Agenda — Twentynine Palms City Council, December 12, 2023 (part 4 of 4)

SW
SP
SP-SM
112.7
El. 1964.5'
El. 1958.0'
El. 1954.0'
El. 1946.5'
Direct Shear
Corrosion
Sieve

2.6 1.1

0.5'

7.0'

11.0'

18.5'
Approximately 6 inches thick AC
Fill:Well Graded SAND (SW); brown, moist, fine to coarse grained sand.

Medium dense
Quaternary Alluvium (Qa):Poorly Graded SAND (SP);
brown, moist, very dense, fine to coarse grained sand,
trace gravel.

Poorly Graded SAND with Silt (SP-SM); brown, moist, fine to coarse grained sand
Medium dense
Brown to reddish brown, medium dense
Medium dense
Very dense
G- 1
SPT- 1
SPT- 2
CAL- 1
G- 2
SPT- 3
SPT- 4
Notes: Hollow-Stem Auger. Boring terminated at approximately 18.5' bgs. Groundwater not encountered. Refusal not encountered. Backfilled with soil cuttings. Patched with Aquaphalt. 7 6
4 10
20 25
8 11
16 7
8 12
12 20
21 Boring No.

Depth (ft.)
Project Number
Completed: 6/6/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: Northwest of intersection Inn Ave & National Park Dr Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.132571
Sheet 1 of 1
Started: 6/6/2023 Graphical Log
Longitude: -116.048579 Moisture Content (%)
1965'
Boring Log
B-05
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 485 of 672 ends

SP
SM
SM
SW-SM
SM
SP
El. 1943.5'
El. 1940.0'
El. 1934.0'
El. 1928.0'
El. 1924.0'
El. 1916.5'
Direct Shear
Sieve

1.2 3.3

1.9 4.5'

8.0'

14.0'

20.0'

24.0'

31.5'
Quaternary Alluvium (Qa):Poorly Graded SAND (SP);
brown to dark brown, moist, fine to coarse grained sand.

Silty SAND (SM); light brown to brown, dry, medium dense, fine grained sand, trace coarse sand, trace gravel.

Silty SAND with Gravel (SM); light brown to brown, dry, dense, fine sand, trace coarse sand, trace fine subangular gravel.

Well Graded SAND with Silt (SW-SM); brown to light
brown, moist, dense, fine to coarse grained sand, trace gravel.

Silty SAND (SM); light brown to brown, moist, very dense, fine to coarse grained sand, moderately to weakly
cemented, trace gravel.

Poorly Graded SAND (SP); light brown to brown with orange oxidation, moist, fine to coarse grained sand, trace
gravel.

Dense
Very dense
G- 1
SPT- 1
CAL- 1
SPT- 2
CAL- 2
SPT- 3
CAL- 3
SPT- 4
Notes: Hollow-Stem Auger. Boring terminated at approximately 31.5' bgs. Groundwater not encountered. Refusal not encountered. Backfilled with grout and soil cuttings.
4 5
13 14
15 18
10 10
16 50/6"
20 20
25 15
18 25
15 21
29 Boring No.

Depth (ft.)
Project Number
Completed: 8/23/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: Desert Knoll Shoulder & 62 Intersection
Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 25
30 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.135480
Sheet 1 of 1
Started: 8/23/2023 Graphical Log
Longitude: -116.045661 Moisture Content (%)
1948'
Boring Log
B-06
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 486 of 672 ends

SM
SM
SP-SM
SW
117.9
110.7
El. 1947.7'
El. 1945.0'
El. 1933.0'
El. 1920.0'
El. 1916.5'
*Corrosion
*Sieve
*Sand Equivalent
*Combined Sample

6.0' - 6.5' / 7' - 9' /
10' - 11.5'
Direct Shear
**Sieve
**Sand Equivalent
**Combined Sample

16.0'-16.5' / 20' - 21.5'/
26' - 26.5'

4.8 1.7

0.3'

3.0'

15.0'

28.0'

31.5'
Approximately 4 inches thick AC
Fill:Silty SAND (SM); brown, moist, fine grained sand,
trace coarse sand, trace fine gravel.

Quaternary Alluvium (Qa):Silty SAND (SM); brown to
orange brown with white mottling, moist, fine to coarse grained sand, trace fine gravel.

Medium dense
Dense, moderately to weakly cemented
Poorly Graded SAND with Silt (SP-SM); brown, moist, fine to coarse grained sand,
Dense
Dense
Very dense, trace white fine sand
Well Graded SAND (SW); brown, moist, very dense, fine to coarse grained sand.

G- 1
CAL- 1
G- 2
SPT- 1
CAL- 2
SPT- 2
CAL- 3
SPT- 3
Notes: Hollow-Stem Auger. Boring terminated at approximately 31.5' bgs. Groundwater not encountered. Refusal not encountered. Backfilled with grout and soil cuttings. Patched with Aquaphalt. 5 8
12 10
10 14
8 13
18 8
13 17
15 28
28 16
21 23
Boring No.

Depth (ft.)
Project Number
Completed: 8/23/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: Southbound edge of Desert Knoll
Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 25
30 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.136022
Sheet 1 of 1
Started: 8/23/2023 Graphical Log
Longitude: -116.045659 Moisture Content (%)
1948'
Boring Log
B-07
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 487 of 672 ends

SW
SW
SC
SP
SM
118.2
El. 1934.7'
El. 1932.0'
El. 1928.0'
El. 1926.0'
El. 1921.0'
El. 1903.5'
*Sieve
*Sand Equivalent
*Combined Sample

15.0'-16.5' / 21' - 21.5' /
26' - 26.5
Direct Shear

4.3 3.0

0.3'

3.0'

7.0'

9.0'

14.0'

31.5'
Approximately 4 inches thick AC
Fill:Well Graded SAND (SW); brown with orange
oxidation, moist, fine to coarse grained sand, trace silt.

Quaternary Alluvium (Qa):Well Graded SAND (SW);
brown to orange brown with orange mottling, moist,
medium dense, fine to coarse grained sand, trace silt.

Clayey SAND (SC); brown with white mottling, moist,
dense, fine grained sand, trace coarse grained sand,
weakly cemented.

Poorly Graded SAND (SP): brown to grayish brown, moist, dense, fine to coarse grained sand, weakly cemented.

Silty SAND (SM); brown, moist, fine grained sand, trace coarse grained sand, trace gravel, moderately to weakly cemented.

Very dense
Very dense
Dense, white mottling, increased cementation
Very dense
G- 1
SPT- 1
SPT- 2
CAL- 1
SPT- 3
CAL- 2
SPT- 4
CAL- 3
Notes: Hollow-Stem Auger. Boring terminated at approximately 31.5' bgs. Groundwater not encountered. Refusal not encountered. Backfilled with grout and soil cuttings. Patched with Aquaphalt. 4 5
5 7
8 15
15 19
20 14
20 20
22 27
29 12
15 17
27 25
31 Boring No.

Depth (ft.)
Project Number
Completed: 8/23/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: East of intersection Desert Knoll Ave and Buena Vista Dr.

Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 25
30 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.141045
Sheet 1 of 1
Started: 8/23/2023 Graphical Log
Longitude: -116.045473 Moisture Content (%)
1935'
Boring Log
B-08
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 488 of 672 ends

SP
SM
115.7
El. 1933.6'
El. 1933.2'
El. 1927.0'
El. 1914.0'
R Value

6.1 0.4'

0.8'

7.0'

20.0'
Approximately 5 inches thick AC
Approximately 5 inches thick AB
Fill:Poorly Graded SAND (SP); brown, moist, fine to
coarse grained sand.

Medium dense
Quaternary Old Alluvium (Qoa):Silty SAND (SM); brown,
moist, fine to coarse grained.

Reddish brown, dense
Light brown, moist, dense, fine to coarse grained sand, weakly cemented
Very dense, small caliche
G- 1
SPT- 1
G- 2
CAL- 1
SPT- 2
CAL- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
9 4
12 15
20 30
5 12
16 16
25 31
Boring No.

Depth (ft.)
Project Number
Completed: 6/6/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: South of intersection Joe Davis Dr & Desert Knoll Ave Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.144701
Sheet 1 of 1
Started: 6/6/2023 Graphical Log
Longitude: -116.045470 Moisture Content (%)
1934'
Boring Log
B-09
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 489 of 672 ends

SP-SM
SP
SM
108.2
119.9
El. 1978.6'
El. 1974.0'
El. 1970.0'
El. 1959.0'
Proctor
Sand Equivalent

1.5 4.0

0.4'

5.0'

9.0'

20.0'
Approximately 5 inches thick AC
Fill:Poorly Graded SAND with Silt (SP-SM); brown, moist, fine to coarse grained sand, trace subangular gravel.

Quaternary Old Alluvium (Qoa):Poorly Graded SAND
(SP); light brown, moist, dense, fine to coarse grained sand.

Silty SAND (SM); brown, moist, fine to coarse grained sand, weakly cemented
Dense
Very dense
Very dense
G- 1
CAL- 1
SPT- 1
CAL- 2
SPT- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
21 26
15 18
14 12
30 35
32 19
18 17
Boring No.

Depth (ft.)
Project Number
Completed: 6/6/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: East of intersection Ocotillo Ave & S. Slope Dr Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.144925
Sheet 1 of 1
Started: 6/6/2023 Graphical Log
Longitude: -116.052843 Moisture Content (%)
1979'
Boring Log
B-10
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 490 of 672 ends

SP
SW-SM
SM
114.5
El. 1956.7'
El. 1953.0'
El. 1942.0'
El. 1937.0'
*Sieve
*Combined Sample

7.0' - 9.0' / 10' - 11.5' /

11.5' - 13'

2.4 0.3'

4.0'

15.0'

20.0'
Approximately 4 inches thick AC
Fill:Poorly Graded SAND (SP); light brown, moist, fine to coarse grained sand, trace subangular gravel
Quaternary Old Alluvium (Qoa):Well Graded SAND with
Silt (SW-SM); light brown, moist, fine to coarse grained sand, trace subangular gravel
Dense
Medium dense, trace silt
Dense, trace fines
Silty SAND (SM); dark brown, moist, dense, fine to coarse grained sand, weakly cemented, trace subrounded gravel
G- 1
CAL- 1
G- 2
SPT- 1
SPT- 2
CAL- 2
SPT- 3
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
12 17
17 5
5 8
11 15
18 15
18 19
15 15
17 Boring No.

Depth (ft.)
Project Number
Completed: 6/6/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: East of Aztec Ave & Buena Vista Dr
Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.140990
Sheet 1 of 1
Started: 6/6/2023 Graphical Log
Longitude: -116.048891 Moisture Content (%)
1957'
Boring Log
B-11
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 491 of 672 ends

SM
SM
113.8
El. 1975.3'
El. 1971.0'
El. 1953.0'
Proctor
Sieve
Direct Shear

8.1 3.7

0.7'

5.0'

23.0'
Approximately 8 inches thick AC
Fill:Silty SAND (SM); brown, dry, fine to coarse grained sand.

Moist
Quaternary Old Allluvium (Qoa):Silty SAND (SM);
orangish brown, moist, fine to coarse sand, trace white powder.

Medium dense
Very dense
Black mottling, dense
Very dense
Medium dense
Medium dense
Very dense
G- 1
SPT- 1
SPT- 2
CAL- 1
SPT- 3
CAL- 2
SPT- 4
SPT- 5
Notes: Hollow-Stem Auger. Boring terminated at approximately 23' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
3 5
8 15
20 28
18 20
21 13
15 20
7 7
8 5
5 7
10 15
24 Boring No.

Depth (ft.)
Project Number
Completed: 6/6/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: North of intersection Gorgonio Dr & Ocotillo Ave Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.140932
Sheet 1 of 1
Started: 6/6/2023 Graphical Log
Longitude: -116.053041 Moisture Content (%)
1976'
Boring Log
B-12
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 492 of 672 ends

SM
SM
115.9
120.3
El. 1994.3'
El. 1991.0'
El. 1975.0'
*Sieve
*Combined Sample

6.0' - 6.5' / 10' - 11.5' /
16' - 16.5'

4.5 3.7

0.8'

4.0'

20.0'
Approximately 9 inches thick AC
Fill:Silty SAND (SM); dark brown, moist, fine to coarse grained sand.

Quaternary Alluvium (Qa):Silty SAND (SM); dark brown,
moist, fine to coarse grained sand.

Medium dense
Dense, increase in silt
Dark brown to light brown, medium dense
Dense, medium to coarse grained sand, weakly cemented
G- 1
CAL- 1
SPT- 1
CAL- 2
SPT- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
13 14
14 10
11 11
12 14
14 11
11 12
Boring No.

Depth (ft.)
Project Number
Completed: 6/13/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: West of intersection Cholla Ave & Buena Vista Dr Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.140419
Sheet 1 of 1
Started: 6/13/2023 Graphical Log
Longitude: -116.055843 Moisture Content (%)
1995'
Boring Log
B-13
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 493 of 672 ends

SM
SM
SP
SM
SP
124.7
107.8
El. 2010.8'
El. 2005.0'
El. 1994.5'
El. 1989.5'
El. 1984.5'
El. 1979.5'
*Corrosion
*Sieve
*Sand Equivalent
*Combined Sample

5.0' - 6.5' / 11' - 11.5'
Direct Shear

3.5 5.4

2.0 0.3'

6.0'

16.5'

21.5'

26.5'

31.5'
Approximately 3 inches thick AC
Fill:Silty SAND (SM); brown to orange brown, moist, fine to coarse grained sand, trace fine gravel.

Loose
Quaternary Alluvium (Qa):Silty SAND (SM); brown to
orange brown, moist, fine to coarse grained sand, trace fine gravel.

Medium dense
Medium dense, fine gravel
Dense
Poorly Graded SAND (SP); brown to light brown, moist, fine grained sand, trace coarse grained sand, weakly
cemented.

Dense
Silty SAND (SM); brown to light brown, moist, dense, fine grained sand, trace coarse grained sand, weakly
cemented.

Poorly Graded SAND (SP); brown to orange brown, moist,
fine grained sand, trace coarse grained sand.

Very dense
G- 1
SPT- 1
SPT- 2
CAL- 1
SPT- 3
CAL- 2
SPT- 4
CAL- 3
SPT- 5
Notes: Hollow-Stem Auger. Boring terminated at approximately 31.5' bgs. Groundwater not encountered. Refusal not encountered. Backfilled with grout and soil cuttings. Patched with Aquaphalt. 2 2
4 7
7 8
7 8
13 13
14 16
10 15
16 12
14 18
16 19
21 22
25 27
Boring No.

Depth (ft.)
Project Number
Completed: 8/23/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: Northbound Tamarisk Ave
Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 25
30 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.139967
Sheet 1 of 1
Started: 8/23/2023 Graphical Log
Longitude: -116.058661 Moisture Content (%)
2011'
Boring Log
B-14
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 494 of 672 ends

SM
SM
El. 2003.6'
El. 2000.0'
El. 1989.0'
*Sieve
*Combined Sample

5.0' - 6.5' / 6.5' - 8' /
11' - 11.5'

0.4'

4.0'

15.0'
Approximately 5 inches thick AC
Fill:Silty SAND (SM); dark brown, moist, fine to coarse grained sand, trace fine gravel.

Quaternary Old Alluvium (Qoa):Silty SAND (SM); dark
brown, moist, fine to coarse grained sand, silt.

Medium dense
Reddish brown, medium dense
Reddish brown to dark brown, dense, caliche
Very dense, weakly to moderately cemented
G- 1
SPT- 1
SPT- 2
CAL- 1
SPT- 3
Notes: Hollow-Stem Auger. Boring terminated at approximately 15' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
2 4
4 7
8 8
10 17
19 17
17 18
Boring No.

Depth (ft.)
Project Number
Completed: 6/15/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: West of intersection Adobe Rd & Sun Valley Dr Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.144341
Sheet 1 of 1
Started: 6/15/2023 Graphical Log
Longitude: -116.056230 Moisture Content (%)
2004'
Boring Log
B-15
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 495 of 672 ends

SM
SM
123.6
114.1
El. 2083.6'
El. 2081.0'
El. 2067.5'
Proctor
Direct Shear
Sieve 5.2

1.7 0.4'

3.0'

16.5'
Approximately 5 inches thick AC
Fill:Silty SAND (SM); dark brown, moist, fine to coarse grained sand.

Quaternary Old Alluvium (Qoa):Silty SAND (SM); dark
brown, moist, fine to coarse grained sand, trace fines.

Very dense
Dense
Dense
G- 1
CAL- 1
SPT- 1
CAL- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 16.5' bgs. Groundwater not encountered. Refusal not encountered. Backfilled with soil cuttings. Patched with Aquaphalt. 17 18
34 11
12 12
10 12
20 Boring No.

Depth (ft.)
Project Number
Completed: 6/12/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: West of intersection Hillside Ave & Sun Valley Dr Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.144087
Sheet 1 of 1
Started: 6/12/2023 Graphical Log
Longitude: -116.067144 Moisture Content (%)
2084'
Boring Log
B-16
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 496 of 672 ends

SP
SP-SM
SP
115.2
El. 2137.6'
El. 2134.0'
El. 2123.0'
El. 2121.5'
*Sand Equivalent
*Combined Sample

5.0' - 6.5' / 11' - 11.5'

2.4 2.0

0.4'

4.0'

15.0'

16.5'
Approximately 8 inches thick AC
Fill:Poorly Graded SAND with Gravel (SP); dark brown,
moist, medium to coarse grained sand, trace fines.

Quaternary Old Alluvium (Qoa):Poorly Graded SAND with
Silt (SP-SM); dark brown, moist, fine to coarse grained sand.

Dense
Dark brown to light gray, very dense, trace fine gravel Poorly Graded SAND (SP); brown, moist, dense, medium to coarse grained sand, trace fines.

G- 1
SPT- 1
CAL- 1
SPT- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 16.5' bgs. Groundwater not encountered. Refusal not encountered. Backfilled with soil cuttings. Patched with Aquaphalt. 15 15
17 23
24 29
14 14
15 Boring No.

Depth (ft.)
Project Number
Completed: 6/12/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: West of Intersection Mesquite Spring Rd & Wildcat Way Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.141745
Sheet 1 of 1
Started: 6/12/2023 Graphical Log
Longitude: -116.072891 Moisture Content (%)
2138'
Boring Log
B-17
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 497 of 672 ends

SM
SP-SM
SW
SW-SM
SM
110.8
El. 1968.5'
El. 1965.0'
El. 1959.0'
El. 1954.0'
El. 1952.5'
El. 1951.0'
*Sand Equivalent
*Combined Sample

6.5' - 8' / 8' - 9.5'

0.2 0.6

0.5'

4.0'

10.0'

15.0'

16.5'

18.0'
Approximately 6 inches thick AC
Fill:Silty SAND (SM); dark brown, moist, fine to coarse grained sand.

Quaternary Old Alluvium (Qoa):Poorly Graded SAND with
Silt (SP-SM); brown, moist, medium dense, fine to
coarse grained sand.

Trace fine gravel
Well Graded SAND (SW); light brown to brown, moist,
medium dense, fine to coarse grained sand.

Well Graded SAND with Silt (SW-SM); brown, moist,
dense, fine to coarse grained sand.

Silty SAND (SM); brown, moist, dense, fine to coarse
grained sand.

G- 1
CAL- 1
SPT- 1
SPT- 2
CAL- 2
SPT- 3
SPT- 4
Notes: Hollow-Stem Auger. Boring terminated at approximately 18' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
9 10
14 4
5 5
7 7
9 12
13 13
11 11
15 12
13 17
Boring No.

Depth (ft.)
Project Number
Completed: 6/14/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: North of intersection Joe Davis Dr & Desert Knoll Ave Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.147478
Sheet 1 of 1
Started: 6/14/2023 Graphical Log
Longitude: -116.045444 Moisture Content (%)
1969'
Boring Log
B-18
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 498 of 672 ends

SM
SM
ML
SM
125.0
El. 1901.3'
El. 1897.0'
El. 1895.5'
El. 1892.0'
El. 1887.0'

0.6 3.2

0.7'

5.0'

6.5'

10.0'

15.0'
Approximately 8 inches thick AC
Fill:Silty SAND (SM); dark brown, moist, fine to coarse grained sand, trace subangular gravel.

Quaternary Old Alluvium (Qoa):Silty SAND (SM); dark
brown, moist, medium dense, fine to coarse grained
sand.

Sandy SILT (ML); dark brown, moist, hard, fine to coarse grained sand, low plasticity.

Silty SAND (SM); dark brown, moist, fine to coarse grained sand.

Dense
Very dense, caliche, moderately cemented
G- 1
SPT- 1
SPT- 2
CAL- 1
SPT- 3
Notes: Hollow-Stem Auger. Boring terminated at approximately 15' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
3 4
5 8
10 12
12 17
18 18
20 27
Boring No.

Depth (ft.)
Project Number
Completed: 6/14/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: West of intersection Halsey Ave & Two Mile Rd Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.150404
Sheet 1 of 1
Started: 6/14/2023 Graphical Log
Longitude: -116.042531 Moisture Content (%)
1902'
Boring Log
B-19
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 499 of 672 ends

SM
SM
SP
SM
SW-SM
SW
118.6
117
El. 2015.6'
El. 2009.5'
El. 2007.0'
El. 2002.0'
El. 1997.0'
El. 1992.0'
El. 1984.5'
Sieve
Sand Equivalent
Sieve

2.7 3.1

2.2 0.4'

6.5'

9.0'

14.0'

19.0'

24.0'

31.5'
Approximately 5 inches thick AC
Fill:Silty SAND (SM); brown to orange brown, moist, fine to coarse grained sand, trace fine gravel.

Medium dense
Quaternary Alluvium (Qa):Silty SAND (SM); brown to
orange brown, moist, fine to coarse grained sand, trace gravel.

Poorly Graded SAND (SP); brown to orange brown, moist,
fine to coarse grained sand, weakly cemented.

Medium dense
Silty SAND (SM); brown to light brown, moist, dense, fine to coarse grained sand, trace fine gravel, weakly cemented.

Well Graded SAND with Silt (SW-SM); brown to light
brown, moist, very dense, fine to coarse grained sand,
trace fine gravel, moderately cemented.

Well Graded SAND (SW); brown to light brown, moist, fine to coarse grained sand, trace white sand.

Dense
Very dense
G- 1
SPT- 1
CAL- 1
CAL- 2
SPT- 2
CAL- 3
SPT- 3
SPT- 4
Notes: Hollow-Stem Auger. Boring terminated at approximately 31.5' bgs. Groundwater not encountered. Refusal not encountered. Backfilled with grout and soil cuttings. Patched with Aquaphalt. 4 5
6 6
8 20
20 20
21 14
14 16
29 31
37 15
16 18
20 20
21 Boring No.

Depth (ft.)
Project Number
Completed: 8/22/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: Southbound Tamarisk Ave
Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 25
30 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.140451
Sheet 1 of 1
Started: 8/22/2023 Graphical Log
Longitude: -116.059230 Moisture Content (%)
2016'
Boring Log
B-20
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 500 of 672 ends

SM
SM
SM
118.6
El. 2078.0'
El. 2070.0'
El. 2048.5'
Direct Shear
*Sieve
*Combined Sample
16' - 16.5' / 20' - 21.5' /
26' - 26.5'

5.5 2.2

1.3 2.0'

10.0'

31.5'
Fill:Silty SAND (SM); brown, moist, fine to coarse grained sand.

Quaternary Alluvium (Qa):Silty SAND with Gravel (SM);
brown to orange brown, moist, fine to coarse grained
sand, fine to coarse gravel, trace cobble.

Medium dense
Silty SAND (SM); brown to light brown, dry, very dense, fine grained sand, moderately to weakly cemented, trace coarse grained sand.

Very dense
Dense
Very dense
Very dense
Very dense
G- 1
SPT- 1
CAL- 1
SPT- 2
CAL- 2
SPT- 3
CAL- 3
SPT- 4
Notes: Hollow-Stem Auger. Boring terminated at approximately 31.5' bgs. Groundwater not encountered. Refusal not encountered. Backfilled with grout and soil cuttings.
7 9
5 20
25 27
7 25
40 12
16 25
17 18
18 17
24 29
15 19
20 Boring No.

Depth (ft.)
Project Number
Completed: 8/22/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: Northbound Bullion Ave Shoulder
Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 25
30 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.132619
Sheet 1 of 1
Started: 8/22/2023 Graphical Log
Longitude: -116.063083 Moisture Content (%)
2080'
Boring Log
B-21
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 501 of 672 ends

SM
SM
117.7
El. 2017.0'
El. 2004.0'
Sand Equivalent

2.8 1.8

5.0'

18.0'
Fill:Silty SAND (SM); brown, moist, fine to coarse grained sand, trace subangular gravel.

Quaternary Alluvium (Qa):Silty SAND (SM); brown,
moist, fine to coarse grained sand.

Dense
Very dense, trace gravel
Brown to light brown, increase in silt, weakly cemented Medium dense
Very dense
G- 1
SPT- 1
CAL- 1
SPT- 2
SPT- 3
Notes: Hollow-Stem Auger. Boring terminated at approximately 18' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings.
14 13
20 22
24 50
16 10
10 10
12 35
Boring No.

Depth (ft.)
Project Number
Completed: 6/7/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: South of 29 Palms Hwy & Oasis Ave
Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.134946
Sheet 1 of 1
Started: 6/7/2023 Graphical Log
Longitude: -116.061121 Moisture Content (%)
2022'
Boring Log
B-22
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 502 of 672 ends

ML
SP-SM
SM
SP
SM
114.2
104.2
El. 2016.5'
El. 2013.0'
El. 2009.5'
El. 2005.5'
El. 2002.0'
El. 1997.0'
R Value
Sand Equivalent

3.8 0.6

0.5'

4.0'

7.5'

11.5'

15.0'

20.0'
Approximately 6 inches thick AC
Fill:Sandy SILT (ML); dark brown, moist, fine to coarse grained sand, low plasticity.

Quaternary Alluvium (Qa):Poorly Graded SAND with Silt
(SP-SM); dark brown, moist, medium dense, fine to
coarse grained sand.

Silty SAND (SM); dark brown to brown, moist, dense, fine to coarse grained sand, trace fine gravel.

Poorly Graded SAND (SP); dark brown, moist, medium to
coarse grained sand, weakly cemented.

Silty SAND (SM); dark brown, moist, dense, medium to
coarse grained sand, weakly cemented.

Weakly cemented
G- 1
CAL- 1
G- 2
SPT- 1
CAL- 2
SPT- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
8 12
14 8
10 12
16 19
20 13
14 16
Boring No.

Depth (ft.)
Project Number
Completed: 6/13/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: South of intersection Joshua Dr & Desert Queen Ave Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.137081
Sheet 1 of 1
Started: 6/13/2023 Graphical Log
Longitude: 116.059201 Moisture Content (%)
2017'
Boring Log
B-23
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 503 of 672 ends

SP
SP
SW
SW-SM
SP-SM
121.2
110.7
El. 2002.6'
El. 1999.0'
El. 1995.5'
El. 1993.0'
El. 1984.0'
El. 1983.0'
Proctor
*Sieve
*Combined Sample

11.0' - 11.5' / 15' - 16.5'

3.1 1.2

0.4'

4.0'

7.5'

10.0'

19.0'

20.0'
Approximately 5 inches thick AC
Fill:Poorly Graded SAND (SP); dark brown, moist, medium to coarse grained sand, trace fine subangular gravel.

Quaternary Alluvium (Qa):Poorly Graded SAND (SP); dark
brown, moist, medium to coarse grained sand.

Medium dense
Dense
Well Graded SAND (SW); dark brown, moist, fine to coarse grained sand.

Well Graded SAND with Silt (SW-SM); dark brown to light brown, moist, dense, fine to coarse grained sand, trace fine gravel.

Poorly Graded SAND with Silt (SP-SM); brown, moist, very dense, fine to coarse grained sand, coarse sand.

G- 1
SPT- 1
SPT- 2
CAL- 1
SPT- 3
CAL- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
8 6
7 10
12 17
21 21
22 11
14 15
18 21
33 Boring No.

Depth (ft.)
Project Number
Completed: 6/13/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: South of intersection Joshua Dr & Smoketree Ave Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.137069
Sheet 1 of 1
Started: 6/13/2023 Graphical Log
Longitude: -116.056278 Moisture Content (%)
2003'
Boring Log
B-24
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 504 of 672 ends

SP-SM
SW-SM
SM
115.1
El. 2005.5'
El. 1996.0'
El. 1989.0'
*Corrosion
*Combined Sample

10.0' - 11.5' / 11.5' - 13'

1.3 3.5'

13.0'

20.0'
Fill:Poorly Graded SAND with Silt (SP-SM); brown, dry,
fine to coarse grained sand, trace subangular gravel.

Quaternary Alluvium (Qa):Well Graded SAND with Silt
(SW-SM); brown, dry, fine to coarse grained sand, trace subangular gravel.

Medium dense
Medium dense, moist, chatter
Brown to light brown, moist, medium dense, trace silt
Dense
Silty SAND (SM); brown, moist, medium dense, fine to
coarse grained sand, trace gravel
G- 1
CAL- 1
SPT- 1
SPT- 2
SPT- 3
CAL- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings.
9 8
9 4
4 6
5 5
6 7
7 15
10 18
23 Boring No.

