Agenda packet — Los Alamitos City Council, November 18, 2024 (part 14 of 18)

4.0 PROPOSED CONDITIONS:

The proposed development will consist of 169 for sale single family residential units (55 detached condos and 114 attached townhome units) and 77 for rent units (3 apartment buildings); for a total of 246 dwelling units. Proposed associated drive aisles, parking and flatwork will increase the overall impervious area compared to the existing condition of the site.

The proposed site’s stormwater runoff will be conveyed by roof downspouts or street surface flow to proposed gutters and collected by thru-curb inlet biofiltration devices or catch basin inlets for water quality treatment. The biofiltration devices include an internal overflow bypass that direct flows via an onsite underground storm drain system to an underground detention system located under parking areas at the southwest portion of the site. From the detention system, a stormwater sump pump located in the southwest corner of the site will outlet flows into the existing 18” storm drain pipe at the southwest corner of the site, which conveys stormwater runoff to the JFTB property located directly west of the site. The detention system and pump will be sized so that the outlet flows from the developed site will be equal to, or less than, existing conditions for all storm events. In the event the stormwater pump fails or the outlet pipe becomes clogged, the emergency overflow for the site will be conveyed through a parkway drain discharging flow onto Lampson Avenue, matching historical drainage patterns.

Proposed pad elevations for the onsite buildings shall be set a minimum 1’ above the 100-year water surface elevation in accordance with Orange County Flood Protection requirements.

A proposed 10’ wide dedication area along the northern the property line is proposed to support the adjacent park. The 10’ wide dedication area is outside the proposed residential development and does not flow to the site’s proposed storm drain system. Existing conditions show that this area of site currently drains in the northerly direction.

Alternative Drainage System Outlets to Lampson Avenue:

There currently is no existing cross lot drainage arrangement between the JFTB and the subject property allowing for the proposed development’s flows to outlet onto the JFTB. The JFTB controls all improvements on their property. If, for whatever reason, proposed flows from the project are not allowed to outlet to the JFTB, then the emergency overflow parkway drain will be utilized as the 3

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primary discharge location. Placement of the proposed parkway drain is near the existing overflow location as described within the Section 3.0 Existing Conditions of this study, therefore closely matches the existing conditions.

A proposed stormwater pump system with upstream detention storage has been incorporated into the onsite drainage design to provide onsite peak flow and volume minimization for the development for all storm events. The pump system will control the outflow discharge rate matching the existing 2- year peak flow at approximately 8.9 cfs. The pump system along with upstream detention will ensure stormwater inundation within Lampson Avenue is minimized and no additional impact is anticipated whether the discharge location is to the existing JFTB 18” CMP storm drain pipe or the proposed park drain on Lampson Avenue.

Approaches to Drainage System Outlets Deemed Infeasible:

As part of this preliminary hydrology study, the following drainage designs with different outlet locations each of which were found to be infeasible upon closer review:

1. Construct storm drain pipe in Lampson Avenue to west:

The proposed installation of approximately 2,400 linear feet (LF) of 30” underground gravityfed storm drain pipe in Lampson Avenue to directly connect to closest downstream existing 36” storm drain pipe (north of Guava Avenue extended) was found to be infeasible due to conflicts with existing utilities; including existing 16” water, 8” sewer, and 34” gas mains. Installing 2,400 LF of force main, as opposed to gravity main, may also create long-term maintenance concerns. In addition, the installation of 2,400 LF of force main is not desirable due to head losses created by such a long length of pipe.

Refer to the exhibits in Appendix D.3.

2. Construct storm drain pipe under Heather Street, Hazelnut Avenue, and Guava Avenue to south and west:

Since there is no existing underground storm drain to connect within Heather Street or Hazelnut Avenue, a new storm drain pipe would need to be extended 3,000 LF through these streets to connect to the existing 36” storm drain pipe in Guava Avenue. The existing storm drain system is undersized according to the City of Seal Beach Master Plan of Drainage Update dated August 2008. Future City of Seal Beach capital improvements to the downstream storm drain system are recommended in the Master Plan of Drainage Update at this location (CPE 1A and CPE 1B as shown on Figure 1-3 in Appendix D.2), but there is no current timeline to install any capital improvements. Without the capital improvements in place, redirecting stormwater runoff flows from the site to the currently undersized storm drain system in Guava Avenue is infeasible since it would exacerbate the existing flooding condition at this location adjacent to single family homes.

Refer to the exhibits in Appendix D.2 and D.3.

3. Outlet Runoff to Arbor Park to North:

Arbor Park is within the JFTB property and drains south to the same earthen channel outlet as the project site. If the proposed flows from the project are not allowed to outlet to the JFTB at the southwest corner of the site, proposed flows from the project would not be allowed to outlet to the JFTB to the north of the site either since they are essentially the same outlet location. In addition, the existing site does not flow in the northerly Arbor Park/ JFTB area as the site drains in the southwesterly direction, therefore directing stormwater runoff to the north would change the historic drainage pattern which can potentially cause downstream flooding. 4

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4. Outlet Runoff to Golf Course to East:

The golf course to the east of the site is within the JFTB property and drains east, ultimately to the Bolsa Chica Channel. Discharging to the east does not match the historical drainage pattern and the Bolsa Chica Channel was not designed to accommodate flows from the site, therefore potentially cause downstream flooding. In addition, the golf course and Bolsa Chica Channel are upstream from the site, therefore not feasible due to elevation differences.

5. Construct storm drain pipe in Lampson Avenue to East:

Discharging to the east does not match the historical drainage pattern and the Bolsa Chica Channel was not designed to accommodate flows from the site. Additionally, installation of underground storm drain pipe within Lampson Avenue is infeasible for same reasons as noted in #1 above. Similarly to item #4, changing the historical drainage pattern may potentially cause unforeseen drainage impacts.

Refer to the Proposed Conditions Hydrology Map located in Appendix A.2. 5

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5.0 METHODOLOGY:

The existing/proposed subarea was analyzed for acreage, land-use, soil type, peak flow rate, and time of concentration according to the Rational Method.

Recommended perviousness values are based on existing and proposed land use.

Proposed conditions were analyzed using the rational method to determine the detention volume.

Rational Method Analysis identify offsite 25-year storm event flow allowed to prevent flooding of one travel lane of the half-street per Orange County Public Works Flood Local Drainage Manual.

6.0 RESULTS:

Existing Conditions

DA AREA
(AC)

PERVIOUS

AREA (AC)

IMPERVIOUS

AREA (SF)

PERCENT

IMPERVIOUS
Q10
(CFS)
Q25
(CFS)
Q100
(CFS)
100-YR
TC
(MIN)
X1 0.20 0.20 0 0% 0.45 0.55 0.72 9.09
X2 3.05 3.05 0 0% 4.57 5.83 7.94 14.51
X3 8.87 0.89 7.98 90% 14.11 17.40 22.85 17.43
TOTAL 12.12 4.14 7.98 66% 19.12 23.78 31.51 -
Existing Offsite Drainage Area Conditions
DA AREA (AC) Q2 (CFS) Q25 (CFS) 25-YR TC
(MIN) Q100 (CFS) 100-YR TC (MIN)
X4 0.44 0.68 1.48 7.69 1.90 7.69
X5 2.51 0.87 2.36 40.00 3.13 38.01
X6 1.92 0.32 0.93 65.21 1.23 61.61
TOTAL 4.87 1.87 4.77 - 6.26 -
Proposed Conditions
(for Existing JTFB 18” Storm Drain Pipe or Lampson Avenue Parkway Drain:

DA AREA
(AC)
Q10 (CFS)
[unmitigated]
Q25 (CFS)
[unmitigated]
Q100 (CFS)
[unmitigated]
100-
YR TC
(MIN)
Q10 (CFS)
[mitigated]
Q100 (CFS)
[mitigated]
1 0.73 2.08 2.50 3.22 7.2 - -
2 6.07 13.29 16.30 21.45 10.0 - -
3 3.16 6.30 7.76 10.23 10.6 - -
4 0.64 1.82 2.18 2.81 7.2 - -
5 1.52 3.21 3.94 5.21 9.5 - -
TOTAL 12.12 26.15 32.06 42.15 11.3 8.90 8.90
6

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Catch Basin Sizing
Catch basin Sizing will be analyzed for the 100-year storm event peak flow and provided during final engineering.

Pipe Sizing
Onsite underground storm drain pipe will be analyzed for the 100-year storm event peak flow rate utilizing WSPG software and provided during final engineering. 100-Year Water Surface Ponding Exhibit/ Calculations
Water surface elevations for the 100-year storm event peak flow rates will verify that the proposed building pad elevations are a minimum 1’ above the water surface elevation. A ponding exhibit will be prepared based on the 100-year water surface elevation tributary to each subarea during final engineering.

Detention Calculations
Due to increased peak runoff flows created from the proposed change in land use and increased impervious coverage of the proposed development, stormwater will need to be detained to minimize and ultimately match existing conditions. A 24-hour inflow hydrograph and detention basin routing was analyzed to determine the amount of increased volume runoff to be minimized based on existing vs. proposed flows. However, the existing outlet pipe with headwall limits flow from the site similar to an orifice. Based on the maximum flows conveyed by the outlet pipe based on analyzing the pipe as an orifice, it appears the existing flows may overflow into Lampson Ave (Refer to Appendix C.2 for orifice calculations). To prevent overflow into Lampson Ave, the detention system shall be sized to match the maximum flows conveyed by the outlet pipe.

