the traffic study.Table 6-3 provides the time of day (daytime, evening, and nighttime) vehicle splits and the traffic flow by vehicle type (vehicle mix) used for all without Project traffic scenarios. Tables 6-4 to 6-6 show the with Project vehicle mix. Due to the added Project truck trips, the increase in Project traffic volumes and the distributions of trucks on the study area road segments, the percentage of autos, medium trucks and heavy trucks will vary for each of the traffic scenarios. This explains why the existing and future traffic volumes and vehicle mixes vary between seemingly identical study area roadway segments.

TABLE 6-1: OFF-SITE ROADWAY PARAMETERS
ID Roadway Segment Receiving
Land Use1
Classification2
Distance from
Centerline to
Receiving
Land Use
(Feet)3
Vehicle
Speed
(mph)
1 Palm Dr. n/o Varner Rd. Non-Sensitive Urban Arterial 71' 60 2 Palm Dr. s/o Varner Rd. Non-Sensitive Urban Arterial 71' 60 3 Palm Dr. n/o Paul Rd. Non-Sensitive Urban Arterial 71' 60 4 Palm Dr. s/o Paul Rd. Non-Sensitive Urban Arterial 71' 60 5 Palm Dr. s/o I-10 Fwy. Non-Sensitive Urban Arterial 71' 60 6 Varner Rd. e/o Palm Dr. Non-Sensitive Secondary 50' 55 1 Based on a review of existing aerial imagery.
2 Varner Road / West Drive Logistics Traffic Analysis, Urban Crossroads, Inc. 3 Distance to receiving land use is based upon the right-of-way distances.

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16328-02 NA 27 Varner Road / West Drive Logistics
TABLE 6-2: AVERAGE DAILY TRAFFIC VOLUMES
ID Roadway Segment
Average Daily Traffic Volumes (Actual Vehicles)1
Existing
Without
Project
Existing
With
Project
EAC
(2027)
Without
Project
EACP
(2027)
With
Project
Horizon
Year
(2045)
Without
Project
Horizon
Year
(2045)
With
Project
1 Palm Dr. n/o Varner Rd. 35,987 36,230 44,193 44,436 50,060 50,303 2 Palm Dr. s/o Varner Rd. 37,484 40,305 45,750 48,571 49,991 52,812 3 Palm Dr. n/o Paul Rd. 37,484 40,305 45,750 48,571 50,071 52,892 4 Palm Dr. s/o Paul Rd. 38,707 41,528 47,023 49,844 52,981 55,802 5 Palm Dr. s/o I-10 Fwy. 29,625 29,868 34,247 34,490 41,596 41,839 6 Varner Rd. e/o Palm Dr. 1,866 1,997 1,941 2,072 5,716 5,847 1 Varner Road / West Drive Logistics Traffic Analysis, Urban Crossroads, Inc.

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16328-02 NA 28 Varner Road / West Drive Logistics
TABLE 6-3: TIME OF DAY VEHICLE SPLITS
Time of Day
Vehicle Mix1
Time of Day
Split1
Autos2 Medium Trucks3 Heavy Trucks4
Daytime 70.71% 1.52% 1.46% 73.68%
Evening 10.16% 0.10% 0.09% 10.36%
Nighttime 15.40% 0.26% 0.30% 15.96%
Daily 96.27% 1.88% 1.85% 100.00%
1 Based on the 24-hour directional vehicle classification count collected on Palm Drive north of the I-10 Freeway on February 20, 2025 (Varner Road / West Drive Logistics Traffic Analysis, Urban Crossroads, Inc.) 2 All vehicles with two axles and four wheels designed primarily for transportation of nine or fewer passengers (automobiles) or transportation of cargo (light trucks).
3 All vehicles with two axles and six wheels designed for transportation of cargo. 4 All vehicles with three or more axles designed for the transportation of cargo.

TABLE 6-4: EXISTING WITH PROJECT VEHICLE MIX
ID Roadway Segment
With Project1
Autos Medium
Trucks
Heavy
Trucks Total2
1 Palm Dr. n/o Varner Rd. 96.24% 1.88% 1.88% 100.00%
2 Palm Dr. s/o Varner Rd. 94.24% 2.21% 3.55% 100.00%
3 Palm Dr. n/o Paul Rd. 94.24% 2.21% 3.55% 100.00%
4 Palm Dr. s/o Paul Rd. 94.30% 2.20% 3.50% 100.00%
5 Palm Dr. s/o I-10 Fwy. 96.23% 1.88% 1.89% 100.00%
6 Varner Rd. e/o Palm Dr. 95.55% 1.95% 2.50% 100.00%
1 Total of vehicle mix percentage values rounded to the nearest one-hundredth.

TABLE 6-5: EACP (2027) WITH PROJECT VEHICLE MIX
ID Roadway Segment
With Project1
Autos Medium
Trucks
Heavy
Trucks Total2
1 Palm Dr. n/o Varner Rd. 96.25% 1.88% 1.87% 100.00%
2 Palm Dr. s/o Varner Rd. 94.59% 2.15% 3.26% 100.00%
3 Palm Dr. n/o Paul Rd. 94.59% 2.15% 3.26% 100.00%
4 Palm Dr. s/o Paul Rd. 94.63% 2.15% 3.22% 100.00%
5 Palm Dr. s/o I-10 Fwy. 96.24% 1.88% 1.88% 100.00%
6 Varner Rd. e/o Palm Dr. 95.58% 1.95% 2.47% 100.00%
1 Total of vehicle mix percentage values rounded to the nearest one-hundredth.

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16328-02 NA 29 Varner Road / West Drive Logistics
TABLE 6-6: HY (2045)WITH PROJECT VEHICLE MIX
ID Roadway Segment
With Project1
Autos Medium
Trucks
Heavy
Trucks Total2
1 Palm Dr. n/o Varner Rd. 96.25% 1.88% 1.87% 100.00%
2 Palm Dr. s/o Varner Rd. 94.72% 2.13% 3.15% 100.00%
3 Palm Dr. n/o Paul Rd. 94.72% 2.13% 3.15% 100.00%
4 Palm Dr. s/o Paul Rd. 94.81% 2.12% 3.08% 100.00%
5 Palm Dr. s/o I-10 Fwy. 96.24% 1.88% 1.88% 100.00%
6 Varner Rd. e/o Palm Dr. 96.02% 1.91% 2.07% 100.00%
1 Total of vehicle mix percentage values rounded to the nearest one-hundredth.

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16328-02 NA 31 Varner Road / West Drive Logistics
7 OFF-SITE TRAFFIC NOISE ANALYSIS
To assess the off-site transportation CNEL noise level impacts associated with the development of the proposed Project, noise contours were developed based on the Varner Road / West Drive Logistics Traffic Analysis prepared by Urban Crossroads, Inc. (21) Noise contour boundaries represent the equal levels of noise exposure and are measured in CNEL from the center of the roadway.

7.1 TRAFFIC NOISE CONTOURS
Noise contours were used to assess the Project’s incremental 24-hour dBA CNEL traffic-related noise impacts at land uses adjacent to roadways conveying Project traffic. The noise contours represent the distance to noise levels of a constant value and are measured from the center of the roadway for the 70, 65, and 60 dBA CNEL noise levels. The noise contours do not consider the effect of any existing noise barriers or topography that may attenuate ambient noise levels. In addition, because the noise contours reflect modeling of vehicular noise on area roadways, they appropriately do not reflect noise contributions from the surrounding stationary noise sources within the Project study area. Tables 7-1 through 7-6 present a summary of the exterior dBA CNEL traffic noise levels for each traffic condition. Appendix 7.1 includes a summary of the dBA CNEL traffic noise level contour worksheets for each of the traffic conditions.