Depth (ft.)
Project Number
Completed: 6/7/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: East of intersection Tamarisk Ave & Cedar Dr
Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.131084
Sheet 1 of 1
Started: 6/7/2023 Graphical Log
Longitude: -116.057707 Moisture Content (%)
2009'
Boring Log
B-25
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 505 of 672 ends

SW-SM
SM
112.8
El. 1983.6'
El. 1981.0'
El. 1964.0'
Sieve
R Value
*Sieve
*Combined Sample

10.0' - 11.5' / 15' - 16.5'
Direct Shear

0.6 2.4

0.4'

3.0'

20.0'
Approximately 5 inches thick AC
Fill:Well Graded SAND with Silt (SW-SM); light brown,
dry, fine to coarse grained sand.

Quaternary Alluvium (Qa):Silty SAND (SM); brown,
moist, fine to coarse grained sand, trace fine gravel.

Loose
Medium dense
Increase in silt
Medium dense
Light brown, medium dense
Dense, weakly cemented, coarse gravel
G- 1
SPT- 1
SPT- 2
SPT- 3
SPT- 4
CAL- 1
SPT- 5
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
3 3
3 6
5 6
11 6
6 9
8 9
11 14
16 17
17 17
Boring No.

Depth (ft.)
Project Number
Completed: 6/7/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: South of intersection Cactus Dr & Palo Verde Ave Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.134251
Sheet 1 of 1
Started: 6/7/2023 Graphical Log
Longitude: -116.052302 Moisture Content (%)
1984'
Boring Log
B-26
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 506 of 672 ends

SP
SW-SM
115.4
118.1
El. 1963.7'
El. 1959.0'
El. 1944.5'
*Sieve
*Combined Sample

6.0' - 6.5' / 6.5' - 8' /
11' - 11.5'

1.2 1.5

0.3'

5.0'

19.5'
Approximately 4 inches thick AC
Fill:Poorly Graded SAND (SP); dark brown, moist, fine to coarse grained sand, trace subangular gravel.

Quaternary Alluvium (Qa):Well Graded SAND with Silt
(SW-SM); brown, moist, fine to coarse grained sand.

Medium dense
Medium dense
Very dense, weakly cemented
Dense, small caliche
Very dense
G- 1
CAL- 1
SPT- 1
CAL- 2
SPT- 2
CAL- 3
Notes: Hollow-Stem Auger. Boring terminated at approximately 19.5' bgs. Groundwater not encountered. Refusal not encountered. Backfilled with soil cuttings. Patched with Aquaphalt. 11 8
10 10
7 8
18 22
34 11
13 13
36 50/6"
Boring No.

Depth (ft.)
Project Number
Completed: 6/7/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: South of intersection Verbena Dr & Cienega Dr Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.136253
Sheet 1 of 1
Started: 6/7/2023 Graphical Log
Longitude: -116.048579 Moisture Content (%)
1964'
Boring Log
B-27
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 507 of 672 ends

SM
SM
110.0
El. 1956.5'
El. 1950.5'
El. 1935.5'

1.6 6.3

0.5'

6.5'

21.5'
Approximately 6 inches thick AC
Fill:Silty SAND (SM); light brown moist, fine to coarse grained sand, trace subangular gravel.

Loose, increase in fines
Quaternary Alluvium (Qa):Silty SAND (SM); light brown,
moist, fine to coarse grained sand.

Dense
Dense, caliche
Brown
Medium dense, weakly cemented
Tan, moist, dense, fine to coarse grained sand
G- 1
SPT- 1
SPT- 2
CAL- 1
SPT- 3
CAL- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
3 3
4 22
14 12
9 15
25 10
9 8
13 18
22 Boring No.

Depth (ft.)
Project Number
Completed: 6/7/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: East of intersection Gorgonio Dr & Cienega Ave Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.139359
Sheet 1 of 1
Started: 6/7/2023 Graphical Log
Longitude: -116.048316 Moisture Content (%)
1957'
Boring Log
B-28
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 508 of 672 ends

SP-SM
SM
SP-SM
114.8
El. 2035.8'
El. 2033.0'
El. 2023.0'
El. 2019.5'
*Corrosion
*Sieve
*Sand Equivalent
*Combined Sample

6.0' - 6.5' / 6.5' - 8' /
8' - 9.5'

5.1 1.5

0.3'

3.0'

13.0'

16.5'
Approximately 3 to 3.5 inches thick AC
Fill:Poorly Graded SAND with Silt (SP-SM); dark brown,
moist, medium to coarse grained sand, trace gravel.

Quaternary Alluvium (Qa):Silty SAND (SM); dark brown,
moist, fine to coarse grained sand, trace gravel.

Medium dense
Medium dense, moderately cemented
Medium dense
Medium dense
Dense
Poorly Graded SAND with Silt (SP-SM); dark brown, moist, very dense, fine to coarse grained sand.

G- 1
CAL- 1
SPT- 1
SPT- 2
SPT- 3
SPT- 4
SPT- 5
Notes: Hollow-Stem Auger. Boring terminated at approximately 16.5' bgs. Groundwater not encountered. Refusal not encountered. Backfilled with soil cuttings. Patched with Aquaphalt. 7 8
8 6
6 8
8 10
10 5
5 7
8 10
12 17
21 25
Boring No.

Depth (ft.)
Project Number
Completed: 6/13/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: West of intersection Bagley Ave & Split Rock Ave Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.139855
Sheet 1 of 1
Started: 6/13/2023 Graphical Log
Longitude: -116.061775 Moisture Content (%)
2036'
Boring Log
B-29
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 509 of 672 ends

SM
SM
El. 2043.3'
El. 2040.0'
El. 2027.5'
Sieve
R Value
*Sieve
*Combined Sample

6.5' - 8.5' / 11' - 11.5'

5.6 5.2

0.8'

4.0'

16.5'
Approximately 9 inches thick AC
Fill:Silty SAND (SM); reddish brown to dark brown, moist, fine grained sand, low to medium plasticity.

Quaternary Old Alluvium (Qoa):Silty SAND (SM); dark
brown, moist, very dense, fine grained sand, moderately to strongly cemented.

Dry, strongly cemented, caliche
G- 1
SPT- 1
G- 2
CAL- 1
SPT- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 16.5' bgs. Groundwater not encountered. Refusal not encountered. Backfilled with soil cuttings. Patched with Aquaphalt. 17 18
19 28
31 32
28 35
35 Boring No.

Depth (ft.)
Project Number
Completed: 6/12/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: West of Intersection Yucca Ave & El Paseo Dr
Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.142743
Sheet 1 of 1
Started: 6/12/2023 Graphical Log
Longitude: -116.062252 Moisture Content (%)
2044'
Boring Log
B-30
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 510 of 672 ends

SM
SM
SP-SM
117.8
113.9
El. 2167.7'
El. 2162.0'
El. 2150.5'
El. 2148.0'
*Sieve
*Sand Equivalent
*Combined Sample

6.5' - 8.0' / 10' - 11.5'

4.2 4.1

0.3'

6.0'

17.5'

20.0'
Approximately 4 inches thick AC
Fill:Silty SAND (SM); dark brown, moist, fine to coarse grained sand, trace fine gravel.

Quaternary Old Alluvium (Qoa):Silty SAND (SM); dark
brown, moist, dense, fine to coarse grained sand, weakly cemented.

Caliche, silt, moderately cemented
Black mottling
Poorly Graded SAND with Silt (SP-SM); dark brown, moist, very dense, fine to coarse grained sand.

G- 1
CAL- 1
SPT- 1
SPT- 2
CAL- 2
SPT- 3
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
15 12
12 9
12 12
13 13
17 14
13 18
15 16
19 Boring No.

Depth (ft.)
Project Number
Completed: 6/8/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: West of Sunnyslope Dr & Alpine Ave
Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.145569
Sheet 1 of 1
Started: 6/8/2023 Graphical Log
Longitude: -116.087295 Moisture Content (%)
2168'
Boring Log
B-31
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 511 of 672 ends

SM
SM
SP-SM
SM
El. 2147.4'
El. 2145.0'
El. 2142.0'
El. 2133.0'
El. 2129.8'

0.6 2.5

0.6'

3.0'

6.0'

15.0'

18.3'
Approximately 7 inches thick AC
Fill:Silty SAND (SM); dark brown, mosit, fine to coarse grained sand, trace gravel.

Quaternary Old Alluvium (Qoa):Silty SAND (SM); dark
brown, moist, fine to coarse grained sand.

Loose
Poorly Graded SAND with Silt (SP-SM); light brown, moist, fine to coarse grained sand, trace subangular gravel.

Medium dense
Dense
Silty SAND (SM): brown, moist, trace coarse gravel
Dense
Very dense
G- 1
SPT- 1
SPT- 2
CAL- 1
SPT- 3
CAL- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 18'3" bgs. Groundwater not encountered. Refusal not encountered. Backfilled with soil cuttings. Patched with Aquaphalt. 4 2
3 7
7 10
18 20
20 12
12 20
50/3"
Boring No.

Depth (ft.)
Project Number
Completed: 6/12/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: South of intersection Granite Ave & Juniper Ave Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.142478
Sheet 1 of 1
Started: 6/12/2023 Graphical Log
Longitude: -116.077375 Moisture Content (%)
2148'
Boring Log
B-32
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 512 of 672 ends

SM
SW-SM
119.9
El. 2118.0'
El. 2103.0'
*Sieve
*Sand Equivalent
*Combined Sample

8.0' - 9.5' / 10' - 11.5'

3.8 5.0'

20.0'
Quaternary Old Alluvium (Qoa):Silty SAND (SM); light
brown, dry, fine to coarse grained sand.

Well Graded Sand with Silt (SW-SM); light brown, dry,
medium dense, fine to coarse grained sand, subangular
gravel.

Increase in silt
G- 1
CAL- 1
SPT- 1
SPT- 2
SPT- 3
CAL- 2
SPT- 4
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings.
6 7
7 5
5 7
8 8
12 14
11 18
19 25
22 4
11 13
Boring No.

Depth (ft.)
Project Number
Completed: 6/8/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: Northeast of intersection Desert Trail Dr & Larrea Ave Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.148233
Sheet 1 of 1
Started: 6/8/2023 Graphical Log
Longitude: -116.073909 Moisture Content (%)
2123'
Boring Log
B-33
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 513 of 672 ends

SW-SM
SP
SM
112.8
El. 2164.8'
El. 2160.0'
El. 2150.0'
El. 2145.5'
Sieve
R Value
*Sieve
*Combined Sample

5.0' - 6.5' / 6.5' - 8'

1.4 0.7

0.3'

5.0'

15.0'

19.5'
Approximately 3 inches thick AC
Fill:Well Graded SAND with Silt (SW-SM); light brown,
dry, fine to coarse grained sand, trace subangular gravel.

Quaternary Old Alluvium (Qoa):Poorly Graded SAND
(SP); dark brown, moist, fine to coarse grained sand.

Loose
Very dense
Dense, trace gravel
Silty SAND (SM); dark brown, moist, very dense, fine to coarse grained sand, trace subangular gravel
G- 1
SPT- 1
SPT- 2
CAL- 1
SPT- 3
CAL- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 19.5' bgs. Groundwater not encountered. Refusal not encountered. Backfilled with soil cuttings. Patched with Aquaphalt. 4 3
3 15
25 16
14 20
22 21
25 22
26 50/6"
Boring No.

Depth (ft.)
Project Number
Completed: 6/8/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: Northeast of intersection Desert Trail Dr & La Luna Ave Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.146963
Sheet 1 of 1
Started: 6/8/2023 Graphical Log
Longitude: -116.082571 Moisture Content (%)
2165'
Boring Log
B-34
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 514 of 672 ends

SM
SM
107.3
El. 2055.6'
El. 2052.0'
El. 2039.5'

0.8 5.2

0.4'

4.0'

16.5'
Approximately 5 inches thick AC
Fill:Silty SAND (SM); dark brown, moist, fine to coarse grained sand.

Quaternary Old Alluvium (Qoa):Silty SAND (SM); brown,
moist, fine to coarse grained sand, trace subangular
gravel.

Medium dense
Medium dense, increase in silt
Medium dense
Dense, moderately cemented
Light brown, very dense, caliche
G- 1
CAL- 1
SPT- 1
SPT- 2
SPT- 3
SPT- 4
Notes: Hollow-Stem Auger. Boring terminated at approximately 16.5' bgs. Groundwater not encountered. Refusal not encountered. Backfilled with soil cuttings. Patched with Aquaphalt. 6 6
7 5
6 6
5 6
6 12
12 16
17 17
18 Boring No.

Depth (ft.)
Project Number
Completed: 6/13/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: East of intersection Hillside Ave & Sunnyvale Dr Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.145548
Sheet 1 of 1
Started: 6/13/2023 Graphical Log
Longitude: -116.061661 Moisture Content (%)
2056'
Boring Log
B-35
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 515 of 672 ends

SM
SM
El. 2027.6'
El. 2025.0'
El. 2013.0'
Sand Equivalent
R Value

0.4'

3.0'

15.0'
Approximately 5 inches thick AC
Fill:Silty SAND (SM); dark brown, moist, fine to coarse grained sand.

Quaternary Old Alluvium (Qoa):Silty SAND (SM); dark
brown, moist, fine to coarse grained sand, weakly
cemented.

Dense
Light brown, very dense, caliche
Dense, trace subangular gravel
G- 1
SPT- 1
CAL- 1
SPT- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 15' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
8 9
15 15
29 29
12 13
18 Boring No.

Depth (ft.)
Project Number
Completed: 6/15/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: East of intersection Bagley Ave & Sunnyslope Dr Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.147131
Sheet 1 of 1
Started: 6/15/2023 Graphical Log
Longitude: -116.056975 Moisture Content (%)
2028'
Boring Log
B-36
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 516 of 672 ends

SP
SP
SP-SM
108.6
El. 2009.7'
El. 2006.0'
El. 2002.0'
El. 1995.0'
Direct Shear0.9

0.3'

4.0'

8.0'

15.0'
Approximately 4 inches thick AC
Fill:Poorly Graded SAND with Gravel (SP); dark brown,
moist, fine to coarse grained sand, trace gravel.

Quaternary Old Alluvium (Qoa):Poorly Graded SAND
(SP); light brown to dark brown, moist, dense, fine to
coarse grained sand.

Poorly Graded SAND with Silt (SP-SM); dark brown, moist, fine to coarse grained sand.

Dense
Medium dense
G- 1
CAL- 1
SPT- 1
CAL- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 15' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings. Patched with Aquaphalt.
10 15
16 10
13 15
12 13
17 Boring No.

Depth (ft.)
Project Number
Completed: 6/15/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: East of intersection Ocotillo Ave & Desert Trail Dr Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.147528
Sheet 1 of 1
Started: 6/15/2023 Graphical Log
Longitude: -116.052312 Moisture Content (%)
2010'
Boring Log
B-37
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 517 of 672 ends

SM
110.6
118.7
El. 1896.0'
Proctor
*Sand Equivalent
*Combined Sample

11.0' - 11.5' / 15' - 16.5' /

19.5' - 20'

5.7 1.4

20.0'
Quaternary Old Alluvium (Qoa):Silty SAND (SM); dark
brown, moist, fine to coarse grained sand.

Brown to reddish brown
Medium dense
Very dense, caliche
Light brown, very dense
Very dense, increase in silt, caliche
G- 1
SPT- 1
CAL- 1
SPT- 2
CAL- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings.
7 9
9 21
25 27
27 23
27 27
27 42
Boring No.

Depth (ft.)
Project Number
Completed: 6/14/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: South of Marine Ave & Joe Davis Dr
Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.145639
Sheet 1 of 1
Started: 6/14/2023 Graphical Log
Longitude: -116.043189 Moisture Content (%)
1916'
Boring Log
B-38
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 518 of 672 ends

SM
SM
112.1
121.6
El. 1895.0'
El. 1878.0'
*Sieve
*Combined Sample

6.0' - 6.5' / 6.5' - 8' /
8' - 9.5' / 10' - 11.5'
Direct Shear

1.9 4.5

3.0'

20.0'
Fill:Silty SAND (SM); dark brown, moist, fine to coarse grained sand.

Quaternary Old Alluvium (Qoa):Silty SAND (SM); dark
brown, moist, fine to coarse grained sand, trace fine
gravel.

Medium dense
Medium dense
Very dense, weakly cemented
Dense, moderately cemented
Very dense, increase in silt
Dense
G- 1
CAL- 1
SPT- 1
SPT- 2
SPT- 3
CAL- 2
SPT- 4
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings.
4 5
7 4
5 7
8 15
23 13
13 15
22 32
42 9
15 15
Boring No.

Depth (ft.)
Project Number
Completed: 6/14/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: North of intersection Wainwright Ave & Joe Davis Dr Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.147220
Sheet 1 of 1
Started: 6/14/2023 Graphical Log
Longitude: -116.041059 Moisture Content (%)
1898'
Boring Log
B-39
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 519 of 672 ends

SP
SP
SM
SW-SM
SW
113.7
El. 1871.1'
El. 1869.0'
El. 1862.0'
El. 1861.0'
El. 1856.0'
El. 1853.5'
*Sieve
*Combined Sample

11.5' - 13.0' / 13' - 14.5' /

14.5' - 16'

3.0 8.2

0.9'

3.0'

10.0'

11.0'

16.0'

18.5'
Approximately 11 inches thick AC
Fill:Poorly Graded SAND (SP); dark brown, moist, fine to coarse grained sand.

Quaternary Alluvium (Qa):Poorly Graded SAND (SP); dark
brown, moist, fine to coarse grained sand, moderately
cemented.

Dense
Silty SAND (SM); dark brown, moist, fine to coarse grained sand.

Well Graded SAND with Silt (SW-SM); dark brown, moist,
medium dense, fine to coarse grained sand.

Trace fine gravel
Well Graded SAND (SW); brown, moist, dense, fine to
coarse grained sand.

G- 1
SPT- 1
CAL- 1
SPT- 2
SPT- 3
SPT- 4
SPT- 5
Notes: Hollow-Stem Auger. Boring terminated at approximately 18.5' bgs. Groundwater not encountered. Refusal not encountered. Backfilled with soil cuttings. Patched with Aquaphalt. 7 9
16 8
11 12
4 4
5 5
7 7
9 10
10 9
12 18
Boring No.

Depth (ft.)
Project Number
Completed: 6/14/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: South of intersection Utah Trail & Two Mile Rd Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.149018
Sheet 1 of 1
Started: 6/14/2023 Graphical Log
Longitude: -116.036578 Moisture Content (%)
1872'
Boring Log
B-40
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 520 of 672 ends

SP-SM
SP-SM
SW-SM
110.3
El. 2167.0'
El. 2162.0'
El. 2152.0'
Proctor
Corrosion
Sieve
R Value

2.6 5.0'

10.0'

20.0'
Fill:Poorly Graded SAND with Silt (SP-SM); brown, moist, fine to coarse grained sand, trace fine subangular gravel.

Quaternary Old Alluvium (Qoa):Poorly Graded SAND with
Silt (SP-SM); brown, moist, dense, fine to coarse
grained sand, trace subangular gravel.

Well Graded SAND with Silt (SW-SM); brown, moist,
medium to coarse grained sand.

Very dense
Light brown, very dense
Dark brown, dense, trace fines
G- 1
CAL- 1
SPT- 1
G- 2
CAL- 2
SPT- 2
Notes: Hollow-Stem Auger. Boring terminated at approximately 20' bgs. Groundwater not encountered. Refusal not encountered.

Backfilled with soil cuttings.
15 23
17 11
14 24
23 29
36 17
18 17
Boring No.

Depth (ft.)
Project Number
Completed: 6/8/2023 227522-0000190.00 Sample ID Dry Weight (pcf) USCS Class.

Location: East of intersection Alpine Ave & El Paseo Dr Rig Type: Diedrich 70 Logged By: V. Hernandez
Date
PenetrationResistance(Blows per 6 in.)
0 5
10 15
20 GroundwaterDepth (ft.)Sample Taken
Visual Classification
Other Tests
and Remarks
Hammer Efficiency: 88.5
Latitude: 34.142917
Sheet 1 of 1
Started: 6/8/2023 Graphical Log
Longitude: -116.083600 Moisture Content (%)
2172'
Boring Log
B-41
Groundwater
Depth (ft) Hour Date
Sample Type
G - Bulk / Grab Sample
SPT - 2" O.D. 1.4" I.D. Tube Sample
CAL - 3 " O.D. 2.4" I.D. Ring Sample
NR - No Recovery
* - Uncorrected Blow Counts
Surface Elevation:

Project
Reviewed By: S. Roy
NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO BACKUP.GLB \ CITY OF TWENTNINE PALMS SEPTIC TO SEWER.GPJ

Page 521 of 672 ends

227522-0000190.00 NV5.COM |

APPENDIX C
Laboratory Test Results

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227522-0000190.00 NV5.COM |

SUMMARY OF LABORATORY TEST RESULTS
In-situ Moisture and Density Tests
The in-situ moisture content and dry density of selected samples obtained from the test borings were evaluated in general accordance with the latest versions of ASTM D2216 and D2937 laboratory test methods. The methods involve obtaining the moist weight of the sample and then drying the sample to obtain its dry weight. The moisture content is calculated by taking the difference between the wet and dry weights, dividing it by the dry weight of the sample and expressing the result as a percentage.

The results of the in-situ moisture content and dry density tests are presented in the following table and on the field exploration logs in Appendix B.

RESULTS OF MOISTURE CONTENT AND DENSITY TESTS
(ASTM D2216 and ASTM D2937)
Exploration Location
Sample Depth
in feet bgs
Dry Density
(pcf)
Moisture Content
(percent)
B-1 11 – 11.5 115.4 1.4
B-1 19.5 – 20 112.8 2.9
B-2 6 – 6.5 106.3 2.9
B-2 12 – 14 - 3.8
B-2 16 – 16.5 117.7 1.0
B-3 1 – 3 - 1.2
B-3 11 – 11.5 118.0 0.9
B-4 15 – 15.5 114.7 1.5
B-5 1 – 3 - 2.6
B-5 11 – 11.5 112.7 1.1
B-6 5 – 6.5 - 1.2
B-6 20 – 20.5 - 3.3
B-6 20.5 – 22 - 1.9
B-7 6 – 6.5 117.9 4.8
B-7 26 – 26.5 110.7 1.7
B-8 5 – 6.5 - 4.3
B-8 11 – 11.5 118.2 3.0
B-9 11 – 11.5 115.7 6.1
B-10 6 – 6.5 108.2 1.5

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227522-0000190.00 NV5.COM |
Exploration Location
Sample Depth
in feet bgs
Dry Density
(pcf)
Moisture Content
(percent)
B-10 15 – 16.5 119.9 4.0
B-11 6 – 6.5 114.5 2.4
B-12 1 – 3 - 8.1
B-12 19.5 – 20 113.8 3.7
B-13 6 – 6.5 115.9 4.5
B-13 16 – 16.5 120.3 3.7
B-14 5 – 6.5 - 3.5
B-14 11 – 11.5 124.7 5.4
B-14 26 – 26.5 107.8 2.0
B-16 6 – 6.5 123.6 5.2
B-16 16 – 16.5 114.1 1.7
B-17 1 – 3 - 2.4
B-17 11 – 11.5 115.2 2.0
B-18 6 – 6.5 - 0.2
B-18 11 – 11.5 110.8 0.6
B-19 5 – 6.5 - 0.6
B-19 11 – 11.5 125.0 3.2
B-20 5 – 6.5 - 2.7
B-20 11 – 11.5 118.6 3.1
B-20 21 – 21.5 117.0 2.2
B-21 5 – 6.5 - 5.5
B-21 11.5 – 13 - 2.2
B-21 26 – 26.5 118.6 1.3
B-22 1 – 3 - 2.8
B-22 11 – 11.5 117.7 1.8
B-23 6 – 6.5 114.2 3.8
B-23 16 – 16.5 104.2 0.6
B-24 11 – 11.5 121.2 3.1
B-24 19 – 19.5 110.7 1.2
B-25 19.5 – 20 115.1 1.3
B-26 5 – 6.5 - 0.6

Page 524 of 672 ends

227522-0000190.00 NV5.COM |
Exploration Location
Sample Depth
in feet bgs
Dry Density
(pcf)
Moisture Content
(percent)
B-26 16 – 16.5 112.8 2.4
B-27 6 – 6.5 115.4 1.2
B-27 11 – 11.5 118.1 1.5
B-28 6 – 6.5 - 1.6
B-28 11 – 11.5 110.0 6.3
B-29 6 – 6.5 114.8 5.1
B-29 10 – 11.5 - 1.5
B-30 1 – 3 - 5.6
B-30 11 – 11.5 - 5.2
B-31 6 – 6.5 117.8 4.2
B-31 16 – 16.5 113.9 4.1
B-32 6 – 6.5 - 0.6
B-32 11 – 11.5 - 2.5
B-33 16 – 16.5 119.9 3.8
B-34 5 – 6.5 - 1.4
B-34 11 – 11.5 112.8 0.7
B-35 6 – 6.5 107.3 0.8
B-35 8 – 9.5 - 5.2
B-37 6 – 6.5 108.6 0.9
B-38 11 – 11.5 110.6 5.7
B-38 19.5 – 20 118.7 1.4
B-39 6 – 6.5 112.1 1.9
B-39 16 – 16.5 121.6 4.5
B-40 1 – 3 - 3.0
B-40 11 – 11.5 113.7 8.2
B-41 16 – 16.5 110.3 2.6

Classification
Soils were visually and texturally classified in general accordance with the Unified Soil Classification System (ASTM D2487 and ASTM D2488).

Page 525 of 672 ends

227522-0000190.00 NV5.COM |
Particle-size Distribution Tests
An evaluation of the grain-size distribution of selected soil samples was performed in general accordance with the latest version of ASTM D6913 (Subgrade Material was Tested). These test results were utilized in evaluating the soil classifications in accordance with the Unified Soil Classification System. Particle size distribution test results are presented on the laboratory test sheets attached in this appendix.

Sand Equivalent Tests
Sand equivalent tests were performed on samples of the on-site soils. The tests were performed in general accordance with ASTM D2419. The results of the tests are presented below and attached in this appendix.

RESULTS OF SAND EQUIVALENT TESTS
(ASTM D2419)
Location Material Type
Sand
Equivalent
Value
Boring 2 @ 6 - 8 ft. (combined) Poorly Graded SAND
(SP) 25
Boring 3 @ 1 - 3 ft. and 5 – 6.5 ft.
(combined)
Poorly Graded
SAND with Gravel
(SP)
44 Boring 7 @ 6 – 6.5 ft. and 7 – 9 ft.
and 10 – 11.5 ft. (combined) Silty SAND (SM) 20
Boring 7 @ 16 – 16.5 ft. and 20 –

21.5 ft. and 26 – 26.5 ft.
(combined)
Silty SAND (SM) 27
Boring 8 @ 15 – 16.5 ft. and 21 –

21.5 ft. and 25 – 26.5 ft.
(combined)
Silty SAND (SM) 14
Boring 10 @ 1 - 3 ft.

Poorly Graded
SAND with Silt (SPSM)
37 Boring 14 @ 5 – 6.5 ft. and 11 –

11.5 ft. (combined) Silty SAND (SM) 21
Boring 17 @ 5 – 6.5 ft. and 11 –

11.5 ft. (combined)
Poorly Graded
SAND with Silt (SM) 40
Boring 18 @ 6.5 – 9.5 ft. Poorly Graded
SAND with Silt (SM) 76
Boring 20 @ 16 – 16.5 ft. and

16.5 – 18 ft. (combined) Silty SAND (SM) 18

Page 526 of 672 ends

227522-0000190.00 NV5.COM |
Location Material Type
Sand
Equivalent
Value
Boring 22 @ 15 – 16.5 ft. Silty SAND (SM) 24
Boring 23 @ 8 – 10 ft. Silty SAND (SM) 27
Boring 29 @ 6 – 6.5 ft. and 6.5 –

8.0 ft. and 8 – 9.5 ft. (combined) Silty SAND (SM) 19
Boring 31 @ 6.5 – 8 ft. and 10 –

11.5 ft. (combined) Silty SAND (SM) 19
Boring 33 @ 8 – 9.5 ft. and 10 –

11.5 ft. (combined)
Well Graded SAND
with Silt (SW-SM) 29
Boring 36 @ 1 – 3 ft. Silty SAND (SM) 20
Boring 38 @ 11 – 11.5 ft. and 15
– 16.5 ft. and 19.5 – 20 ft.
(combined)
Silty SAND (SM) 15
Maximum Dry Density and Optimum Moisture Content
The laboratory maximum dry density and optimum moisture content of the subgrade soil materials were tested in general accordance with ASTM D1557. The results of the laboratory tests are included to provide a reference of the in-situ subgrade characteristics at the location tested.