In addition, a proposed stormwater pump system with upstream detention storage has been incorporated into the onsite drainage design to provide onsite peak flow and volume minimization for the development for all storm events. The pump system will control the outflow discharge rate matching the existing 2-year peak flow at approximately 8.9 cfs. Refer to Appendix C.3 for detention calculations.

Lampson Avenue Street Capacity
An offsite street capacity analysis was performed for Lampson Avenue to determine the tributary area and corresponding peak flows. This information was utilized to determine the existing development is responsible of potential flooding of Lampson Avenue during larger storm events. Two (2) areas were analyzed; Section A-A is located near the southwest corner of the site and Section B-B at the existing low-point sump catch basin approximately 2,100 LF from the site near the Old Ranch Country Club.

Both street capacity analysis indicate that the 100-year water surface elevation is held within the street and less than the existing top of curb elevations.

Refer to Appendix A.3 Offsite Existing Conditions Hydrology Map and Appendix C.5 for street capacity calculations.
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7.0 CONCLUSION:

The results from this preliminary hydrology study demonstrate that the proposed condition of the project site will generate a higher peak runoff flowrate than the existing condition of the site due to an increase in impervious area and change in land use. The proposed detention facilities will be designed to detain at the flows and times indicated by the produced hydrographs in Appendix C.1.

Detained volumes will be discharged from the site via a pump system at flow rates that do not exceed the existing condition flow rates. Downstream facilities will not be hydrologically impacted by the proposed project site improvements. Existing historic drainage patterns will be maintained without causing the potential increase of tributary flooding. Proposed discharges from the development will not exceed the existing peak flow rates as described with the proposed conditions and alternative drainage system scenario.
8

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8.0 DESIGN PARAMETERS:

1. The onsite drainage area was analyzed for a 10, 25, 100-year storm event using Rational Method Analysis per the County of Orange Hydrology Manual.

2. The drainage area is classified as Soil Group A (See Appendix E of this report). According to the Geotechnical Investigation report prepared by LGC Geotechnical, Inc. (dated December 21, 2021), the site is underlain by alluvial fan deposits to the maximum depth of 46.5’ below existing grade.

It consists of clay, clayey sand, silty clay, and silty sand. The soil is to be very moist to wet with depth and soft to stiff and medium dense to dense.

3. Assumed commercial and undeveloped cover for existing land use. A manning’s “n” value of 0.040 is applied to undeveloped cover flow path and a value of 0.015 is applied to the concrete gutter.

4. Assumed apartments and condominium for proposed land use.

5. Time of concentration Tc were calculated by using the County of Orange Hydrology Manual to calculate flow rates and volume amounts.

6. There is no offsite run-on tributary to the site.

9.0 REFERENCES:

1. Orange County Hydrology Manual. Orange County Environmental Management Agency. dated October 1986.

2. Orange County Flood Control District Design Manual. County of Orange Public Facilities and Resources Department. November 2000.

3. HydraFlow Express Extension. Autodesk AutoCAD Civil 3D

4. Existing Storm Drain As-Built Plans.

5. Orange County Technical Guidance Document.

6. U.S. Department of Transportation, Federal Highway Administration, Hydraulic Toolbox, Version 5.4.0
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APPENDIX A

HYDROLOGY MAPS

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National Flood Hazard Layer FIRMette
0 250 500 1,000 1,500 2,000
Feet
Ü

SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT

SPECIAL FLOOD

HAZARD AREAS
Without Base Flood Elevation (BFE)
Zone A, V, A99
With BFE or DepthZone AE, AO, AH, VE, AR
Regulatory Floodway

0.2% Annual Chance Flood Hazard, Areas
of 1% annual chance flood with average
depth less than one foot or with drainage
areas of less than one square mileZone X
Future Conditions 1% Annual
Chance Flood HazardZone X
Area with Reduced Flood Risk due to
Levee. See Notes.Zone X
Area with Flood Risk due to LeveeZone D
NO SCREENArea of Minimal Flood Hazard Zone X
Area of Undetermined Flood HazardZone D
Channel, Culvert, or Storm Sewer
Levee, Dike, or Floodwall
Cross Sections with 1% Annual Chance

17.5 Water Surface Elevation
Coastal Transect
Coastal Transect Baseline
Profile Baseline
Hydrographic Feature
Base Flood Elevation Line (BFE)
Effective LOMRs
Limit of Study
Jurisdiction Boundary
Digital Data Available
No Digital Data Available
Unmapped
This map complies with FEMA's standards for the use of
digital flood maps if it is not void as described below.

The basemap shown complies with FEMA's basemap
accuracy standards
The flood hazard information is derived directly from the authoritative NFHL web services provided by FEMA. This map was exported on 8/18/2022 at 12:30 PM and does not
reflect changes or amendments subsequent to this date and time. The NFHL and effective information may change or
become superseded by new data over time.

This map image is void if the one or more of the following map elements do not appear: basemap imagery, flood zone labels, legend, scale bar, map creation date, community identifiers, FIRM panel number, and FIRM effective date. Map images for unmapped and unmodernized areas cannot be used for
regulatory purposes.

Legend

OTHER AREAS OF

FLOOD HAZARD

OTHER AREAS

GENERAL

STRUCTURES
OTHER

FEATURES

MAP PANELS
8 B

20.2 The pin displayed on the map is an approximate
point selected by the user and does not represent
an authoritative property location.
1:6,000
118°3'12"W 33°47'7"N
118°2'34"W 33°46'38"N
Basemap: USGS National Map: Orthoimagery: Data refreshed October, 2020

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A.1 - Existing Conditions Hydrology Map

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DWG: P:\K\KBHO-007\dwg\Sheets\Exhibits\EH_PE-EX HYD_COMBINED.dwg BY: jhendricks Aug 19, 2024 - 10:56:00am PROJ: KBHO-007 REVISIONS ONSITE EXISTING CONDITIONS HYDROLOGY MAP TENTATIVE TRACT MAP NO. 19263 4665 LAMPSON AVENUE CITY OF LOS ALAMITOS, COUNTY OF ORANGE, STATE OF CALIFORNIA 38%/I&:OR.S$*EN&< 0 SCALE: 1" = 40' 20 40 80 ΣΣΣ ΣΣΣ

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A.2 - Proposed Conditions Hydrology Map

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DWG: P:\K\KBHO-007\dwg\Sheets\Exhibits\EH_PE-PROP HYD.dwg BY: jhendricks Aug 19, 2024 - 10:49:49am PROJ: KBHO-007 REVISIONS ONSITE PROPOSED CONDITIONS HYDROLOGY MAP TENTATIVE TRACT MAP NO. 19263 4665 LAMPSON AVENUE CITY OF LOS ALAMITOS, COUNTY OF ORANGE, STATE OF CALIFORNIA 38%/I&:OR.S$*EN&< 0 SCALE: 1" = 40' 20 40 80 T T T T T T NO PARKING Trans.

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A.3 – Offsite Existing Conditions Hydrology Map

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DWG: P:\K\KBHO-007\dwg\Sheets\Exhibits\EH_PE-EX HYD_COMBINED.dwg BY: klam Jul 10, 2024 - 9:37:16pm PROJ: KBHO-007 REVISIONS OFFSITE EXISTING CONDITIONS HYDROLOGY MAP TENTATIVE TRACT MAP NO. 19263 4665 LAMPSON AVENUE CITY OF LOS ALAMITOS, COUNTY OF ORANGE, STATE OF CALIFORNIA 38%/I&:OR.S$*EN&<0 SCALE: 1" = 40' 20 40 80 ΣΣΣ ΣΣ

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APPENDIX B

HYDROLOGY CALCULATIONS

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B.1 - Existing Conditions Hydrology Calculations
(10, 25, 100-year Storm Event)

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Orange County Rational Hydrology Program
(Hydrology Manual Date(s) October 1986 & November 1996) CIVILCADD/CIVILDESIGN Engineering Software, (c) 1989-2018 Version 9.0 Rational Hydrology Study, Date: 03/12/24 File Name: kb07x10.roc ------------------------------------------------------------------------

LOS ALAMITOS
TTM 19263
EXISTING Q10

------------------------------------------------------------------------ Program License Serial Number 6618
------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Rational hydrology study storm event year is 10.0
Decimal fraction of study above 2000 ft., 600M = 0.0000 English Units Used for input data
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 100.000 to Point/Station 101.000 **** INITIAL AREA EVALUATION ****
______________________________________________________________________ UNDEVELOPED (poor cover) subarea
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 67.00
Pervious ratio(Ap) = 1.0000 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.400(In/Hr)
Initial subarea data:

Initial area flow distance = 92.000(Ft.)
Top (of initial area) elevation = 26.000(Ft.)
Bottom (of initial area) elevation = 25.500(Ft.)
Difference in elevation = 0.500(Ft.)
Slope = 0.00543 s(%)= 0.54
TC = k(0.525)*[(length^3)/(elevation change)]^0.2
Initial area time of concentration = 9.092 min.