7.2 EXISTING PROJECT TRAFFIC NOISE LEVEL INCREASES
An analysis of existing traffic noise levels plus traffic noise generated by the proposed Project has been included in this report to fully analyze all the existing traffic scenarios identified in the traffic study. This condition is provided solely for informational purposes and will not occur, since the Project will not be fully developed and occupied under Existing conditions. Table 7-1 shows the Existing without Project conditions CNEL noise levels. The Existing without Project exterior noise levels is expected to range from 64.2 to 77.0 dBA CNEL, without accounting for any noise attenuation features such as noise barriers or topography. Table 7-2 shows the Existing with Project conditions will range from 64.9 to 78.4 dBA CNEL. Table 7-7 shows that the Project off-site traffic noise level impacts will range from 0.0 to 1.4 dBA CNEL. Based on the significance criteria for off-site traffic noise presented in Table 4-1, land uses adjacent to the study area roadway segments would experience less than significant noise level impacts due to unmitigated Project-related traffic noise levels.

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16328-02 NA 32 Varner Road / West Drive Logistics
TABLE 7-1: EXISTING WITHOUT PROJECT CONTOURS
ID Road Segment Receiving
Land Use1
CNEL at
Receiving
Land Use
(dBA)2
Distance to Contour from
Centerline (Feet)
70 dBA
CNEL
65 dBA
CNEL
60 dBA
CNEL
1 Palm Dr. n/o Varner Rd. Non-Sensitive 76.7 56 122 262 2 Palm Dr. s/o Varner Rd. Non-Sensitive 76.9 RW 111 240 3 Palm Dr. n/o Paul Rd. Non-Sensitive 76.9 RW 75 161
4 Palm Dr. s/o Paul Rd. Non-Sensitive 77.0 75 162 350
5 Palm Dr. s/o I-10 Fwy. Non-Sensitive 75.9 75 161 347
6 Varner Rd. e/o Palm Dr. Non-Sensitive 64.2 170 367 790 1 Based on a review of existing aerial imagery.
2 The CNEL is calculated at the boundary of the right-of-way of the receiving adjacent land use. "RW" = Location of the respective noise contour falls within the right-of-way of the road.

TABLE 7-2: EXISTING WITH PROJECT CONTOURS
ID Road Segment Receiving
Land Use1
CNEL at
Receiving
Land Use
(dBA)2
Distance to Contour from
Centerline (Feet)
70 dBA
CNEL
65 dBA
CNEL
60 dBA
CNEL
1 Palm Dr. n/o Varner Rd. Non-Sensitive 76.8 56 122 262 2 Palm Dr. s/o Varner Rd. Non-Sensitive 78.3 RW 111 240 3 Palm Dr. n/o Paul Rd. Non-Sensitive 78.3 RW 75 161
4 Palm Dr. s/o Paul Rd. Non-Sensitive 78.4 75 162 350
5 Palm Dr. s/o I-10 Fwy. Non-Sensitive 75.9 75 161 347
6 Varner Rd. e/o Palm Dr. Non-Sensitive 64.9 170 367 790 1 Based on a review of existing aerial imagery.
2 The CNEL is calculated at the boundary of the right-of-way of the receiving adjacent land use. "RW" = Location of the respective noise contour falls within the right-of-way of the road.

TABLE 7-3: EAC(2027)WITHOUT PROJECT CONTOURS
ID Road Segment Receiving
Land Use1
CNEL at
Receiving
Land Use
(dBA)2
Distance to Contour from
Centerline (Feet)
70 dBA
CNEL
65 dBA
CNEL
60 dBA
CNEL
1 Palm Dr. n/o Varner Rd. Non-Sensitive 77.6 56 122 262 2 Palm Dr. s/o Varner Rd. Non-Sensitive 77.8 RW 111 240 3 Palm Dr. n/o Paul Rd. Non-Sensitive 77.8 RW 75 161
4 Palm Dr. s/o Paul Rd. Non-Sensitive 77.9 75 162 350
5 Palm Dr. s/o I-10 Fwy. Non-Sensitive 76.5 75 161 347
6 Varner Rd. e/o Palm Dr. Non-Sensitive 64.3 170 367 790 1 Based on a review of existing aerial imagery.
2 The CNEL is calculated at the boundary of the right-of-way of the receiving adjacent land use. "RW" = Location of the respective noise contour falls within the right-of-way of the road.

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16328-02 NA 33 Varner Road / West Drive Logistics
TABLE 7-4: EACP (2027) WITH PROJECT CONTOURS
ID Road Segment Receiving
Land Use1
CNEL at
Receiving
Land Use
(dBA)2
Distance to Contour from
Centerline (Feet)
70 dBA
CNEL
65 dBA
CNEL
60 dBA
CNEL
1 Palm Dr. n/o Varner Rd. Non-Sensitive 77.6 56 122 262 2 Palm Dr. s/o Varner Rd. Non-Sensitive 78.9 RW 111 240 3 Palm Dr. n/o Paul Rd. Non-Sensitive 78.9 RW 75 161
4 Palm Dr. s/o Paul Rd. Non-Sensitive 79.0 75 162 350
5 Palm Dr. s/o I-10 Fwy. Non-Sensitive 76.6 75 161 347
6 Varner Rd. e/o Palm Dr. Non-Sensitive 65.1 170 367 790 1 Based on a review of existing aerial imagery.
2 The CNEL is calculated at the boundary of the right-of-way of the receiving adjacent land use. "RW" = Location of the respective noise contour falls within the right-of-way of the road.

TABLE 7-5: HY (2045)WITHOUT PROJECT CONTOURS
ID Road Segment Receiving
Land Use1
CNEL at
Receiving
Land Use
(dBA)2
Distance to Contour from
Centerline (Feet)
70 dBA
CNEL
65 dBA
CNEL
60 dBA
CNEL
1 Palm Dr. n/o Varner Rd. Non-Sensitive 78.2 56 122 262 2 Palm Dr. s/o Varner Rd. Non-Sensitive 78.1 RW 111 240 3 Palm Dr. n/o Paul Rd. Non-Sensitive 78.2 RW 75 161
4 Palm Dr. s/o Paul Rd. Non-Sensitive 78.4 75 162 350
5 Palm Dr. s/o I-10 Fwy. Non-Sensitive 77.3 75 161 347
6 Varner Rd. e/o Palm Dr. Non-Sensitive 69.0 170 367 790 1 Based on a review of existing aerial imagery.
2 The CNEL is calculated at the boundary of the right-of-way of the receiving adjacent land use. "RW" = Location of the respective noise contour falls within the right-of-way of the road.

TABLE 7-6: HY (2045)WITH PROJECT CONTOURS
ID Road Segment Receiving
Land Use1
CNEL at
Receiving
Land Use
(dBA)2
Distance to Contour from
Centerline (Feet)
70 dBA
CNEL
65 dBA
CNEL
60 dBA
CNEL
1 Palm Dr. n/o Varner Rd. Non-Sensitive 78.2 56 122 262 2 Palm Dr. s/o Varner Rd. Non-Sensitive 79.2 RW 111 240 3 Palm Dr. n/o Paul Rd. Non-Sensitive 79.2 RW 75 161
4 Palm Dr. s/o Paul Rd. Non-Sensitive 79.4 75 162 350
5 Palm Dr. s/o I-10 Fwy. Non-Sensitive 77.4 75 161 347
6 Varner Rd. e/o Palm Dr. Non-Sensitive 69.3 170 367 790 1 Based on a review of existing aerial imagery.
2 The CNEL is calculated at the boundary of the right-of-way of the receiving adjacent land use. "RW" = Location of the respective noise contour falls within the right-of-way of the road.