Exploration Location
(Sample Depth in feet bgs)
USCS Classification
Maximum Dry
Density (pcf)
Optimum
Moisture
Content
(percent)
B-3 (1.0 – 3.0)
(5.0 – 6.5)
(combined)
Brown Poorly Graded SAND with
Gravel (SP)
123.0 4.3
B-10 (1.0 – 3.0) Brown Poorly Graded SAND with
Silt (SP-SM) 122.0 8.6
B-12 (1.0 – 3.0) Brown Silty SAND (SM) 131.1 8.1
B-16 (1.0 – 3.0) Dark Brown Silty SAND (SM) 131.5 7.1

Page 527 of 672 ends

227522-0000190.00 NV5.COM |
Exploration Location
(Sample Depth in feet bgs)
USCS Classification
Maximum Dry
Density (pcf)
Optimum
Moisture
Content
(percent)
B-24 (1.0 – 3.0) Dark Brown Poorly Graded SAND
(SP) 119.3 8.7
B-38 (1.0 – 3.0) Dark Brown Silty SAND (SM) 126.9 5.3
B-41 (1.0 – 3.0) Brown Poorly Graded SAND with
Silt (SP-SM) 118.4 10.5

Resistance “R” Values Tests
R-Value tests were performed on representative samples of the on-site soils. The tests were performed in general accordance with California Test Method 301/ ASTM D2844. The result of the tests are presented below and attached in this appendix.

RESULTS OF R-VALUE TESTS
(ASTM D2844 and CTM 301)
Exploration Location and
Sample Depth
“R” Value Material Type
B-3 @ 1’ – 3’ and 5’ – 6.5’
(combined) 73 Poorly Graded SAND with Gravel (SP)
B-9 @ 1’ – 3’ 76 Poorly Graded SAND (SP)
B-23 @ 1’ – 3’ 67 Sandy SILT (ML)
B-26 @ 1’ – 3’ 78 Well Graded SAND with Silt (SW-SM)
B-30 @ 1’ – 3’ 22 Silty SAND (SM)
B-34 @ 1’ – 3’ 76 Well Graded SAND with Silt (SW-SM)

Page 528 of 672 ends

227522-0000190.00 NV5.COM |
Exploration Location and
Sample Depth
“R” Value Material Type
B-36 @ 1’ – 3’ 64 Silty SAND (SM)
B-41 @ 12’ – 14’ 79 Well Graded SAND with Silt (SW-SM)

Direct Shear Tests

Direct shear testing was performed on representative relatively undisturbed samples in general accordance with ASTM D3080 to evaluate the shear strength characteristics of on-site materials. The test method consists of placing the soil sample in the direct shear device, applying a series of normal stresses, and then shearing the sample at the constant rate of shearing deformation. The shearing force and horizontal displacements are measured and recorded as the soil specimen is sheared. The shearing is continued well beyond the point of maximum stress until the stress reaches a constant or residual value. The results of the tests at one of the boring locations are presented in the following table and attached in this appendix.

RESULTS OF DIRECT SHEAR TESTS
(ASTM D3080)
Location
USCS
Classification
Peak
Friction
(degrees)
Ultimate
Friction
(degrees)
Peak
Cohesion
(psf)
Ultimate
Cohesion
(psf)
Notes
Boring 2 @ 16 – 16.5 ft. SM 39.1 33.7 150 50 Relatively undisturbed
Boring 4 @ 15 – 15.5 ft. SM 39.6 34.7 480 130 Relatively undisturbed
Boring 5 @ 11 – 11.5 ft. SP-SM 32.5 31.5 200 150 Relatively undisturbed
Boring 6 @ 11 – 11.5 ft. SM 31.5 31 250 200 Relatively
undisturbed
Boring 7 @ 16 – 16.5 ft. SP-SM 38.3 34.1 375 100 Relatively undisturbed
Boring 8 @ 21 – 21.5 ft. SM 35.7 34.1 550 150 Relatively undisturbed
Boring 12 @ 19.5 – 20 ft. SM 32.7 32 300 150 Relatively undisturbed
Boring 14 @ 21 – 21.5 ft. SP 38.1 34.7 150 100 Relatively undisturbed

Page 529 of 672 ends

227522-0000190.00 NV5.COM |
Location
USCS
Classification
Peak
Friction
(degrees)
Ultimate
Friction
(degrees)
Peak
Cohesion
(psf)
Ultimate
Cohesion
(psf)
Notes
Boring 16 @ 6 – 6.5 ft. SM 42.3 33.9 300 300 Relatively undisturbed
Boring 21 @ 16 – 16.5 ft. SM 39.6 38.3 50 50 Relatively undisturbed
Boring 26 @ 16 – 16.5 ft. SM 36 34.8 225 50 Relatively
undisturbed
Boring 37 @ 6 – 6.5 ft. SP 40.2 35 200 100 Relatively
undisturbed
Boring 39 @ 16 – 16.5 ft. SM 41.2 31.6 300 150 Relatively undisturbed

Soil Corrosivity Tests
Water soluble sulfate & chloride, resistivity and pH tests were performed by Clarkson Laboratory and Supply Inc., in general accordance with California Test Methods 643, 417 and 422 to provide an indication of the degree of corrosivity of the subgrade soils at locations tested with regard to concrete and normal grade steel.

RESULTS OF CORROSIVITY TESTS
(CTM 417, CTM 422 and CTM 643)
Exploration Location
and Sample Depth
pH
Minimum
Resistivity
(Ohm-cm)
Water
Soluble
Sulfates
(ppm)
Water
Soluble
Chlorides
(ppm)
Material Type
B-3 @ 1’ – 3’pH 8.3 9,100 30 32
Poorly Graded
SAND with
Gravel (SP)
B-5 @ 12’ – 14’ 8.2 2,300 81 53
Poorly Graded
SAND with Silt
(SP-SM)
B-7 @ 6’ – 6.5’ and 7’
– 9’ and 10’ – 11.5’
(combined)

8.8 1,600 51 120 Silty SAND (SM)
B-14 @ 5’ – 6.5’ and
11’ – 11.5’
(combined)

8.9 2,800 51 53 Silty SAND (SM)
B-25 @ 10’ – 11.5’
and 11.5’ – 13’
(combined)

8.3 7,200 30 11
Well Graded
SAND with Silt
(SW-SM)

Page 530 of 672 ends

227522-0000190.00 NV5.COM |
Exploration Location
and Sample Depth
pH
Minimum
Resistivity
(Ohm-cm)
Water
Soluble
Sulfates
(ppm)
Water
Soluble
Chlorides
(ppm)
Material Type
B-29 @ 6’ – 6.5’ and

6.5’ – 8’ and 8’ – 9.5’
(combined)

8.8 3,400 45 11 Silty SAND (SM)
B-41 @ 12’ – 14’ 9.1 7,000 30 11
Well Graded
SAND with Silt
(SW-SM)

Page 531 of 672 ends

Job Number: 227522-0000190.00
Report Number:

Lab Number:

Sampled By: Veronica Hernandez
Submitted By: Veronica Hernandez
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Respectfully Submitted,
NV5 West, Inc.
140-23-00508-01,

3.8 1-3

1.2 140-23-00508-03 to
140-23-00508-07
6-6.5

2.9 112.8 106.3

1.4 2.9
Twentynine Palms, CA
Twentynine Palms Septic to Sewer
- -
Twentynine Palms, CA
6/5/2023
6/9/2023
B1 B1 B2 B3
140-23-00508-01 140-23-00508-03
115.4
11-11.5 19.5-20
Date:
12-14
11/20/2023
City of Twentynine Palms RVS
140-23-00508-04
Project Address:

Date Sampled:

Date Recieved:

Client:

Client Address:
140-23-00508-05
B2
140-23-00508-06
Project Name:
140-23-00508-07
B3
In-Situ Moisture & Density
(ASTM D2216 & ASTM D2937)
118.0
11-11.5

0.9 15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 532 of 672 Job Number: 227522-0000190.00
Report Number:

Lab Number:

Sampled By: Veronica Hernandez
Submitted By: Veronica Hernandez
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Respectfully Submitted,
NV5 West, Inc.
124696, 124697,

5.6 11-11.5

5.2 124699-124700,
124702-124704
11-11.5

2.0 - 115.2

1.7 2.4
Twentynine Palms, CA
Twentynine Palms Septic to Sewer
- -
Twentynine Palms, CA
6/12/2023
6/15/2023
B16 B17 B17 B30
124696 124697
114.1
16-16.5 1-3
Date:
1-3
11/20/2023
City of Twentynine Palms 9671
124699
Project Address:

Date Sampled:

Date Recieved:

Client:

Client Address:
124700
B30
124702
Project Name:
124703 124704
B32 B32
In-Situ Moisture & Density
(ASTM D2216 & ASTM D2937)
- -
6-6.5 11-11.5

0.6 2.5
15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 533 of 672 Job Number: 227522-0000190.00
Report Number:

Lab Number:

Sampled By: Veronica Hernandez
Submitted By: Veronica Hernandez
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Respectfully Submitted,
NV5 West, Inc.
124705-124706,124708

0.6 11-11.5

3.1 124710, 124712-124717
6-6.5

3.8 120.3 114.2

4.5 3.7
Twentynine Palms, CA
Twentynine Palms Septic to Sewer
104.2 121.2
Twentynine Palms, CA
6/13/2023
6/13/2023
B13 B13 B23 B24
124705 124706
115.9
6-6.5 16-16.5
Date:
16-16.5
11/20/2023
City of Twentynine Palms 9671
124708
Project Address:

Date Sampled:

Date Recieved:

Client:

Client Address:
124710
B23
124712
Project Name:
124713 124714 124715 124716 124717
B24 B29 B29 B35 B35
In-Situ Moisture & Density
(ASTM D2216 & ASTM D2937)
110.7 114.8 - 107.3 -
19-19.5 6-6.5 6-6.5 8-9.5

1.2 5.1 0.8 5.2
10-11.5

1.5 15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 534 of 672 Job Number: 227522-0000190.00
Report Number:

Lab Number:

Sampled By: Veronica Hernandez
Submitted By: Veronica Hernandez
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Respectfully Submitted,
NV5 West, Inc.
124718, 124720-124722

3.2 11-11.5

5.7 124724-124726, 124728-
124729
5-6.5

0.6 110.8 -

0.2 0.6
Twentynine Palms, CA
Twentynine Palms Septic to Sewer
125.0 110.6
Twentynine Palms, CA
6/14/2023
6/16/2023
B18 B18 B19 B38
124718 124720
-
6-6.5 11-11.5
Date:
11-11.5
11/20/2023
City of Twentynine Palms 9671
124721
Project Address:

Date Sampled:

Date Recieved:

Client:

Client Address:
124722
B19
124724
Project Name:
124725 124726 124728 124729
B38 B39 B40 B40
In-Situ Moisture & Density
(ASTM D2216 & ASTM D2937)
118.7 112.1 - 113.7

19.5-20 6-6.5 11-11.5

1.4 1.9 8.2
1-3

3.0 15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 535 of 672 Job Number: 227522-0000190.00
Report Number:

Lab Number:

Sampled By: Veronica Hernandez
Submitted By: Veronica Hernandez
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Respectfully Submitted,
NV5 West, Inc.
124732-124735, 124737

1.4 11-11.5

0.7 Project Name:

Twentynine Palms, CA
Twentynine Palms Septic to Sewer

4.2 4.1
16-16.5 16-16.5

3.8 - 112.8
Twentynine Palms, CA
6/8/2023
6/9/2023
B31 B31 B33 B34
124732 124733
117.8
6-6.5
113.9 119.9
In-Situ Moisture & Density
(ASTM D2216 & ASTM D2937)
Date:
5-6.5-
11/20/2023
City of Twentynine Palms 9671
12734
Project Address:

Date Sampled:

Date Recieved:

Client:

Client Address:
124735
B34
124737
15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 536 of 672 Job Number: 227522-0000190.00
Report Number:

Lab Number:
124795
Sampled By:

Submitted By:

Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Respectfully Submitted,
NV5 West, Inc.

In-Situ Moisture & Density
(ASTM D2216 & ASTM D2937)
- - 117.9 110.7 -

3.3 1.9 4.8 1.7 4.3
20-20.5 20.5-22 6-6.5 26-26.5 5-6.5
B-6 B-6 B-7 B-7 B-8
124790 124791 124792 124794 124795
117.0 - - 118.6 -
21-21.5 5-6.5 26-26.5 5-6.5

2.2 5.5 1.3 1.2

11.5-13

2.2 B-20 B-21 B-21 B-21 B-6
124781 124782 124784 124786 124787
Date:
5-6.5
11/20/2023
City of Twentynine Palms 9695
124777
Project Address:

Date Sampled:

Date Recieved:

William Barton
Client:

Client Address:
124778
B-20
124779
Project Name:

Twentynine Palms, CA
Twentynine Palms Septic to Sewer
- 118.6
Twentynine Palms, CA
8/22/2023-8/23/2023
8/23/2023
B-20
William Barton
B-14 B-14 B-14
124774 124775
-
5-6.5 11-11.5 26-26.5

2.0 124.7 107.8

3.5 5.4
124774-124775, 124777-

2.7 11-11.5

3.1 124779, 124781-124782,
124784,124786-124787
124790-124792,124794-
15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 537 of 672 Job Number: 227522-0000190.0
Report Number:

Lab Number:

Sampled By:

Submitted By:

Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Respectfully Submitted,
NV5 West, Inc.
124796
118.2
11-11.5

3.0 Project Name:

Twentynine Palms, CA
Twentynine Palms Septic to Sewer
Twentynine Palms, CA
8/22/2023-8/23/2023
8/23/2023 William Barton
B-8
124796
In-Situ Moisture & Density
(ASTM D2216 & ASTM D2937)
Date: 11/20/2023
City of Twentynine Palms 9695
Project Address:

Date Sampled:

Date Recieved:

William Barton
Client:

Client Address:
15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 538 of 672

Page 539 of 672 ends

Job Number: 227522-0000190.00
Report Number:

Lab Number:

Sampled By: Veronica Hernandez
Submitted By: Veronica Hernandez
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Respectfully Submitted,
NV5 West, Inc.

In-Situ Moisture & Density
(ASTM D2216 & ASTM D2937)
-
1-3

8.1 B12
124661
Date:
15-16.5
11/20/2023
City of Twentynine Palms 9671
124656
Project Address:

Date Sampled:

Date Recieved:

Client:

Client Address:
124657
B10
124658
Project Name:

Twentynine Palms, CA
Twentynine Palms Septic to Sewer
119.9 114.5
Twentynine Palms, CA
6/6/2023
6/9/2023
B5 B9 B10 B11
124648 124654
-
1-3 11-11.5 6-6.5

1.5 115.7 108.2

2.6 6.1
124648, 124654

4.0 6-6.5

2.4 124656-124658, 124661
15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 540 of 672 Job Number: 227522-0000190.00
Report Number:

Lab Number:

Sampled By: Veronica Hernandez
Submitted By: Veronica Hernandez
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Respectfully Submitted,
NV5 West, Inc.

0.6 6-6.5

1.2 124664, 124666, 124668-
124669, 124671, 124676-
124677, 124679

19.5-20

1.3 - 115.1

1.8 2.8
- 115.4
B22 B22 B25 B27
124679 124677
117.7
11-11.5 1-3
Date:
5-6.5
11/20/2023
City of Twentynine Palms
Twentynine Palms, CA
Twentynine Palms Septic to Sewer
Twentynine Palms, CA
6/7/2023
6/9/2023
9671
124676
Project Address:

Date Sampled:

Date Recieved:

Client:

Client Address:
124671
B26
124668
Project Name:
124669 124664 124666
B27 B28 B28
In-Situ Moisture & Density
(ASTM D2216 & ASTM D2937)
118.1 - 110.0
11-11.5 6-6.5

1.5 1.6
11-11.5

6.3 15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 541 of 672 Job Number: 227522-0000190.00
Report Number:

Lab Number:

Sampled By: Veronica Hernandez
Submitted By: Veronica Hernandez
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Lab Number
Exploration No.

Depth, ft.

Moisture Content, %
Dry Density, pcf
Respectfully Submitted,
NV5 West, Inc.

In-Situ Moisture & Density
(ASTM D2216 & ASTM D2937)
110.3
16-16.5

2.6 B41
124693
Date:
5-6.5
11/27/2023
City of Twentynine Palms 9671
124687
Project Address:

Date Sampled:

Date Recieved:

Client:

Client Address:
124689
B34
124690
Project Name:

Twentynine Palms, CA
Twentynine Palms Septic to Sewer
- 112.8
Twentynine Palms, CA
6/8/2023
6/9/2023
B31 B31 B33 B34
124682 124684
117.8
6-6.5 16-16.5 16-16.5

3.8 113.9 119.9

4.2 4.1
124682, 124684, 124687,

1.4 11-11.5

0.7 124689-124690, 124693
15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 542 of 672 Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Report No.:

Project Address: Twentynine Palms, CA Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Material
Source
Sample Location
Date Tested
Tested By
Sample ID: 124695 124700 124701
Sieve Size
63mm (2 1/2") 100 100 100
50mm (2") 100 100 100

37.5mm (1 1/2") 100 100 100
25mm (1") 100 100 100
19mm (3/4") 100 100 100

12.5mm (1/2") 100 100 100

9.5mm (3/8") 100 99 99

4.75mm (#4) 99 98 96
2mm (#10) 92 91 85
850µm (#20) 79 72 67
425µm (#40) 62 53 50
250µm (#60) 45 41 39
150 µm (#100) 32 33 30 Respectfully Submitted,
75 um (#200) washµ 22.8 25.8 22.0 NV5 West, Inc.

Coef. of Curvature (CC) NR NR NR
Coef. of Uniformity (CU) NR NR NR
% Gravel 1 2 4
% Sand 76 72 74
% Fines 22.8 25.8 22.0
USCS Class: SM SM SM
% Passing
Onsite
B16 @ 6'-6.5' B30 @ 1'-3'
B30 @ 6.5'-8.5' & 11'-

11.5' (Combined
Sample)
Noah Regalado

REPORT OF SIEVE ANALYSIS TEST
ASTM D6913 - Soil
LC
124700
Alina Hernandez
9/5/2023
November 20, 2023
Dark Brown Silty SAND
(SM)
Twentynine Palms Septic to Sewer 9671
124695, 124700, 124701
6/12/2023
6/15/2023
Veronica Hernandez
8/31/2023 9/11/2023
Onsite Onsite
124695
Reddish Brown Silty

SAND (SM)
124701
Dark Brown Silty SAND
(SM)
Veronica Hernandez
0 10
20 30
40 50
60 70
80 90
100
100 10 1 0.1 0.01

PERCENT FINER BY WEIGHT
GRAIN SIZE (mm)
124695
124700
124701
GRAVEL
coarse fine
SAND
coarse medium fine CBL SILT or CLAY
4 3.5 3 2.5 2 1.5 1 3/4 1/2 3/8 4 8 16 30 40 50 100 200 U.S. SIEVE OPENING (INCHES) U.S. SIEVE NUMBER HYDROMETER 15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 543 of 672 Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Report No.:

Project Address: Twentynine Palms, CA Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Material
Source
Sample Location
Date Tested
Tested By
Sample ID: 124705 124712 124714
Sieve Size
63mm (2 1/2") 100 100 100
50mm (2") 100 100 100

37.5mm (1 1/2") 100 100 100
25mm (1") 100 100 100
19mm (3/4") 100 100 100

12.5mm (1/2") 100 100 100

9.5mm (3/8") 99 100 100

4.75mm (#4) 98 97 98
2mm (#10) 84 78 92
850µm (#20) 67 52 74
425µm (#40) 53 34 54
250µm (#60) 43 23 40
150 µm (#100) 34 17 29 Respectfully Submitted,
75 um (#200) washµ 22.7 10.6 19.5 NV5 West, Inc.

Coef. of Curvature (CC) NR 2.2 15.8
Coef. of Uniformity (CU) NR 21.5 175.5
% Gravel 2 3 2
% Sand 75 86 79
% Fines 22.7 10.6 19.5
USCS Class: SM SW-SM SM
% Passing
Onsite
B13 @ 6'-6.5, 10'-11.5'
& 16'-16.5' (Combined
Sample)
B24 @ 11'-11.5' & 15'-

16.5' (Combined
Sample)
B29 @ 6'-9.5'
(Combined Sample)
Alina Hernandez

REPORT OF SIEVE ANALYSIS TEST
ASTM D6913 - Soil
Alina Hernandez
124712
Alina Hernandez
9/4/2023
November 20, 2023
Dark Brown Silty SAND
(SM)
Twentynine Palms Septic to Sewer 9671
124705, 124712 & 124714
6/13/2023
6/13/2023
Veronica Hernandez
9/4/2023 9/4/2023
Onsite Onsite
124705
Dark Brown Well
Graded SAND w/Silt
(SW-SM)
124714
Dark Brown Silty SAND
(SM)
Veronica Hernandez
0 10
20 30
40 50
60 70
80 90
100
100 10 1 0.1 0.01

PERCENT FINER BY WEIGHT
GRAIN SIZE (mm)
124705
124712
124714
GRAVEL
coarse fine
SAND
coarse medium fine CBL SILT or CLAY
4 3.5 3 2.5 2 1.5 1 3/4 1/2 3/8 4 8 16 30 40 50 100 200 U.S. SIEVE OPENING (INCHES) U.S. SIEVE NUMBER HYDROMETER 15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 544 of 672 Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Report No.:

Project Address: Twentynine Palms, CA Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Material
Source
Sample Location
Date Tested
Tested By
Sample ID: 124726 124730
Sieve Size
63mm (2 1/2") 100 100
50mm (2") 100 100

37.5mm (1 1/2") 100 100
25mm (1") 100 100
19mm (3/4") 100 98

12.5mm (1/2") 100 97

9.5mm (3/8") 100 95

4.75mm (#4) 100 88
2mm (#10) 95 69
850µm (#20) 76 48
425µm (#40) 57 30
250µm (#60) 42 20
150 µm (#100) 30 13 Respectfully Submitted,
75 um (#200) washµ 19.0 7.6 NV5 West, Inc.

Coef. of Curvature (CC) NR 1.3
Coef. of Uniformity (CU) NR 13.6
% Gravel 0 12
% Sand 81 80
% Fines 19.0 7.6
USCS Class: SM SW-SM
Veronica Hernandez
Onsite Onsite
124726
Dark Brown Well
Graded SAND w/Silt
(SW-SM)
Dark Brown Silty SAND
(SM)
Twentynine Palms Septic to Sewer
124726 & 124730
6/14/2023
6/16/2023
Veronica Hernandez
9/1/2023 9/1/2023
November 20, 2023
9671
Alina Hernandez

REPORT OF SIEVE ANALYSIS TEST
ASTM D6913 - Soil
Alina Hernandez
124730
% Passing
B39 @ 6'-11.5'
(Combined Sample)
B40 @ 11.5'-16'
(Combined Sample)
0 10
20 30
40 50
60 70
80 90
100
100 10 1 0.1 0.01

PERCENT FINER BY WEIGHT
GRAIN SIZE (mm)
124726
124730
GRAVEL
coarse fine
SAND
coarse medium fine CBL SILT or CLAY
4 3.5 3 2.5 2 1.5 1 3/4 1/2 3/8 4 8 16 30 40 50 100 200 U.S. SIEVE OPENING (INCHES) U.S. SIEVE NUMBER HYDROMETER 15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 545 of 672 Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Report No.:

Project Address: Twentynine Palms, CA Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Material
Source
Sample Location
Date Tested
Tested By
Sample ID: 124731
Sieve Size
63mm (2 1/2") 100
50mm (2") 100

37.5mm (1 1/2") 100
25mm (1") 100
19mm (3/4") 100

12.5mm (1/2") 100

9.5mm (3/8") 99

4.75mm (#4) 98
2mm (#10) 89
850µm (#20) 65
425µm (#40) 42
250µm (#60) 28
150 µm (#100) 20 Respectfully Submitted,
75 um (#200) washµ 12.8 NV5 West, Inc.

Coef. of Curvature (CC) NR
Coef. of Uniformity (CU) NR
% Gravel 2
% Sand 85
% Fines 12.8
USCS Class: SM
% Passing
B15 @ 5'-8' & 11'-11.5
(Combined Sample)

REPORT OF SIEVE ANALYSIS TEST
ASTM D6913 - Soil
Alina Hernandez
November 20, 2023
Twentynine Palms Septic to Sewer 9671
124731
6/15/2023
6/15/2023
Veronica Hernandez
9/7/2023
Onsite
124731
Dark Brown Silty SAND
(SM)
Veronica Hernandez
0 10
20 30
40 50
60 70
80 90
100
100 10 1 0.1 0.01

PERCENT FINER BY WEIGHT
GRAIN SIZE (mm)
124731
GRAVEL
coarse fine
SAND
coarse medium fine CBL SILT or CLAY
4 3.5 3 2.5 2 1.5 1 3/4 1/2 3/8 4 8 16 30 40 50 100 200 U.S. SIEVE OPENING (INCHES) U.S. SIEVE NUMBER HYDROMETER 15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 546 of 672 Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Report No.:

Project Address: Twentynine Palms, CA Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Material
Source
Sample Location
Date Tested
Tested By
Sample ID: 124774 124780 124781 124785 124789 124792
Sieve Size
63mm (2 1/2") 100 100 100 100 100 100
50mm (2") 100 100 100 100 100 100

37.5mm (1 1/2") 100 100 100 100 100 100
25mm (1") 100 100 100 100 100 95
19mm (3/4") 100 99 100 100 100 95

12.5mm (1/2") 98 99 100 99 100 92

9.5mm (3/8") 98 98 100 97 100 92

4.75mm (#4) 96 96 98 91 98 90
2mm (#10) 84 85 86 80 79 79
850µm (#20) 63 68 61 65 49 60
425µm (#40) 45 54 38 51 28 45
250µm (#60) 33 42 24 39 17 34
150 µm (#100) 26 31 15 29 11 26 Respectfully Submitted, 75 um (#200) washµ 17.5 17.5 8.1 17.9 5.9 17.4 NV5 West, Inc.

Coef. of Curvature (CC) N/A N/A 1.3 N/A 1.4 N/A
Coef. of Uniformity (CU) N/A N/A 9.1 N/A 8.9 N/A
% Gravel 4 4 2 9 2 10
% Sand 79 79 90 73 92 73
% Fines 17.5 17.5 8.1 17.9 5.9 17.4
USCS Class: SM SM SW-SM SM SW-SM SM
William Barton
Alina Hernandez Alina Hernandez
9/14/2023
B-7 @ 6-6.5,
7-9, 10-11.5
(Combined Sample)
Native
B-6 @ 15-16.5
Native
124792
Native Native
124774 124785
Brown Silty SAND (SM)
124789
Brown Well Graded
SAND w/Silt (SW-SM)
124781
Brown Silty SAND (SM)
Twentynine Palms Septic to Sewer
124774, 124780-124781, 124785,
124789, 124792
8/22/2023- 8/23/2023
8/23/2023
William Barton
9/13/2023 9/13/2023 9/14/2023 9/22/2023
November 27, 2023
Brown Well Graded
SAND w/Silt (SW-SM) Brown Silty SAND (SM) Brown Silty SAND (SM) 9695
Alina Hernandez

REPORT OF SIEVE ANALYSIS TEST
ASTM D6913 - Soil
Alina Hernandez
9/18/2023
124780
Alina Hernandez
% Passing
Native Native
LC
B-14 @ 5-6.5,
11-11.5
(Combined Sample)
B20 @ 16'-16.5' & 16.5-
18 B-20 @ 21-21.5
B-21 @ 16-16.5,
20-21.5, 26-26.5
(Combined Sample)
0 10
20 30
40 50
60 70
80 90
100
100 10 1 0.1 0.01

PERCENT FINER BY WEIGHT
GRAIN SIZE (mm)
124774 124780
124781 124785
124789 124792
GRAVEL
coarse fine
SAND
coarse medium fine CBL SILT or CLAY
4 3.5 3 2.5 2 1.5 1 3/4 1/2 3/8 4 8 16 30 40 50 100 200 U.S. SIEVE OPENING (INCHES) U.S. SIEVE NUMBER HYDROMETER 15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 547 of 672 Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Report No.:

Project Address: Twentynine Palms, CA Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Material
Source
Sample Location
Date Tested
Tested By
Sample ID: 124793 124797
Sieve Size
63mm (2 1/2") 100 100
50mm (2") 100 100

37.5mm (1 1/2") 100 100
25mm (1") 100 100
19mm (3/4") 100 100

12.5mm (1/2") 100 100

9.5mm (3/8") 100 100

4.75mm (#4) 97 97
2mm (#10) 89 93
850µm (#20) 72 82
425µm (#40) 50 66
250µm (#60) 29 48
150 µm (#100) 15 33 Respectfully Submitted,
75 um (#200) washµ 7.8 21.9 NV5 West, Inc.