Rainfall intensity = 2.882(In/Hr) for a 10.0 year storm

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Effective runoff coefficient used for area (Q=KCIA) is C = 0.775 Subarea runoff = 0.447(CFS)
Total initial stream area = 0.200(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 101.000 to Point/Station 102.000 **** IMPROVED CHANNEL TRAVEL TIME ****
______________________________________________________________________ Upstream point elevation = 25.500(Ft.)
Downstream point elevation = 23.800(Ft.)
Channel length thru subarea = 469.000(Ft.)
Channel base width = 5.000(Ft.)
Slope or 'Z' of left channel bank = 0.000
Slope or 'Z' of right channel bank = 0.000
Estimated mean flow rate at midpoint of channel = 2.778(CFS) Manning's 'N' = 0.040
Maximum depth of channel = 1.400(Ft.)
Flow(q) thru subarea = 2.778(CFS)
Depth of flow = 0.464(Ft.), Average velocity = 1.197(Ft/s) Channel flow top width = 5.000(Ft.)
Flow Velocity = 1.20(Ft/s)
Travel time = 6.53 min.

Time of concentration = 15.62 min.

Critical depth = 0.213(Ft.)
Adding area flow to channel
UNDEVELOPED (poor cover) subarea
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 67.00
Pervious ratio(Ap) = 1.0000 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.400(In/Hr)
Rainfall intensity = 2.113(In/Hr) for a 10.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.730
Subarea runoff = 4.565(CFS) for 3.050(Ac.)
Total runoff = 5.012(CFS) Total area = 3.25(Ac.)
Area averaged Fm value = 0.400(In/Hr)
Depth of flow = 0.680(Ft.), Average velocity = 1.474(Ft/s) Critical depth = 0.316(Ft.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 102.000 to Point/Station 103.000 **** IMPROVED CHANNEL TRAVEL TIME ****
______________________________________________________________________ Upstream point elevation = 23.800(Ft.)
Downstream point elevation = 20.500(Ft.)

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Channel length thru subarea = 861.000(Ft.)
Channel base width = 3.000(Ft.)
Slope or 'Z' of left channel bank = 0.000
Slope or 'Z' of right channel bank = 0.000
Estimated mean flow rate at midpoint of channel = 12.039(CFS) Manning's 'N' = 0.015
Maximum depth of channel = 1.500(Ft.)
Flow(q) thru subarea = 12.039(CFS)
Depth of flow = 0.942(Ft.), Average velocity = 4.259(Ft/s) Channel flow top width = 3.000(Ft.)
Flow Velocity = 4.26(Ft/s)
Travel time = 3.37 min.

Time of concentration = 18.99 min.

Critical depth = 0.797(Ft.)
Adding area flow to channel
COMMERCIAL subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.1000 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.040(In/Hr)
Rainfall intensity = 1.890(In/Hr) for a 10.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.835
Subarea runoff = 14.111(CFS) for 8.870(Ac.)
Total runoff = 19.123(CFS) Total area = 12.12(Ac.)
Area averaged Fm value = 0.137(In/Hr)
Depth of flow = 1.317(Ft.), Average velocity = 4.841(Ft/s) Critical depth = 1.078(Ft.)
End of computations, total study area = 12.12 (Ac.)
The following figures may
be used for a unit hydrograph study of the same area.

Note: These figures do not consider reduced effective area effects caused by confluences in the rational equation.

Area averaged pervious area fraction(Ap) = 0.341
Area averaged SCS curve number (AMC 2) = 41.4

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Orange County Rational Hydrology Program
(Hydrology Manual Date(s) October 1986 & November 1996) CIVILCADD/CIVILDESIGN Engineering Software, (c) 1989-2018 Version 9.0 Rational Hydrology Study, Date: 03/12/24 File Name: kb07x25.roc ------------------------------------------------------------------------

LOS ALAMITOS
TTM 19263
EXISTING Q25

------------------------------------------------------------------------ Program License Serial Number 6618
------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Rational hydrology study storm event year is 25.0
Decimal fraction of study above 2000 ft., 600M = 0.0000 English Units Used for input data
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 100.000 to Point/Station 101.000 **** INITIAL AREA EVALUATION ****
______________________________________________________________________ UNDEVELOPED (poor cover) subarea
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 67.00
Pervious ratio(Ap) = 1.0000 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.400(In/Hr)
Initial subarea data:

Rainfall intensity = 3.439(In/Hr) for a 25.0 year storm

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Effective runoff coefficient used for area (Q=KCIA) is C = 0.795 Subarea runoff = 0.547(CFS)
Total initial stream area = 0.200(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 101.000 to Point/Station 102.000 **** IMPROVED CHANNEL TRAVEL TIME ****
______________________________________________________________________ Upstream point elevation = 25.500(Ft.)
Downstream point elevation = 23.800(Ft.)
Channel length thru subarea = 469.000(Ft.)
Channel base width = 5.000(Ft.)
Slope or 'Z' of left channel bank = 0.000
Slope or 'Z' of right channel bank = 0.000
Estimated mean flow rate at midpoint of channel = 3.490(CFS) Manning's 'N' = 0.040
Maximum depth of channel = 1.400(Ft.)
Flow(q) thru subarea = 3.490(CFS)
Depth of flow = 0.537(Ft.), Average velocity = 1.299(Ft/s) Channel flow top width = 5.000(Ft.)
Flow Velocity = 1.30(Ft/s)
Travel time = 6.02 min.

Time of concentration = 15.11 min.

Critical depth = 0.246(Ft.)
Adding area flow to channel
UNDEVELOPED (poor cover) subarea
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 67.00
Pervious ratio(Ap) = 1.0000 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.400(In/Hr)
Rainfall intensity = 2.579(In/Hr) for a 25.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.760
Subarea runoff = 5.828(CFS) for 3.050(Ac.)
Total runoff = 6.375(CFS) Total area = 3.25(Ac.)
Area averaged Fm value = 0.400(In/Hr)
Depth of flow = 0.797(Ft.), Average velocity = 1.599(Ft/s) Critical depth = 0.367(Ft.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 102.000 to Point/Station 103.000 **** IMPROVED CHANNEL TRAVEL TIME ****
______________________________________________________________________ Upstream point elevation = 23.800(Ft.)
Downstream point elevation = 20.500(Ft.)

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Channel length thru subarea = 861.000(Ft.)
Channel base width = 3.000(Ft.)
Slope or 'Z' of left channel bank = 0.000
Slope or 'Z' of right channel bank = 0.000
Estimated mean flow rate at midpoint of channel = 15.074(CFS) Manning's 'N' = 0.015
Maximum depth of channel = 1.500(Ft.)
Flow(q) thru subarea = 15.074(CFS)
Depth of flow = 1.107(Ft.), Average velocity = 4.540(Ft/s) Channel flow top width = 3.000(Ft.)
Flow Velocity = 4.54(Ft/s)
Travel time = 3.16 min.

Time of concentration = 18.27 min.

Critical depth = 0.922(Ft.)
Adding area flow to channel
COMMERCIAL subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.1000 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.040(In/Hr)
Rainfall intensity = 2.316(In/Hr) for a 25.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.847
Subarea runoff = 17.404(CFS) for 8.870(Ac.)
Total runoff = 23.779(CFS) Total area = 12.12(Ac.)
Area averaged Fm value = 0.137(In/Hr)
Depth of flow = 1.539(Ft.), Average velocity = 5.150(Ft/s) !!Warning: Water is above left or right bank elevations ERROR - Channel depth exceeds maximum allowable depth
Critical depth = 1.250(Ft.)
End of computations, total study area = 12.12 (Ac.)
The following figures may
be used for a unit hydrograph study of the same area.

Note: These figures do not consider reduced effective area effects caused by confluences in the rational equation.

Area averaged pervious area fraction(Ap) = 0.341
Area averaged SCS curve number (AMC 2) = 41.4

Page 2315 of 3005 ends

Orange County Rational Hydrology Program
(Hydrology Manual Date(s) October 1986 & November 1996) CIVILCADD/CIVILDESIGN Engineering Software, (c) 1989-2018 Version 9.0 Rational Hydrology Study, Date: 03/12/24 File Name: kb07x100.roc ------------------------------------------------------------------------

LOS ALAMITOS
TTM 19263
EXISTING Q100

------------------------------------------------------------------------ Program License Serial Number 6618
------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Rational hydrology study storm event year is 100.0
Decimal fraction of study above 2000 ft., 600M = 0.0000 English Units Used for input data
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 100.000 to Point/Station 101.000 **** INITIAL AREA EVALUATION ****
______________________________________________________________________ UNDEVELOPED (poor cover) subarea
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 67.00
Pervious ratio(Ap) = 1.0000 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.400(In/Hr)
Initial subarea data:

Rainfall intensity = 4.392(In/Hr) for a 100.0 year storm

Page 2316 of 3005 ends

Effective runoff coefficient used for area (Q=KCIA) is C = 0.818 Subarea runoff = 0.719(CFS)
Total initial stream area = 0.200(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 101.000 to Point/Station 102.000 **** IMPROVED CHANNEL TRAVEL TIME ****
______________________________________________________________________ Upstream point elevation = 25.500(Ft.)
Downstream point elevation = 23.800(Ft.)
Channel length thru subarea = 469.000(Ft.)
Channel base width = 5.000(Ft.)
Slope or 'Z' of left channel bank = 0.000
Slope or 'Z' of right channel bank = 0.000
Estimated mean flow rate at midpoint of channel = 4.723(CFS) Manning's 'N' = 0.040
Maximum depth of channel = 1.400(Ft.)
Flow(q) thru subarea = 4.723(CFS)
Depth of flow = 0.654(Ft.), Average velocity = 1.444(Ft/s) Channel flow top width = 5.000(Ft.)
Flow Velocity = 1.44(Ft/s)
Travel time = 5.41 min.