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16328-02 NA 34 Varner Road / West Drive Logistics
TABLE 7-7: EXISTING WITH PROJECT TRAFFIC NOISE LEVEL INCREASES ID Road Segment Receiving
Land Use1
CNEL at Receiving
Land Use (dBA)2
Incremental Noise Level
Increase Threshold3
No
Project
With
Project
Project
Addition Limit Exceeded?
1 Palm Dr. n/o Varner Rd. Non-Sensitive 76.7 76.8 0.1 3.0 No 2 Palm Dr. s/o Varner Rd. Non-Sensitive 76.9 78.3 1.4 3.0 No 3 Palm Dr. n/o Paul Rd. Non-Sensitive 76.9 78.3 1.4 3.0 No 4 Palm Dr. s/o Paul Rd. Non-Sensitive 77.0 78.4 1.4 3.0 No 5 Palm Dr. s/o I-10 Fwy. Non-Sensitive 75.9 75.9 0.0 3.0 No 6 Varner Rd. e/o Palm Dr. Non-Sensitive 64.2 64.9 0.7 n/a No 1 Based on a review of existing aerial imagery. Noise sensitive uses limited to existing residential land uses. 2 The CNEL is calculated at the boundary of the right-of-way of each roadway and the property line of the receiving land use. 3 Does the Project create an incremental noise level increase exceeding the significance criteria (Table 4-1)? "n/a" Per the City of Hot Springs General Plan Noise Element, Table SN-2, Noise and Land Use Compatibility Guidelines, unmitigated normally acceptable exterior noise levels of less than 70 dBA CNEL are considered less than significant and a barely perceptible 3 dBA or greater noise level increase is considered a significant impact when the non-noise sensitive noise level is greater than the normally acceptable 70 dBA CNEL land use compatibility guidelines.

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16328-02 NA 35 Varner Road / West Drive Logistics

7.3 EACP (2027) PROJECT TRAFFIC NOISE LEVEL INCREASES
Table 7-3 presents the EAC (2027) without Project conditions CNEL noise levels. The EAC (2027) without Project exterior noise levels are expected to range from 64.3 to 77.9 dBA CNEL, without accounting for any noise attenuation features such as noise barriers or topography. Table 7-4 shows the EACP (2027) with Project conditions will range from 65.1 to 79.0 dBA CNEL. Table 7-8 shows that the Project off-site traffic noise level increases will range from 0.0 to 1.1 dBA CNEL. Based on the significance criteria for off-site traffic noise presented in Table 4-1, land uses adjacent to the study area roadway segments would experience less than significant noise level impacts due to unmitigated Project-related traffic noise levels.

7.4 HY (2045) PROJECT TRAFFIC NOISE LEVEL INCREASES
Table 7-5 presents the Horizon Year (2045) without Project conditions CNEL noise levels. The HY (2045) without Project exterior noise levels are expected to range from 69.0 to 78.4 dBA CNEL, without accounting for any noise attenuation features such as noise barriers or topography. Table 7- 6 shows the HY (2045) with Project conditions will range from 69.3 to 79.4 dBA CNEL. Table 7-9 shows that the Project off-site traffic noise level increases will range from 0.0 to 1.1 dBA CNEL.

Based on the significance criteria for off-site traffic noise presented in Table 4-1, land uses adjacent to the study area roadway segments would experience less than significant noise level impacts due to unmitigated Project-related traffic noise levels.

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16328-02 NA 36 Varner Road / West Drive Logistics
TABLE 7-8: EACP (2027) WITH PROJECT TRAFFIC NOISE LEVEL INCREASES ID Road Segment Receiving
Land Use1
CNEL at Receiving
Land Use (dBA)2
Incremental Noise Level
Increase Threshold3
No
Project
With
Project
Project
Addition Limit Exceeded?
1 Palm Dr. n/o Varner Rd. Non-Sensitive 77.6 77.6 0.0 3.0 No 2 Palm Dr. s/o Varner Rd. Non-Sensitive 77.8 78.9 1.1 3.0 No 3 Palm Dr. n/o Paul Rd. Non-Sensitive 77.8 78.9 1.1 3.0 No 4 Palm Dr. s/o Paul Rd. Non-Sensitive 77.9 79.0 1.1 3.0 No 5 Palm Dr. s/o I-10 Fwy. Non-Sensitive 76.5 76.6 0.1 3.0 No 6 Varner Rd. e/o Palm Dr. Non-Sensitive 64.3 65.1 0.8 n/a No 1 Based on a review of existing aerial imagery. Noise sensitive uses limited to existing residential land uses. 2 The CNEL is calculated at the boundary of the right-of-way of each roadway and the property line of the receiving land use. 3 Does the Project create an incremental noise level increase exceeding the significance criteria (Table 4-1)? "n/a" Per the City of Hot Springs General Plan Noise Element, Table SN-2, Noise and Land Use Compatibility Guidelines, unmitigated normally acceptable exterior noise levels of less than 70 dBA CNEL are considered less than significant and a barely perceptible 3 dBA or greater noise level increase is considered a significant impact when the non-noise sensitive noise level is greater than the normally acceptable 70 dBA CNEL land use compatibility guidelines.

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TABLE 7-9: HY (2045)WITH PROJECT TRAFFIC NOISE LEVEL INCREASES ID Road Segment Receiving
Land Use1
CNEL at Receiving
Land Use (dBA)2
Incremental Noise Level
Increase Threshold3
No
Project
With
Project
Project
Addition Limit Exceeded?
1 Palm Dr. n/o Varner Rd. Non-Sensitive 78.2 78.2 0.0 3.0 No 2 Palm Dr. s/o Varner Rd. Non-Sensitive 78.1 79.2 1.1 3.0 No 3 Palm Dr. n/o Paul Rd. Non-Sensitive 78.2 79.2 1.0 3.0 No 4 Palm Dr. s/o Paul Rd. Non-Sensitive 78.4 79.4 1.0 3.0 No 5 Palm Dr. s/o I-10 Fwy. Non-Sensitive 77.3 77.4 0.1 3.0 No 6 Varner Rd. e/o Palm Dr. Non-Sensitive 69.0 69.3 0.3 n/a No 1 Based on a review of existing aerial imagery. Noise sensitive uses limited to existing residential land uses. 2 The CNEL is calculated at the boundary of the right-of-way of each roadway and the property line of the receiving land use. 3 Does the Project create an incremental noise level increase exceeding the significance criteria (Table 4-1)? "n/a" Per the City of Hot Springs General Plan Noise Element, Table SN-2, Noise and Land Use Compatibility Guidelines, unmitigated normally acceptable exterior noise levels of less than 70 dBA CNEL are considered less than significant and a barely perceptible 3 dBA or greater noise level increase is considered a significant impact when the non-noise sensitive noise level is greater than the normally acceptable 70 dBA CNEL land use compatibility guidelines.

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8 RECEIVER LOCATIONS
To assess the potential for long-term operational and short-term construction noise impacts, the following receiver locations, as shown on Exhibit 8-1, were identified as representative locations for analysis. The selection of receiver locations is based on FHWA guidelines and is consistent with additional guidance provided by Caltrans and the FTA, as previously described in Section 5.2.

Sensitive receivers are generally defined as locations where people reside or where the presence of unwanted sound could otherwise adversely affect the use of the land. Noise-sensitive land uses are generally considered to include schools, hospitals, single-family dwellings, mobile home parks, churches, libraries, and recreation areas. Moderately noise-sensitive land uses typically include multi-family dwellings, hotels, motels, dormitories, out-patient clinics, cemeteries, golf courses, country clubs, athletic/tennis clubs, and equestrian clubs. Land uses that are considered relatively insensitive to noise include business, commercial, and professional developments. Land uses that are typically not affected by noise include: industrial, manufacturing, utilities, agriculture, undeveloped land, parking lots, warehousing, liquid and solid waste facilities, salvage yards, and transit terminals.

To describe the potential off-site Project noise levels, six receiver locations in the vicinity of the Project site were identified. Other sensitive land uses in the Project study area that are located at greater distances than those identified in this noise study will experience lower noise levels than those presented in this report due to the additional attenuation from distance and the shielding of intervening structures. Distance is measured in a straight line from the Project boundary to each receiver location.