Coef. of Curvature (CC) 1.2 N/A
Coef. of Uniformity (CU) 6.3 N/A
% Gravel 3 3
% Sand 89 75
% Fines 7.8 21.9
USCS Class: SP-SM SM
% Passing
B-7 @ 16-16.5,
20-21.5, 26-26.5
(Combined Sample)
B-8 @ 15-16.5,
21-21.5, 25-26.5
(Combined Sample)
LC

REPORT OF SIEVE ANALYSIS TEST
ASTM D6913 - Soil
LC
124797
9/22/2023
November 27, 2023
Twentynine Palms Septic to Sewer 9695
124793-124797
8/22/2023-8/23/2023
8/23/2023
William Barton
9/22/2023
Native Native
124793
Brown Silty SAND (SM) Brown Poorly Graded
SAND w/Silt (SP-SM)
William Barton
0 10
20 30
40 50
60 70
80 90
100
100 10 1 0.1 0.01

PERCENT FINER BY WEIGHT
GRAIN SIZE (mm)
124793
124797
GRAVEL
coarse fine
SAND
coarse medium fine CBL SILT or CLAY
4 3.5 3 2.5 2 1.5 1 3/4 1/2 3/8 4 8 16 30 40 50 100 200 U.S. SIEVE OPENING (INCHES) U.S. SIEVE NUMBER HYDROMETER 15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 548 of 672

Page 549 of 672 ends

Page 550 of 672 ends

Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Report No.:

Project Address: Twentynine Palms, CA Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Material
Source
Sample Location
Date Tested
Tested By
Sample ID: 140-23-
00508-02
140-23-
00508-08
Sieve Size
63mm (2 1/2") 100 100
50mm (2") 100 100

37.5mm (1 1/2") 100 100
25mm (1") 96 100
19mm (3/4") 96 99

12.5mm (1/2") 92 98

9.5mm (3/8") 89 97

4.75mm (#4) 80 91
2mm (#10) 71 60
850µm (#20) 60 32
425µm (#40) 53 18
250µm (#60) 49 11
150 µm (#100) 46 8 Respectfully Submitted,
75 um (#200) washµ 43.7 4.7 NV5 West, Inc.

Coef. of Curvature (CC) N/A 1.4
Coef. of Uniformity (CU) N/A 9.5
% Gravel 20 9
% Sand 36 86
% Fines 43.7 4.7
USCS Class: SM SW
% Passing
B1 @ 11.5'-13' &
15'-16.5' (Combined
Sample)
B4 @ 1'-3'
Alina Hernandez

REPORT OF SIEVE ANALYSIS TEST
ASTM D6913 - Soil
Joseph Stefano
140-23-00508-08
9/6/2023
November 27, 2023
Twentynine Palms Septic to Sewer RVS
140-23-00508-02,
140-23-00508-08
6/5/2023
6/9/2023
Veronica Hernandez
6/28/2023
Onsite Onsite
140-23-00508-02
Light Brown Well
Graded SAND (SW)
Light Brown Silty SAND
w/ Gravel (SM)
Veronica Hernandez
0 10
20 30
40 50
60 70
80 90
100
100 10 1 0.1 0.01

PERCENT FINER BY WEIGHT
GRAIN SIZE (mm)
140-23-00508-02
140-23-00508-08
GRAVEL
coarse fine
SAND
coarse medium fine CBL SILT or CLAY
4 3.5 3 2.5 2 1.5 1 3/4 1/2 3/8 4 8 16 30 40 50 100 200 U.S. SIEVE OPENING (INCHES) U.S. SIEVE NUMBER HYDROMETER 15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 551 of 672 Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Report No.:

Project Address: Twentynine Palms, CA Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Material
Source
Sample Location
Date Tested
Tested By
Sample ID: 124650 124659 124661
Sieve Size
63mm (2 1/2") 100 100 100
50mm (2") 100 100 100

37.5mm (1 1/2") 100 100 100
25mm (1") 100 100 100
19mm (3/4") 99 100 100

12.5mm (1/2") 98 100 100

9.5mm (3/8") 97 99 100

4.75mm (#4) 93 97 99
2mm (#10) 78 80 94
850µm (#20) 56 55 77
425µm (#40) 38 36 59
250µm (#60) 27 25 45
150 µm (#100) 19 17 33 Respectfully Submitted,
75 um (#200) washµ 12.0 10.8 21.8 NV5 West, Inc.

Coef. of Curvature (CC) 3.4 2.2 16.9
Coef. of Uniformity (CU) 39.9 22.0 212.0
% Gravel 7 3 1
% Sand 81 86 77
% Fines 12.0 10.8 21.8
USCS Class: SP-SM SW-SM SM
% Passing
Onsite
B5 @ 12'-14'
B11 @ 7'-9', 10'-11.5'
& 11.5'-13' (Combined
Sample)
B12 @ 1'-3'
Alina Hernandez

REPORT OF SIEVE ANALYSIS TEST
ASTM D6913 - Soil
Alina Hernandez
124659
Alina Hernandez
8/28/2023
November 20, 2023
Brown Silty SAND (SM)
Twentynine Palms Septic to Sewer 9671
124650, 124659 & 124661
6/6/2023
6/9/2023
Veronica Hernandez
8/28/2023 8/28/2023
Onsite Onsite
124650
Light Brown Well
Graded SAND w/Silt
(SW-SM)
124661
Brown Poorly Graded
SAND w/Silt (SP-SM)
Veronica Hernandez
0 10
20 30
40 50
60 70
80 90
100
100 10 1 0.1 0.01

PERCENT FINER BY WEIGHT
GRAIN SIZE (mm)
124650
124659
124661
GRAVEL
coarse fine
SAND
coarse medium fine CBL SILT or CLAY
4 3.5 3 2.5 2 1.5 1 3/4 1/2 3/8 4 8 16 30 40 50 100 200 U.S. SIEVE OPENING (INCHES) U.S. SIEVE NUMBER HYDROMETER 15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 552 of 672 Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Report No.:

Project Address: Twentynine Palms, CA Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Material
Source
Sample Location
Date Tested
Tested By
Sample ID: 124668 124670 124672 124675
Sieve Size
63mm (2 1/2") 100 100 100 100
50mm (2") 100 100 100 100

37.5mm (1 1/2") 100 100 100 100
25mm (1") 100 100 100 100
19mm (3/4") 100 100 100 98

12.5mm (1/2") 98 100 100 95

9.5mm (3/8") 98 99 99 93

4.75mm (#4) 96 96 97 85
2mm (#10) 86 82 90 69
850µm (#20) 56 58 77 50
425µm (#40) 31 37 62 35
250µm (#60) 20 24 46 27
150 µm (#100) 13 15 31 19 Respectfully Submitted,
75 um (#200) washµ 8.4 8.8 17.5 10.3 NV5 West, Inc.

Coef. of Curvature (CC) 1.8 1.3 NR 1.1
Coef. of Uniformity (CU) 10.0 10.6 NR 21.6
% Gravel 4 4 3 15
% Sand 88 87 80 75
% Fines 8.4 8.8 17.5 10.3
USCS Class: SW-SM SW-SM SM SW-SM
Veronica Hernandez
Onsite Onsite
124668 124675
Light Brown Well
Graded SAND w/Silt
(SW-SM)
124672
Brown Well Graded
SAND w/Silt (SW-SM)
Twentynine Palms Septic to Sewer
124668, 124670, 124672,
124675
6/7/2023
6/9/2023
Veronica Hernandez
9/12/2023 9/5/2023 8/31/2023 8/18/2023
November 20, 2023
Ligth Brown Silty SAND
(SM)
Brown Well Graded
SAND w/Silt (SW-SM)
9671
Alina Hernandez

REPORT OF SIEVE ANALYSIS TEST
ASTM D6913 - Soil
Alina Hernandez
124670
LC
% Passing
Onsite Onstie
Alina Hernandez
B27 @ 6.5'-8' B26 @ 1'-3'
B26 @ 10'-11.5' & 15'-
16'
(Combined Sample)
B25 @ 10'-11.5' &

11.5'-13' (Combined
Sample)
0 10
20 30
40 50
60 70
80 90
100
100 10 1 0.1 0.01

PERCENT FINER BY WEIGHT
GRAIN SIZE (mm)
124668
124670
124672
124675
GRAVEL
coarse fine
SAND
coarse medium fine CBL SILT or CLAY
4 3.5 3 2.5 2 1.5 1 3/4 1/2 3/8 4 8 16 30 40 50 100 200 U.S. SIEVE OPENING (INCHES) U.S. SIEVE NUMBER HYDROMETER 15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 553 of 672 Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Report No.:

Project Address: Twentynine Palms, CA Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Material
Source
Sample Location
Date Tested
Tested By
Sample ID: 124683 124686 124688 124689 124692
Sieve Size
63mm (2 1/2") 100 100 98 100 100
50mm (2") 100 100 98 100 100

37.5mm (1 1/2") 100 100 98 100 100
25mm (1") 100 100 98 100 100
19mm (3/4") 100 100 97 100 100

12.5mm (1/2") 99 99 97 100 100

9.5mm (3/8") 99 99 96 99 99

4.75mm (#4) 97 96 94 95 98
2mm (#10) 91 85 83 82 83
850µm (#20) 77 65 61 61 58
425µm (#40) 59 45 41 35 37
250µm (#60) 43 29 26 18 24
150 µm (#100) 31 17 17 9 15 Respectfully Submitted,
75 um (#200) washµ 20.2 8.5 10.1 4.5 8.9 NV5 West, Inc.

Coef. of Curvature (CC) NR 1.1 1.4 1.0 1.3
Coef. of Uniformity (CU) NR 8.4 11.7 5.2 10.7
% Gravel 3 4 6 5 2
% Sand 77 88 84 91 89
% Fines 20.2 8.5 10.1 4.5 8.9
USCS Class: SM SW-SM SW-SM SP SW-SM
% Passing
Onsite Onstie
Alina Hernandez
B31 6.5'-8' & 10'-11.5'
(Combined Sample)
B33 @ 8'-9.5' &
10'-11.5'
(Combined Sample)
B34 @ 1'-3' B34 @ 6.5'-8'
Alina Hernandez

REPORT OF SIEVE ANALYSIS TEST
ASTM D6913 - Soil
Alina Hernandez
124686
Alina Hernandez
9/6/2023 9/6/2023
November 20, 2023
Light Brown Well
Graded SAND w/Silt
(SW-SM)
Dark Brown Poorly
Graded SAND (SP)
Twentynine Palms Septic to Sewer 9671
124683, 124686, 124688,
124689, 124692
6/8/2023
6/9/2023
Veronica Hernandez
9/6/2023 9/6/2023
Onsite Onsite
124683 124689
Dark Brown Well
Graded SAND
(SW-SM) w/Silt
124692
Brown Well Graded
SAND w/Silt (SW-SM)
124688
Dark Brown Silty SAND
(SM)
Veronica Hernandez
Alina Hernandez
9/6/2023
B41 @ 12'-14'
Onsite
0 10
20 30
40 50
60 70
80 90
100
100 10 1 0.1 0.01

PERCENT FINER BY WEIGHT
GRAIN SIZE (mm)
124683
124686
124688
124689
124692
GRAVEL
coarse fine
SAND
coarse medium fine CBL SILT or CLAY
4 3.5 3 2.5 2 1.5 1 3/4 1/2 3/8 4 8 16 30 40 50 100 200 U.S. SIEVE OPENING (INCHES) U.S. SIEVE NUMBER HYDROMETER 15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400 Page 554 of 672 Date:

Client:

Client Address: Twentynine Palms, CA
Job Number:

Project Name: Report Number:

Project Address: Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Respectfully Submitted,
NV5 West, Inc.

REPORT SAND EQUIVALENT TEST RESULT
(CTM 217 Caltrans /ASTM D2419)
City of Twentynine Palms
11/20/2023
Twentynine Palms Septic to Sewer
Twentynine Palms, CA
6/6/2023
6/9/2023
227522-0000190.00
9671
Veronica Hernandez
6/9/2023
124655
Lab Number
Sand Equivalent Value
124655
37 Material
Material Location
Brown Poorly Graded
SAND w/Silt (SP-SM)
B10 @ 1'-3'
15092 Avenue of Science Suite 200 - San Diego, CA 92128 - www.NV5.com - Office 858.385.0500 - Fax 858.715.5810 CQA - Infrastructure - Energy - Program Management - Environmental Page 555 of 672 Date:

Client:

Client Address: Twentynine Palms, CA
Job Number:

Project Name: Report Number:

Project Address: Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Lab Number
Sand Equivalent Value
124680
24 Material
Material Location
Light Brown Silty Sand
(SM)
B22 @ 15'-16.5'
Veronica Hernandez
Veronica Hernandez
124680
Respectfully Submitted,
NV5 West, Inc.

REPORT SAND EQUIVALENT TEST RESULT
(CTM 217 Caltrans /ASTM D2419)
City of Twentynine Palms
11/20/2023
Twentynine Palms Septic to Sewer
Twentynine Palms, CA
6/8/2023
6/9/2023
227522-0000190.00
9671
15092 Avenue of Science Suite 200 - San Diego, CA 92128 - www.NV5.com - Office 858.385.0500 - Fax 858.715.5810 CQA - Infrastructure - Energy - Program Management - Environmental Page 556 of 672 Date:

Client:

Client Address: Twentynine Palms, CA
Job Number:

Project Name: Report Number:

Project Address: Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Respectfully Submitted,
NV5 West, Inc.

REPORT SAND EQUIVALENT TEST RESULT
(CTM 217 Caltrans /ASTM D2419)
City of Twentynine Palms
11/20/2023
Twentynine Palms Septic to Sewer
Twentynine Palms, CA
6/8/2023
6/9/2023
227522-0000190.00
9671
Veronica Hernandez
6/9/2023
124686
29 124683 & 124686
Lab Number
Sand Equivalent Value
124683
19 Material
Material Location
Dark Brown Silty SAND
(SM)
Dark Brown Well
Graded SAND
(SW-SM) w/Silt
B31 6.5'-8' & 10'-11.5'
(Combined Sample)
B33 @ 8'-9.5' &
10'-11.5'
(Combined Sample)
15092 Avenue of Science Suite 200 - San Diego, CA 92128 - www.NV5.com - Office 858.385.0500 - Fax 858.715.5810 CQA - Infrastructure - Energy - Program Management - Environmental Page 557 of 672 Date:

Client:

Client Address: Twentynine Palms, CA
Job Number:

Project Name: Report Number:

Project Address: Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Respectfully Submitted,
NV5 West, Inc.

REPORT SAND EQUIVALENT TEST RESULT
(CTM 217 Caltrans /ASTM D2419)
City of Twentynine Palms
11/20/2023
Twentynine Palms Septic to Sewer
Twentynine Palms, CA
6/12/2023
6/15/2023
227522-0000190.00
9671
Veronica Hernandez
Veronica Hernandez
124698
Lab Number
Sand Equivalent Value
124698
40 Material
Material Location
Dark Brown Poorly
Graded SAND w/Silt (SPSM)
B17 @ 5'-6.5' & 11'-

11.5' (Combined
Sample)
15092 Avenue of Science Suite 200 - San Diego, CA 92128 - www.NV5.com - Office 858.385.0500 - Fax 858.715.5810 CQA - Infrastructure - Energy - Program Management - Environmental Page 558 of 672 Date:

Client:

Client Address: Twentynine Palms, CA
Job Number:

Project Name: Report Number:

Project Address: Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Lab Number
Sand Equivalent Value
124709
27 Material
Material Location
Dark Brown Silty SAND
(SM)
Dark Brown Silty SAND
(SM)
B23 @ 8'-10' B29 @ 6'-9.5'
(Combined Sample)
Veronica Hernandez
6/13/2023
124714
19 124709 - 124714
Respectfully Submitted,
NV5 West, Inc.

REPORT SAND EQUIVALENT TEST RESULT
(CTM 217 Caltrans /ASTM D2419)
City of Twentynine Palms
11/20/2023
Twentynine Palms Septic to Sewer
Twentynine Palms, CA
6/13/2023
6/13/2023
227522-0000190.00
9671
15092 Avenue of Science Suite 200 - San Diego, CA 92128 - www.NV5.com - Office 858.385.0500 - Fax 858.715.5810 CQA - Infrastructure - Energy - Program Management - Environmental Page 559 of 672 Date:

Client:

Client Address: Twentynine Palms, CA
Job Number:

Project Name: Report Number:

Project Address: Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Respectfully Submitted,
NV5 West, Inc.

REPORT SAND EQUIVALENT TEST RESULT
(CTM 217 Caltrans /ASTM D2419)
City of Twentynine Palms
11/20/2023
Twentynine Palms Septic to Sewer
Twentynine Palms, CA
6/14/2023
6/16/2023
227522-0000190.00
9671
Veronica Hernandez
6/16/2023
124724
15 124719 & 124724
Lab Number
Sand Equivalent Value
124719
76 Material
Material Location
Brown Poorly Graded
SAND w/Silt (SP-SM)
Reddish Brown Silty

SAND (SM)
B18 @ 6.5'-8'
B38 @ 11'-11.5', 15'-

16.5' & 19.5'-20'
(Combined Samples)
15092 Avenue of Science Suite 200 - San Diego, CA 92128 - www.NV5.com - Office 858.385.0500 - Fax 858.715.5810 CQA - Infrastructure - Energy - Program Management - Environmental Page 560 of 672 Date:

Client:

Client Address: Twentynine Palms, CA
Job Number:

Project Name: Report Number:

Project Address: Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Lab Number
Sand Equivalent Value
124734
20 Material
Material Location
Dark Brown Silty SAND
(SM)
B36 @ 1'-3'
Veronica Hernandez
6/15/2023
124734
Respectfully Submitted,
NV5 West, Inc.

REPORT SAND EQUIVALENT TEST RESULT
(CTM 217 Caltrans /ASTM D2419)
City of Twentynine Palms
11/20/2023
Twentynine Palms Septic to Sewer
Twentynine Palms, CA
6/15/2023
6/15/2023
227522-0000190.00
9671
15092 Avenue of Science Suite 200 - San Diego, CA 92128 - www.NV5.com - Office 858.385.0500 - Fax 858.715.5810 CQA - Infrastructure - Energy - Program Management - Environmental Page 561 of 672 Date:

Client:

Client Address: Twentynine Palms, CA
Job Number:

Project Name: Report Number:

Project Address: Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

City Twentynine Palms Septic to Sewer
Twentynine Palms, CA
8/22/2023- 8/23/2023
8/23/2023
227522-0000190.0
9695
124774, 124780, 124792,
124793, and 124797

REPORT SAND EQUIVALENT TEST RESULT
(CTM 217 Caltrans /ASTM D2419)
City of Twentynine Palms
11/27/2023
Respectfully Submitted,
NV5 West, Inc.

Lab Number 124793
Sand Equivalent Value 27
William Barton
8/23/2023
124780
18 124797
Lab Number
Sand Equivalent Value
124774
21 124792
20 Material
Material Location
Brown Silty SAND (SM) Brown Silty SAND (SM) Brown Silty SAND (SM) B-14 @ 5-6.5, 11-11.5
(Combined Sample)
B-20 @ 16-16.5, 16.5-18
(Combined Sample)
B-7 @ 6-6.5,
7-9, 10-11.5
(Combined Sample)
Material Brown Silty SAND (SM)
Material Location
B-7 @ 16-16.5,
20-21.5, 26-26.5
(Combined Sample)
B-8 @ 15-16.5,
21-21.5, 25-26.5
(Combined Sample)
Brown Silty SAND (SM)
14 15092 Avenue of Science Suite 200 - San Diego, CA 92128 - www.NV5.com - Office 858.385.0500 - Fax 858.715.5810 CQA - Infrastructure - Energy - Program Management - Environmental Page 562 of 672 Date:

Client:

Client Address: Twentynine Palms, CA
Job Number:

Project Name: Report Number:

Project Address: Lab Number:

Date Sampled: Sampled By:

Date Submitted: Submitted By:

Lab Number
Sand Equivalent Value
140-23-00508-04
25 Material
Material Location
Light Brown Poorly
Graded SAND (SP)
Brown Poorly Graded
SAND with Gravel (SP)
B2 @ 6'-8' (Combined
Sample)
B3 @ 1'-3' & 5'-6.5'
(Combined Sample)
Veronica Hernandez
6/9/2023
140-23-00508-06
44 140-23-00508-04 & 06
Respectfully Submitted,
NV5 West, Inc.

REPORT SAND EQUIVALENT TEST RESULT
(CTM 217 Caltrans /ASTM D2419)
City of Twentynine Palms
11/20/2023
Twentynine Palms Septic to Sewer
Twentynine Palms, CA
6/8/2023
6/9/2023
227522-0000190.00
RVS
15092 Avenue of Science Suite 200 - San Diego, CA 92128 - www.NV5.com - Office 858.385.0500 - Fax 858.715.5810 CQA - Infrastructure - Energy - Program Management - Environmental Page 563 of 672 Date:

Client: City of Twentynine Palms
Client Address: Twentynine Palms, CA Job Number: 227522-0000190.00 Project Name: Report Number: 9671
Project Address: Twentynine Palms, CA Lab Number: 124691 Date Sampled: 06/08/23 Sampled By: Veronica Hernandez
Date Submitted: 06/09/23 Submitted By: Veronica Hernandez Sample Location: Test Designation: ASTM_D1557
Material Description: Brown Poorly Graded SAND w/ Silt (SP-SM) Method: A Material Source: Sample Preparation: Dry
Oversize Correction? No Type of Hammer Used: Automatic
Sieve Results (Retained %): 5
3/4": 1 3/8": 1 #4: 4
Respectfully Submitted,
NV5 West, Inc. 118.4

10.5 Maximum Density, pcf N/A
N/A
Report of Moisture/Density Relationship Test
(ASTM D1557)
Optimum Moisture, %
Optimum Moisture, %
Maximum Density, pcf
Test Results
Oversize Corrected Results
11/20/2023
Curve Number:

B41 @ 1'-3'
Onsite
Twentynine Palms Septic to Sewer
SpGr = 2.6
SpGr = 2.5
SpGr = 2.7
15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400

Page 564 of 672 ends

Date:

Client: City of Twentynine Palms
Client Address: Twentynine Palms, CA Job Number: 227522-0000190.00 Project Name: Report Number: 9671
Project Address: Twentynine Palms, CA Lab Number: 124694 Date Sampled: 06/12/23 Sampled By: Veronica Hernandez
Date Submitted: 06/15/23 Submitted By: Veronica Hernandez Sample Location: Test Designation: ASTM_D1557
Material Description: Dark Brown Silty SAND (SM) Method: A Material Source: Sample Preparation: Dry
Oversize Correction? No Type of Hammer Used: Automatic
Sieve Results (Retained %): 6
3/4": 0 3/8": 1 #4: 2
Respectfully Submitted,
NV5 West, Inc. 131.5

7.1 Maximum Density, pcf N/A
N/A
Report of Moisture/Density Relationship Test
(ASTM D1557)
Optimum Moisture, %
Optimum Moisture, %
Maximum Density, pcf
Test Results
Oversize Corrected Results
11/20/2023
Curve Number:

B16 @ 1'-3'
Onsite
Twentynine Palms Septic to Sewer
SpGr = 2.6
SpGr = 2.5
SpGr = 2.7
15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400

Page 565 of 672 ends

Date:

Client: City of Twentynine Palms
Client Address: Twentynine Palms, CA Job Number: 227522-0000190.00 Project Name: Report Number: 9671
Project Address: Twentynine Palms, CA Lab Number: 124711 Date Sampled: 06/13/23 Sampled By: Veronica Hernandez
Date Submitted: 06/13/23 Submitted By: Veronica Hernandez Sample Location: Test Designation: ASTM_D1557
Material Description: Dark Brown Poorly Graded SAND (SP) Method: A Material Source: Sample Preparation: Dry
Oversize Correction? No Type of Hammer Used: Automatic
Sieve Results (Retained %): 7
3/4": 0 3/8": 1 #4: 2
Respectfully Submitted,
NV5 West, Inc. 119.3

8.7 Maximum Density, pcf N/A
N/A
Report of Moisture/Density Relationship Test
(ASTM D1557)
Optimum Moisture, %
Optimum Moisture, %
Maximum Density, pcf
Test Results
Oversize Corrected Results
11/20/2023
Curve Number:

B24 @ 1'-3'
Onsite
Twentynine Palms Septic to Sewer
SpGr = 2.6
SpGr = 2.5
SpGr = 2.7
15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400

Page 566 of 672 ends

Date:

Client: City of Twentynine Palms
Client Address: Twentynine Palms, CA Job Number: 227522-0000190.00 Project Name: Report Number: 9671
Project Address: Twentynine Palms, CA Lab Number: 124723 Date Sampled: 06/14/23 Sampled By: Veronica Hernandez
Date Submitted: 06/16/23 Submitted By: Veronica Hernandez Sample Location: Test Designation: ASTM_D1557
Material Description: Dark Brown Silty SAND (SM) Method: A Material Source: Sample Preparation: Dry
Oversize Correction? No Type of Hammer Used: Automatic
Sieve Results (Retained %): 4
3/4": 0 3/8": 1 #4: 3
Respectfully Submitted,
NV5 West, Inc. 126.9

5.3 Maximum Density, pcf N/A
N/A
Report of Moisture/Density Relationship Test
(ASTM D1557)
Optimum Moisture, %
Optimum Moisture, %
Maximum Density, pcf
Test Results
Oversize Corrected Results
11/20/2023
Curve Number:

B38 @ 1'-3'
Onsite
Twentynine Palms Septic to Sewer
SpGr = 2.6
SpGr = 2.5
SpGr = 2.7
15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400

Page 567 of 672 ends

Date:

Client: City of Twentynine Palms
Client Address: Twentynine Palms, CA Job Number: 227522-0000190.00 Project Name: Report Number: RVS
Project Address: Twentynine Palms, CA Lab Number: 140-23-00508-06 Date Sampled: 06/05/23 Sampled By: Veronica Hernandez
Date Submitted: 06/09/23 Submitted By: Veronica Hernandez Sample Location: Test Designation: ASTM_D1557
Material Description: Brown Poorly Graded SAND w/ Gravel (SP) Method: B Material Source: Sample Preparation: Dry
Oversize Correction? No Type of Hammer Used: Automatic
Sieve Results (Retained %): 1
3/4": 1 3/8": 4 #4: 12
Respectfully Submitted,
NV5 West, Inc. 123.0

4.3 Maximum Density, pcf N/A
N/A
Report of Moisture/Density Relationship Test
(ASTM D1557)
Optimum Moisture, %
Optimum Moisture, %
Maximum Density, pcf
Test Results
Oversize Corrected Results
11/20/2023
Curve Number:

B3 @ 1'-3' & 5'-6.5'
(Combined Sample)
Onsite
Twentynine Palms Septic to Sewer
SpGr = 2.6
SpGr = 2.5
SpGr = 2.7
15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400

Page 568 of 672 ends

Date:

Client: City of Twentynine Palms
Client Address: Twentynine Palms, CA Job Number: 227522-0000190.00 Project Name: Report Number: 9671
Project Address: Twentynine Palms, CA Lab Number: 124655 Date Sampled: 06/06/23 Sampled By: Veronica Hernandez
Date Submitted: 06/09/23 Submitted By: Veronica Hernandez Sample Location: Test Designation: ASTM_D1557
Material Description: Brown Poorly Graded SAND w/Silt (SP-SM) Method: A Material Source: Sample Preparation: Dry
Oversize Correction? No Type of Hammer Used: Automatic
Sieve Results (Retained %): 1
3/4": 1 3/8": 4 #4: 12
Respectfully Submitted,
NV5 West, Inc. 122.0

8.6 Maximum Density, pcf N/A
N/A
Report of Moisture/Density Relationship Test
(ASTM D1557)
Optimum Moisture, %
Optimum Moisture, %
Maximum Density, pcf
Test Results
Oversize Corrected Results
11/20/2023
Curve Number:

B10 @ 1'-3'
Onsite
Twentynine Palms Septic to Sewer
SpGr = 2.6
SpGr = 2.5
SpGr = 2.7
15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400

Page 569 of 672 ends

Date:

Client: City of Twentynine Palms
Client Address: Twentynine Palms, CA Job Number: 227522-0000190.00 Project Name: Report Number: 9671
Project Address: Twentynine Palms, CA Lab Number: 124661 Date Sampled: 06/06/23 Sampled By: Veronica Hernandez
Date Submitted: 06/09/23 Submitted By: Veronica Hernandez Sample Location: Test Designation: ASTM_D1557
Material Description: Brown Silty SAND (SM) Method: A
Material Source: Sample Preparation: Dry
Oversize Correction? No Type of Hammer Used: Automatic
Sieve Results (Retained %): 3
3/4": 1 3/8": 4 #4: 12
Respectfully Submitted,
NV5 West, Inc. 131.1

8.1 Maximum Density, pcf N/A
N/A
Report of Moisture/Density Relationship Test
(ASTM D1557)
Optimum Moisture, %
Optimum Moisture, %
Maximum Density, pcf
Test Results
Oversize Corrected Results
11/20/2023
Curve Number:

B12 @ 1'-3'
Onsite
Twentynine Palms Septic to Sewer
SpGr = 2.6
SpGr = 2.5
SpGr = 2.7
15092 Avenue of Science, Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.385.0400

Page 570 of 672 ends

Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Twentynine Palms Septic to Sewer Report Number: RVS Project Address : Twentynine Palms, CA Lab Number: 140-23-00508-06 Material: Brown Poorly Graded SAND w/ Gravel (SP)
Material Source: Onsite
Location: B3 @ 1'-3' and 5'-6.5'
Sampled By: Veronica Hernandez
Date Sampled:

Date Received: Noah Regelado
Respectfully Submitted,
NV5 West, Inc.
11/27/2023

R-VALUE BY EXUDATION
451

7.4 14.6
73 A
350

7.4 14.1
718
73 B
350

C
350

7.4 15.0
234
RESISTANCE "R" VALUE TEST
Construction Quality Assurance · Infrastructure · Energy · Program Management · Environmental

TEST SPECIMEN
15092 Avenue of Science Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.715.5810

73 D

114.7
0 (CTM301 Caltrans / ASTM D2844)
73 115.6
TRAFFIC INDEX (ASSUMED) 4.5

6/9/2023
114.8
R-VALUE AT EQUILIBRIUM 73
COMP. FOOT PRESSURE, psi
INITIAL MOISTURE %
MOISTURE @ COMPACTION %
DRY DENSITY, pcf
EXUDATION PRESSURE, psi

STABILOMETER VALUE 'R'

R-VALUE BY EXPANSION
6/5/2023
Tested By:
73 73 73
0 5
10 15
20 25
30 35
40 45
50 55
60 65
70 75
80 85
90 95
100
800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 Exudation Presure (psi)

EXUDATION PRESSURE CHART

0.0 0.1

0.2 0.3

0.4 0.5

0.6 0.7

0.8 0.9

1.0 1.1

1.2 1.3

1.4 1.5

0.00.10.20.30.40.50.60.70.80.91.01.11.21.31.41.5 Cover Thickness By Stabilometer,(ft) Cover Thickness by Expansion Pressure (ft)

EXPANSION PRESSURE CHART

Page 571 of 672 ends

Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Twentynine Palms Septic to Sewer Report Number: 9671 Project Address : Twentynine Palms, CA Lab Number: 124652 Material: Brown Poorly Graded SAND (SP)
Material Source: Onsite
Location: B9 @ 1'-3'
Sampled By: Veronica Hernandez
Date Sampled:

Date Received: Noah Regelado
Respectfully Submitted,
NV5 West, Inc.
11/20/2023

R-VALUE BY EXUDATION
362

1.9 8.7
76 A
350

1.9 8.2
701
79 B
350

C
350

1.9 9.5
171
RESISTANCE "R" VALUE TEST
Construction Quality Assurance · Infrastructure · Energy · Program Management · Environmental

TEST SPECIMEN
15092 Avenue of Science Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.715.5810

75 D

123.7
0 (CTM301 Caltrans / ASTM D2844)
76 124.2
TRAFFIC INDEX (ASSUMED) 4.5

6/9/2023
121.9
R-VALUE AT EQUILIBRIUM 76
COMP. FOOT PRESSURE, psi
INITIAL MOISTURE %
MOISTURE @ COMPACTION %
DRY DENSITY, pcf
EXUDATION PRESSURE, psi

STABILOMETER VALUE 'R'

R-VALUE BY EXPANSION
6/6/2023
Tested By:
79 76 75
0 5
10 15
20 25
30 35
40 45
50 55
60 65
70 75
80 85
90 95
100
800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 Exudation Presure (psi)

EXUDATION PRESSURE CHART

0.0 0.1

0.2 0.3

0.4 0.5

0.6 0.7

0.8 0.9

1.0 1.1

1.2 1.3

1.4 1.5

0.00.10.20.30.40.50.60.70.80.91.01.11.21.31.41.5 Cover Thickness By Stabilometer,(ft) Cover Thickness by Expansion Pressure (ft)

EXPANSION PRESSURE CHART

Page 572 of 672 ends

Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Twentynine Palms Septic to Sewer Report Number: 9671 Project Address : Twentynine Palms, CA Lab Number: 124707 Material: Dark Brown Sandy SILT (ML)
Material Source: Onsite
Location: B23 @ 1'-3'
Sampled By: Veronica Hernandez
Date Sampled:

Date Received: Noah Regelado
Respectfully Submitted,
NV5 West, Inc.
6/13/2023
Tested By:

R-VALUE AT EQUILIBRIUM 67
COMP. FOOT PRESSURE, psi
INITIAL MOISTURE %
MOISTURE @ COMPACTION %
DRY DENSITY, pcf
EXUDATION PRESSURE, psi

STABILOMETER VALUE 'R'

R-VALUE BY EXPANSION
67 128.5
TRAFFIC INDEX (ASSUMED) 4.5

6/13/2023
127.3
(CTM301 Caltrans / ASTM D2844)
0 Construction Quality Assurance · Infrastructure · Energy · Program Management · Environmental

TEST SPECIMEN
15092 Avenue of Science Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.715.5810

25 D

128.4
RESISTANCE "R" VALUE TEST
412
78 B
350

C
250

5.1 10.5
129
11/20/2023

R-VALUE BY EXUDATION
212

5.1 9.5
56 A
350

5.1 8.6
78 56
25 0
5 10
15 20
25 30
35 40
45 50
55 60
65 70
75 80
85 90
95 100
800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 Exudation Presure (psi)

EXUDATION PRESSURE CHART

0.0 0.1

0.2 0.3

0.4 0.5

0.6 0.7

0.8 0.9

1.0 1.1

1.2 1.3

1.4 1.5

0.00.10.20.30.40.50.60.70.80.91.01.11.21.31.41.5 Cover Thickness By Stabilometer,(ft) Cover Thickness by Expansion Pressure (ft)

EXPANSION PRESSURE CHART

Page 573 of 672 ends

Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Twentynine Palms Septic to Sewer Report Number: 9671 Project Address : Twentynine Palms, CA Lab Number: 124670 Material: Light Brown Well Graded SAND w/Silt (SW-SM)
Material Source: Onsite
Location: B26 @ 1 - 3
Sampled By: Veronica Hernandez
Date Sampled:

Date Received: Noah Regelado
Respectfully Submitted,
NV5 West, Inc.
11/20/2023

R-VALUE BY EXUDATION
350

1.7 8.9
78 A
350

1.7 8.5
549
78 B
180

C
110

1.7 9.3
151
RESISTANCE "R" VALUE TEST
Construction Quality Assurance · Infrastructure · Energy · Program Management · Environmental

TEST SPECIMEN
15092 Avenue of Science Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.715.5810

75 D

126.1
0 (CTM301 Caltrans / ASTM D2844)
78 126.0
TRAFFIC INDEX (ASSUMED) 4.5

6/9/2023
125.5
R-VALUE AT EQUILIBRIUM 78
COMP. FOOT PRESSURE, psi
INITIAL MOISTURE %
MOISTURE @ COMPACTION %
DRY DENSITY, pcf
EXUDATION PRESSURE, psi

STABILOMETER VALUE 'R'

R-VALUE BY EXPANSION
6/7/2023
Tested By:
78 78
75 0
5 10
15 20
25 30
35 40
45 50
55 60
65 70
75 80
85 90
95 100
800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 Exudation Presure (psi)

EXUDATION PRESSURE CHART

0.0 0.1

0.2 0.3

0.4 0.5

0.6 0.7

0.8 0.9

1.0 1.1

1.2 1.3

1.4 1.5

0.00.10.20.30.40.50.60.70.80.91.01.11.21.31.41.5 Cover Thickness By Stabilometer,(ft) Cover Thickness by Expansion Pressure (ft)

EXPANSION PRESSURE CHART

Page 574 of 672 ends

Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Twentynine Palms Septic to Sewer Report Number: 9671 Project Address : Twentynine Palms, CA Lab Number: 124700 Material: Reddish Brown Silty SAND (SM)
Material Source: Onsite
Location: B30 @ 1'-3'
Sampled By: Veronica Hernandez
Date Sampled:

Date Received: Noah Regelado
Respectfully Submitted,
NV5 West, Inc.
11/20/2023

R-VALUE BY EXUDATION
423

5.4 10.6
31 A
350

5.4 9.7
622
49 B
180

C
110

5.4 11.5
255
RESISTANCE "R" VALUE TEST
Construction Quality Assurance · Infrastructure · Energy · Program Management · Environmental

TEST SPECIMEN
15092 Avenue of Science Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.715.5810

18 D

128.5
0 (CTM301 Caltrans / ASTM D2844)
22 125.4
TRAFFIC INDEX (ASSUMED) 4.5

6/15/2023
123.3
R-VALUE AT EQUILIBRIUM 22
COMP. FOOT PRESSURE, psi
INITIAL MOISTURE %
MOISTURE @ COMPACTION %
DRY DENSITY, pcf
EXUDATION PRESSURE, psi

STABILOMETER VALUE 'R'

R-VALUE BY EXPANSION
6/12/2023
Tested By:
49 31
18 0
5 10
15 20
25 30
35 40
45 50
55 60
65 70
75 80
85 90
95 100
800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 Exudation Presure (psi)

EXUDATION PRESSURE CHART

0.0 0.1

0.2 0.3

0.4 0.5

0.6 0.7

0.8 0.9

1.0 1.1

1.2 1.3

1.4 1.5

0.00.10.20.30.40.50.60.70.80.91.01.11.21.31.41.5 Cover Thickness By Stabilometer,(ft) Cover Thickness by Expansion Pressure (ft)

EXPANSION PRESSURE CHART

Page 575 of 672 ends

Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Twentynine Palms Septic to Sewer Report Number: 9671 Project Address : Twentynine Palms, CA Lab Number: 124688 Material: Light Brown Well Graded SAND w/Silt (SW-SM)
Material Source: Onsite
Location: B34 @ 1'-3'
Sampled By: Veronica Hernandez
Date Sampled:

Date Received: Noah Regelado
Respectfully Submitted,
NV5 West, Inc.
11/20/2023

R-VALUE BY EXUDATION
438

1.4 9.0
79 A
350

1.4 8.4
780
81 B
350

C
350

1.4 9.4
161
RESISTANCE "R" VALUE TEST
Construction Quality Assurance · Infrastructure · Energy · Program Management · Environmental

TEST SPECIMEN
15092 Avenue of Science Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.715.5810

73 D

128.1
0 (CTM301 Caltrans / ASTM D2844)
76 127.8
TRAFFIC INDEX (ASSUMED) 4.5

6/9/2023
127.0
R-VALUE AT EQUILIBRIUM 76
COMP. FOOT PRESSURE, psi
INITIAL MOISTURE %
MOISTURE @ COMPACTION %
DRY DENSITY, pcf
EXUDATION PRESSURE, psi

STABILOMETER VALUE 'R'

R-VALUE BY EXPANSION
6/8/2023
Tested By:
81 79
73 0
5 10
15 20
25 30
35 40
45 50
55 60
65 70
75 80
85 90
95 100
800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 Exudation Presure (psi)

EXUDATION PRESSURE CHART

0.0 0.1

0.2 0.3

0.4 0.5

0.6 0.7

0.8 0.9

1.0 1.1

1.2 1.3

1.4 1.5

0.00.10.20.30.40.50.60.70.80.91.01.11.21.31.41.5 Cover Thickness By Stabilometer,(ft) Cover Thickness by Expansion Pressure (ft)

EXPANSION PRESSURE CHART

Page 576 of 672 ends

Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Twentynine Palms Septic to Sewer Report Number: 9671 Project Address : Twentynine Palms, CA Lab Number: 124734 Material: Dark Brown Silty SAND (SM)
Material Source: Onsite
Location: B36 @ 1'-3'
Sampled By: Veronica Hernandez
Date Sampled:

Date Received: Noah Regelado
Respectfully Submitted,
NV5 West, Inc.
6/13/2023
Tested By:

R-VALUE AT EQUILIBRIUM 64
COMP. FOOT PRESSURE, psi
INITIAL MOISTURE %
MOISTURE @ COMPACTION %
DRY DENSITY, pcf
EXUDATION PRESSURE, psi

STABILOMETER VALUE 'R'

R-VALUE BY EXPANSION
64 127.9
TRAFFIC INDEX (ASSUMED) 4.5

6/13/2023
126.5
(CTM301 Caltrans / ASTM D2844)
0 Construction Quality Assurance · Infrastructure · Energy · Program Management · Environmental

TEST SPECIMEN
15092 Avenue of Science Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.715.5810

50 D

128.0
RESISTANCE "R" VALUE TEST
471
77 B
350

C
350

1.9 10.4
223
11/20/2023

R-VALUE BY EXUDATION
287

1.9 9.9
63 A
350

1.9 9.5
77 63
50 0
5 10
15 20
25 30
35 40
45 50
55 60
65 70
75 80
85 90
95 100
800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 Exudation Presure (psi)

EXUDATION PRESSURE CHART

0.0 0.1

0.2 0.3

0.4 0.5

0.6 0.7

0.8 0.9

1.0 1.1

1.2 1.3

1.4 1.5

0.00.10.20.30.40.50.60.70.80.91.01.11.21.31.41.5 Cover Thickness By Stabilometer,(ft) Cover Thickness by Expansion Pressure (ft)

EXPANSION PRESSURE CHART

Page 577 of 672 ends

Date:

Client: City of Twentynine Palms
Address: Twentynine Palms, CA
Job Number: 227522-0000190.00
Project : Twentynine Palms Septic to Sewer Report Number: 9671 Project Address : Twentynine Palms, CA Lab Number: 124692 Material: Brown Well Graded SAND w/Silt (SW-SM)
Material Source: Onsite
Location: B41 @ 12'-14'
Sampled By: Veronica Hernandez
Date Sampled:

Date Received: Noah Regelado
Respectfully Submitted,
NV5 West, Inc.
6/8/2023
Tested By:

R-VALUE AT EQUILIBRIUM 79
COMP. FOOT PRESSURE, psi
INITIAL MOISTURE %
MOISTURE @ COMPACTION %
DRY DENSITY, pcf
EXUDATION PRESSURE, psi

STABILOMETER VALUE 'R'

R-VALUE BY EXPANSION
79 125.8 126.6
TRAFFIC INDEX (ASSUMED) 4.5
222
6/9/2023
126.1
(CTM301 Caltrans / ASTM D2844)
0 Construction Quality Assurance · Infrastructure · Energy · Program Management · Environmental

TEST SPECIMEN
15092 Avenue of Science Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.715.5810

1.7 10.2
80 D
350
124.5
RESISTANCE "R" VALUE TEST
788
83 B
350
77 C
350

1.7 10.0
391
11/20/2023

R-VALUE BY EXUDATION
561

1.7 9.7
82 A
350

1.7 9.5
83 82 80
77 0
5 10
15 20
25 30
35 40
45 50
55 60
65 70
75 80
85 90
95 100
800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 Exudation Presure (psi)

EXUDATION PRESSURE CHART

0.0 0.1

0.2 0.3

0.4 0.5

0.6 0.7

0.8 0.9

1.0 1.1

1.2 1.3

1.4 1.5

0.00.10.20.30.40.50.60.70.80.91.01.11.21.31.41.5 Cover Thickness By Stabilometer,(ft) Cover Thickness by Expansion Pressure (ft)

EXPANSION PRESSURE CHART

Page 578 of 672 ends

Page 579 of 672 ends

Project No.

Client:

Proj. Name:

Location:
227522-0000190.00 PH 05 TK01
City of Twentynine Palms
Twentynine Palms Septic to Sewer
Lab No.: 124793 / 90169
Test Date: 9/20/2023
Sample date: 8/23/2023 Sample Location: B-7@ 16-16.Sft
TEST DATA:

Sample ID: 1 KSF 2 KSF 4 KSF
Water Content(%) 2.3 2.3 2.3
� Dry Density(%) 105.4 105.4 105.4 -
:s Saturation (%) 11.1 11.1 11.1
Normal Stress (psf) 1000 -2000 4000 ---- Peak Shear Stress (psf) 1176 1944 3540 Residual Shear Stress (psf) � -1428 2820
Strain Rate: 0.005 in/min
s
..s
5000 ,__
4000 1-----t-
- - -1 KSF
••••••••• 2 KSF
4 KSF
/"� - -....�. - ::I 3000 ---+-v�""' I ,-....,. f
Sample Type: Undisturbed (soaked prior to shearing)
Description: Brown Poorly Graded SAND w/ Silt
,,, ., . . ,,,,,-, ,....
1 ..
.. ··••••• ·
······"• •······
·
··
� 2000 �- ••
•
••••••• ·······:::: • -t- iii 0.02 V • V u 0.015 � · •
•
"f ,,, •' .• ./
• �.-----+----I- -
1000 - - - - - -_
.. ... _�---...-----
' ------
>CII 0.01 ,---+---. "' . ...-;-. .....:-+7'""''------,f----l-----+-----! •·•••__,,,-r

0.005 -1------.n.:-s,..,.,c:_-t
0 _ .... �I---""" -·
0 ,:---�--�--..----..----,l,---� --0.005
0 0.05 0.1 0.15 0.2 0.25 0.3
Horizontal Displacement (in)
4500
4000
3500
� 3000
en"
2500
u,
... 2000
u, 1500
1000
500 ,,,..
0 0
Peak Cohesion, C'(psf): 375
Peak Friction.Cl>' (deg): 38.3
NVS
1000
A
2000 3000
Effective Normal Stress, (psf)
Residual Cohesion, C'(psf): 100
Residual Friction.Cl>' (deg): 34.1
NVS WEST, INC.
1868 Palma Drive Suite A
Ventura CA 93003
P. (805)656-6074 F. (805)650-6264
0 4000

0.05 0.1 0.15 0.2 0.25
Horizontal Displacement (in)
5000
-- Linear (Peak Strength
Envelope)
Linear (Residual Strength
Envelope)
Residual
y = 0.7904x + 375
y = 0.677x + 100

0.3 DIRECT SHEAR TEST (ASTM D3080)
Figure No.: DS.B-7@ 16-16.5ft
(SP-SM)

Page 580 of 672 ends

Page 581 of 672 ends

Page 582 of 672 ends

Project No.

Client:

Proj. Name:

Location:
227522-0000190.00 PH 05 TK01
City of Twentynine Palms
Twentynine Palms Septic to Sewer
Lab No.: 124786 / 90169
--
Test Date: 9/27/2023 ---
Sample date: 8/22/2023 Sample Location: B-21 @ 16-16.Sft TEST DATA:

Sample ID: 1 KSF 2 KSF 4 KSF
Water Content(%) 1.3 1.3 1.3
� Dry Density (%) 118.6 118.6 118.6
·c Saturation(%) 9.2 9.2
- �
Normal Stress (psf) 1000 2000 4000
Peak Shear Stress (psf) 840 1752 3348-
Residual Shear Stress (psf) 804 1704 3180-
Strain Rate: 0.005 in/min
5000
- - -1 KSF
·······-- 2 KSF
4000 � - --4KSF
_!:!;
-"'
3000 --,� ,_,. --� - V "- "'
CII
.... /
...
2000 - . ········"•• ·····•·••· •. ···•• .. ••••·••• "' ···••• ....

CII ...

Ill ,,•·
·-
Sample Type:

Description:

0.04 0.035
-
:§. 0.03
� 0.025
CII
E 0.02 CII u
'E.. 0.015
"'
o 0.01
ia u 0.005 -
'f
CII 0
Undisturbed (soaked prior to shearing)
Light Brown Silty SAND (SM)
-�
r-
--r- -- -
-
.... ... - � ..
--1- .. ····
. __,,,,.,.
.. ,-�
� .. .. .-- --
I - - -1 KSF
......... 2 KSF
--4KSF
-L--�- ...
,.• ....
.. -----
I
.. -
-- - -
-�-
1000 r7· --- - --- - - .. - - > ---... -- - -- - - --
; -0.005 ..__ --�--
0 � -0.01 -- - -- -
0 0.05 0.1 0.15 0.2 0.25 0.3 0 0.05 0.1 0.15 0.2 0.25 0.3 Horizontal Displacement (in) Horizontal Displacement (in) 5000 -- Linear (Peak Strength
4500 Envelope)
4000 ./ Linear (Residual Strength
i � Envelope)
3500 /' E:
(/)
...
in
2500
3000
�
/
Peak y = 0.8279x + 50
cu
Cl) 2000 �-
1500 � Residual y = 0.7896x + 50
1000 �r
500
0 /
0 1000 2000 3000 4000 5000
Effective Normal Stress, (psf)
Peak Cohesion, C'(psf): 50 Residual Cohesion, C'(psf): 50 DIRECT SHEAR TEST (ASTM D3080) Peak Friction,¢' (deg): 39.6 Residual Friction,ct>' (deg): 38.3 N V 5 NVS WEST, INC.
1868 Palma Drive Suite A
Ventura CA 93003
P. (805)656-6074 F. (805)650-6264 Figure No.: DS.B-21@ 16-16.5ft

Page 583 of 672 ends

Page 584 of 672 ends

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Page 591 of 672 ends

L A B O R A T O R Y R E P O R T
Telephone (619) 425-1993 Fax 425-7917 Established 1928
C L A R K S O N L A B O R A T O R Y A N D S U P P L Y I N C. 350 Trousdale Dr. Chula Vista, Ca. 91910 www.clarksonlab.com

A N A L Y T I C A L A N D C O N S U L T I N G C H E M I S T S Date: September 15, 2023
Purchase Order Number: 23-0064
Sales Order Number: 61101
Account Number: NV5.SD
To:
*-------------------------------------------------*
NV5 West Inc
15092 Avenue of Science #200
San Diego, CA 92128
Attention: Michelle Albrecht
Laboratory Number: SO9811-3 Customers Phone: 858-715-5800 Sample Designation:
*-------------------------------------------------*
One soil sample received on 09/11/23 at 2:50pm,
taken from Twentynine Palms Septic to Sewer
Project 227522-0000190.00 Report 9671
marked as B-25@10'-11.5'&11.5'-13' Lab No 124675
Analysis By California Test 643, 1999, Department of Transportation Division of Construction, Method for Estimating the Service Life of Steel Culverts.
pH 8.3
Water Added (ml) Resistivity (ohm-cm)

10 13000
5 10000
5 8600
5 7200
5 7200
5 7300
5 7600
69 years to perforation for a 16 gauge metal culvert.
89 years to perforation for a 14 gauge metal culvert.
124 years to perforation for a 12 gauge metal culvert.
158 years to perforation for a 10 gauge metal culvert.
192 years to perforation for a 8 gauge metal culvert.

Water Soluble Sulfate Calif. Test 417 <0.003% (<30ppm)
Water Soluble Chloride Calif. Test 422 0.001% (11ppm)
______________________________
Rosa Bernal
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A N A L Y T I C A L A N D C O N S U L T I N G C H E M I S T S Date: September 15, 2023
Purchase Order Number: 23-0064
Sales Order Number: 61101
Account Number: NV5.SD
To:
*-------------------------------------------------*
NV5 West Inc
15092 Avenue of Science #200
San Diego, CA 92128
Attention: Michelle Albrecht
Laboratory Number: SO9811-4 Customers Phone: 858-715-5800 Sample Designation:
*-------------------------------------------------*
One soil sample received on 09/11/23 at 2:50pm,
taken from Twentynine Palms Septic to Sewer
Project 227522-0000190.00 Report 9671
marked as B-29@6'-6.5'&6.5'-8'&8'-9.5' Lab No 124714
Analysis By California Test 643, 1999, Department of Transportation Division of Construction, Method for Estimating the Service Life of Steel Culverts.
pH 8.8
Water Added (ml) Resistivity (ohm-cm)

10 5400
5 4900
5 4200
5 3400
5 3500
5 3600
50 years to perforation for a 16 gauge metal culvert.
66 years to perforation for a 14 gauge metal culvert.
91 years to perforation for a 12 gauge metal culvert.
116 years to perforation for a 10 gauge metal culvert.
141 years to perforation for a 8 gauge metal culvert.

Water Soluble Sulfate Calif. Test 417 0.005% (45ppm)
Water Soluble Chloride Calif. Test 422 0.001% (11ppm)
______________________________
Rosa Bernal
RMB/js

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A N A L Y T I C A L A N D C O N S U L T I N G C H E M I S T S Date: September 15, 2023
Purchase Order Number: 23-0064
Sales Order Number: 61101
Account Number: NV5.SD
To:
*-------------------------------------------------*
NV5 West Inc
15092 Avenue of Science #200
San Diego, CA 92128
Attention: Michelle Albrecht
Laboratory Number: SO9811-5 Customers Phone: 858-715-5800 Sample Designation:
*-------------------------------------------------*
One soil sample received on 09/11/23 at 2:50pm,
taken from Twentynine Palms Septic to Sewer
Project 227522-0000190.00 Report 9671
marked as B-41@12'-14' Lab No 124692
Analysis By California Test 643, 1999, Department of Transportation Division of Construction, Method for Estimating the Service Life of Steel Culverts.
pH 9.1
Water Added (ml) Resistivity (ohm-cm)

10 12000
5 9600
5 7900
5 7200
5 7000
5 7100
5 7200
68 years to perforation for a 16 gauge metal culvert.
88 years to perforation for a 14 gauge metal culvert.
122 years to perforation for a 12 gauge metal culvert.
156 years to perforation for a 10 gauge metal culvert.
190 years to perforation for a 8 gauge metal culvert.

Water Soluble Sulfate Calif. Test 417 0.003% (30ppm)
Water Soluble Chloride Calif. Test 422 0.001% (11ppm)
______________________________
Rosa Bernal
RMB/js

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A N A L Y T I C A L A N D C O N S U L T I N G C H E M I S T S Date: September 19, 2023
Purchase Order Number: 23-0067
Sales Order Number: 61152
Account Number: NV5.SD
To:
*-------------------------------------------------*
NV5 West Inc
15092 Avenue of Science #200
San Diego, CA 92128
Attention: Michelle Albrecht
Laboratory Number: SO9814-1 Customers Phone: 858-715-5800 Sample Designation:
*-------------------------------------------------*
One soil sample received on 09/14/23 at 1:30pm, taken from Twenty Nine Palms Septic to Sewer Project 227522-0000190.00 Report 9695 marked as B-7@6'-6.5'&7'-9'&10'-11.5' Lab No 124792.

Analysis By California Test 643, 1999, Department of Transportation Division of Construction, Method for Estimating the Service Life of Steel Culverts.
pH 8.8
Water Added (ml) Resistivity (ohm-cm)

10 2600
5 2100
5 1800
5 1600
5 1600
5 1700
5 1800
37 years to perforation for a 16 gauge metal culvert.
48 years to perforation for a 14 gauge metal culvert.
67 years to perforation for a 12 gauge metal culvert.
85 years to perforation for a 10 gauge metal culvert.
104 years to perforation for a 8 gauge metal culvert.

Water Soluble Sulfate Calif. Test 417 0.005% (51ppm)
Water Soluble Chloride Calif. Test 422 0.012% (120ppm)
______________________________
Rosa Bernal
RMB/js

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A N A L Y T I C A L A N D C O N S U L T I N G C H E M I S T S Date: September 19, 2023
Purchase Order Number: 23-0067
Sales Order Number: 61152
Account Number: NV5.SD
To:
*-------------------------------------------------*
NV5 West Inc
15092 Avenue of Science #200
San Diego, CA 92128
Attention: Michelle Albrecht
Laboratory Number: SO9814-2 Customers Phone: 858-715-5800 Sample Designation:
*-------------------------------------------------*
One soil sample received on 09/14/23 at 1:30pm, taken from Twenty Nine Palms Septic to Sewer Project 227522-0000190.00 Report 9695 marked as B-14@5'-6.5'&6.5'-8'&11'-11.5' Lab No 124774.

Analysis By California Test 643, 1999, Department of Transportation Division of Construction, Method for Estimating the Service Life of Steel Culverts.
pH 8.9
Water Added (ml) Resistivity (ohm-cm)

10 5400
5 3500
5 3100
5 2800
5 2900
5 3000
47 years to perforation for a 16 gauge metal culvert.
61 years to perforation for a 14 gauge metal culvert.
84 years to perforation for a 12 gauge metal culvert.
107 years to perforation for a 10 gauge metal culvert.
131 years to perforation for a 8 gauge metal culvert.

Water Soluble Sulfate Calif. Test 417 0.005% (51ppm)
Water Soluble Chloride Calif. Test 422 0.005% (53ppm)
______________________________
Rosa Bernal
RMB/js

Page 596 of 672 ends

A N A L Y T I C A L A N D C O N S U L T I N G C H E M I S T S Date: September 15, 2023
Purchase Order Number: 23-0064
Sales Order Number: 61101
Account Number: NV5.SD
To:
*-------------------------------------------------*
NV5 West Inc
15092 Avenue of Science #200
San Diego, CA 92128
Attention: Michelle Albrecht
Laboratory Number: SO9811-1 Customers Phone: 858-715-5800 Sample Designation:
*-------------------------------------------------*
One soil sample received on 09/11/23 at 2:50pm,
taken from Twentynine Palms Septic to Sewer
Project 227522-0000190.00 Report 9671
marked as B-3@1'-3' Lab No 140-23-00508-06
Analysis By California Test 643, 1999, Department of Transportation Division of Construction, Method for Estimating the Service Life of Steel Culverts.
pH 8.3
Water Added (ml) Resistivity (ohm-cm)

10 17000
5 15000
5 12000
5 9600
5 9500
5 9100
5 9200
5 9300
76 years to perforation for a 16 gauge metal culvert.
98 years to perforation for a 14 gauge metal culvert.
136 years to perforation for a 12 gauge metal culvert.
174 years to perforation for a 10 gauge metal culvert.
212 years to perforation for a 8 gauge metal culvert.