Time of concentration = 14.51 min.

Critical depth = 0.301(Ft.)
Adding area flow to channel
UNDEVELOPED (poor cover) subarea
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 67.00
Pervious ratio(Ap) = 1.0000 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.400(In/Hr)
Rainfall intensity = 3.361(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.793
Subarea runoff = 7.942(CFS) for 3.050(Ac.)
Total runoff = 8.660(CFS) Total area = 3.25(Ac.)
Area averaged Fm value = 0.400(In/Hr)
Depth of flow = 0.979(Ft.), Average velocity = 1.769(Ft/s) Critical depth = 0.453(Ft.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 102.000 to Point/Station 103.000 **** IMPROVED CHANNEL TRAVEL TIME ****
______________________________________________________________________ Upstream point elevation = 23.800(Ft.)
Downstream point elevation = 20.500(Ft.)

Page 2317 of 3005 ends

Channel length thru subarea = 861.000(Ft.)
Channel base width = 3.000(Ft.)
Slope or 'Z' of left channel bank = 0.000
Slope or 'Z' of right channel bank = 0.000
Estimated mean flow rate at midpoint of channel = 20.110(CFS) Manning's 'N' = 0.015
Maximum depth of channel = 1.500(Ft.)
Flow(q) thru subarea = 20.110(CFS)
Depth of flow = 1.367(Ft.), Average velocity = 4.905(Ft/s) Channel flow top width = 3.000(Ft.)
Flow Velocity = 4.90(Ft/s)
Travel time = 2.93 min.

Time of concentration = 17.43 min.

Critical depth = 1.117(Ft.)
Adding area flow to channel
COMMERCIAL subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.1000 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.040(In/Hr)
Rainfall intensity = 3.025(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.859
Subarea runoff = 22.847(CFS) for 8.870(Ac.)
Total runoff = 31.507(CFS) Total area = 12.12(Ac.)
Area averaged Fm value = 0.137(In/Hr)
Depth of flow = 1.822(Ft.), Average velocity = 5.764(Ft/s) !!Warning: Water is above left or right bank elevations ERROR - Channel depth exceeds maximum allowable depth
Critical depth = 1.500(Ft.)
End of computations, total study area = 12.12 (Ac.)
The following figures may
be used for a unit hydrograph study of the same area.

Note: These figures do not consider reduced effective area effects caused by confluences in the rational equation.

Area averaged pervious area fraction(Ap) = 0.341
Area averaged SCS curve number (AMC 2) = 41.4

Page 2318 of 3005 ends

B.2 - Offsite Existing Conditions Hydrology Calculations For Lampson Avenue
(2, 25, 100-year Storm Event)

Page 2319 of 3005 ends

Orange County Rational Hydrology Program
(Hydrology Manual Date(s) October 1986 & November 1996) CIVILCADD/CIVILDESIGN Engineering Software, (c) 1989-2018 Version 9.0 Rational Hydrology Study, Date: 03/12/24 File Name: kb07xo2.roc ------------------------------------------------------------------------

LOS ALAMITOS
TTM 19263
EXISTING Q2

OFFSITE - LAMPSON AVE
------------------------------------------------------------------------ Program License Serial Number 6618
------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Rational hydrology study storm event year is 2.0
Decimal fraction of study above 2000 ft., 600M = 0.0000 English Units Used for input data
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 200.000 to Point/Station 201.000 **** INITIAL AREA EVALUATION ****
______________________________________________________________________ COMMERCIAL subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.1000 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.040(In/Hr)
Initial subarea data:

Initial area flow distance = 292.000(Ft.)
Top (of initial area) elevation = 28.700(Ft.)
Bottom (of initial area) elevation = 26.300(Ft.)
Difference in elevation = 2.400(Ft.)
Slope = 0.00822 s(%)= 0.82
TC = k(0.304)*[(length^3)/(elevation change)]^0.2
Initial area time of concentration = 7.692 min.

Rainfall intensity = 1.768(In/Hr) for a 2.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.880

Page 2320 of 3005 ends

Subarea runoff = 0.684(CFS)
Total initial stream area = 0.440(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 201.000 to Point/Station 202.000 **** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION **** ______________________________________________________________________ Top of street segment elevation = 26.300(Ft.)
End of street segment elevation = 21.500(Ft.)
Length of street segment = 2400.000(Ft.)
Height of curb above gutter flowline = 8.0(In.)
Width of half street (curb to crown) = 36.000(Ft.)
Distance from crown to crossfall grade break = 34.000(Ft.) Slope from gutter to grade break (v/hz) = 0.020
Slope from grade break to crown (v/hz) = 0.020
Street flow is on [1] side(s) of the street
Distance from curb to property line = 10.000(Ft.)
Slope from curb to property line (v/hz) = 0.020
Gutter width = 2.000(Ft.)
Gutter hike from flowline = 2.000(In.)
Manning's N in gutter = 0.0150
Manning's N from gutter to grade break = 0.0150
Manning's N from grade break to crown = 0.0150
Estimated mean flow rate at midpoint of street = 1.151(CFS) Depth of flow = 0.328(Ft.), Average velocity = 1.013(Ft/s) Streetflow hydraulics at midpoint of street travel:

Halfstreet flow width = 10.043(Ft.)
Flow velocity = 1.01(Ft/s)
Travel time = 39.47 min. TC = 47.17 min.

Adding area flow to street
COMMERCIAL subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.1000 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.040(In/Hr)
Rainfall intensity = 0.624(In/Hr) for a 2.0 year storm
Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.842
Subarea runoff = 0.867(CFS) for 2.510(Ac.)
Total runoff = 1.551(CFS) Total area = 2.95(Ac.)
Area averaged Fm value = 0.040(In/Hr)
Street flow at end of street = 1.551(CFS)
Half street flow at end of street = 1.551(CFS)
Depth of flow = 0.355(Ft.), Average velocity = 1.086(Ft/s) Flow width (from curb towards crown)= 11.410(Ft.)
End of computations, total study area = 2.95 (Ac.)

Page 2321 of 3005 ends

The following figures may
be used for a unit hydrograph study of the same area.

Note: These figures do not consider reduced effective area effects caused by confluences in the rational equation.

Area averaged pervious area fraction(Ap) = 0.100
Area averaged SCS curve number (AMC 2) = 32.0

Page 2322 of 3005 ends

Orange County Rational Hydrology Program
(Hydrology Manual Date(s) October 1986 & November 1996) CIVILCADD/CIVILDESIGN Engineering Software, (c) 1989-2018 Version 9.0 Rational Hydrology Study, Date: 03/12/24 File Name: kb07xo25.roc ------------------------------------------------------------------------

LOS ALAMITOS
TTM 19263
EXISTING Q25

OFFSITE - LAMPSON AVE
------------------------------------------------------------------------ Program License Serial Number 6618
------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Rational hydrology study storm event year is 25.0
Decimal fraction of study above 2000 ft., 600M = 0.0000 English Units Used for input data
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 200.000 to Point/Station 201.000 **** INITIAL AREA EVALUATION ****
______________________________________________________________________ COMMERCIAL subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.1000 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.040(In/Hr)
Initial subarea data:

Rainfall intensity = 3.780(In/Hr) for a 25.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.890

Page 2323 of 3005 ends

Subarea runoff = 1.481(CFS)
Total initial stream area = 0.440(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 201.000 to Point/Station 202.000 **** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION **** ______________________________________________________________________ Top of street segment elevation = 26.300(Ft.)
End of street segment elevation = 21.500(Ft.)
Length of street segment = 2400.000(Ft.)
Height of curb above gutter flowline = 8.0(In.)
Width of half street (curb to crown) = 36.000(Ft.)
Distance from crown to crossfall grade break = 34.000(Ft.) Slope from gutter to grade break (v/hz) = 0.020
Slope from grade break to crown (v/hz) = 0.020
Street flow is on [1] side(s) of the street
Distance from curb to property line = 10.000(Ft.)
Slope from curb to property line (v/hz) = 0.020
Gutter width = 2.000(Ft.)
Gutter hike from flowline = 2.000(In.)
Manning's N in gutter = 0.0150
Manning's N from gutter to grade break = 0.0150
Manning's N from grade break to crown = 0.0150
Estimated mean flow rate at midpoint of street = 2.697(CFS) Depth of flow = 0.413(Ft.), Average velocity = 1.238(Ft/s) Streetflow hydraulics at midpoint of street travel:

Halfstreet flow width = 14.323(Ft.)
Flow velocity = 1.24(Ft/s)
Travel time = 32.31 min. TC = 40.00 min.

Adding area flow to street
COMMERCIAL subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.1000 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.040(In/Hr)
Rainfall intensity = 1.487(In/Hr) for a 25.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.876
Subarea runoff = 2.360(CFS) for 2.510(Ac.)
Total runoff = 3.841(CFS) Total area = 2.95(Ac.)
Area averaged Fm value = 0.040(In/Hr)
Street flow at end of street = 3.841(CFS)
Half street flow at end of street = 3.841(CFS)
Depth of flow = 0.457(Ft.), Average velocity = 1.348(Ft/s) Flow width (from curb towards crown)= 16.498(Ft.)
End of computations, total study area = 2.95 (Ac.)

Page 2324 of 3005 ends

The following figures may
be used for a unit hydrograph study of the same area.