R1: Location R1 represents the existing residence at 66625 20thAvenue, approximately 4,892 feet northeast of the Project site. Receiver R1 is placed in the private outdoor living area (backyard) facing the Project site.

A 24-hour noise measurement was taken near this location, L1, to describe the existing ambient noise environment.

R2: Location R2 represents the existing residence at 11233 Finders Court, approximately 5,865 feet east of the Project site Receiver R2 is placed in the private outdoor living area (backyard) facing the Project site. A 24- hour noise measurement was taken near this location, L2, to describe the existing ambient noise environment.

R3: Location R3 represents the existing residence at 65900 Thornton Road, approximately 2,154 feet east of the Project site. Receiver R3 is placed in the private outdoor living area (backyard) facing the Project site.

A 24-hour noise measurement was taken near this location, L3, to describe the existing ambient noise environment.

R4: Location R4 represents the existing residence at 3301 Salvia Road, approximately 1,678 feet south of the Project site. Receiver R4 is placed in the private outdoor living area (backyard) facing the Project site. A 24-hour noise measurement was taken near this location, L4, to describe the existing ambient noise environment.

R5: Location R5 represents the existing residence at 65995 Thornton Road, approximately 189 feet south of the Project site. Receiver R5 is placed in the private outdoor living area (backyard) facing the Project site.

A 24-hour noise measurement was taken near this location, L5, to describe the existing ambient noise environment.

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R6: Location R6 represents the existing residence at 1810 Fan Palm Way, approximately 8,735 feet southwest of the Project site. Receiver R6 is placed in the private outdoor living area (backyard) facing the Project site. A 24-hour noise measurement was taken near this location, L6, to describe the existing ambient noise environment.

EXHIBIT 8-1: RECEIVER LOCATIONS
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9 OPERATIONAL NOISE ANALYSIS
This section analyzes the potential stationary-source operational noise impacts at the nearby receiver locations, identified in Section 8, resulting from the operation of the proposed Varner Road / West Drive Logistics Project. To conservatively describe the potential worst-case noise environment, Exhibit 9-1 presents the 38 individual noise sources used to assess the operational noise levels.

9.1 OPERATIONAL NOISE SOURCES
This operational noise analysis is intended to describe noise level impacts associated with the expected typical daytime and nighttime activities at the Project site. To present the potential worstcase noise conditions, this analysis assumes the Project would be operational 24 hours per day, seven days per week. Consistent with similar warehouse and industrial uses, the Project business operations would primarily be conducted within the enclosed buildings, except for traffic movement, parking, as well as loading and unloading of trucks at designated loading bays. The onsite Project-related noise sources are expected to include: cold storage loading dock activity, tractor trailer storage activity, truck movements, trash enclosure activity, roof-top air conditioning units, and parking lot vehicle movements.

9.2 REFERENCE NOISE LEVELS
To estimate the Project operational noise impacts, reference noise level measurements were collected from similar types of activities to represent the noise levels expected with the development of the proposed Project. This section provides a detailed description of the reference noise level measurements shown on Table 9-1 used to estimate the Project operational noise impacts. It is important to note that the following projected noise levels assume the worst-case noise environment with all noise source activity all operating at the same time. These sources of noise activity will likely vary throughout the day.

9.2.1 Measurement Procedures
The reference noise level measurements presented in this section were collected using a Larson Davis LxT Type 1 precisions sound level meter (serial number 01146). The LxT sound level meter was calibrated using a Larson-Davis calibrator, Model CAL 200, was programmed in "slow" mode to record noise levels in "A" weighted form and was located at approximately five feet above the ground elevation for each measurement. The sound level meters and microphones were equipped with a windscreen during all measurements. All noise level measurement equipment satisfies the American National Standards Institute (ANSI) standard specifications for sound level meters ANSI S1.4- 2014/IEC 61672-1:2013. (18)
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EXHIBIT 9-1: OPERATIONAL NOISE SOURCE LOCATIONS
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TABLE 9-1: REFERENCE NOISE LEVEL MEASUREMENTS
Reference
Noise Source
Noise
Source
Height
(Feet)
Min./
Hour1
Reference
Noise Level
(dBA Leq)
@ 50 Feet
Sound
Power
Level
(dBA) Day Night 2
Cold Storage Loading Dock Activity 8' 60 60 65.7 111.5
Tractor Trailer Storage Activity 8' 60 60 62.8 103.4
Truck Movements 8' 60 60 59.8 93.2
Trash Enclosure Activity 5' 60 30 57.3 89.0
Roof-Top Air Conditioning Units 5' 39 28 57.2 88.9
Parking Lot Vehicle Movements 5' 60 60 52.6 81.1
1 Anticipated duration (minutes within the hour) of noise activity during typical hourly conditions expected at the Project site. "Daytime" = 7:00 a.m. - 10:00 p.m.; "Nighttime" = 10:00 p.m. - 7:00 a.m. 2 Sound power level represents the total amount of acoustical energy (noise level) produced by a sound source independent of distance or surroundings. Sound power levels calculated using the CadnaA noise model at the reference distance to the noise source. Numbers may vary due to size differences between point and area noise sources.

9.2.2 Cold Storage Loading Dock Activity
The reference cold storage loading dock activities are intended to describe the typical outdoor operational noise activities associated with the Project. This includes truck idling, reefer activity (refrigerator truck/cold storage), deliveries, backup alarms, trailer docking including a combination of tractor trailer semi-trucks, two-axle delivery trucks, and background operation activities. Since the noise levels generated by cold storage loading dock activity can be higher due to the use of refrigerated trucks or reefers, this reference noise level conservatively assumes that all loading dock activity is associated with cold storage facilities. (21) The reference noise level measurement was taken in the center of the loading dock activity area and represents multiple concurrent noise sources resulting in a combined noise level of 65.7 dBA Leq at a uniform distance of 50 feet. Specifically, the reference noise level measurement represents one truck located approximately 30 feet from the noise level meter with another truck passing by to park roughly 20 feet away, both with their engines idling. Throughout the reference noise level measurement, a separate docked and running reefer truck was located approximately 50 feet east of the measurement location. Additional background noise sources included truck pass-by noise, truck drivers talking to each other next to docked trucks, and air brake release noise when trucks parked.

9.2.3 Tractor Trailer Storage Activity
To evaluate the noise levels associated with truck idling, backup alarms, trailer movements and storage activities, Urban Crossroads collected a reference noise level measurement at an existing parcel hub facility to describe the potential operational noise levels associated with Project tractor trailer storage activities. The measured reference noise level at 50 feet from activity was measured at 62.8 dBA Leq. The reference noise level measurement includes a semi-truck with trailer pass-by event, background switcher cab trailer towing, drop-off, idling, and backup alarm events. Tractor trailer activity is estimated during all the daytime, evening, and nighttime hours.

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9.2.3 Truck Movements
The truck movements reference noise level measurement was collected over a period of 1 hour and 28 minutes and represent multiple heavy trucks entering and exiting the outdoor loading dock area producing a reference noise level of 59.8 dBA Leq at 50 feet. The noise sources included at this measurement location account for trucks entering and existing the Project driveways and maneuvering in and out of the outdoor loading dock activity area.

9.2.4 Trash Enclosure Activity
To describe the noise levels associated with a trash enclosure activity, Urban Crossroads collected a reference noise level measurement at an existing trash enclosure containing two dumpster bins. The trash enclosure noise levels describe metal gates opening and closing, metal scraping against concrete floor sounds, dumpster movement on metal wheels, and trash dropping into the metal dumpster. The reference noise levels describe trash enclosure noise activities when trash is dropped into an empty metal dumpster, as would occur at the Project Site. The measured reference noise level at the uniform 50-foot reference distance is 59.3 dBA Leq for the trash enclosure activity. The reference noise level describes the expected noise source activities associated with the trash enclosures for the Project’s proposed building.