Water Soluble Sulfate Calif. Test 417 0.003% (30ppm)
Water Soluble Chloride Calif. Test 422 0.003% (32ppm)
______________________________
Rosa Bernal
RMB/js

Page 597 of 672 ends

A N A L Y T I C A L A N D C O N S U L T I N G C H E M I S T S Date: September 15, 2023
Purchase Order Number: 23-0064
Sales Order Number: 61101
Account Number: NV5.SD
To:
*-------------------------------------------------*
NV5 West Inc
15092 Avenue of Science #200
San Diego, CA 92128
Attention: Michelle Albrecht
Laboratory Number: SO9811-2 Customers Phone: 858-715-5800 Sample Designation:
*-------------------------------------------------*
One soil sample received on 09/11/23 at 2:50pm,
taken from Twentynine Palms Septic to Sewer
Project 227522-0000190.00 Report 9671
marked as B-5@12'-14' Lab No 124650
Analysis By California Test 643, 1999, Department of Transportation Division of Construction, Method for Estimating the Service Life of Steel Culverts.
pH 8.2
Water Added (ml) Resistivity (ohm-cm)

10 4200
5 3700
5 2300
5 2300
5 2400
5 2500
43 years to perforation for a 16 gauge metal culvert.
56 years to perforation for a 14 gauge metal culvert.
77 years to perforation for a 12 gauge metal culvert.
99 years to perforation for a 10 gauge metal culvert.
120 years to perforation for a 8 gauge metal culvert.

Water Soluble Sulfate Calif. Test 417 0.008% (81ppm)
Water Soluble Chloride Calif. Test 422 0.005% (53ppm)
______________________________
Rosa Bernal
RMB/js

Page 598 of 672 ends

227522-0000190.00 NV5.COM |
Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California Prepared by NV5 (2022)

APPENDIX D

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Preliminary Screening Study
of Groundwater Recharge Sites,
Twentynine Palms, California
by:

NV5, Inc.

Phoenix, Arizona
for:

City of Twentynine Palms
Twentynine Palms,
California January 26th 2022

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Table of Contents
1 INTRODUCTION....................................................................................................................... 3

1.1. Background....................................................................................................................... 3

1.2. Local Conditions............................................................................................................... 3 2 Preliminary Screening of Sites................................................................................................ 5

2.1.1. Surface soils .............................................................................................................. 6

2.1.2. Surface geology......................................................................................................... 8

2.2. Subsurface Conditions.................................................................................................... 12

2.2.1. Depth to groundwater............................................................................................ 12

2.2.2. Depth to crystalline basement................................................................................ 14

2.2.3. Water quality .......................................................................................................... 14

2.2.4. Hydrogeology.......................................................................................................... 16

2.3. Location.......................................................................................................................... 18

2.3.1. Distance to proposed WWTP.................................................................................. 18

2.3.2. Land use .................................................................................................................. 18

2.3.3. Land ownership....................................................................................................... 18

2.3.4. Size .......................................................................................................................... 19

2.3.5. Existing infrastructure............................................................................................. 19

2.3.6. Areas of preservation or open space...................................................................... 21 3 Candidate Sites ..................................................................................................................... 21

3.1. Field Work ...................................................................................................................... 21

3.1.1. Fluoride Site ............................................................................................................ 23

3.1.2. Morongo Site .......................................................................................................... 23

3.1.3. Flood Site ................................................................................................................ 24

3.1.4. Summary of Field Testing........................................................................................ 24

3.2. Application of Criteria .................................................................................................... 24 4 Conclusion and Recommendation........................................................................................ 28 5 References ............................................................................................................................ 31

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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California Figures
Figure 1.1 - - Map of locations cited in report............................................................................................................... 4 Figure 2- - Local soils data retrieved from NRCS SSURGO/STATSGO2 data series. ....................................................... 9 Figure 2.2 - - Local geology as generalized from Riley and Worts (1952), Dibblee (1968), and TPWD (2016)............11 Figure 2.3 - - Local groundwater basins from CalDWR 2021 and TPWD (2016)..........................................................13 Figure 2.4 - - Local depth to groundwater. Data from Dick and Kjos (2016)...............................................................15 Figure 6 - - Local depth to bedrock. Reproduction of figure from Li and Martin (2011). ............................................17 Figure 7 - - Local land ownership. Data from San Bernardino County Planning Department (2021)..........................20 Figure 3.1- -Location of three sites examined during infiltration measurement field work .......................................22 Figure 3.2 - - Detail map of Fluoride Site. ....................................................................................................................25 Figure 3.3 - - Detail map of Morongo Site. ..................................................................................................................26 Figure 3.4 - - Detail map of Flood Site. ........................................................................................................................27 Tables
Table 3.1 - - Criteria data used for the three sites.......................................................................................................29 Table 3.2 - - Ranking of the three sites........................................................................................................................30 Attachments (follows Section 5)
Attachment 1 - - Technical Memorandum on Infiltration Measurements.

Attachment 2 - - Well Completion Report for TPWD Well TP-1

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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California 1 INTRODUCTION

1.1. Background
This screening investigation of potential recharge sites near Twentynine Palms, California was contracted to NV5, Inc. by the City of Twentynine Palms (City) as part of a larger, wastewaterdesign, feasibility study in 2021 (Figure 1.1). The City lies in the Morongo Basin and similar to other developed parts of the Mojave Desert, groundwater levels are declining. The City is intent upon recycling treated wastewater, if practicable (TPWD 2016). NV5 was tasked under the feasibility study to recommend a site for the location of a surface-spreading infiltration basin to use for recharge of the regional groundwater system treated effluent.

Selection of a successful groundwater recharge basin requires the evaluation of multiple physical factors and criteria. Ideally, the selection would be entirely based upon the ability of the upper geological layers of the target area to accept infiltrated surface water and to allow gravitational and other site conditions to effect transmission of the water through percolation to the target aquifer. Despite this, there are additional variables that need to be considered, including the location of the basin, relative to the treatment facility, the availability and value of land, groundwater rights issues, water quality concerns, and cost.

NV5 examined each of these issues and developed a screening strategy using weighted factors appropriate to the importance of that concern. This analysis resulted in a candidate site that will be advanced to further and more detailed analysis.

1.2. Local Conditions
In 2014, the City and Twentynine Palms Water District (TPWD) commissioned a study of the wastewater option best suited to projected growth and revenue availability. At that time, dispersed sewer systems, primarily septic tanks, were the most common method for urban sewage disposal. The need for a centralized system was felt by City leadership, using a facility either owned by the City or shared with Marine Corp Air Ground Combat Station-Twentynine Palms (MCAGCC), located approximately 6.4 miles north of City Hall.

The recommendation of the report and plan was to focus on a 9.3-million-gallon per day (MGD) wastewater treatment plant (WWTP) central to the metropolitan area that could use City streets for collection alignments. The 2014 report did not recommend a joint-use facility with MCAGCC. Integration of these objectives with a water resource management plan, yet to be written, was also recommended (City and TPWD 2014).
page 3

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Twentynine Palms Water District
Fluoride Removal Facility
Marine Corp Air Ground Combat StationTwentynine Palms BULLION MOUNTAINS

LITTLE SAN BERNARDINO MOUNTAINS
2 Mile Road
Adobe Road
Utah Trail
Amboy Road
Twentynine Palms Highway
Oasis of Mara
Twentynine Palms
City Hall
Fortynine Palms Canyon
Document Path: E:\227521-0000132.00 29 Palms WWTP Support\Report Figures\Figure 1-1.mxd ¯ 8,100
Feet
Service Layer Credits: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community
Figure 1.1 - - Map of locations cited in report
page 4

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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California Subsequently, TPWD developed the anticipated water resource management plan (TPWD 2016). Under California Water Code (CWC) sections 10610 through 10657, and the Urban Water Management Planning Act (UWMP Act) of 1983, such a plan is required of an urban water supplier. From a water supply reliability analysis, the TPWD determined that it has adequate supplies to meet demands during normal, single-dry, and multiple-dry years throughout the 20- year planning period. Despite this, other State regulations require that a groundwater management plan be written and the Sustainable Groundwater Management Act (SGMA) passed in 2014 and amended in 2015, requires management of high-priority, local groundwater sources in California. The groundwater basins supplying TPWD are all considered low priority. under SGMA.

Despite this, the water resource management plan includes many suggestions and practices to extend groundwater resources as long as possible (TPWD 2016). These include conservation and stormwater recharge. Because there is no central WWTP available, effluent recharge (called “recycled water” in the report) was not considered.

Recharge of groundwater with treated effluent is uncommon but not unknown in the desert regions of San Bernardino County. Although most of the recharge facilities in the region use imported water from the Mojave Water Agency, Victor Valley Wastewater Reclamation Authority (VVWRA) recharges treated effluent along the Mojave River bed (Stamos, et al 2001).

The City of Barstow recharges wastewater and Mojave Water Agency imports and recharges 2,800 acre-ft of treated wastewater from the Lake Arrowhead and Big Bear areas (MWA 2020). 2 Preliminary Screening of Sites
At this level of study, a screening study must make a number of assumptions in order to make progress. The first assumption was in the location and management of the WWTP. Although previous investigations concluded that an MCAGCC joint-use facility was not feasible, the need for additional base capacity remains and the City requested that this location needs to be considered.

Sites in and around the Project Area of the current wastewater feasibility study, including MCAGCC were chosen for preliminary screening. The list of criteria were taken from Milczarek and co-authors (2014) and included:

Surface Conditions
• Soil Properties
page 5

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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California • Surface Geology
Subsurface Conditions
• Depth to Basement.
• Depth to Groundwater.
• Groundwater quality.
• Hydrogeology.

Location.
• Distance to proposed city-owned WWTP
• Distance to MCAGCC
• Land use
• Land ownership
• Existing infrastructure
• Recharged groundwater basin
• Areas of preservation or open space
Each of these criteria was applied to the list of available sites and three were chosen for ranking. Based upon infrastructure cost decisions of the City, the Area of Interest for the screening study was confined to a 1-mile “bubble” surrounding the City limits (Figure 2.1).

2.1. Surface conditions
Surface conditions criteria include the physical and geological description of soil and active alluvial sediment data.

2.1.1. Surface soils
Soil survey data was extracted from the regional descriptive data cataloged by the Natural Resource Conservation Service (NRCS) of the U.S. Department of Agriculture. NRCS soil data is found in the National Soil Survey, a compilation of field data mapped by NRCS soil scientists in each of the fifty states on a county-wide and Indian reservation basis. Currently, the data is stored digitally and available as downloadable, GIS data, or the SSURGO/STATSGO2 data series.

The soil survey data of interest used was the Mojave Desert Area, West Central Part (Figure

2.2).

Each of the area soil series was assigned a generalized set of physical parameters over the survey area by NRCS staff scientists. GIS covers of soil series spatial extent were used to map saturated hydraulic conductivity (Ksat) and clay content (%) over the area of interest. Ksat is a page 6

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Document Path: E:\227521-0000132.00 29 Palms WWTP Support\Report Figures\Figure 2-1 - Site Map.mxd LEGEND
City of Twentynine Palms 2-Mile Buffer ¯ 15,000
Feet
Service Layer Credits: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community
Figure 2.1 - - Limits of screening study
page 7

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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California parameter widely used to indicate the rate of infiltration of surface spread water. Clay percentage in the soil represents the presence of fine particles that might inhibit porous-media flow of water in the subsurface. These two estimated factors were used as criteria to select the candidate sites.

2.1.2. Surface geology
Surface geological maps were used to qualitatively extrapolate infiltration properties over a wider area and be used to interpret morphological features, such as ancestral streambeds that might offer abundant coarse-grained substrate. Alternatively, playas or other lakebed features would be expected to be underlain by finer-grained materials (Figure 2.3).

GIS geological maps were acquired from the USGS California Water Science Center. The USGS has done considerable work on the hydrogeology and geology of the area in support of the MCAGCC. Geological data was also extracted from the California Department of Conservation, California Geological Survey regional geologic map of the San Bernardino 30’ x 60’ sheet (1:250,000 scale). In addition, the geological sections of several hydrogeological reports were used, particularly, TPWD (2016).

The surface geology of the Twentynine Palms region is dominated by fault-bounded uplift of the surrounding mountains relative to the central basin. Riley and Worts (1952) defined the Mesquite Basin as a structural depression receiving sediment from the Little San Bernardino Mountains to the south, the San Bernardino Mountains to the west, and the Bullion Mountains to the east. The basin was part of a series of structural depressions that aligned in a northwesterly direction.

Bedrock geological units are exposed in all three of these bounding ranges and in smaller fault blocks aligned with larger mountains. The units were primarily composed of Jurassic granitics and Precambrian crystalline rocks. Riley and Worts (1952) assumed a Precambrian age for the older granitics, including gabbro-diorite, gneiss, granite, and monzonitic porphyry; however, age dating by Lanphere (1964) and mapping by Dibblee (1968) suggested that only the gneiss was Precambrian and distinguished an older Mesozoic granitic phase. Lying unconformably upon the crystalline rocks is a series of late Tertiary continental sedimentary rocks, chiefly sandstones and conglomerates, dipping to the east.

The youngest units are exposed extensively across the study area and are the principal target of this study. These Quaternary deposits include alluvial fan sands, silts, clays, and cobbles, extending from the mountain fronts to the basin axis and culminating in playa lake deposits. page 8

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s1135
s1009
s1032
s1130
s1126
s1032
s1130
s1134
s1134
s1130
s1038
s1126
s1130
s1142
s1142
Document Path: E:\227521-0000132.00 29 Palms WWTP Support\Report Figures\Figure 2-2 - Soils Map.mxd LEGEND
s1009 Ramona-Hanford-Greenfield
s1032 Wasco-Helendale-Bryman
s1038 Playas
s1126 Tecopa-Rock outcrop-Lithic Torriorthents
s1130 Rock outcrop-Lithic Torriorthents
s1134 Trigger-Rock outcrop-Calvista
s1135 Dune land-Cajon
s1142 Nickel-Bitter-Arizo ¯ 18,000
Feet
Service Layer Credits: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community
Figure 2.2 - - Local soils data retrieved from NRCS SSURGO/STATSGO2 data series. page 9

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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California Dibblee (1968) separates several Quaternary deposits representing unique depositional facies.

An older alluvial unit fans outward across the city from Fortynine Palms Canyon, the main drainage feature, in a northeasterly direction. Lying on top of these deposits in the northeastern edge of the urban area is a younger alluvial unit, distinguished by a higher proportion of fine-grained sand and silt. Further to the northeast, this unit grades into windblown sand. The significance of these Quaternary units and their location will be developed in Section 3.

Structural elements clearly are controlling groundwater recharge and storage in the Area of Interest (Riley and Worts 1952, Li and Martin 2011, TPWD 2016)(Figure 2.3). At the northern boundary of the Mesquite Basin, a structural high (arch) in bedrock is used by Riley and Worts (1952) to limit the extent of groundwater flow. On the east, these authors conclude that the north-northeast trending Mesquite Lake Fault forms a groundwater flow boundary. On the south, the Pinto Mountain Fault has the largest effect of groundwater dynamics.

The Mesquite Lake Fault as a regionally extensive fault, exhibiting right-lateral, slip-strike motion (SCEDC 2013). Paleoseismic data suggest up to four prehistoric earthquakes since the latest Pleistocene, with three large, Holocene surface-rupturing events (Madden, et al 2006).

The Pinto Mountain Fault, exhibiting left-lateral, strike-slip motion, and an offshoot of it (Oasis Fault) have juxtaposed the Precambrian to Mesozoic crystalline rocks relative to the late Tertiary basin-filling sediments of the north (Riley and Worts 1952). Movement on the Oasis Fault is inferred from geomorphic evidence to have occurred five times since 13,600 years before present, the latest at 1700 years before present. The contrast in water-bearing properties between these units defines the southern boundary of the basin.

California Department of Water Resources (CalDWR) has designated two groundwater basins that cover the Area of Interest (CalDWR 2021), separated by the east-west running Oasis Fault, the Twentynine Palms Valley Groundwater Basin (DWR# 7-10), which extends north of the fault and the Joshua Tree Groundwater Basin (DWR#7-62), which lies to the south. Within the Twentynine Palms Valley Groundwater Basin, two subbasins are distinguished, the Main Subbasin which extends north from the Pinto Mountain Fault and which is separated from the Mesquite Lake Subbasin on the west by the Mesquite Fault (Riley and Worts 1952, Li and Martin 2011, TPWD 2016) (Figure 2.4).

Within the Joshua Tree Basin, three subbasins are defined between the Oasis Fault and the surface exposure of the crystalline rock (TPWD 2016). The Indian Cove Subbasin extends from the western edge of the Area of Interest eastward to a subsurface narrowing of the Tertiary page 10

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PINTO MOUNTAIN FAULT

MESQUITE FAULT

OASIS FAULT

BULLION MOUNTAINS

LITTLE SAN BERNARDINO MOUNTAINS LITTLE SAN BERNARDINO MOUNTAINS Document Path: E:\227521-0000132.00 29 Palms WWTP Support\Report Figures\Figure 2-3 - Geology.mxd LEGEND
Quaternary Faults
alluvium
dune sand
gabbro
gneiss
granodiorite
intermediate volcanic rock
plutonic rock (phaneritic)
schist
City of Twentynine Palms Outline
2-Mile Buffer ¯ 18,000
Feet
Service Layer Credits: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community"Preliminary integrated geologic map databases for the United States". http://pubs.usgs.gov/of/2005/1305 Original source of this data was the Arizona Geological Survey. USGS Geologic Hazards Science Center Golden, CO U.S. Quaternary Faults https://www.arcgis.com/apps/webappviewer/index.html?id=5a6038b3a1684561a9b0aadf88412fcf Figure 2.3 - - Local geology as generalized from Riley and Worts (1952), Dibblee (1968), and TPWD (2016)
page 11

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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California sediments (TPWD 2016). The Fortynine Palms Subsection extends from this boundary westward to a boundary with the Eastern Subbasin, where the constriction between bedrock and the Oasis Fault widens. The Eastern Subbasin extend easterly to the end of the Area of Interest.

2.2. Subsurface Conditions
There are several primary data sets that have been used in the screening study. These are depth to groundwater, depth to basement, and groundwater quality.

2.2.1. Depth to groundwater
Depth to groundwater is used to estimate the thickness of the unsaturated zone. Presumably, introduced effluent will infiltrate and saturate this zone and therefore a greater thickness of unsaturated media indicates greater storage capacity. Shallow groundwater levels could indicate that recharged water will locally “daylight,” causing stability problems.

The USGS has monitored and interpreted water levels near MCAGCC for many years (Riley and Worts 1952, Schaefer 1978, Akers, 1986, Stamos et al 2004, 2007, 2009, Li and Martin 2011, Dick and Kjos 2016). In addition, the City has collected groundwater data for specific studies that was added to the analysis (TPWD 2016).

Groundwater elevations for this study were acquired from Dick and Kjos (2016). Depth to groundwater contours were mapped by subtracting topographic elevation from these data (Figure 2.5). These calculations suggest that the maximum depth to groundwater, <300 feet below ground surface (ft bgs), probably lies east of the Mesquite Fault, in the Main Subbasin. A second maximum occurs at the west side of the Area of Interest in the Mesquite Lake Subbasin.

The most shallow groundwater is found at the eastern edge of the city center, west of Utah Trail. For example, a set of TPWD wells near the Fluoride Treatment Facility produces a depth to water of 50 to 62 ft bgs.

These data suggest that there is a groundwater elevation maximum at the southern boundary of both basins (Figure 2.5) (TPWD 2016). A groundwater elevation greater than 2400 feet above sea level (ft asl) is measured at TPWD supply wells in the Indian Cove Subbasin. A second high is found at the eastern boundary of the Mesquite Subbasin (TPWD 2016). Groundwater elevations in wells in that part of the Area of Interest exceed 1850 ft asl. The lowest elevations are just west of MCAGCC at about 1760 ft asl.
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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California In 1993, TPWD drilled a 1,250-foot-deep monitoring well (TP-1) in the vicinity (Amboy Road and Utah Trail) of the proposed WWTP (Attachment 2). The well was screened from 350 to 440 and from 460 to 620 feet below surface (fbs). Static water was measured at 50 fbs. See section 2.2.4 for a discussion of the probable source of the groundwater sampled by this well.

2.2.2. Depth to crystalline basement
Depth to the Mesozoic and Precambrian crystalline rock is used to establish the relative thickness of potentially water-bearing formations in the subsurface among candidate sites.

Although some water is certainly available in the fractured granitic rocks, the difference in yield is great enough to preclude them as the location of an effective aquifer. Geological cross sections developed by Riley and Worts (1952) and Dibblee (1968) indicate a range in depth to bedrock from 0 ft bgs along the southern boundary of the Area, to over 2000 ft bgs adjacent to the Mesquite Lake Fault. Subsequent gravity surveys by Roberts and co-workers (2002) allowed Li and Martin (2011) to infer depth to basement that exceeded 16,000 feet in the northeastern part of the Area of Interest (Figure 2.6); however, basement rock depth across most of the Area ranges from 0 to 4000 ft bgs .

2.2.3. Water quality
Water quality is dependent upon the depth, screen position, and location of monitoring wells.

In general, it is not a critical determinant in siting a recharge area, unless a specific area or plume of contamination exists in the subsurface.

It is generally recognized in the Area of Interest that the only groundwater components of concern are nitrates from septic tank discharge and naturally occurring high fluoride and arsenic concentrations. Presumably, nitrate contamination would be reduced across the city subsurface as residents switched from septic tank use to the proposed City sewer system.

Isolated areas of remnant nitrate contamination would remain, as would residential areas not connected to the City system. Currently, the average nitrate concentration in the Mesquite Lake Subbbasin is 3.5 mg/L and in the three subbasins south of the Oasis Fault, 6.5-11.3 mg/L, well below the maximum contamination level (MCL) of 45 mg/L (TPWD 2016).

Fluoride exceedances are common in shallow Western aquifers. Fluoride concentrations in the Indian Cove, Fortynine Palms and Eastern Subbasins generally average 1.3 to 2.7 mg/L, while the Mesquite Lake Subbasin averages more than twice that at 5.9 mg/L, above the MCL of 4.0 mg/L (TPWD 2016). The difference probably reflects the presumed recharge source of the two page 14

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200
300
400
100
100
300
300
400
200
200
300
200
300
100
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MojaveWater
Groundwater Direction
Quaternary Faults
Depth to GW
City of Twentynine Palms Outline
2-Mile Buffer ¯ 18,000
Feet
Service Layer Credits: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community
Figure 2.5 - - Local depth to groundwater. Data from Dick and Kjos (2016) page 15

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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California basins, with the Mesquite Lake Subbasin water leaching fluoride salts from buried evaporite deposits (Robertson 1991).

Arsenic concentrations show the opposite relationship between the subbasins. The Indian Cove, Fortynine Palms and Eastern Subbasins average 1.8 to 5.7 µg/L of arsenic and the Mesquite Lake Subbasin averages 2.4 µg/L. The MCL for arsenic is 10 µg/L.

All of the water introduced by the recharge system would be treated to drinking water standards, as set by the California State Water Resources Control Board, Indirect Potable Reuse program. In that sense, the recharged water would be of better quality than the existing groundwater. In any case, there would be little difference in the location of the recharge basin for water quality concerns.

2.2.4. Hydrogeology
These distributions of elevations suggest that groundwater flow is principally from west to east in both basins in the west and from southeast to northwest on the eastside, mimicking the topographic gradient and structural discontinuities. This was also the conclusion of TPWD (2016). These groundwater dynamics would also suggest two principal recharge areas for the greater basin: the western bounding ranges of the San Bernardino Mountains and the northern margin of the Little San Bernardino Mountains. In fact, several springs emerge from the northern trending canyons of the Little San Bernardino Mountains. Springs are reported from Fortynine Palms Canyon, in addition to the historically flowing Oasis of Mara in the Eastern Subbasin (Cadena 2014).

The recognized water-bearing formations in the subsurface have emerged from deep borings that have been constructed across the area and the recognition of these formations by the USGS and other hydrogeological investigations (Li and Martin 2011). Li and Martin define three water-bearing formations in the Project are subsurface. The Upper system is hosted by the younger Quaternary, fan-deposited sands and gravel (Qtf2, Li and Martin 2011). It ranges from 250 to zero feet in saturated thickness, thinning from west to east. Underlying the Upper system are an older set of Quaternary (Qtf1, Li and Martin 2011) fan-deposited units that contain intercalated clay layers. These beds make up the Middle unit of the regional aquifer.

Saturated thicknesses of the Middle unit range from 100 feet in the north basin to 500 feet in the southeast direction. The Lower unit is found within the poorly-sorted sands, gravel, silt, and clay of the Tertiary unit (Ts, Li and Martin 2011).
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Document Path: E:\227521-0000132.00 29 Palms WWTP Support\Report Figures\Figure 2-6 - Depth to Basement Li&Martin2011.mxd Service Layer Credits: Li and Martin 2011
¯ 18,000
Feet
City of Twentynine Palms Outline
2-Mile Buffer
Figure 2.6 - - Local depth to bedrock. Reproduction of figure from Li and Martin (2011) page 17

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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California The permeability of the Middle unit is much lower than Upper unit. Despite this, most watersupply wells in the region are screened in coarser-grained, water-bearing beds of the Middle unit. In some parts of the Project area, recharge to the Middle unit may be acting as an aquatard, restricting downward movement of surface infiltration.

As discussed in Section 2.2.1, monitoring well TP-1 (Attachment 2) was logged as ‘sand’ or ‘sand and clay’ in the driller’s record from 0 to 65 fbs. At 65 fbs, the log records ‘clay,’ which extends down to 100 fbs. Given the stratigraphic data reported by Li and Martin (2011), the upper 65 feet of the boring probably encountered Qtf2 and the Upper unit of the local aquifer. The clay encountered between 65 and 100 fbs is probably the aquitard that marks the top of Qtf1 and the Middle unit. The Middle unit in the southeast corner of the Mesquite Subbasin is reported to be approximately 500 feet thick (Li and Martin 2011). Thus, it is likely that the screened interval is primarily sampling groundwater extracted from the Middle aquifer, although the integrity of the upper confining clay is unknown.

2.3. Location
Location takes in all of the factors that would make the recharge basins economically and operationally feasible under City financial and administrative constraints.

2.3.1. Distance to proposed WWTP
The location of the proposed WWTP is just south east of the corner of Amboy Road and Utah Trail.

2.3.2. Distance to the existing MCAGCC WWTP
Although a joint-use WWTP has been discussed, the location has not been selected (1/2022).

The existing plant is used as a proxy. The current WWTP serving MCAGCC is located on Del Valle Street on base and directly across the road from Marine Corps Exchange -29 Palms.

2.3.3. Land use
Land use was important in that changes in zoning might cause delays or generate public opposition. A land use GIS cover was retrieved from the San Bernardino County Planning Department web site.

2.3.4. Land ownership
page 18

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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California Land ownership could also cause delays and potential opposition (Figure 2.7). Private land would necessitate establishment of a purchase or lease agreement. Public land administered by the Bureau of Land Management (BLM) would require a lease agreement and additional potential permitting requirements, including National Environmental Policy Act (NEPA) documentation and compliance. State or county land would also require use authorization from the responsible agencies. The simplest land ownership situation would be the use of City land.

Regardless, any of these options would most likely trigger California Environmental Quality Act (CEQA) requirements.

2.3.5. Size
The size of the available land is also critical, as surface-spreading basins require a relatively large, moderately undisturbed, flat topography. For example, the Bighorn-Desert View Water Agency estimated that a spreading basin of five acres was required to recharge 1500 acre-feet over six months at an infiltration rate of 1.64 feet/day (BDVWA ). Ideally, three basins are used for normal operation in order to allow for scarification and cleaning of 25% of the infiltration surface while 75% remains in operation. Thus, the size of the facility needs to be much greater than the actual basin surface area.

Hi-Desert Water District has been recharging imported Mojave Water Agency water at its Warren Valley Basin Groundwater Recharge facility in Yucca Valley since 2015 (HDWD ). The District recently constructed a new wastewater treatment plant and began discharging water into its three percolation ponds in February of 2020. The facility occupies approximately 30 acres in Yucca Valley, including the three ponds and other supporting infrastructure.

Green Valley Municipal WWTP is operated by Pima County in southern Arizona. The Green Valley WWTP averages 2335 acre-feet per annum of treated effluent to be infiltrated in 7.1 acres of pond. The size of the entire complex is approximately 50 acres (Pima County RWRD 2021).