Note: These figures do not consider reduced effective area effects caused by confluences in the rational equation.

Area averaged pervious area fraction(Ap) = 0.100
Area averaged SCS curve number (AMC 2) = 32.0

Page 2325 of 3005 ends

Orange County Rational Hydrology Program
(Hydrology Manual Date(s) October 1986 & November 1996) CIVILCADD/CIVILDESIGN Engineering Software, (c) 1989-2018 Version 9.0 Rational Hydrology Study, Date: 03/12/24 File Name: kb07xo100.roc ------------------------------------------------------------------------

LOS ALAMITOS
TTM 19263
EXISTING Q100

OFFSITE - LAMPSON AVE
------------------------------------------------------------------------ Program License Serial Number 6618
------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Rational hydrology study storm event year is 100.0
Decimal fraction of study above 2000 ft., 600M = 0.0000 English Units Used for input data
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 200.000 to Point/Station 201.000 **** INITIAL AREA EVALUATION ****
______________________________________________________________________ COMMERCIAL subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.1000 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.040(In/Hr)
Initial subarea data:

Rainfall intensity = 4.834(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.893

Page 2326 of 3005 ends

Subarea runoff = 1.898(CFS)
Total initial stream area = 0.440(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 201.000 to Point/Station 202.000 **** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION **** ______________________________________________________________________ Top of street segment elevation = 26.300(Ft.)
End of street segment elevation = 21.500(Ft.)
Length of street segment = 2400.000(Ft.)
Height of curb above gutter flowline = 8.0(In.)
Width of half street (curb to crown) = 36.000(Ft.)
Distance from crown to crossfall grade break = 34.000(Ft.) Slope from gutter to grade break (v/hz) = 0.020
Slope from grade break to crown (v/hz) = 0.020
Street flow is on [1] side(s) of the street
Distance from curb to property line = 10.000(Ft.)
Slope from curb to property line (v/hz) = 0.020
Gutter width = 2.000(Ft.)
Gutter hike from flowline = 2.000(In.)
Manning's N in gutter = 0.0150
Manning's N from gutter to grade break = 0.0150
Manning's N from grade break to crown = 0.0150
Estimated mean flow rate at midpoint of street = 3.510(CFS) Depth of flow = 0.445(Ft.), Average velocity = 1.319(Ft/s) Streetflow hydraulics at midpoint of street travel:

Halfstreet flow width = 15.919(Ft.)
Flow velocity = 1.32(Ft/s)
Travel time = 30.32 min. TC = 38.01 min.

Adding area flow to street
COMMERCIAL subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.1000 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.040(In/Hr)
Rainfall intensity = 1.935(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.881
Subarea runoff = 3.133(CFS) for 2.510(Ac.)
Total runoff = 5.032(CFS) Total area = 2.95(Ac.)
Area averaged Fm value = 0.040(In/Hr)
Street flow at end of street = 5.032(CFS)
Half street flow at end of street = 5.032(CFS)
Depth of flow = 0.494(Ft.), Average velocity = 1.440(Ft/s) Flow width (from curb towards crown)= 18.350(Ft.)
End of computations, total study area = 2.95 (Ac.)

Page 2327 of 3005 ends

The following figures may
be used for a unit hydrograph study of the same area.

Note: These figures do not consider reduced effective area effects caused by confluences in the rational equation.

Area averaged pervious area fraction(Ap) = 0.100
Area averaged SCS curve number (AMC 2) = 32.0

Page 2328 of 3005 ends

B.3 - Proposed Conditions Hydrology Calculations
(10, 25, 100-year Storm Event)

Page 2329 of 3005 ends

Orange County Rational Hydrology Program
(Hydrology Manual Date(s) October 1986 & November 1996) CIVILCADD/CIVILDESIGN Engineering Software, (c) 1989-2018 Version 9.0 Rational Hydrology Study, Date: 03/12/24 File Name: kb07p10.roc ------------------------------------------------------------------------

LOS ALAMITOS
TTM 19263
PROPOSED Q10

------------------------------------------------------------------------ Program License Serial Number 6618
------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Rational hydrology study storm event year is 10.0
Decimal fraction of study above 2000 ft., 600M = 0.0000 English Units Used for input data
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 100.000 to Point/Station 101.000 **** INITIAL AREA EVALUATION ****
______________________________________________________________________ CONDOMINIUM subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.3500 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.140(In/Hr)
Initial subarea data:

Initial area flow distance = 159.000(Ft.)
Top (of initial area) elevation = 25.800(Ft.)
Bottom (of initial area) elevation = 24.500(Ft.)
Difference in elevation = 1.300(Ft.)
Slope = 0.00818 s(%)= 0.82
TC = k(0.360)*[(length^3)/(elevation change)]^0.2
Initial area time of concentration = 7.151 min.

Rainfall intensity = 3.307(In/Hr) for a 10.0 year storm

Page 2330 of 3005 ends

Effective runoff coefficient used for area (Q=KCIA) is C = 0.862 Subarea runoff = 2.081(CFS)
Total initial stream area = 0.730(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 101.000 to Point/Station 102.000 **** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION **** ______________________________________________________________________ Top of street segment elevation = 24.500(Ft.)
End of street segment elevation = 21.400(Ft.)
Length of street segment = 525.000(Ft.)
Height of curb above gutter flowline = 6.0(In.)
Width of half street (curb to crown) = 16.500(Ft.)
Distance from crown to crossfall grade break = 14.500(Ft.) Slope from gutter to grade break (v/hz) = 0.010
Slope from grade break to crown (v/hz) = 0.010
Street flow is on [1] side(s) of the street
Distance from curb to property line = 10.000(Ft.)
Slope from curb to property line (v/hz) = 0.020
Gutter width = 2.000(Ft.)
Gutter hike from flowline = 2.000(In.)
Manning's N in gutter = 0.0150
Manning's N from gutter to grade break = 0.0150
Manning's N from grade break to crown = 0.0150
Estimated mean flow rate at midpoint of street = 8.766(CFS) Depth of flow = 0.425(Ft.), Average velocity = 2.597(Ft/s) Note: depth of flow exceeds top of street crown.

Streetflow hydraulics at midpoint of street travel:

Halfstreet flow width = 16.500(Ft.)
Flow velocity = 2.60(Ft/s)
Travel time = 3.37 min. TC = 10.52 min.

Adding area flow to street
CONDOMINIUM subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.3500 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.140(In/Hr)
Rainfall intensity = 2.651(In/Hr) for a 10.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.852
Subarea runoff = 13.286(CFS) for 6.070(Ac.)
Total runoff = 15.366(CFS) Total area = 6.80(Ac.)
Area averaged Fm value = 0.140(In/Hr)
Street flow at end of street = 15.366(CFS)
Half street flow at end of street = 15.366(CFS)
Depth of flow = 0.511(Ft.), Average velocity = 3.206(Ft/s)

Page 2331 of 3005 ends

Warning: depth of flow exceeds top of curb
Note: depth of flow exceeds top of street crown.

Distance that curb overflow reaches into property = 0.53(Ft.) Flow width (from curb towards crown)= 16.500(Ft.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 102.000 to Point/Station 103.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 16.400(Ft.)
Downstream point/station elevation = 15.210(Ft.)
Pipe length = 238.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 15.366(CFS)
Nearest computed pipe diameter = 24.00(In.)
Calculated individual pipe flow = 15.366(CFS)
Normal flow depth in pipe = 18.87(In.)
Flow top width inside pipe = 19.68(In.)
Critical Depth = 16.97(In.)
Pipe flow velocity = 5.80(Ft/s)
Travel time through pipe = 0.68 min.

Time of concentration (TC) = 11.20 min.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION ****
______________________________________________________________________ CONDOMINIUM subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.3500 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.140(In/Hr)
Time of concentration = 11.20 min.

Rainfall intensity = 2.557(In/Hr) for a 10.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.851
Subarea runoff = 6.298(CFS) for 3.160(Ac.)
Total runoff = 21.665(CFS) Total area = 9.96(Ac.)
Area averaged Fm value = 0.140(In/Hr)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 1.100 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 15.210(Ft.)

Page 2332 of 3005 ends

Downstream point/station elevation = 13.690(Ft.)
Pipe length = 304.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 21.665(CFS)
Nearest computed pipe diameter = 27.00(In.)
Calculated individual pipe flow = 21.665(CFS)
Normal flow depth in pipe = 21.87(In.)
Flow top width inside pipe = 21.18(In.)
Critical Depth = 19.55(In.)
Pipe flow velocity = 6.28(Ft/s)
Travel time through pipe = 0.81 min.

Time of concentration (TC) = 12.01 min.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 1.100 **** CONFLUENCE OF MINOR STREAMS ****
______________________________________________________________________ Along Main Stream number: 1 in normal stream number 1
Stream flow area = 9.960(Ac.)
Runoff from this stream = 21.665(CFS)
Time of concentration = 12.01 min.

Rainfall intensity = 2.457(In/Hr)
Area averaged loss rate (Fm) = 0.1400(In/Hr)
Area averaged Pervious ratio (Ap) = 0.3500
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 200.000 to Point/Station 201.000 **** INITIAL AREA EVALUATION ****
______________________________________________________________________ CONDOMINIUM subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.3500 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.140(In/Hr)
Initial subarea data:

Initial area flow distance = 157.000(Ft.)
Top (of initial area) elevation = 25.120(Ft.)
Bottom (of initial area) elevation = 23.900(Ft.)
Difference in elevation = 1.220(Ft.)
Slope = 0.00777 s(%)= 0.78
TC = k(0.360)*[(length^3)/(elevation change)]^0.2
Initial area time of concentration = 7.187 min.