9.2.5 Roof-Top Air Conditioning Units
The reference noise level represents a Lennox SCA120 series 10-ton model packaged air conditioning unit. At the uniform reference distance of 50 feet, the reference noise level is 59.2 dBA Leq. Based on the typical operating conditions observed over a four-day measurement period, the roof-top air conditioning units are estimated to operate for and average 39 minutes per hour during the daytime hours, and 28 minutes per hour during the nighttime hours. These operating conditions reflect peak summer cooling requirements with measured temperatures approaching 96 degrees Fahrenheit (°F) with average daytime temperatures of 82°F. For this noise analysis, the air conditioning units are expected to be located on the roof of the Project buildings.

9.2.6 Parking Lot Vehicle Movements
To describe the on-site parking lot activity, a long-term reference noise level measurement was collected in the center of activity within the staff parking lot of a warehouse distribution center. At 50 feet from the center of activity, the parking lot produced a reference noise level of 56.1 dBA Leq.

Parking activities are expected to take place during the full hour (60 minutes) throughout the daytime and evening hours. The parking lot noise levels are mainly due to cars pulling in and out of parking spaces in combination with car doors opening and closing.

9.3 CADNAANOISE PREDICTION MODEL
To fully describe the exterior operational noise levels from the Project, Urban Crossroads, Inc. developed a noise prediction model using the CadnaA (Computer Aided Noise Abatement) computer program. CadnaA can analyze multiple types of noise sources using the spatially accurate Project site plan, georeferenced Nearmap aerial imagery, topography, buildings, and barriers in its calculations to predict outdoor noise levels. Using the ISO 9613-2 protocol, CadnaA will calculate the distance from each noise source to the noise receiver locations, using the ground absorption, distance, and barrier/building attenuation inputs to provide a summary of noise level at each receiver Item Number: 1.

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and the partial noise level contributions by noise source. Consistent with the ISO 9613-2 protocol, the CadnaA noise prediction model relies on the reference sound power level (Lw) to describe individual noise sources. While sound pressure levels (e.g., Leq) quantify in decibels the intensity of given sound sources at a reference distance, sound power levels (Lw) are connected to the sound source and are independent of distance.

Sound pressure levels vary substantially with distance from the source and diminish because of intervening obstacles and barriers, air absorption, wind, and other factors. Sound power is the acoustical energy emitted by the sound source and is an absolute value that is not affected by the environment. The operational noise level calculations provided in this noise study account for the distance attenuation provided due to geometric spreading, when sound from a localized stationary source (i.e., a point source) propagates uniformly outward in a spherical pattern. A default ground attenuation factor of 0.5 was used in the noise analysis to account for mixed ground representing a combination of hard and soft surfaces. This approach ensures a reasonable approximation in environments where both hard and soft surfaces exist, aligning with typical real-world conditions.

Appendix 9.1 includes the detailed noise dBA Leq model inputs used to estimate the Project operational noise levels presented in this section.

9.4 PROJECT OPERATIONAL NOISE LEVELS
Using the reference noise levels to represent the Project operations that include cold storage loading dock activity, tractor trailer storage activity, truck movements, trash enclosure activity, roof-top air conditioning units, and parking lot vehicle movements, Urban Crossroads, Inc. calculated the operational source noise levels that are expected to be generated at the Project site and the Projectrelated noise level increases that would be experienced at each of the sensitive receiver locations.

Table 9-2 shows the Project operational noise levels during the daytime hours of 7:00 a.m. to 10:00 p.m. The daytime hourly noise levels at the off-site receiver locations are expected to range from

29.0 to 43.9 dBA Leq.

TABLE 9-2:DAYTIMEPROJECT OPERATIONAL NOISE LEVELS
Noise Source1
Operational Noise Levels by Receiver Location (dBA Leq) R1 R2 R3 R4 R5 R6
Cold Storage Loading Dock Activity 32.6 30.2 37.4 39.8 36.3 25.7 Tractor Trailer Storage Activity 28.8 28.7 39.1 41.4 42.2 25.9 Truck Movements 17.1 15.8 26.8 28.7 28.0 13.9
Trash Enclosure Activity 12.4 10.2 20.0 19.6 15.9 5.2
Roof-Top Air Conditioning Units 10.6 10.3 19.2 21.1 16.8 7.7 Parking Lot Vehicle Movements 10.5 9.0 18.7 20.0 18.8 5.0 Total (All Noise Sources) 34.3 32.7 41.6 43.9 43.4 29.0 1 See Exhibit 9-1 for the noise source locations. CadnaA noise model calculations are included in Appendix 9.1.

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Table 9-3 shows the Project operational noise levels during the nighttime hours from 10:00 p.m. to 7:00 a.m. The nighttime hourly noise levels at the existing off-site receiver locations are expected to range from 29.0 to 43.9 dBA Leq. The differences between the daytime and nighttime noise levels are largely related to the estimated duration of noise activity as outlined in Table 9-1. Appendix 9.1 includes the detailed noise model inputs.

TABLE 9-3:NIGHTTIME PROJECT OPERATIONAL NOISE LEVELS
Noise Source1
Operational Noise Levels by Receiver Location (dBA Leq) R1 R2 R3 R4 R5 R6
Cold Storage Loading Dock Activity 32.6 30.2 37.4 39.8 36.3 25.7 Tractor Trailer Storage Activity 28.8 28.7 39.1 41.4 42.2 25.9 Truck Movements 17.1 15.8 26.8 28.7 28.0 13.9
Trash Enclosure Activity 12.4 10.2 20.0 19.6 15.9 5.2
Roof-Top Air Conditioning Units 10.6 10.3 19.2 21.1 16.8 7.7 Parking Lot Vehicle Movements 10.5 9.0 18.7 20.0 18.8 5.0 Total (All Noise Sources) 34.3 32.7 41.6 43.9 43.4 29.0 1 See Exhibit 9-1 for the noise source locations. CadnaA noise model calculations are included in Appendix 9.1.

9.5 PROJECT OPERATIONAL NOISE LEVEL COMPLIANCE
To demonstrate compliance with local noise regulations, the unmitigated Project-only operational noise levels are evaluated against exterior noise level thresholds at nearby receiver locations. Table 9-4 shows that the mitigated operational noise levels associated with Project will not exceed the daytime and nighttime exterior noise level standards at the existing nearby noise-sensitive receiver locations. Therefore, the mitigated operational noise impacts are considered less than significant at the nearby noise-sensitive receiver locations.

TABLE 9-4: OPERATIONAL NOISE LEVEL COMPLIANCE
Receiver
Location1
Project Operational
Noise Levels (dBA Leq)2
Noise Level Standards
(dBA Leq)3
Noise Level Standards
Exceeded?4
Daytime Nighttime Daytime Nighttime Daytime Nighttime
R1 34.3 34.3 65.0 45.0 No No
R2 32.7 32.7 65.0 45.0 No No
R3 41.6 41.6 65.0 45.0 No No
R4 43.9 43.9 65.0 45.0 No No
R5 43.4 43.4 65.0 45.0 No No
R6 29.0 29.0 65.0 45.0 No No
1 See Exhibit 8-1 for the receiver locations.
2 Proposed Project unmitigated operational noise levels as shown on Tables 9-2 and 9-3. 3 Exterior noise level standards, as shown on Table 4-1. 4 Do the estimated Project operational noise source activities exceed the noise level standards? "Daytime" = 7:00 a.m. - 10:00 p.m.; "Nighttime" = 10:00 p.m. - 7:00 a.m.