2.3.6. Existing infrastructure
Once again, the required effluent infrastructure has not yet been determined by the City and it is unknown where these alignments will be located. In all likelihood, buried collection pipelines will follow major road rights-of-way and effluent return lines would most likely be proposed for the same corridors. Therefore, distance to existing major City streets would be one proxy for this criterion.
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Document Path: E:\227521-0000132.00 29 Palms WWTP Support\Report Figures\Figure 2-7 - Land Use.mxd LEGEND
Private
United States of America
Government Land
County of San Bernardino
City of Twentynine Palms
City of Twentynine Palms Outline
2-Mile Buffer
¯ 18,000
Feet
Service Layer Credits: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community
Figure 2.7 - - Local land ownership. Data from San Bernardino County Planning Department (2021)
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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California Another important infrastructure component would be groundwater wells that could serve as monitoring wells or locations for new points of compliance. Under California State Law the permitting of a Department of Public Health Groundwater Replenishment Reuse Project (GRRP), monitoring of the aquifer receiving treated effluent is required.

2.3.7. Areas of preservation or open space
Although the recharge basins would not require much in the way of built structures, they would be a disruption of the natural topography and vegetation. Location in an area of well-known cultural resource distribution could also cause issues in permitting and approval of the facility. 3 Candidate Sites
Using these broad data sets on currently available land areas, three sites were chosen for sitespecific fieldwork (Figure 3.1). These sites included a section of land owned by TPWD directly north of the well TP-1, south of the Fluoride Removal Facility, and adjacent to Utah Trail (Fluoride). The City-owned parcel that comprises Section 19 of Township 1N, Range 9E and that is bordered on the west by Morongo Road and on the south by Two Mile Road (Morongo) was another site. The third site is located south of Twentynine Palms Highway (SR62), east of Encelia Drive on San Bernardino County Flood Control property (Flood).

3.1. Field Work
The percolation rate of introduced water through the surface soils is of paramount importance in locating a recharge facility. Although the NRCS Soil Survey database includes saturated hydraulic conductivity values for each represented soil series, a better estimate is required from the actual surfaces used, on site. Three candidate sites were surveyed as part of the field investigation. . Attachment 1 is a detailed description of the field activities. A summary of field activities is provided in this section. .

Field work at the three sites occurred during the period of August 17-19, 2021. The methodology of Bouwer et al (1999), as modified by Rice et al (2014), was used during this effort. The Bouwer method employs a single-ring infiltrometer to generate a series of estimates of the saturated hydraulic conductivity of surface soils. The principal source of error in the method, which was corrected by Bouwer and co-workers (1999) is the lateral expansion of the wetting front as it progresses downward. The measurement of the lateral expansion is accomplished by digging exterior to the ring and measuring the radial extent of saturation with a soil moisture probe. For soils similar to the candidate sites, this methodology has been demonstrated to improve the estimates by a factor of 3.4 to 7.0 (Rice, et al 2014). page 21

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2 Mile Road
Twentynine
Palms City Hall
Amboy Road
Morongo Road
Adobe Road
Utah Road
Twentynine Palms Highway (California 62)
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Infiltration Test Location ¯ 4,000
Feet
Service Layer Credits: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community
Morongo
Fluoride
Flood
Figure 3.1 - - Location of three sites examined during infiltration measurement field work.
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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California Measurements were made at four locations at each of the three sites. Locations were chosen based upon the general topography and field texture inspection of the sites to be representative of the general area. The measurements were straightforward. At each location the 50-cm-diameter, steel ring was driven a few inches into the ground. Water was introduced carefully so as not to disturb the ground surface. The water level was maintained at a few centimeters below the rim of the steel rim in order that a constant head was maintained at the soil surface. The drop in water was recorded as infiltration progressed until 21 to 62 centimeters of entry was recorded or four hours of measurement occurred. Approximately six hours per site was necessary for the test.

Upon conclusion of the test, excavations were made in three direction from the ring and lateral divergence of the wetting front was recorded. Finally, the cylinder was drained, the center of the wetted soil was hand augered to the depth of the wetting front, and a sample was recovered for textural analysis.

3.1.1. Fluoride Site
The site was accessed from Utah Trail on a dirt road (Figure 3.2). The topography was flat with mildly eroded drainage to the west. At the surface, loamy sand makes up the most common material supporting a mixture of creosote bush, yucca, annual grasses and forbs. The NRCS soil survey assigned this site to the Duneland-Cajon 1135 map unit and estimated the mean K(sat) to be 4.23E-05 to 1.41E-04 cm/s with 10% clay. The four Fluoride site K(sat) values ranged from

7.8E-04 cm/s to 1.4E-03 cm/s, with a median of 8.7E-04 cm/s and a geometric mean of 9.51E04 cm/s.

3.1.2. Morongo Site
The Morongo Site was located within the City-owned Section 19 parcel, adjacent to the dirt extension of Morongo Road and approximately 0.8 miles north of 2 Mile Road (Figure 3.3). The land slopes off approximately 3% to the north-northeast. The surface soil is a loamy sand; however, the location is bisected by a 2-meter-deep gully that appears to have formed from adjacent stormwater runoff. The gully exposes an approximately 0.5-meter layer of whitishgrey, firmly cemented, calcareous caliche. Sparse surface vegetation includes creosote bush. bursage, joshua tree, annual grasses and forbs. The NRCS describes the area as WascoHelendale-Map 1032 map unit, estimating the mean K(sat) to be 1.41E-05 to 4.23E-05 cm/s with page 23

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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California a clay content of 0.8%. This investigation produced K(sat)ranging from 3.5E-04 cm/s to 1.2E-03 cm/s with a median of 4.9E-04 cm/s and a geometric mean of 5.63-04 cm/s and.

3.1.3. Flood Site
The Flood Site was within the San Bernardino County Flood Control District property (Figure

3.4). The area is topographically much more rugged than the previous sites and includes a number of off-channel gullies and terraces. The site is located within a mountain-front alluvial fan associated with Fortynine Palm Canyon, a major through-going drainage. The texture is also coarser and poorly graded, ranging from cobbles to fine sand; however, the four locations tested were more uniform, ranging from medium sand to loamy sand. Vegetation includes the same community as the Morongo Site with the addition of abundant smoke tree shrubs. The NRCS mapped the locations as part of the Ramona-Hanford-Greenfield 1009 map series. For this series, a K(sat) of 1.41E-05 to 4.23E-05 cm/s was estimated by the NRCS at a clay content of

0.2%. The results of the current study for the Flood Site ranged in K(sat)from 1.1E-03 cm/s to

9.5E-03 cm/s, with a median of 1.5E-03 cm/s and a geometric mean of 2.24E-03 cm/s.

3.1.4. Summary of Field Testing
While all three sites were within a reasonable range of K(sat) and clay content, the Flood Site was more than two times more permeable than the Fluoride Site and infiltration was almost 4 times faster than the Morongo Site. Permeability at the Morongo Site was probably inhibited by the thick layer of caliche exposed in the stormwater gully. Coarser material composing the alluvial fan at the Flood Site appears to contribute to the faster infiltration rate at that locality.

3.2. Application of Criteria
The data used in making the selection are summarized in Table 3.1. Each site was ranked from one to three, with three being the highest score relative to the others in fulfilling that criterion (Table 3.2). In some cases, the criterion weighed heavier in importance to the needs of a surface-spreading, groundwater recharge facility. In these cases, the criteria was multiplied by a weighing factor. Hydrogeology, land ownership, and the presence of existing water conveyance, ground transportation, and power infrastructure were weighted heavier than most other criteria. The results of the field infiltration testing were considered to be of even greater importance.
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Fluoride 4
Fluoride 3
Fluoride 2
Fluoride 1
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Infiltration Test Location ¯ 250
Feet
Service Layer Credits: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community
Twentynine Palms Water District
Fluoride Removal Facility
Utah Trail
Figure 3.2 - - Detail map of Fluoride Site.
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Morongo 4
Morongo 3
Morongo 2
Morongo 1
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Infiltration Test Location ¯ 500
Feet
Service Layer Credits: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community
Morongo Road
Samarkand Drive
Figure 3.3 - - Detail map of Morongo Site.
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Flood 4
Flood 3
Flood 2
Flood 1
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Infiltration Test Location ¯ 400
Feet
Service Layer Credits: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community
Encelia Road
San Bernardino County Twentynine Palms
Flood Control Channely
Figure 3.4 - - Detail map of Flood Site.
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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California These component scores were summed for the cumulative score (Table 3.2). Using this system, all three sites were very close. The Fluoride Site was highest, scoring very high on existing infrastructure and proximity to the proposed WWTP site. The Flood site was very close, receiving high marks for the hydrogeology, surface conditions, and field infiltration data.

Measured infiltration values were reasonably good. The Morongo Site scored highest in land ownership and use but was limited by its low infiltration rate and the presence of caliche layers in the subsurface.
4 Conclusion and Recommendation
Based upon the results of the screening study, the Fluoride Site seems to be the best location for a recharge facility. The presence of favorable subsurface geological material, its location in the Mesquite Lake Subbasin, and the co-location of several TPWD wells would all be helpful; however, the proximity to the proposed City-only or joint-use WWTP is probably the main discriminator. If and when a joint-use facility location is selected, this conclusion may need to be revised to accommodate a site closer to the alternate WWTP.

Presumably, the required land used for the existing Fluoride Treatment Plant could be leased from the TPWD and the basins sited off of Amboy Road. Despite this, the potential existence of an approximately 35-foot clay layer at 50 feet might be an issue. There are many ways to accommodate subsurface fine-grained units subjacent to a recharge spreading basin. A combination basin that includes several deep dry wells is one possibility. Regardless, it will be important to initiate a complete subsurface investigation before the Fluoride site is advanced to the design phase.

There may also be an issue with the Regional Water Quality Control Board (RWQCB) regarding the Fluoride facility evaporation ponds. If an elevation of the local groundwater levels interferes with the pond leakage points of compliance, the RWQCB might object to the facility. The hydrogeology of this issue should be analyzed further and discussed with the RWQCB before finalizing the choice of this site.

NV5 has proposed a single boring to 100 feet bgs as part of the Twentynine Palms WWTP project. This boring will allow laboratory testing of retrieved samples for texture, moisture content and laboratory K(sat) . These data can support estimates of basin size and capacity can be calculated, as can the impact of the recharge facility on local groundwater levels. It may be necessary to expand this investigation before a decision is reached. page 28

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Soils Survey Data (NRCS)
Surficial geology (Dibblee)Depth to groundwater Depth to crystalline basementWater quality*HydrogeologyDistance to proposed WWTP siteLand useLand ownershipAvailable SizeExisting infrastructureGroundwater BasinAreas of preservation or open spaceMeasured K(sat) Fluoride
Duneland-Cajon,
K(sat) = 4.23E-05 to 1.41E04 cm/s 10% clay.

Qa, Detrital sediments ranging from
subangular boulders and cobbles in small
alluvial fans adjacent to mountains, through
pebbly arkosic sand down slope, to arkosic
sand and silt in valleys; includes sand and
gravel of stream washes.
50 to 60 ft bgs 4,300 to 6,700 ft
bgs
Ave F = 5.9 mg/L
Ave NO3 = 3.5
mg/L
Upper aquifer,
GW flow to east 1.5 miles industrial
Twentynine
Palms Water
District
84 acres
adjacent streets
and power,
existing TPWD
wells
Twentynine Palms
Valley Groundwater
Basin, Mesquite Lake
Subbasin
none
Morongo
Wasco-Helendale,
K(sat) = 1.41E-05 to 4.23E05 cm/s 0.8%
clay.

Qoa, Old weakly consolidated alluvial
deposits that fill valley and former valley
areas; dissected where elevated. May be as
thick as a thousand or more feet. Light-gray,
poorly bedded to non-bedded, fine to coarse,
arkosic sand and minor pebble-cobble gravel;
in places a little micaceous silt or clay.
100 to 200 ft bgs 2,200 to 4,300 ft
bgs
Ave F = 5.9 mg/L
Ave NO3 = 3.5
mg/L
Upper aquifer,
GW flow to east 2.3 miles single-family residential
City of
Twentynine
Palms
472 acres adjacent streets
and power
Twentynine Palms
Valley Groundwater
Basin, Mesquite Lake
Subbasin
none
Flood
Ramona-HanfordGreenfield,
K(sat) = 1.41E-05 to 4.23E05 cm/s 0.2%
clay.

Qa, Detrital sediments ranging from
subangular boulders and cobbles in small
alluvial fans adjacent to mountains, through
pebbly arkosic sand down slope, to arkosic
sand and silt in valleys; includes sand and
gravel of stream washes.
200 to 300 ft bgs 0-400 ft bgs
F = 1.3-2.7 mg/L
NO3 = 6.5-11.3
mg/L
Upper aquifer,
GW flow to east 2.5 miles public facilities County of San Bernardino 203 acres adjacent streets
and power,
existing TPWD
wells
Joshua Tree Basin,
Fortynine Palms
Subbasin
Joshua Tree
National Park
* same data characterizes both sites.

2.24E-03 cm/s
Surface Conditions Subsurface Conditions Location Field Work

9.51E-04 cm/s

5.63-04 cm/s
Table 3.1 - Selection criteria used to rank sites. See text for discussion. page 29

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Soils Survey Data
Surficial geologyDepth to groundwater Depth to crystalline basementWater qualityHydrogeologyDistance to proposed WWTPLand useLand ownershipSizeExisting infrastructureGroundwater BasinPreserve or open space issuesTOTAL RATING Fluoride 2 3 2 3 3 4 6 3 4 1 6 1 3 49
Morongo 1 2 3 3 3 2 4 2 6 3 2 1 3 39
Flood 3 3 3 1 2 6 2 3 2 2 2 3 1 45
4 12
Surface
Conditions Subsurface Conditions Location
Field
WorkMeasured K(sat)
8 page 30
Table 3.2 - - Ranking of the three sites.

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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California 5 References
SCEDC, Southern California Earthquake Center
SCEDC (2013)
BDVWA, Bighorn/Desert View Water Association
______, 2012, Groundwater Management Plan Pipes and Reche Groundwater Subbasins of the Ames Valley Groundwater Basin San Bernardino County, California. Bighorn/Desert View Water Association Consultant Report, 175 p.

Bouwer, H., Back, J.T. and Oliver, J.M., 1999. Predicting infiltration and ground-water mounds for artificial recharge. Journal of Hydrologic Engineering, 4(4), pp.350-357.

Cal DWR, 2019, California's Groundwater (Bulletin 118), https://water.ca.gov/programs/groundwater-management/bulletin-118, visited 9/9/2021 City and TPWD, City of Twentynine Palms and Twentynine Palms Water District ____________, Twentynine Palms Wastewater Master Plan, Consultant Report, 98 p.

Dahlke, H.E., LaHue, G.T., Mautner, M.R., Murphy, N.P., Patterson, N.K., Waterhouse, H., Yang, F. and Foglia, L., 2018. Managed aquifer recharge as a tool to enhance sustainable groundwater management in California: examples from field and modeling studies. In Advances in Chemical Pollution, Environmental Management and Protection (Vol. 3, pp. 215-275). Elsevier.

Dibblee T.W., 1968. Geologic map of the Twentynine Palms quadrangle, San Bernardino and Riverside counties, California. US Geological Survey, Miscellaneous Geologic Investigations Map I-561, 1 sheet and explanation.

Dick, M. and Kjos, A., 2017. Regional water table (2016) in the Mojave River and Morongo groundwater basins, southwestern Mojave Desert, California. U.S. Geological Survey Scientific Investigations Map 3391, scale 1:170,000,
HDWD, Hi-Desert Water District
_____, Hi-Desert Water District 2020 Urban Water Management Plan, Consultant Report, 85 p.

Hutchinson, A.S., Rodriguez, G., Woodside, G. and Milczarek, M., 2017. Maximizing infiltration rates by removing suspended solids: Results of demonstration testing of riverbed filtration in Orange County, California. Water, 9(2), p.119.

Lanphere, M.A., 1964. Geochronologic studies in the eastern Mojave Desert, California. The Journal of Geology, 72(4), pp.381-399.
page 31

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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California Madden, C.L., Rubin, C.M. and Streig, A., 2006. Holocene and latest Pleistocene activity on the Mesquite Lake fault near Twentynine Palms, eastern California shear zone: Implications for fault interaction. Bulletin of the Seismological Society of America, 96(4A), pp.1305-1320 MWA, Mojave Water Agency
-------, 2020, 2020 Urban Water Management Plan, 109 p.

Pima County RWRD, Pima County Regional Water Reclamation Department, website Rice, R, Milczarek, M and Keller J. 2014. A Critical Review of Single Ring Cylinder Infiltrometers with Lateral Flow Compensation. 14th Biennial Symposium on Managed Aquifer Recharge, Orange, CA, July 31–August 1.

Riley FS and Worts Jr GF., 1952. Geologic Reconnaissance and Test-Well Drilling Program, Marine Corps Training Center, Twentynine Palms, California. US Dept. of the Interior, US Geological Survey; Open-File Report 98-166. 71 p.

Roberts, C.W., Katzenstein, R.C., Smith, A. and GA Johnson, R., 2002. Gravity map and data of the eastern half of the Big Bear Lake 100,000 scale quadrangle, California and analysis of the depths of several basins. U.S. Geological Survey Open-File Report 02-353 Robertson, F.N., 1991. Geochemistry of ground water in alluvial basins of Arizona and adjacent parts of Nevada, New Mexico, and California (Vol. 1406). US Geological Survey. Geological Survey Professional Paper 1406-C, 102 p.

TPWD, Twentynine Palms Water District
--------, 2016, 2015 Urban Water Management Plan Update Amended Final. Consultant Report, 340 p.
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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California Attachment 1 - - Technical memorandum on infiltration testing.

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TECHNICAL MEMORANDUM
To: Mark Murphy Date: August 26, 2021
From: Kirk F. Creswick, RG Project: 227521-0000132.00
CC:

Subject: Infiltration Testing – 29 Palms
This Technical Memorandum discusses the estimation of soil hydraulic conductivity (K) from cylinder infiltrometer testing.

Theory
The rate of infiltration of water into soil is directly proportional to the hydraulic conductivity (K) of the soil and the hydraulic gradient. Cylinder infiltrometer testing estimates the hydraulic conductivity by measuring the infiltration rate and estimating the hydraulic gradient. The hydraulic conductivity is then calculated based on these measurements/estimates.

Measuring the infiltration rate from the cylinder (in) is fairly straightforward: the change of water level in the cylinder infiltrometer (yn) is measured over time (tn) and the infiltration rate is yn/Δtn, for any nth measurement.

The hydraulic gradient is a little less straightforward since it involves both direct measurement and estimation. The following equation shows the pertinent parameters:
𝑖𝑖𝑤𝑤 = 𝐾𝐾 𝑧𝑧+𝐿𝐿−ℎ𝑤𝑤𝑤𝑤
𝐿𝐿 (Equation 1)
where:
iw – the infiltration rate of water in the soil (L/T)
K – the hydraulic conductivity (L/T)
z – the head of water in the cylinder (L)
L – the depth to the wetted front from ground surface (L) hwe – the water entry pressure of the soil (L)
The values in the numerator of Equation 1 (z+L+ hwe) make up the head over the length (L) in the denominator that represent the hydraulic gradient. The value z is measured directly in the cylinder during the test. The value L is measured directly after the test. The value hwe is, however, estimated based on soil type. The water entry pressure is the head required to force water into the pore space.

For most soil, the value of hwe is negative since capillary suction pulls water into the soil. Generally, the finer the soil, the greater the capillary suction and the more negative the water entry value.

Values for hwe reported in Bouwer et al., 1999 are:
• Coarse Sand, -5 cm
• Medium Sand, -10 cm

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• Fine Sand, -15 cm
• Loamy Sands, -20 cm
• Sandy Loams, -25 cm
• Loams, -35 cm
• Structured Clay Soils, -30 cm
• Nonstructured Clay Soils, -100 +
As the wetting depth (L) increases, the water entry value (hwe) becomes less significant as an overall percentage of the head, such that a 5 cm misestimate of hwe would result in about 4.2 to 6.5% error in overall head (and gradient) in this particular study.

The capillary suction responsible for hwe values also causes lateral wetting (divergence, x), which much be accounted for since it impacts the downward infiltration rate of water in the soil (iw). The relationship between cylinder infiltration rate (in), the infiltration rate in the soil (iw), and divergence (x) is shown in Equation 2:
𝑖𝑖𝑤𝑤 = 𝑖𝑖𝑛𝑛𝜋𝜋𝑟𝑟2
𝜋𝜋(𝑟𝑟+𝑥𝑥)2 Equation 2
where r is the radius of the cylinder.

This shows that the volumetric flow through the area of the cylinder (with a radius, r) will flow through a greater area of soil (with a radius, r+x), thereby reducing the downward infiltration rate in the soil (iw) relative to the infiltration rate in the cylinder (in) by the ratio of the areas.

Similarly, the increase in cross-sectional area caused by divergence (x) affects the depth of the wetted front (L) as shown in Equation 3:

𝐿𝐿 = 𝑦𝑦𝑡𝑡𝜋𝜋𝑟𝑟2
𝑛𝑛 (𝑟𝑟+𝑥𝑥)2 Equation 3
where:
yt – total length (depth) of water from through the cylinder n – soil fillable porosity
Note that fillable porosity is porosity not already occupied by water or by entrapped air.

Field Work
Field methods for measuring/estimating parameters for use in the above equations are described in this section.

Three areas were predetermined for this study (see Figure 1):
• Adjacent to the Fluoride Removal Plant, south of Amboy Rd. and west of Utah Trail (see Figure 2)
• North of the Morongo neighborhood, east of Morongo Rd and north of Samarkand Dr. (see Figure 3)
• On Flood Control property south of Hwy 62 and east of Encela Ave. (see Figure 4)

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Locations were selected for testing within each study area that were relatively free of vegetation, rocks or local disturbance (trail compaction, animal/insect burrows, etc.).

The following procedure was used for conducting the test:
 Four different cylinder infiltrometers were used in this study, with diameters of 50.8, 50.9,

50.9 and 52.5 cm. All where 30.5 cm tall.
 The cylinders were secured 4-8 cm into the soil using a sledgehammer. The soil around the interior of the cylinder was tamped against the cylinder wall with the handle of the sledgehammer and the soil on the exterior was tamped with the head of the sledgehammer and/or foot pressure.
 A wooden ruler was clipped vertically to the inside of the cylinder with one end at the soil level to allow for water level measurements.
 A foam pad was placed in the cylinder during filling to limit soil disturbance.  Two buckets of water (10-12 gallons) were poured into the cylinder and the foam was removed.
 A reading of the water level was taken from the ruler and recorded with the time on the field data sheet.
 As the water level dropped, additional water level and time readings were collected and recorded. Where wind caused fluctuation of water levels, the average reading was approximated.
 Additional water was added to maintain head in the cylinder with readings collected immediately before and after the filling.
 40 cm of cumulative water drop was the goal for a test. The actual range was 21 to 62 cm.  Immediately after the test, three trenches were hand-dug at approximately 120° spacing to approximately 6 to 9 inches depth to locate the divergence (x) of the wetted zone beyond the cylinder. This was generally visually observable, but a moisture meter was also used to reduce the potential for error due to smearing the interface during excavation. Dry soil read 0% moisture and wetted soil generally read 10% or more (up to about 22% next to the cylinder).
 After draining any remaining water from the cylinder, a hand auger was used to determine the depth (L) of the wetted front. In practice, this was the depth that either dry material was found in the bottom of the hand auger, or the depth that non-cohesive material would not be retained in the hand auger due to lack of moisture.
 The second auger bucket of material (from approximately 6-12 inches below ground surface), was retained for visual soil description. Additionally, a portion of the retained soil was placed in a jar with water above the sample surface and shaken/swirled to determine relative percentage of silt and clay. Silt settles within several seconds while clay settles overnight.

The thickness of silt and clay layers in the jars were compared to the total sediment thickness to determine silt and clay percentages.

Spreadsheet Analysis
Values of yn, tn, x (average), and L were entered into a spreadsheet that uses the three equations above to calculate the hydraulic conductivity, K.
• The value for iw is calculated from the final in value (yn/Δtn), the radius of the cylinder (r) and the average divergence (x) using Equation 2.
• Although L is measured directly, an iterative approach using Equation 3 and adjusting fillable porosity (n) is used until the measure value of L is approximated. • Equation 1 is then solved for K. The water entry value in Equation 1 is approximated from soil type and manually entered. The value of head in the cylinder (z) is taken from the starting head value for the last yn pair. Note that z should actually be the average value during that

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interval, but this error is small, particularly if frequent measurements were made during the latter part of the test.

Note that the ruler used for measurement of the head in the cylinder was installed with the larger values at the bottom. This would result in improper values of z in the calculations if used as is.

Therefore, these values were corrected by subtracting the field values from 30, effectively flipping the ruler to the proper orientation.

Results
Table 1 shows some of the measured and modeled values from the testing for discussion. These values are reported to two significant digits.

Table 1 - Results of Infiltration Testing
Location Soil Type hwe
(cm)
X
(cm)
L
(cm) n K (cm/s)
Fluoride 1 Loamy Sand -20 24 56 0.14 1.4E-03
Fluoride 2 Loamy Sand -20 30 56 0.15 8.8E-04
Fluoride 3 Loamy Sand -20 28 54 0.11 8.6E-04
Fluoride 4 Loamy Sand -20 27 55 0.14 7.8E-04
Morongo 1 Sandy Loam -25 63 38 0.14 3.5E-04
Morongo 2 Sandy Loam Sandy Clay Loam -27 56 49 0.11 5.0E-04 Morongo 3 Loamy Sand -20 42 58 0.11 1.2E-03
Morongo 4 Sandy Clay Loam -30 16 72 0.11 4.9E-04
Flood 1 Medium Sand -10 42 55 0.12 1.7E-03
Flood 2 Medium Sand -10 23 101 0.13 9.5E-03
Flood 3 Sandy Loam -25 30 82 0.12 1.1E-03
Flood 4 Medium to fine sand -13 19 88 0.15 1.4E-03
With respect to hydraulic conductivity:
• Fluoride Area hydraulic conductivity values ranged from 7.8E-04 cm/s to 1.4E-03 cm/s, with an average of 9.8E-04 cm/s and a median of 8.7E-04 cm/s. • Morongo Area hydraulic conductivity values ranged from 3.5E-04 cm/s to 1.2E-03 cm/s, with an average of 6.3E-04 cm/s and a median of 4.9E-04 cm/s. • Flood Area hydraulic conductivity values ranged from 1.1E-03 cm/s to 9.5E-03 cm/s, with an average of 3.4E-03 cm/s and a median of 1.5E-03 cm/s.

These values are in general agreement with their soil types.

Some observations on the data in Table 1 include:
• The value of divergence exceeds the water entry value in all tests except Morongo 4. • Divergences exceeds the water entry value significantly in Morongo 1, Morongo 2, Morongo 3, Flood 1, and Flood 2.
• Divergence does not show a high degree of correlation with hydraulic conductivity, but hwe correlates fairly well.
• Fillable porosity values range from 11% to 15%, but average site values are not much different.

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These observations suggest that lateral divergence is being affected by factors other than water entry pressure. For homogeneous material, these values would be expected to be more predictable. In most of the tests, the content of fines appeared to increase from soil observed at the surface. If the infiltration rate of the shallow soils is in excess of the infiltration rate of the soil below, this would cause lateral spreading that may be observable during investigation of divergence in the shallow soil.

Additionally, the fillable porosity is somewhat lower than a suggested value of 0.3 for dry, uniform soil. Having both visual and quantitative confirmation of very dry soils, this suggests a high degree of air entrapment during testing is responsible for the reduced fillable porosity.

Reducing the porosity will result in more lateral and vertical spreading of the moisture front until the air is effectively purged from the pore space. It may be that this occurs to a large extent during the test, but that the extent of the divergence is expressed by the early effects of the lower porosity. This higher apparent divergence will reduce the calculated value of iw and K.

Bouwer et al., 1999 acknowledges that saturated hydraulic conductivity (Ksat) is generally two times the K value for sandy soils and four times the K value for finer soils determined by cylinder testing.

Conclusions
Flood Area soils appear most favorable, with average conductivities 3.5 times the Fluoride locations and 5.5 times the Morongo locations, and median hydraulic conductivities 1.8 times the Fluoride Locations and 3.1 times the Morongo Locations; however, all three locations have good permeabilities.

The lack of significant clay and silt at the Flood site would help to limit surface clogging. It is also likely that the Flood location would have less fines at depth since fines tend to wash down further into the basin. The Morongo and Fluoride locations are further into the basin, and therefore likely have more fines, although the Morongo area appears to have a higher surface gradient than the Fluoride site, resulting in coarser surface texture.

Saturated hydraulic conductivity values would likely be two to four times higher.

Recommendations
Cylinder infiltrometer testing of these sites has evaluated the short-term, unsaturated hydraulic conductivities of the upper 38 to 101 cm of soil at the sites. Additional geotechnical investigation should be conducted to investigate the possibilities of less permeable layers at depth that could cause mounding.