Rainfall intensity = 3.297(In/Hr) for a 10.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.862 Subarea runoff = 1.819(CFS)
Total initial stream area = 0.640(Ac.)

Page 2333 of 3005 ends

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 201.000 to Point/Station 202.000 **** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION **** ______________________________________________________________________ Top of street segment elevation = 23.900(Ft.)
End of street segment elevation = 21.400(Ft.)
Length of street segment = 323.000(Ft.)
Height of curb above gutter flowline = 6.0(In.)
Width of half street (curb to crown) = 16.500(Ft.)
Distance from crown to crossfall grade break = 14.500(Ft.) Slope from gutter to grade break (v/hz) = 0.010
Slope from grade break to crown (v/hz) = 0.010
Street flow is on [1] side(s) of the street
Distance from curb to property line = 10.000(Ft.)
Slope from curb to property line (v/hz) = 0.020
Gutter width = 2.000(Ft.)
Gutter hike from flowline = 2.000(In.)
Manning's N in gutter = 0.0150
Manning's N from gutter to grade break = 0.0150
Manning's N from grade break to crown = 0.0150
Estimated mean flow rate at midpoint of street = 3.460(CFS) Depth of flow = 0.328(Ft.), Average velocity = 1.947(Ft/s) Note: depth of flow exceeds top of street crown.

Streetflow hydraulics at midpoint of street travel:

Halfstreet flow width = 16.500(Ft.)
Flow velocity = 1.95(Ft/s)
Travel time = 2.77 min. TC = 9.95 min.

Adding area flow to street
CONDOMINIUM subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.3500 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.140(In/Hr)
Rainfall intensity = 2.736(In/Hr) for a 10.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.854
Subarea runoff = 3.205(CFS) for 1.510(Ac.)
Total runoff = 5.024(CFS) Total area = 2.15(Ac.)
Area averaged Fm value = 0.140(In/Hr)
Street flow at end of street = 5.024(CFS)
Half street flow at end of street = 5.024(CFS)
Depth of flow = 0.355(Ft.), Average velocity = 2.258(Ft/s) Note: depth of flow exceeds top of street crown.

Flow width (from curb towards crown)= 16.500(Ft.)

Page 2334 of 3005 ends

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 202.000 to Point/Station 1.100 **** CONFLUENCE OF MINOR STREAMS ****
______________________________________________________________________ Along Main Stream number: 1 in normal stream number 2
Stream flow area = 2.150(Ac.)
Runoff from this stream = 5.024(CFS)
Time of concentration = 9.95 min.

Rainfall intensity = 2.736(In/Hr)
Area averaged loss rate (Fm) = 0.1400(In/Hr)
Area averaged Pervious ratio (Ap) = 0.3500
Summary of stream data:

Stream Area Flow rate TC Fm Rainfall Intensity
No. (Ac.) (CFS) (min) (In/Hr) (In/Hr)
1 9.96 21.665 12.01 0.140 2.457
2 2.15 5.024 9.95 0.140 2.736
Qmax(1) =

1.000 * 1.000 * 21.665) +

0.892 * 1.000 * 5.024) + = 26.148
Qmax(2) =

1.121 * 0.829 * 21.665) +

1.000 * 1.000 * 5.024) + = 25.141
Total of 2 streams to confluence:

Flow rates before confluence point:

21.665 5.024
Maximum flow rates at confluence using above data:

26.148 25.141
Area of streams before confluence:

9.960 2.150
Effective area values after confluence:

12.110 10.403
Results of confluence:

Total flow rate = 26.148(CFS)
Time of concentration = 12.010 min.

Effective stream area after confluence = 12.110(Ac.)
Study area average Pervious fraction(Ap) = 0.350
Study area average soil loss rate(Fm) = 0.140(In/Hr)
Study area total (this main stream) = 12.11(Ac.)
End of computations, total study area = 12.11 (Ac.)
The following figures may
be used for a unit hydrograph study of the same area.

Note: These figures do not consider reduced effective area effects caused by confluences in the rational equation.

Area averaged pervious area fraction(Ap) = 0.350

Page 2335 of 3005 ends

Area averaged SCS curve number (AMC 2) = 32.0

Page 2336 of 3005 ends

Orange County Rational Hydrology Program
(Hydrology Manual Date(s) October 1986 & November 1996) CIVILCADD/CIVILDESIGN Engineering Software, (c) 1989-2018 Version 9.0 Rational Hydrology Study, Date: 03/12/24 File Name: kb07p25.roc ------------------------------------------------------------------------

LOS ALAMITOS
TTM 19263
PROPOSED Q25

------------------------------------------------------------------------ Program License Serial Number 6618
------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Rational hydrology study storm event year is 25.0
Decimal fraction of study above 2000 ft., 600M = 0.0000 English Units Used for input data
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 100.000 to Point/Station 101.000 **** INITIAL AREA EVALUATION ****
______________________________________________________________________ CONDOMINIUM subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.3500 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.140(In/Hr)
Initial subarea data:

Rainfall intensity = 3.939(In/Hr) for a 25.0 year storm

Page 2337 of 3005 ends

Effective runoff coefficient used for area (Q=KCIA) is C = 0.868 Subarea runoff = 2.496(CFS)
Total initial stream area = 0.730(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 101.000 to Point/Station 102.000 **** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION **** ______________________________________________________________________ Top of street segment elevation = 24.500(Ft.)
End of street segment elevation = 21.400(Ft.)
Length of street segment = 525.000(Ft.)
Height of curb above gutter flowline = 6.0(In.)
Width of half street (curb to crown) = 16.500(Ft.)
Distance from crown to crossfall grade break = 14.500(Ft.) Slope from gutter to grade break (v/hz) = 0.010
Slope from grade break to crown (v/hz) = 0.010
Street flow is on [1] side(s) of the street
Distance from curb to property line = 10.000(Ft.)
Slope from curb to property line (v/hz) = 0.020
Gutter width = 2.000(Ft.)
Gutter hike from flowline = 2.000(In.)
Manning's N in gutter = 0.0150
Manning's N from gutter to grade break = 0.0150
Manning's N from grade break to crown = 0.0150
Estimated mean flow rate at midpoint of street = 10.691(CFS) Depth of flow = 0.451(Ft.), Average velocity = 2.810(Ft/s) Note: depth of flow exceeds top of street crown.

Streetflow hydraulics at midpoint of street travel:

Halfstreet flow width = 16.500(Ft.)
Flow velocity = 2.81(Ft/s)
Travel time = 3.11 min. TC = 10.26 min.

Adding area flow to street
CONDOMINIUM subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.3500 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.140(In/Hr)
Rainfall intensity = 3.211(In/Hr) for a 25.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.861
Subarea runoff = 16.296(CFS) for 6.070(Ac.)
Total runoff = 18.792(CFS) Total area = 6.80(Ac.)
Area averaged Fm value = 0.140(In/Hr)
Street flow at end of street = 18.792(CFS)
Half street flow at end of street = 18.792(CFS)
Depth of flow = 0.560(Ft.), Average velocity = 3.295(Ft/s)

Page 2338 of 3005 ends

Warning: depth of flow exceeds top of curb
Note: depth of flow exceeds top of street crown.

Distance that curb overflow reaches into property = 3.02(Ft.) Flow width (from curb towards crown)= 16.500(Ft.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 102.000 to Point/Station 103.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 16.400(Ft.)
Downstream point/station elevation = 15.210(Ft.)
Pipe length = 238.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 18.792(CFS)
Nearest computed pipe diameter = 27.00(In.)
Calculated individual pipe flow = 18.792(CFS)
Normal flow depth in pipe = 19.26(In.)
Flow top width inside pipe = 24.41(In.)
Critical Depth = 18.20(In.)
Pipe flow velocity = 6.19(Ft/s)
Travel time through pipe = 0.64 min.

Time of concentration (TC) = 10.90 min.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION ****
______________________________________________________________________ CONDOMINIUM subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.3500 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.140(In/Hr)
Time of concentration = 10.90 min.

Rainfall intensity = 3.102(In/Hr) for a 25.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.859
Subarea runoff = 7.763(CFS) for 3.160(Ac.)
Total runoff = 26.556(CFS) Total area = 9.96(Ac.)
Area averaged Fm value = 0.140(In/Hr)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 1.100 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 15.210(Ft.)

Page 2339 of 3005 ends

Downstream point/station elevation = 13.690(Ft.)
Pipe length = 304.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 26.556(CFS)
Nearest computed pipe diameter = 30.00(In.)
Calculated individual pipe flow = 26.556(CFS)
Normal flow depth in pipe = 22.58(In.)
Flow top width inside pipe = 25.89(In.)
Critical Depth = 21.07(In.)
Pipe flow velocity = 6.70(Ft/s)
Travel time through pipe = 0.76 min.

Time of concentration (TC) = 11.66 min.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 1.100 **** CONFLUENCE OF MINOR STREAMS ****
______________________________________________________________________ Along Main Stream number: 1 in normal stream number 1
Stream flow area = 9.960(Ac.)
Runoff from this stream = 26.556(CFS)
Time of concentration = 11.66 min.