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9.6 PROJECT OPERATIONAL NOISE LEVEL INCREASES
To describe the Project operational noise level increases, the Project operational noise levels are combined with the existing ambient noise levels measurements for the nearby receiver locations that may be potentially impacted by Project operational noise sources. Since the units used to measure noise, decibels (dB), are logarithmic units, the Project-operational and existing ambient noise levels cannot be combined using standard arithmetic equations. (2) Instead, they must be logarithmically added using the following base equation:

SPLTotal = 10log10[10SPL1/10 + 10SPL2/10 + … 10SPLn/10] where “SPL1,” “SPL2,” etc. are equal to the sound pressure levels being combined, or in this case, the Project-operational and existing ambient noise levels. The difference between the combined Project and ambient noise levels describes the Project noise level increases to the existing ambient noise environment. Noise levels that would be experienced at receiver locations when Projectsource noise is added to the daytime and nighttime ambient conditions are presented on Tables 9-5 and 9-6, respectively. As indicated on Table 9-5, the Project will generate daytime operational noise increases ranging from 0.0 to 0.3 dBA Leq at the nearest receiver locations. Table 9-6 shows that the Project will generate nighttime operational noise level increases ranging from 0.0 to 0.9 dBA Leq at the nearest receiver locations. Project-related operational noise level increases would not exceed the operational noise level increase significance criteria presented in Table 4-1. Therefore, Project related operational noise level increases at the sensitive receiver locations will be less than significant.

TABLE 9-5: DAYTIMEPROJECT OPERATIONALNOISE LEVEL INCREASES Receiver
Location1
Total Project
Operational
Noise Level2
Measurement
Location3
Reference
Ambient
Noise Levels4
Combined
Project
and
Ambient5
Project
Increase6
Increase
Criteria7
Increase
Criteria
Exceeded?
R1 34.3 L1 51.9 52.0 0.1 5.0 No
R2 32.7 L2 44.2 44.5 0.3 5.0 No
R3 41.6 L3 57.4 57.5 0.1 5.0 No
R4 43.9 L4 73.7 73.7 0.0 1.5 No
R5 43.4 L5 56.5 56.7 0.2 5.0 No
R6 29.0 L6 45.8 45.9 0.1 5.0 No
1 See Exhibit 8-1 for the receiver locations.
2 Total Project daytime operational noise levels as shown on Table 9-2. 3 Reference noise level measurement locations as shown on Exhibit 5-A. 4 Observed daytime ambient noise levels as shown on Table 5-1. 5 Represents the combined ambient conditions plus the Project activities. 6 The noise level increase expected with the addition of the proposed Project activities. 7 Significance increase criteria as shown on Table 4-1.

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TABLE 9-6: NIGHTTIME OPERATIONALNOISE LEVEL INCREASES
Receiver
Location1
Total Project
Operational
Noise Level2
Measurement
Location3
Reference
Ambient
Noise Levels4
Combined
Project
and
Ambient5
Project
Increase6
Increase
Criteria7
Increase
Criteria
Exceeded?
R1 34.3 L1 48.6 48.8 0.2 5.0 No
R2 32.7 L2 38.9 39.8 0.9 5.0 No
R3 41.6 L3 51.4 51.8 0.4 5.0 No
R4 43.9 L4 68.2 68.2 0.0 1.5 No
R5 43.4 L5 51.2 51.9 0.7 5.0 No
R6 29.0 L6 40.5 40.8 0.3 5.0 No
1 See Exhibit 8-A for the receiver locations.
2 Total Project nighttime operational noise levels as shown on Table 9-3. 3 Reference noise level measurement locations as shown on Exhibit 5-A. 4 Observed nighttime ambient noise levels as shown on Table 5-1. 5 Represents the combined ambient conditions plus the Project activities. 6 The noise level increase expected with the addition of the proposed Project activities. 7 Significance increase criteria as shown on Table 4-1.

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10 CONSTRUCTION IMPACTS
This section analyzes potential impacts resulting from the short-term construction activities associated with the development of the Project. Exhibit 10-1 shows the construction noise source activity in relation to the nearest sensitive receiver locations previously described in Section 8.

Section 9.04.030 of the City’s Code of Ordinances, provided in Appendix 3.2, indicates that construction activity is not permitted between the hours of 5:00 p.m. each day and 7:00 a.m. of the next day, except when daylight savings time is in effect. During such time as daylight savings time is in effect in the City, no such activities shall be permitted between the hours of 6:00 p.m. of each day and 6:00 a.m. of the next day and no construction activities are permitted on Sundays. (13)

10.1 CONSTRUCTION NOISE LEVELS
The FTA Transit Noise and Vibration Impact Assessment Manual recognizes that construction projects are accomplished in several different stages and outlines the procedures for assessing noise impacts during construction. Each stage has a specific equipment mix, depending on the work to be completed during that stage. As a result of the equipment mix, each stage has its own noise characteristics; some stages have higher continuous noise levels than others, and some have higher impact noise levels than others. The Project construction activities are expected to occur in the following stages:
• Site Preparation
• Grading
• Building Construction
• Paving
• Architectural Coating

10.2 CONSTRUCTION REFERENCE NOISE LEVELS
To describe construction noise activities, this construction noise analysis was prepared using reference construction equipment noise levels from the Federal Highway Administration (FHWA) published the Roadway Construction Noise Model (RCNM), which includes a national database of construction equipment reference noise emission levels. (22) The RCNM equipment database provides a comprehensive list of the noise-generating characteristics of specific types of construction equipment. In addition, the database provides an acoustical usage factor to estimate the fraction of time each piece of construction equipment is operating at full power (i.e., its loudest condition) during a construction operation. According to the EPA, FTA, and FHWA, the overall construction noise level is governed primarily by the noisiest pieces of equipment. The quieter pieces do not affect the overall level, but they do reduce the magnitude of the fluctuations in the noise level.

Therefore, a rough estimate of the noise level need only include the noisiest pieces of equipment expected at the site. (8) (23) (24) Consistent with FHWA and FTA guidance for detailed construction noise assessment, Table 10-1 presents the combined noise levels for the loudest construction activities expected for each stage, assuming all equipment operates simultaneously.

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EXHIBIT 10-1: CONSTRUCTION NOISE SOURCE LOCATIONS
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TABLE 10-1: CONSTRUCTION REFERENCE NOISE LEVELS
Construction
Stage
Reference
Construction Equipmnet1
Reference Noise
Level @ 50 Feet
(dBA Leq)
Composite
Reference Noise
Level
(dBA Leq)
2 Reference
Power Level
(dBA Lw)
3 Site
Preparation
Tractor 80
Backhoe 74 84.0 115.6
Grader 81
Grading
Scraper 80
Excavator 77 83.3 114.9
Dozer 78
Building
Construction
Crane 73
Tractor 80 81.1 112.8
Welder/Torch 70
Paving
Paver 74
Dump Truck 72 77.8 109.5
Roller 73
Architectural
Coating
Man Lift 68
Compressor (air) 74 79.8 111.4
Generator 78
1 FHWA Road Construction Noise Model.
2 Represents the combined noise level for all equipment assuming they operate at the same time. 3 The total amount of acoustical energy produced by a sound source independent of distance or surroundings.

10.3 CONSTRUCTION NOISE ANALYSIS
Construction projects involve various stages, and activities frequently shift from one location to another. For example, during site preparation and grading, noise-generating activities may concentrate in an area for a short period to remove an obstruction, while the majority of the grading involves the equipment moving back and forth in a predictable pattern throughout the site; building construction and foundation work generally concentrate near the building footprint, while paving generally involves a predictable pattern of movement throughout the site. Therefore, construction activities are best evaluated as multiple moving point sources within the construction area since the speed and power of the equipment vary, and the equipment constantly changes position in terms of its distance and direction relative to the receivers. (25) Using the reference construction equipment noise levels and the CadnaA noise prediction model, calculations of the Project construction noise level impacts by phase at the nearby sensitive receiver locations were completed. To account for the dynamic nature of construction activities, the CadnaA construction noise analysis evaluates the noise source activities as multiple moving point sources, or construction crews, within the limits of construction. Construction impacts are based on the loudest activity and the highest noise level calculated at each receiver location. As shown on Table 10-2, the construction noise levels are expected to range from 36.5 to 51.2 dBA Leq at the nearby receiver locations. Appendix 10.1 includes the detailed CadnaA construction noise model inputs.