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FIGURE 1
SHT 1 OF 1
DES: RDD DR: RDD
1 W DEER VALLEY ROAD
BUILDING 2, SUITE 305
PHOENIX, ARIZONA 85027
Tel: 623.374.6637 Fax: 623.738.3690
FOR: SITE MAP
Document Path: E:\227521-0000132.00 29 Palms WWTP Support\Figure 1 - Site Map.mxd CHK:

LEGEND
Infiltration Test Location ¯ 4,000
Feet
Service Layer Credits: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community
PROJECT NO. 227521-0000132.00 DATE: 9/2/2021

TWENTYNINE PALMS WWTP SUPPORT
Morongo
Fluoride
Flood

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Fluoride 4
Fluoride 3
Fluoride 2
Fluoride 1
FIGURE 2
SHT 1 OF 1
DES: RDD DR: RDD
1 W DEER VALLEY ROAD
BUILDING 2, SUITE 305
PHOENIX, ARIZONA 85027
Tel: 623.374.6637 Fax: 623.738.3690
FLUORIDE FOR:

INFILTRATION TEST LOCATIONS
Document Path: E:\227521-0000132.00 29 Palms WWTP Support\Figure 2 - Fluoride.mxd CHK:

LEGEND
Infiltration Test Location ¯ 250
Feet
Service Layer Credits: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community
PROJECT NO. 227521-0000132.00 DATE: 9/2/2021

TWENTYNINE PALMS WWTP SUPPORT
Twentynine Palms Water District
Fluoride Removal Facility

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Morongo 4
Morongo 3
Morongo 2
Morongo 1
FIGURE 3
SHT 1 OF 1
DES: RDD DR: RDD
1 W DEER VALLEY ROAD
BUILDING 2, SUITE 305
PHOENIX, ARIZONA 85027
Tel: 623.374.6637 Fax: 623.738.3690
MORONGO FOR:

INFILTRATION TEST LOCATIONS
Document Path: E:\227521-0000132.00 29 Palms WWTP Support\Figure 3 - Morongo.mxd CHK:

LEGEND
Infiltration Test Location ¯ 500
Feet
Service Layer Credits: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community
PROJECT NO. 227521-0000132.00 DATE: 9/2/2021

TWENTYNINE PALMS WWTP SUPPORT

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Flood 4
Flood 3
Flood 2
Flood 1
FIGURE 4
SHT 1 OF 1
DES: RDD DR: RDD
1 W DEER VALLEY ROAD
BUILDING 2, SUITE 305
PHOENIX, ARIZONA 85027
Tel: 623.374.6637 Fax: 623.738.3690
FLOOD FOR:

INFILTRATION TEST LOCATIONS
Document Path: E:\227521-0000132.00 29 Palms WWTP Support\Figure 4 - Flood.mxd CHK:

LEGEND
Infiltration Test Location ¯ 400
Feet
Service Layer Credits: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community
PROJECT NO. 227521-0000132.00 DATE: 9/2/2021

TWENTYNINE PALMS WWTP SUPPORT

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Preliminary Screening Study of Groundwater Recharge Sites, Twentynine Palms, California Attachment 2 - - Driller’s Log for Monitoring Well TP-1.

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Typical Earthwork Guidelines

APPENDIX E

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TYPICAL EARTHWORK GUIDELINES

1. GENERAL
These guidelines and the standard details attached hereto are presented as general procedures for earthwork construction for sites having slopes less than 10 feet high. They are to be utilized in conjunction with the project grading plans. These guidelines are considered a part of the geotechnical report, but are superseded by recommendations in the geotechnical report in the case of conflict.

Evaluations performed by the consultant during the course of grading may result in new recommendations which could supersede these specifications and/or the recommendations of the geotechnical report. It is the responsibility of the contractor to read and understand these guidelines as well as the geotechnical report and project grading plans.

1.1. The contractor shall not vary from these guidelines without prior recommendations by the geotechnical consultant and the approval of the client or the client's authorized representative. Recommendations by the geotechnical consultant and/or client shall not be considered to preclude requirements for approval by the jurisdictional agency prior to the execution of any changes.

1.2. The contractor shall perform the grading operations in accordance with these specifications, and shall be responsible for the quality of the finished product notwithstanding the fact that grading work will be observed and tested by the geotechnical consultant.

1.3. It is the responsibility of the grading contractor to notify the geotechnical consultant and the jurisdictional agencies, as needed, prior to the start of work at the site and at any time that grading resumes after interruption. Each step of the grading operations shall be observed and documented by the geotechnical consultant and, where needed, reviewed by the appropriate jurisdictional agency prior to proceeding with subsequent work.

1.4. If, during the grading operations, geotechnical conditions are encountered which were not anticipated or described in the geotechnical report, the geotechnical consultant shall be notified immediately and additional recommendations, if applicable, may be provided.

1.5. An as-graded report shall be prepared by the geotechnical consultant and signed by a registered engineer and registered engineering geologist. The report documents the geotechnical consultants' observations, and field and laboratory test results, and provides conclusions regarding whether or not earthwork construction was performed in accordance with the geotechnical recommendations and the grading plans.

Recommendations for foundation design, pavement design, subgrade treatment, etc., may also be included in the as-graded report.

1.6. For the purpose of evaluating quantities of materials excavated during grading and/or locating the limits of excavations, a licensed land surveyor or civil engineer shall be retained.

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2. SITE PREPARATION
Site preparation shall be performed in accordance with the recommendations presented in the following sections.

2.1. The client, prior to any site preparation or grading, shall arrange and attend a pre-grading meeting between the grading contractor, the design engineer, the geotechnical consultant, and representatives of appropriate governing authorities, as well as any other involved parties. The parties shall be given two working days notice.

2.2. Clearing and grubbing shall consist of the substantial removal of vegetation, brush, grass, wood, stumps, trees, tree roots greater than 1/2-inch in diameter, and other deleterious materials from the areas to be graded. Clearing and grubbing shall extend to the outside of the proposed excavation and fill areas.

2.3. Demolition in the areas to be graded shall include removal of building structures, foundations, reservoirs, utilities (including underground pipelines, septic tanks, leach fields, seepage pits, cisterns, etc.), and other manmade surface and subsurface improvements, and the backfilling of mining shafts, tunnels and surface depressions.

Demolition of utilities shall include capping or rerouting of pipelines at the project perimeter, and abandonment of wells in accordance with the requirements of the governing authorities and the recommendations of the geotechnical consultant at the time of demolition.

2.4. The debris generated during clearing, grubbing and/or demolition operations shall be removed from areas to be graded and disposed of off site at a legal dump site. Clearing, grubbing, and demolition operations shall be performed under the observation of the geotechnical consultant.

2.5. The ground surface beneath proposed fill areas shall be stripped of loose or unsuitable soil. These soils may be used as compacted fill provided they are generally free of organic or other deleterious materials and evaluated for use by the geotechnical consultant. The resulting surface shall be evaluated by the geotechnical consultant prior to proceeding.

The cleared, natural ground surface shall be scarified to a depth of approximately 8 inches, moisture conditioned, and compacted in accordance with the specifications presented in Section 4 of these guidelines.

3. REMOVALS AND EXCAVATIONS
Removals and excavations shall be performed as recommended in the following sections.

3.1. Removals

3.1.1. Materials which are considered unsuitable shall be excavated under the observation of the geotechnical consultant in accordance with the recommendations contained herein. Unsuitable materials include, but may not be limited to, dry, loose, soft, wet, organic, compressible natural soils, fractured, weathered, soft bedrock, and undocumented or otherwise deleterious fill materials.

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3.1.2. Materials deemed by the geotechnical consultant to be unsatisfactory due to moisture conditions shall be excavated in accordance with the recommendations of the geotechnical consultant, watered or dried as needed, and mixed to generally uniform moisture content in accordance with the specifications presented in Section 4 of this document.

3.2. Excavations

3.2.1. Temporary excavations no deeper than 4 feet in firm fill or natural materials may be made with vertical side slopes. To satisfy California Occupational Safety and Health Administration (CAL OSHA) requirements, any excavation deeper than 4 feet shall be shored or laid back at a 1:1 inclination or flatter, depending on material type, if construction workers are to enter the excavation.

4. COMPACTED FILL
Fill shall be constructed as specified below or by other methods recommended by the geotechnical consultant. Unless otherwise specified, fill soils shall be compacted to 90 percent relative compaction, as evaluated in accordance with ASTM Test Method D1557.

4.1. Prior to placement of compacted fill, the contractor shall request an evaluation of the exposed ground surface by the geotechnical consultant. Unless otherwise recommended, the exposed ground surface shall then be scarified to a depth of approximately 8 inches and watered or dried, as needed, to achieve a generally uniform moisture content at or near the optimum moisture content. The scarified materials shall then be compacted to 90 percent relative compaction. The evaluation of compaction by the geotechnical consultant shall not be considered to preclude any requirements for observation or approval by governing agencies. It is the contractor's responsibility to notify the geotechnical consultant and the appropriate governing agency when project areas are ready for observation, and to provide reasonable time for that review.

4.2. Excavated on-site materials which are in general compliance with the recommendations of the geotechnical consultant may be utilized as compacted fill provided they are generally free of organic or other deleterious materials and do not contain rock fragments greater than 6 inches in dimension. During grading, the contractor may encounter soil types other than those analyzed during the preliminary geotechnical study. The geotechnical consultant shall be consulted to evaluate the suitability of any such soils for use as compacted fill.

4.3. Where imported materials are to be used on site, the geotechnical consultant shall be notified three working days in advance of importation in order that it may sample and test the materials from the proposed borrow sites. No imported materials shall be delivered for use on site without prior sampling, testing, and evaluation by the geotechnical consultant.

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4.4. Soils imported for on-site use shall preferably have very low to low expansion potential (based on CBC Standard 1803.5.3). Lots on which expansive soils may be exposed at grade shall be undercut 3 feet or more and capped with very low to low expansion potential fill. In the event expansive soils are present near the ground surface, special design and construction considerations shall be utilized in general accordance with the recommendations of the geotechnical consultant.

4.5. Fill materials shall be moisture conditioned to near optimum moisture content prior to placement. The optimum moisture content will vary with material type and other factors.

Moisture conditioning of fill soils shall be generally uniform in the soil mass.

4.6. Prior to placement of additional compacted fill material following a delay in the grading operations, the exposed surface of previously compacted fill shall be prepared to receive fill. Preparation may include scarification, moisture conditioning, and recompaction.

4.7. Compacted fill shall be placed in horizontal lifts of approximately 8 inches in loose thickness. Prior to compaction, each lift shall be watered or dried as needed to achieve near optimum moisture condition, mixed, and then compacted by mechanical methods, using sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other appropriate compacting rollers, to the specified relative compaction. Successive lifts shall be treated in a like manner until the desired finished grades are achieved.

4.8. Fill shall be tested in the field by the geotechnical consultant for evaluation of general compliance with the recommended relative compaction and moisture conditions. Field density testing shall conform to ASTM D1556 (Sand Cone method), D2937 (Drive-Cylinder method), and/or D2922 and D3017 (Nuclear Gauge method). Generally, one test shall be provided for approximately every 2 vertical feet of fill placed, or for approximately every 1000 cubic yards of fill placed. In addition, on slope faces one or more tests shall be taken for approximately every 10,000 square feet of slope face and/or approximately every 10 vertical feet of slope height. Actual test intervals may vary as field conditions dictate. Fill found to be out of conformance with the grading recommendations shall be removed, moisture conditioned, and compacted or otherwise handled to accomplish general compliance with the grading recommendations.

4.9. The contractor shall assist the geotechnical consultant by excavating suitable test pits for removal evaluation and/or for testing of compacted fill.

4.10. At the request of the geotechnical consultant, the contractor shall "shut down" or restrict grading equipment from operating in the area being tested to provide adequate testing time and safety for the field technician.

4.11. The geotechnical consultant shall maintain a map with the approximate locations of field density tests. Unless the client provides for surveying of the test locations, the locations shown by the geotechnical consultant will be estimated. The geotechnical consultant shall not be held responsible for the accuracy of the horizontal or vertical locations or elevations.

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4.12. Grading operations shall be performed under the observation of the geotechnical consultant. Testing and evaluation by the geotechnical consultant does not preclude the need for approval by or other requirements of the jurisdictional agencies.

4.13. Fill materials shall not be placed, spread or compacted during unfavorable weather conditions. When work is interrupted by heavy rains, the filling operation shall not be resumed until tests indicate that moisture content and density of the fill meet the project specifications. Regrading of the near-surface soil may be needed to achieve the specified moisture content and density.

4.14. Upon completion of grading and termination of observation by the geotechnical consultant, no further filling or excavating, including that planned for footings, foundations, retaining walls or other features, shall be performed without the involvement of the geotechnical consultant.

4.15. Fill placed in areas not previously viewed and evaluated by the geotechnical consultant may have to be removed and recompacted at the contractor's expense. The depth and extent of removal of the unobserved and undocumented fill will be decided based upon review of the field conditions by the geotechnical consultant.

4.16. Off-site fill shall be treated in the same manner as recommended in these specifications for on-site fills. Off-site fill subdrains temporarily terminated (up gradient) shall be surveyed for future locating and connection.

5. OVERSIZED MATERIAL
Oversized material shall be placed in accordance with the following recommendations.

5.1. During the course of grading operations, rocks or similar irreducible materials greater than 6 inches in dimension (oversized material) may be generated. These materials shall not be placed within the compacted fill unless placed in general accordance with the recommendations of the geotechnical consultant.

5.2. Where oversized rock (greater than 6 inches in dimension) or similar irreducible material is generated during grading, it is recommended, where practical, to waste such material off site, or on site in areas designated as "nonstructural rock disposal areas." Rock designated for disposal areas shall be placed with sufficient sandy soil to generally fill voids. The disposal area shall be capped with a 5-foot thickness of fill which is generally free of oversized material.

5.3. Rocks 6 inches in dimension and smaller may be utilized within the compacted fill, provided they are placed in such a manner that nesting of rock is not permitted. Fill shall be placed and compacted over and around the rock. The amount of rock greater than ¾-inch in dimension shall generally not exceed 40 percent of the total dry weight of the fill mass, unless the fill is specially designed and constructed as a "rock fill."

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5.4. Rocks or similar irreducible materials greater than 6 inches but less than 4 feet in dimension generated during grading may be placed in windrows and capped with finer materials in accordance with the recommendations of the geotechnical consultant and the approval of the governing agencies. Selected native or imported granular soil (Sand Equivalent of 30 or higher) shall be placed and flooded over and around the windrowed rock such that voids are filled. Windrows of oversized materials shall be staggered so that successive windrows of oversized materials are not in the same vertical plane. Rocks greater than 4 feet in dimension shall be broken down to 4 feet or smaller before placement, or they shall be disposed of off site.

6. SLOPES
The following sections provide recommendations for cut and fill slopes.

6.1. Cut Slopes

6.1.1. The geotechnical consultant shall observe cut slopes during excavation. The geotechnical consultant shall be notified by the contractor prior to beginning slope excavations.

6.1.2. If, during the course of grading, adverse or potentially adverse geotechnical conditions are encountered in the slope which were not anticipated in the preliminary evaluation report, the geotechnical consultant shall evaluate the conditions and provide appropriate recommendations.

6.2. Fill Slopes

6.2.1. When placing fill on slopes steeper than 5:1 (horizontal:vertical), topsoil, slope wash, colluvium, and other materials deemed unsuitable shall be removed. Nearhorizontal keys and near-vertical benches shall be excavated into sound bedrock or fine fill material, in accordance with the recommendation of the geotechnical consultant. Keying and benching shall be accomplished. Compacted fill shall not be placed in an area subsequent to keying and benching until the area has been observed by the geotechnical consultant. Where the natural gradient of a slope is less than 5:1, benching is generally not recommended. However, fill shall not be placed on compressible or otherwise unsuitable materials left on the slope face.

6.2.2. Within a single fill area where grading procedures dictate two or more separate fills, temporary slopes (false slopes) may be created. When placing fill adjacent to a temporary slope, benching shall be conducted in the manner described in Section 6.2.1. A 3-foot or higher near-vertical bench shall be excavated into the documented fill prior to placement of additional fill.

6.2.3. Unless otherwise recommended by the geotechnical consultant and accepted by the Building Official, permanent fill slopes shall not be steeper than 2:1 (horizontal:vertical). The height of a fill slope shall be evaluated by the geotechnical consultant.

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6.2.4. Unless specifically recommended otherwise, compacted fill slopes shall be overbuilt and cut back to grade, exposing firm compacted fill. The actual amount of overbuilding may vary as field conditions dictate. If the desired results are not achieved, the existing slopes shall be overexcavated and reconstructed in accordance with the recommendations of the geotechnical consultant. The degree of overbuilding may be increased until the desired compacted slope face condition is achieved. Care shall be taken by the contractor to provide mechanical compaction as close to the outer edge of the overbuilt slope surface as practical.

6.2.5. If access restrictions, property line location, or other constraints limit overbuilding and cutting back of the slope face, an alternative method for compaction of the slope face may be attempted by conventional construction procedures including backrolling at intervals of 4 feet or less in vertical slope height, or as dictated by the capability of the available equipment, whichever is less. Fill slopes shall be backrolled utilizing a conventional sheepsfoot-type roller. Care shall be taken to maintain the specified moisture conditions and/or reestablish the same, as needed, prior to backrolling.

6.2.6. The placement, moisture conditioning and compaction of fill slope materials shall be done in accordance with the recommendations presented in Section 5 of these guidelines.

6.2.7. The contractor shall be ultimately responsible for placing and compacting the soil out to the slope face to obtain a relative compaction of 90 percent as evaluated by ASTM D1557 and a moisture content in accordance with Section 4. The geotechnical consultant shall perform field moisture and density tests at intervals of one test for approximately every 10,000 square feet of slope.

6.2.8. Backdrains shall be provided in fill as recommended by the geotechnical consultant.

6.3. Top-of-Slope Drainage

6.3.1. For pad areas above slopes, positive drainage shall be established away from the top of slope. This may be accomplished utilizing a berm and pad gradient of 2 percent or steeper at the top-of-slope areas. Site runoff shall not be permitted to flow over the tops of slopes.

6.3.2. Gunite-lined brow ditches shall be placed at the top of cut slopes to redirect surface runoff away from the slope face where drainage devices are not otherwise provided.

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6.4. Slope Maintenance

6.4.1. In order to enhance surficial slope stability, slope planting shall be accomplished at the completion of grading. Slope plants shall consist of deep-rooting, variable root depth, drought-tolerant vegetation. Native vegetation is generally desirable.

Plants native to semiarid and mid areas may also be appropriate. Large-leafed ice plant should not be used on slopes. A landscape architect shall be consulted regarding the actual types of plants and planting configuration to be used.

6.4.2. Irrigation pipes shall be anchored to slope faces and not placed in trenches excavated into slope faces. Slope irrigation shall be maintained at a level just sufficient to support plant growth. Property owners shall be made aware that over watering of slopes is detrimental to slope stability. Slopes shall be monitored regularly and broken sprinkler heads and/or pipes shall be repaired immediately.

6.4.3. Periodic observation of landscaped slope areas shall be planned and appropriate measures taken to enhance growth of landscape plants.

6.4.4. Graded swales at the top of slopes and terrace drains shall be installed and the property owners notified that the drains shall be periodically checked so that they may be kept clear. Damage to drainage improvements shall be repaired immediately. To reduce siltation, terrace drains shall be constructed at a gradient of 3 percent or steeper, in accordance with the recommendations of the project civil engineer.

6.4.5. If slope failures occur, the geotechnical consultant shall be contacted immediately for field review of site conditions and development of recommendations for evaluation and repair.

7. TRENCH BACKFILL
The following sections provide recommendations for backfilling of trenches.

7.1. Trench backfill shall consist of granular soils (bedding) extending from the trench bottom to 1 foot or more above the pipe. On-site or imported fill which has been evaluated by the geotechnical consultant may be used above the granular backfill. The cover soils directly in contact with the pipe shall be classified as having a very low expansion potential, in accordance with CBC section 1803.5.3, and shall contain no rocks or chunks of hard soil larger than 3/4-inch in diameter.

7.2. Trench backfill shall, unless otherwise recommended, be compacted by mechanical means to 90 percent relative compaction as evaluated by ASTM D1557. Backfill soils shall be placed in loose lifts 8-inches thick or thinner, moisture conditioned, and compacted in accordance with the recommendations of Section 4 of these guidelines. The backfill shall be tested by the geotechnical consultant at vertical intervals of approximately 2 feet of backfill placed and at spacings along the trench of approximately 100 feet in the same lift.

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7.3. Jetting of trench backfill materials is generally not a recommended method of densification, unless the on-site soils are sufficiently free-draining and provisions have been made for adequate dissipation of the water utilized in the jetting process.

7.4. If it is decided that jetting may be utilized, granular material with a sand equivalent greater than 30 shall be used for backfilling in the areas to be jetted. Jetting shall generally be considered for trenches 2 feet or narrower in width and 4 feet or shallower in depth.

Following jetting operations, trench backfill shall be mechanically compacted to the specified compaction to finish grade.

7.5. Trench backfill which underlies the zone of influence of foundations shall be mechanically compacted to 90 percent or greater relative compaction, as evaluated by ASTM D1557-

02. The zone of influence of the foundations is generally defined as the roughly triangular area within the limits of a 1:1 (horizontal:vertical) projection from the inner and outer edges of the foundation, projected down and out from both edges.

7.6. Trench backfill within slab areas shall be compacted by mechanical means to a relative compaction of 90 percent, as evaluated by ASTM D1557. For minor interior trenches, density testing may be omitted or spot testing may be performed, as deemed appropriate by the geotechnical consultant.

7.7. When compacting soil in close proximity to utilities, care shall be taken by the grading contractor so that mechanical methods used to compact the soils do not damage the utilities. If the utility contractors indicate that it is undesirable to use compaction equipment in close proximity to a buried conduit, then the grading contractor may elect to use light mechanical compaction equipment or, with the approval of the geotechnical consultant, cover the conduit with clean granular material. These granular materials shall be jetted in place to the top of the conduit in accordance with the recommendations of Section 7.4 prior to initiating mechanical compaction procedures. Other methods of utility trench compaction may also be appropriate, upon review by the geotechnical consultant and the utility contractor, at the time of construction.

7.8. Clean granular backfill and/or bedding materials are not recommended for use in slope areas unless provisions are made for a drainage system to mitigate the potential for buildup of seepage forces or piping of backfill materials.

7.9. The contractor shall exercise the specified safety precautions, in accordance with OSHA Trench Safety Regulations, while conducting trenching operations. Such precautions include shoring or laying back trench excavations at 1:1 or flatter, depending on material type, for trenches in excess of 5 feet in depth. The geotechnical consultant is not responsible for the safety of trench operations or stability of the trenches.

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8. DRAINAGE
The following sections provide recommendations pertaining to site drainage.

8.1. Roof, pad, and slope drainage shall be such that it is away from slopes and structures to suitable discharge areas by nonerodible devices (e.g., gutters, downspouts, concrete swales, etc.).

8.2. Positive drainage adjacent to structures shall be established and maintained. Positive drainage may be accomplished by providing drainage away from the foundations of the structure at a gradient of 2 percent or steeper for a distance of 5 feet or more outside the building perimeter, further maintained by a graded swale leading to an appropriate outlet, in accordance with the recommendations of the project civil engineer and/or landscape architect.

8.3. Surface drainage on the site shall be provided so that water is not permitted to pond. A gradient of 2 percent or steeper shall be maintained over the pad area and drainage patterns shall be established to remove water from the site to an appropriate outlet.

8.4. Care shall be taken by the contractor during grading to preserve any berms, drainage terraces, interceptor swales or other drainage devices of a permanent nature on or adjacent to the property. Drainage patterns established at the time of finish grading shall be maintained for the life of the project. Property owners shall be made very clearly aware that altering drainage patterns may be detrimental to slope stability and foundation performance.

9. SITE PROTECTION
The site shall be protected as outlined in the following sections.

9.1. Protection of the site during the period of grading shall be the responsibility of the contractor unless other provisions are made in writing and agreed upon among the concerned parties. Completion of a portion of the project shall not be considered to preclude that portion or adjacent areas from the need for site protection, until such time as the project is finished as agreed upon by the geotechnical consultant, the client, and the regulatory agency.

9.2. The contractor is responsible for the stability of temporary excavations.

Recommendations by the geotechnical consultant pertaining to temporary excavations are made in consideration of stability of the finished project and, therefore, shall not be considered to preclude the responsibilities of the contractor. Recommendations by the geotechnical consultant shall also not be considered to preclude more restrictive requirements by the applicable regulatory agencies.

9.3. Precautions shall be taken during the performance of site clearing, excavation, and grading to protect the site from flooding, ponding, or inundation by surface runoff. Temporary provisions shall be made during the rainy season so that surface runoff is away from and off the working site. Where low areas cannot be avoided, pumps shall be provided to remove water as needed during periods of rainfall.

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9.4. During periods of rainfall, plastic sheeting shall be used as needed to reduce the potential for unprotected slopes to become saturated. Where needed, the contractor shall install check dams, desilting basins, riprap, sandbags or other appropriate devices or methods to reduce erosion and provide recommended conditions during inclement weather.

9.5. During periods of rainfall, the geotechnical consultant shall be kept informed by the contractor of the nature of remedial or precautionary work being performed on site (e.g., pumping, placement of sandbags or plastic sheeting, other labor, dozing, etc.).

9.6. Following periods of rainfall, the contractor shall contact the geotechnical consultant and arrange a walk-over of the site in order to visually assess rain-related damage. The geotechnical consultant may also recommend excavation and testing in order to aid in the evaluation. At the request of the geotechnical consultant, the contractor shall make excavations in order to aid in evaluation of the extent of rain-related damage.

9.7. Rain or irrigation related damage shall be considered to include, but may not be limited to, erosion, silting, saturation, swelling, structural distress, and other adverse conditions noted by the geotechnical consultant. Soil adversely affected shall be classified as "Unsuitable Material" and shall be subject to overexcavation and replacement with compacted fill or to other remedial grading as recommended by the geotechnical consultant.

9.8. Relatively level areas where saturated soils and/or erosion gullies exist to depths greater than 1 foot shall be overexcavated to competent materials as evaluated by the geotechnical consultant. Where adverse conditions extend to less than 1 foot in depth, saturated and/or eroded materials may be processed in-place. Overexcavated or in-place processed materials shall be moisture conditioned and compacted in accordance with the recommendations provided in Section 4. If the desired results are not achieved, the affected materials shall be overexcavated, moisture conditioned, and compacted until the specifications are met.

9.9. Slope areas where saturated soil and/or erosion gullies exist to depths greater than 1 foot shall be overexcavated and replaced as compacted fill in accordance with the applicable specifications. Where adversely affected materials exist to depths of I foot or less below proposed finished grade, remedial grading by moisture conditioning in-place and compaction in accordance with the appropriate specifications may be attempted. If the desired results are not achieved, the affected materials shall be overexcavated, moisture conditioned, and compacted until the specifications are met. As conditions dictate, other slope repair procedures may also be recommended by the geotechnical consultant.

9.10. During construction, the contractor shall grade the site to provide positive drainage away from structures and to keep water from ponding adjacent to structures. Water shall not be allowed to damage adjacent properties. Positive drainage shall be maintained by the contractor until permanent drainage and erosion reducing devices are installed in accordance with project plans.

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Delivering Solutions
Improving Lives

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City of Twentynine Palms – Septic to Sewer
WWTP Site and Collection System Alternatives
December 2023

Summary of Proposed Sewer Connections - DRAFT
GIS data and assessor property data from San Bernardino County was used to categorize and determine the number of properties (parcels) and the number of equivalent residential connections in the service area for each collection system alternative shown on Exhibit 2. This data is summarized below in Table 1 and Table 2. Except for some very large properties, it is anticipated that each occupied property will have only 1 “master” sewer lateral connection, which may serve multiple dwelling units or buildings. Sewer laterals will not be installed for vacant properties. Properties that are connected to the City’s existing Project Phoenix sewer/septic system were excluded from these amounts since they are already connected to a public sewer system.

Table 1 – Phase 1A Alternatives - Parcels
Category
Collection System Alternative
Phase 1A-1
(WWTP Site 1
at APN 062317111)1
Phase 1A-2
(WWTP Site 2
at APN 062317105) 1
Phase 1A-3
(WWTP Site 3
at APN 062321129) 1
Single-Family Residential 246 236 220
Multi-Family Residential 133 128 120
Commercial / Public 58 56 54
Subtotal 437 420 394
Vacant 215 199 192
Parking Lot / Other 32 32 31
Total 684 651 617
Notes:

1. Excludes properties that are connected to the existing Project Phoenix sewer system.

Table 2 – Phase 1A Alternatives - Equivalent Residential Connections Category
Collection System Alternative
Phase 1A-1
(WWTP Site 1
at APN 062317111)1
Phase 1A-2
(WWTP Site 2
at APN 062317105) 1
Phase 1A-3
(WWTP Site 3
at APN 062321129) 1
Single-Family Residential 246 236 220
Multi-Family Residential2 526 512 493
Total 772 748 713
Notes:

1. Excludes properties that are connected to the existing Project Phoenix sewer system.

2. Determined based on the total number of dwelling units per parcel.

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Twentynine Palms City CouncilDecember 12, 2023

Twentynine Palms City Council
December 12, 2023