Rainfall intensity = 2.987(In/Hr)
Area averaged loss rate (Fm) = 0.1400(In/Hr)
Area averaged Pervious ratio (Ap) = 0.3500
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 200.000 to Point/Station 201.000 **** INITIAL AREA EVALUATION ****
______________________________________________________________________ CONDOMINIUM subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.3500 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.140(In/Hr)
Initial subarea data:

Rainfall intensity = 3.928(In/Hr) for a 25.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.868 Subarea runoff = 2.182(CFS)
Total initial stream area = 0.640(Ac.)

Page 2340 of 3005 ends

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 201.000 to Point/Station 202.000 **** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION **** ______________________________________________________________________ Top of street segment elevation = 23.900(Ft.)
End of street segment elevation = 21.400(Ft.)
Length of street segment = 323.000(Ft.)
Height of curb above gutter flowline = 6.0(In.)
Width of half street (curb to crown) = 16.500(Ft.)
Distance from crown to crossfall grade break = 14.500(Ft.) Slope from gutter to grade break (v/hz) = 0.010
Slope from grade break to crown (v/hz) = 0.010
Street flow is on [1] side(s) of the street
Distance from curb to property line = 10.000(Ft.)
Slope from curb to property line (v/hz) = 0.020
Gutter width = 2.000(Ft.)
Gutter hike from flowline = 2.000(In.)
Manning's N in gutter = 0.0150
Manning's N from gutter to grade break = 0.0150
Manning's N from grade break to crown = 0.0150
Estimated mean flow rate at midpoint of street = 4.197(CFS) Depth of flow = 0.341(Ft.), Average velocity = 2.102(Ft/s) Note: depth of flow exceeds top of street crown.

Streetflow hydraulics at midpoint of street travel:

Halfstreet flow width = 16.500(Ft.)
Flow velocity = 2.10(Ft/s)
Travel time = 2.56 min. TC = 9.75 min.

Adding area flow to street
CONDOMINIUM subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.3500 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.140(In/Hr)
Rainfall intensity = 3.306(In/Hr) for a 25.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.862
Subarea runoff = 3.944(CFS) for 1.510(Ac.)
Total runoff = 6.126(CFS) Total area = 2.15(Ac.)
Area averaged Fm value = 0.140(In/Hr)
Street flow at end of street = 6.126(CFS)
Half street flow at end of street = 6.126(CFS)
Depth of flow = 0.372(Ft.), Average velocity = 2.444(Ft/s) Note: depth of flow exceeds top of street crown.

Flow width (from curb towards crown)= 16.500(Ft.)

Page 2341 of 3005 ends

Rainfall intensity = 3.306(In/Hr)
Area averaged loss rate (Fm) = 0.1400(In/Hr)
Area averaged Pervious ratio (Ap) = 0.3500
Summary of stream data:

Stream Area Flow rate TC Fm Rainfall Intensity
No. (Ac.) (CFS) (min) (In/Hr) (In/Hr)
1 9.96 26.556 11.66 0.140 2.987
2 2.15 6.126 9.75 0.140 3.306
Qmax(1) =

1.000 * 1.000 * 26.556) +

0.899 * 1.000 * 6.126) + = 32.064
Qmax(2) =

1.112 * 0.836 * 26.556) +

1.000 * 1.000 * 6.126) + = 30.811
Total of 2 streams to confluence:

Flow rates before confluence point:

26.556 6.126
Maximum flow rates at confluence using above data:

32.064 30.811
Area of streams before confluence:

9.960 2.150
Effective area values after confluence:

12.110 10.476
Results of confluence:

Total flow rate = 32.064(CFS)
Time of concentration = 11.661 min.

Note: These figures do not consider reduced effective area effects caused by confluences in the rational equation.

Area averaged pervious area fraction(Ap) = 0.350

Page 2342 of 3005 ends

Area averaged SCS curve number (AMC 2) = 32.0

Page 2343 of 3005 ends

Orange County Rational Hydrology Program
(Hydrology Manual Date(s) October 1986 & November 1996) CIVILCADD/CIVILDESIGN Engineering Software, (c) 1989-2018 Version 9.0 Rational Hydrology Study, Date: 03/12/24 File Name: kb07p100.roc ------------------------------------------------------------------------

LOS ALAMITOS
TTM 19263
PROPOSED Q100

------------------------------------------------------------------------ Program License Serial Number 6618
------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** ------------------------------------------------------------------------ Rational hydrology study storm event year is 100.0
Decimal fraction of study above 2000 ft., 600M = 0.0000 English Units Used for input data
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 100.000 to Point/Station 101.000 **** INITIAL AREA EVALUATION ****
______________________________________________________________________ CONDOMINIUM subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.3500 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.140(In/Hr)
Initial subarea data:

Rainfall intensity = 5.040(In/Hr) for a 100.0 year storm

Page 2344 of 3005 ends

Effective runoff coefficient used for area (Q=KCIA) is C = 0.875 Subarea runoff = 3.220(CFS)
Total initial stream area = 0.730(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 101.000 to Point/Station 102.000 **** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION **** ______________________________________________________________________ Top of street segment elevation = 24.500(Ft.)
End of street segment elevation = 21.400(Ft.)
Length of street segment = 525.000(Ft.)
Height of curb above gutter flowline = 6.0(In.)
Width of half street (curb to crown) = 16.500(Ft.)
Distance from crown to crossfall grade break = 14.500(Ft.) Slope from gutter to grade break (v/hz) = 0.010
Slope from grade break to crown (v/hz) = 0.010
Street flow is on [1] side(s) of the street
Distance from curb to property line = 10.000(Ft.)
Slope from curb to property line (v/hz) = 0.020
Gutter width = 2.000(Ft.)
Gutter hike from flowline = 2.000(In.)
Manning's N in gutter = 0.0150
Manning's N from gutter to grade break = 0.0150
Manning's N from grade break to crown = 0.0150
Estimated mean flow rate at midpoint of street = 13.972(CFS) Depth of flow = 0.491(Ft.), Average velocity = 3.125(Ft/s) Note: depth of flow exceeds top of street crown.

Streetflow hydraulics at midpoint of street travel:

Halfstreet flow width = 16.500(Ft.)
Flow velocity = 3.13(Ft/s)
Travel time = 2.80 min. TC = 9.95 min.

Adding area flow to street
CONDOMINIUM subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.3500 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.140(In/Hr)
Rainfall intensity = 4.171(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.870
Subarea runoff = 21.450(CFS) for 6.070(Ac.)
Total runoff = 24.670(CFS) Total area = 6.80(Ac.)
Area averaged Fm value = 0.140(In/Hr)
Street flow at end of street = 24.670(CFS)
Half street flow at end of street = 24.670(CFS)
Depth of flow = 0.629(Ft.), Average velocity = 3.450(Ft/s)

Page 2345 of 3005 ends

Warning: depth of flow exceeds top of curb
Note: depth of flow exceeds top of street crown.

Distance that curb overflow reaches into property = 6.43(Ft.) Flow width (from curb towards crown)= 16.500(Ft.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 102.000 to Point/Station 103.000 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 16.400(Ft.)
Downstream point/station elevation = 15.210(Ft.)
Pipe length = 238.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 24.670(CFS)
Nearest computed pipe diameter = 30.00(In.)
Calculated individual pipe flow = 24.670(CFS)
Normal flow depth in pipe = 21.26(In.)
Flow top width inside pipe = 27.26(In.)
Critical Depth = 20.32(In.)
Pipe flow velocity = 6.63(Ft/s)
Travel time through pipe = 0.60 min.

Time of concentration (TC) = 10.55 min.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 103.000 **** SUBAREA FLOW ADDITION ****
______________________________________________________________________ CONDOMINIUM subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.3500 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.140(In/Hr)
Time of concentration = 10.55 min.

Rainfall intensity = 4.034(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.869
Subarea runoff = 10.234(CFS) for 3.160(Ac.)
Total runoff = 34.904(CFS) Total area = 9.96(Ac.)
Area averaged Fm value = 0.140(In/Hr)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 1.100 **** PIPEFLOW TRAVEL TIME (Program estimated size) **** ______________________________________________________________________ Upstream point/station elevation = 15.210(Ft.)

Page 2346 of 3005 ends

Downstream point/station elevation = 13.690(Ft.)
Pipe length = 304.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 34.904(CFS)
Nearest computed pipe diameter = 33.00(In.)
Calculated individual pipe flow = 34.904(CFS)
Normal flow depth in pipe = 25.26(In.)
Flow top width inside pipe = 27.96(In.)
Critical Depth = 23.59(In.)
Pipe flow velocity = 7.15(Ft/s)
Travel time through pipe = 0.71 min.

Time of concentration (TC) = 11.26 min.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 103.000 to Point/Station 1.100 **** CONFLUENCE OF MINOR STREAMS ****
______________________________________________________________________ Along Main Stream number: 1 in normal stream number 1
Stream flow area = 9.960(Ac.)
Runoff from this stream = 34.904(CFS)
Time of concentration = 11.26 min.

Rainfall intensity = 3.886(In/Hr)
Area averaged loss rate (Fm) = 0.1400(In/Hr)
Area averaged Pervious ratio (Ap) = 0.3500
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 200.000 to Point/Station 201.000 **** INITIAL AREA EVALUATION ****
______________________________________________________________________ CONDOMINIUM subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.3500 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.140(In/Hr)
Initial subarea data:

Rainfall intensity = 5.026(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.875 Subarea runoff = 2.814(CFS)
Total initial stream area = 0.640(Ac.)