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TABLE 10-2: CONSTRUCTION EQUIPMENTNOISE LEVEL SUMMARY
Receiver
Location1
Construction Noise Levels (dBA Leq)
Site
Preparation Grading BuildingConstruction Paving ArchitecturalCoating Highest
Levels2
R1 42.8 42.1 39.9 36.7 38.6 42.8
R2 40.8 40.1 37.9 34.7 36.6 40.8
R3 49.6 48.9 46.7 43.5 45.4 49.6
R4 50.8 50.1 47.9 44.7 46.6 50.8
R5 51.2 50.5 48.3 45.1 47.0 51.2
R6 36.5 35.8 33.6 30.4 32.3 36.5
1 Construction noise source and receiver locations are shown on Exhibit 10-1. 2 Construction noise level calculations based on distance from the construction activity, which is measured from the Project site boundary to the nearest receiver locations. CadnaA construction noise model inputs are included in Appendix 10.1.

10.4 PROJECT SITE CONSTRUCTION NOISE LEVEL COMPLIANCE
To evaluate whether the Project will generate potentially significant short-term noise levels at nearest receiver locations, a construction-related daytime noise level threshold of 80 dBA Leq is used as a reasonable threshold to assess the daytime construction noise level impacts. The construction noise analysis shows that the nearest receiver locations will satisfy the reasonable daytime 80 dBA Leq significance threshold during Project construction activities as shown on Table 10-3. Therefore, the noise impacts due to Project construction noise are considered less than significant at all receiver locations.

TABLE 10-3: CONSTRUCTION NOISE LEVEL COMPLIANCE
Receiver
Location1
Construction Noise Levels (dBA Leq)
Highest Construction
Noise Levels2
Threshold3
Threshold
Exceeded?4
R1 42.8 80 No
R2 40.8 80 No
R3 49.6 80 No
R4 50.8 80 No
R5 51.2 80 No
R6 36.5 80 No
1 Construction noise source and receiver locations are shown on Exhibit 10-1. 2 Highest construction noise level calculations based on distance from the construction noise source activity to the nearest receiver locations as shown on Table 10-2.
3 Construction noise level thresholds as shown on Table 4-1. 4 Do the estimated Project construction noise levels exceed the construction noise level threshold? Item Number: 1.

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10.5 TEMPORARY CONSTRUCTION NOISE LEVEL INCREASES
To describe the temporary Project construction noise level contributions to the existing ambient noise environment, the Project construction noise levels were combined with the existing ambient noise levels measurements at the nearest off-site receiver locations. The difference between the combined Project-construction and ambient noise levels is used to describe the construction noise level contributions. Temporary noise level increases that would be experienced at sensitive receiver locations when Project construction-source noise is added to the ambient daytime conditions are presented on Table 10-4. As previously outlined in Section 4.1.3, a temporary noise level increase of 20 dBA Leq is considered significant.

As indicated in Table 10-4, the Project will contribute construction noise increases ranging from 0.0 to 1.6 dBA Leq during the daytime hours at the nearest receiver locations. The unmitigated construction noise analysis shows that the nearest receiver locations will not exceed the 20 dBA Leq noise level increase significance threshold during Project construction activities. The temporary construction noise level increase analysis shows that the noise impacts due to Project construction noise are considered less than significant.

TABLE 10-4: DAYTIME CONSTRUCTION NOISE LEVEL INCREASES
Receiver
Location1
Typical
Project
Construction
Noise Level2
Measurement
Location3
Reference
Ambient
Noise Levels4
Combined
Project
and
Ambient5
Project
Increase6
Increase
Criteria7
Increase
Criteria
Exceeded?
R1 42.8 L1 51.9 52.4 0.5 20 No
R2 40.8 L2 44.2 45.8 1.6 20 No
R3 49.6 L3 57.4 58.1 0.7 20 No
R4 50.8 L4 73.7 73.7 0.0 20 No
R5 51.2 L5 56.5 57.6 1.1 20 No
R6 36.5 L6 45.8 46.3 0.5 20 No
1 Construction noise source and receiver locations are shown on Exhibit 10-1. 2 Typical Project daytime construction noise levels as shown on Table 10-3. 3 Reference noise level measurement locations as shown on Exhibit 5-A. 4 Observed daytime ambient noise levels as shown on Table 5-1. 5 Represents the combined ambient conditions plus the Project construction activities. 6 The noise level increase expected with the addition of the proposed Project construction activities. 7 Temporary construction noise increases that can be tolerated without significant adverse effects.

10.6 NIGHTTIME CONCRETE POUR NOISE ANALYSIS
It is our understanding that nighttime concrete pouring activities may occur as a part of Project building construction activities. Nighttime concrete pouring activities are often used to support reduced concrete mixer truck transit times and lower air temperatures than during the daytime hours and are generally limited to the actual building pad and loading dock areas. Since the nighttime concrete pours will take place outside the hours permitted by Section 9.04.030 of the City’s Code of Ordinances, the Project Applicant will be required to obtain authorization for nighttime work from the City of Desert Hot Springs. Any nighttime construction noise activities shall satisfy the FTA residential 70 dBA Leq noise limit outlined in Table 4-1.

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10.6.1 Nighttime Concrete Pour Reference Noise Level Measurements To estimate the noise levels due to nighttime concrete pour activities, sample reference noise level measurements were taken during a nighttime concrete pour at an unrelated construction site.

Urban Crossroads, Inc. collected short-term nighttime concrete pour reference noise level measurements during the noise-sensitive nighttime hours between 1:00 a.m. to 2:00 a.m. at 27334 San Bernardino Avenue in the City of Redlands. The reference noise levels describe the expected concrete pour noise sources that may include concrete mixer truck movements and pouring activities, concrete paving equipment, rear mounted concrete mixer truck backup alarms, engine idling, air brakes, generators, and workers communicating/whistling. To describe the nighttime concrete pour noise levels associated with the construction of the Varner Road / West Drive Logistics, this analysis relies on reference sound pressure level of 67.7 dBA Leq at 50 feet represented by a sound power level (Lw) of 100.3 dBA Lw. While the Project noise levels will depend on the actual duration of activities and specific equipment fleet in use at the time of construction, the reference sound power level of 100.3 dBA Lw is used to describe the expected Project nighttime concrete pour noise activities.

10.6.2 Nighttime Concrete Pour Noise Level Compliance
As shown on Table 10-5, the noise levels associated with the nighttime concrete pour activities are estimated to range from 21.2 to 35.9 dBA Leq and will satisfy the City of Desert Hot Springs stationary-source nighttime exterior hourly average Leq residential noise level threshold at all the receiver locations. Based on the results of this analysis, all the nearest noise receiver locations will experience less than significant impacts due to the Project related nighttime concrete pour activities.

Appendix 10.2 includes the CadnaA nighttime concrete pour noise model inputs. Therefore, the noise impacts due to Project construction nighttime concrete pour noise activity are considered less than significant at all receiver locations with prior authorization for nighttime work from the City of Desert Hot Springs. Appendix 10.3 includes the CadnaA nighttime concrete pour noise model inputs.

TABLE 10-5: NIGHTTIME CONCRETE POUR NOISE LEVEL COMPLIANCE Receiver
Location1
Concrete Pour Construction Noise Levels (dBA Leq)
Exterior
Noise Levels2
Threshold3
Threshold
Exceeded?4
R1 27.5 70 No
R2 25.5 70 No
R3 34.3 70 No
R4 35.5 70 No
R5 35.9 70 No
R6 21.2 70 No
1 Construction noise source and receiver locations are shown on Exhibit 10-1. 2 Nighttime Concrete Pour noise model inputs are included in Appendix 10.2. 3 Construction noise level thresholds as shown on Table 4-1. 4 Do the estimated Project construction noise levels exceed the construction noise level threshold? Item Number: 1.

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10.7 CONSTRUCTION VIBRATION ANALYSIS
Construction activity can result in varying degrees of ground vibration, depending on the equipment and methods employed. Operation of construction equipment causes ground vibrations that spread through the ground and diminish in strength with distance. Ground vibration levels associated with various types of construction equipment are summarized on Table 10-6. Based on the representative vibration levels presented for various construction equipment types, it is possible to estimate the potential for human response (annoyance) and building damage using the following vibration assessment methods defined by the FTA. To describe the vibration impacts the FTA provides the following equation: PPVequip = PPVref x (25/D)1.5
TABLE 10-6: VIBRATION SOURCE LEVELS FOR CONSTRUCTION EQUIPMENT Equipment PPV (in/sec)
at 25 feet
Small bulldozer 0.003
Jackhammer 0.035
Loaded Trucks 0.076
Large bulldozer 0.089
Vibratory Roller 0.210
Federal Transit Administration, Transit Noise and Vibration Impact Assessment Manual Using the vibration source level of construction equipment provided on Table 10-6 and the construction vibration assessment methodology published by the FTA, it is possible to estimate the Project vibration impacts. Table 10-7 presents the expected Project related vibration levels at the nearby receiver locations. At distances ranging from 189 to 8,735 feet from Project construction activities, construction vibration velocity levels are estimated to range from 0.000 to 0.010 PPV in/sec. Based on maximum acceptable continuous vibration threshold of 0.3 PPV (in/sec), the typical Project construction vibration levels will fall below the building damage thresholds at all the noise sensitive receiver locations. Therefore, the Project-related vibration impacts are considered less than significant during typical construction activities at the Project site.

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TABLE 10-7: PROJECT CONSTRUCTION VIBRATION LEVELS
Location1
Distance
to
Const.

Activity
(Feet)2
Typical Construction Vibration Levels
PPV (in/sec)3 Thresholds
PPV
(in/sec)4
Thresholds
Exceeded?5
Small
bulldozer
JackhammerLoaded
Trucks
Large
bulldozer
Vibratory
Roller
Highest
Vibration
Level
R1 4,892' 0.000 0.000 0.000 0.000 0.000 0.000 0.3 No
R2 5,865' 0.000 0.000 0.000 0.000 0.000 0.000 0.3 No
R3 2,154' 0.000 0.000 0.000 0.000 0.000 0.000 0.3 No
R4 1,678' 0.000 0.000 0.000 0.000 0.000 0.000 0.3 No
R5 189' 0.000 0.002 0.004 0.004 0.010 0.010 0.3 No
R6 8,735' 0.000 0.000 0.000 0.000 0.000 0.000 0.3 No
1 Construction noise source and receiver locations are shown on Exhibit 10-1. 2 Distance from receiver building facade to Project construction boundary (Project site boundary). 3 Based on the Vibration Source Levels of Construction Equipment (Table 10-5). 4 Caltrans Transportation and Construction Vibration Guidance Manual, April 2020, Table 19, p. 38. 5 Does the peak vibration exceed the acceptable vibration thresholds? "PPV" = Peak Particle Velocity
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11 REFERENCES

1. Association of Environmental Professionals. California Environmental Quality Act Statute & Guidelines. 2023.

2. California Department of Transportation Environmental Program. Technical Noise Supplement - A Technical Supplement to the Traffic Noise Analysis Protocol. Sacramento, CA : s.n., September 2013.

3. Environmental Protection Agency Office of Noise Abatement and Control. Information on Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an Adequate Margin of Safety.

March 1974. EPA/ONAC 550/9/74-004.

4. U.S. Department of Transportation, Federal Highway Administration, Office of Environment and Planning, Noise and Air Quality Branch. Highway Traffic Noise Analysis and Abatement Policy and Guidance. December 2011.

5. U.S. Department of Transportation Federal Highway Administration. Highway Noise Barrier Design Handbook. 2001.

6. U.S. Department of Transportation, Federal Highway Administration. Highway Traffic Noise in the United States, Problem and Response. April 2000. p. 3.

7. U.S. Environmental Protection Agency Office of Noise Abatement and Control. Noise Effects HandbookA Desk Reference to Health and Welfare Effects of Noise. October 1979 (revised July 1981). EPA 550/9/82/106.

8. U.S. Department of Transportation, Federal Transit Administration. Transit Noise and Vibration Impact Assessment Manual, FTA Report No. 0123. September 2018.

9. California Department of Transportation. Transportation and Construction Vibration Guidance Manual.

April 2020.

10. Office of Planning and Research. State of California General Plan Guidelines. October 2017.

11. City of Desert Hot Springs. General Plan Safety and Noise Element. May 2020.

12. County of Riverside. General Plan Noise Element. December 2015.

13. City of Desert Hot Springs. Municipal Code, Section 9.04.030.

14. Caltrans. Standard Specifications in Section 14-8.02 Noise Control.

15. California Court of Appeal. Gray v. County of Madera, F053661. 167 Cal.App.4th 1099; - Cal.Rptr.3d, October 2008.

16. Federal Interagency Committee on Noise. Federal Agency Review of Selected Airport Noise Analysis Issues.

August 1992.

17. California Department of Transportation. Technical Noise Supplement. November 2009.

18. American National Standards Institute (ANSI). Specification for Sound Level Meters ANSI S1.4-2014/IEC 61672-1:2013.

19. U.S. Department of Transportation, Federal Highway Administration. FHWA Highway Traffic Noise Prediction Model. December 1978. FHWA-RD-77-108.

20. California Department of Transportation. Traffic Noise Attenuation as a Function of Ground and Vegetation Final Report. June 1995. FHWA/CA/TL-95/23.

21. Urban Crossroads, Inc. Varner Road / West Drive Logistics Traffic Analysis. March 2025.

22. U.S. Department of Transportation, Federal Highway Administration, Office of Environment and Planning. FHWA Roadway Construction Noise Model. January, 2006.

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23. U.S. Environmental Protection Agency. Noise from Construction Equipment and Operations, Building Equipment, and Home Appliances. 1971. NTID300.1.

24. U.S. Department of Transportation, Federal Highway Administration. Special Report - Measurement, Prediction, and Mitigation. Office of Planning, Environment, and Realty - Environment - Noise. [Online] 2017. https://www.fhwa.dot.gov/environment/noise/construction_noise/special_report/hcn00.cfm.

25. —. FHWA Highway Construction Noise Handbook. Final Report August 2006.

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12 CERTIFICATION
The contents of this noise study report represent an accurate depiction of the noise environment and impacts associated with the proposed Varner Road / West Drive Logistics Project. The information contained in this noise study report is based on the best available data at the time of preparation. If you have any questions, please contact me directly at (949) 584-3148.

Bill Lawson, P.E., INCE
Principal
URBAN CROSSROADS, INC.
1133 Camelback #8329
Newport Beach, CA 92658
(949) 581-3148
[email protected]
Education
Master of Science in Civil and Environmental Engineering California Polytechnic State University, San Luis Obispo • December, 1993 Bachelor of Science in City and Regional Planning
California Polytechnic State University, San Luis Obispo • June, 1992 Professional Registrations
PE – Registered Professional Traffic Engineer –TR 2537 • January, 2009 AICP –American Institute of Certified Planners – 013011 • June, 1997–January 1, 2012 PTP – Professional Transportation Planner • May, 2007 – May, 2013 INCE – Institute of Noise Control Engineering • March, 2004 Professional Affiliations
ASA –Acoustical Society of America
ITE – Institute of Transportation Engineers
Professional Certifications
Certified Acoustical Consultant – County of San Diego • March, 2018 Certified Acoustical Consultant – County of Orange • February, 2011 FHWA-NHI-142051 Highway Traffic Noise Certificate of Training • February, 2013 Item Number: 1.

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Desert Hot Springs City CouncilApril 21, 2026

Desert Hot Springs City Council
April 21, 2026