Page 2347 of 3005 ends

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 201.000 to Point/Station 202.000 **** STREET FLOW TRAVEL TIME + SUBAREA FLOW ADDITION **** ______________________________________________________________________ Top of street segment elevation = 23.900(Ft.)
End of street segment elevation = 21.400(Ft.)
Length of street segment = 323.000(Ft.)
Height of curb above gutter flowline = 6.0(In.)
Width of half street (curb to crown) = 16.500(Ft.)
Distance from crown to crossfall grade break = 14.500(Ft.) Slope from gutter to grade break (v/hz) = 0.010
Slope from grade break to crown (v/hz) = 0.010
Street flow is on [1] side(s) of the street
Distance from curb to property line = 10.000(Ft.)
Slope from curb to property line (v/hz) = 0.020
Gutter width = 2.000(Ft.)
Gutter hike from flowline = 2.000(In.)
Manning's N in gutter = 0.0150
Manning's N from gutter to grade break = 0.0150
Manning's N from grade break to crown = 0.0150
Estimated mean flow rate at midpoint of street = 5.443(CFS) Depth of flow = 0.362(Ft.), Average velocity = 2.332(Ft/s) Note: depth of flow exceeds top of street crown.

Streetflow hydraulics at midpoint of street travel:

Halfstreet flow width = 16.500(Ft.)
Flow velocity = 2.33(Ft/s)
Travel time = 2.31 min. TC = 9.50 min.

Adding area flow to street
CONDOMINIUM subarea type
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
SCS curve number for soil(AMC 2) = 32.00
Pervious ratio(Ap) = 0.3500 Max loss rate(Fp)= 0.400(In/Hr) Max Catchment Loss (Fm) = 0.140(In/Hr)
Rainfall intensity = 4.284(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area,(total area with modified rational method)(Q=KCIA) is C = 0.871
Subarea runoff = 5.205(CFS) for 1.510(Ac.)
Total runoff = 8.019(CFS) Total area = 2.15(Ac.)
Area averaged Fm value = 0.140(In/Hr)
Street flow at end of street = 8.019(CFS)
Half street flow at end of street = 8.019(CFS)
Depth of flow = 0.399(Ft.), Average velocity = 2.720(Ft/s) Note: depth of flow exceeds top of street crown.

Flow width (from curb towards crown)= 16.500(Ft.)

Page 2348 of 3005 ends

Rainfall intensity = 4.284(In/Hr)
Area averaged loss rate (Fm) = 0.1400(In/Hr)
Area averaged Pervious ratio (Ap) = 0.3500
Summary of stream data:

Stream Area Flow rate TC Fm Rainfall Intensity
No. (Ac.) (CFS) (min) (In/Hr) (In/Hr)
1 9.96 34.904 11.26 0.140 3.886
2 2.15 8.019 9.50 0.140 4.284
Qmax(1) =

1.000 * 1.000 * 34.904) +

0.904 * 1.000 * 8.019) + = 42.153
Qmax(2) =

1.106 * 0.844 * 34.904) +

1.000 * 1.000 * 8.019) + = 40.591
Total of 2 streams to confluence:

Flow rates before confluence point:

34.904 8.019
Maximum flow rates at confluence using above data:

42.153 40.591
Area of streams before confluence:

9.960 2.150
Effective area values after confluence:

12.110 10.552
Results of confluence:

Total flow rate = 42.153(CFS)
Time of concentration = 11.257 min.

Note: These figures do not consider reduced effective area effects caused by confluences in the rational equation.

Area averaged pervious area fraction(Ap) = 0.350

Page 2349 of 3005 ends

Area averaged SCS curve number (AMC 2) = 32.0

Page 2350 of 3005 ends

APPENDIX C

HYDRAULIC CALCULATIONS

Page 2351 of 3005 ends

C.1 Catch Basin Sizing
(To be provided during Final Engineering)

Page 2352 of 3005 ends

C.2 WSPG Calculations
(To be provided during Final Engineering)

Page 2353 of 3005 ends

C.3 Detention Calculations

Page 2354 of 3005 ends

Hydraulic Analysis Report
Project Data
Project Title: TTM 19263
Designer: C&V Consulting, Inc.

Project Date: Monday, July 8, 2024
Project Units: U.S. Customary Units
Notes:

Detention Basin Analysis: Detention Basin Analysis - Q100 Notes:

Storage Input Parameters
Storage Capacity: Known volume
Elevation ft Volume acre-ft

0.00 0.00

1.00 0.09

2.00 0.19

3.00 0.28

4.00 0.38

5.00 0.47

6.00 0.57

7.00 0.66

8.00 0.76
Discharge Input Parameters
Known Discharge: Pump
Discharge cfs

0.00 0.00

1.00 8.90

2.00 8.90

3.00 8.90

4.00 8.90

5.00 8.90

6.00 8.90

7.00 8.90

8.00 8.90

Page 2355 of 3005 ends

Storage & Discharge Input Parameters
Elevation - Storage - Discharge
Elevation ft Storage acre-ft Discharge cfs

0.00 0.00 0.00

1.00 0.09 8.90

2.00 0.19 8.90

3.00 0.28 8.90

4.00 0.38 8.90

5.00 0.47 8.90

6.00 0.57 8.90

7.00 0.66 8.90

8.00 0.76 8.90
Detention Basin Input Parameters
Inflow Hydrograph
Peak Inflow Discharge: 42.540 cfs, Time to Peak: 970.00 (min), Total Inflow Volume:
185884.50 ft^3
Time (min) Discharge cfs

5.00 0.06

10.00 0.36

15.00 0.64

20.00 0.72

25.00 0.74

30.00 0.75

35.00 0.75

40.00 0.75

45.00 0.75

50.00 0.76

55.00 0.76

60.00 0.76

65.00 0.76

70.00 0.77

75.00 0.77

80.00 0.77

85.00 0.77

90.00 0.78

95.00 0.78
100.00 0.78
105.00 0.79
110.00 0.79
115.00 0.79
120.00 0.79
125.00 0.80
130.00 0.80
135.00 0.80
140.00 0.81

Page 2356 of 3005 ends

145.00 0.81
150.00 0.81
155.00 0.81
160.00 0.82
165.00 0.82
170.00 0.82
175.00 0.83
180.00 0.83
185.00 0.83
190.00 0.84
195.00 0.84
200.00 0.84
205.00 0.85
210.00 0.85
215.00 0.85
220.00 0.86
225.00 0.86
230.00 0.87
235.00 0.87
240.00 0.87
245.00 0.88
250.00 0.88
255.00 0.88
260.00 0.89
265.00 0.89
270.00 0.90
275.00 0.90
280.00 0.90
285.00 0.91
290.00 0.91
295.00 0.92
300.00 0.92
305.00 0.93
310.00 0.93
315.00 0.93
320.00 0.94
325.00 0.94
330.00 0.95
335.00 0.95
340.00 0.96
345.00 0.96
350.00 0.97
355.00 0.97
360.00 0.98
365.00 0.98
370.00 0.99
375.00 0.99
380.00 1.00
385.00 1.00
390.00 1.01

Page 2357 of 3005 ends

395.00 1.01
400.00 1.02
405.00 1.02
410.00 1.03
415.00 1.04
420.00 1.04
425.00 1.05
430.00 1.05
435.00 1.06
440.00 1.07
445.00 1.07
450.00 1.08
455.00 1.09
460.00 1.09
465.00 1.10
470.00 1.11
475.00 1.11
480.00 1.12
485.00 1.13
490.00 1.13
495.00 1.14
500.00 1.15
505.00 1.16
510.00 1.17
515.00 1.17
520.00 1.18
525.00 1.19
530.00 1.20
535.00 1.21
540.00 1.22
545.00 1.22
550.00 1.23
555.00 1.24
560.00 1.25
565.00 1.26
570.00 1.27
575.00 1.28
580.00 1.29
585.00 1.30
590.00 1.31
595.00 1.32
600.00 1.34
605.00 1.35
610.00 1.36
615.00 1.37
620.00 1.38
625.00 1.39
630.00 1.41
635.00 1.42
640.00 1.43

Page 2358 of 3005 ends

645.00 1.45
650.00 1.46
655.00 1.48
660.00 1.49
665.00 1.51
670.00 1.52
675.00 1.54
680.00 1.55
685.00 1.57
690.00 1.59
695.00 1.61
700.00 1.63
705.00 1.64
710.00 1.66
715.00 1.68
720.00 1.70
725.00 1.76
730.00 1.97
735.00 2.16
740.00 2.24
745.00 2.27
750.00 2.30
755.00 2.33
760.00 2.36
765.00 2.39
770.00 2.42
775.00 2.45
780.00 2.49
785.00 2.52
790.00 2.56
795.00 2.60
800.00 2.64
805.00 2.68
810.00 2.72
815.00 2.77
820.00 2.82
825.00 2.87
830.00 2.92
835.00 2.97
840.00 3.04
845.00 3.10
850.00 3.18
855.00 3.25
860.00 3.33
865.00 3.41
870.00 3.50
875.00 3.60
880.00 3.70
885.00 3.82
890.00 3.99

Page 2359 of 3005 ends

895.00 4.17
900.00 4.39
905.00 4.62
910.00 4.90
915.00 5.19
920.00 5.55
925.00 5.86
930.00 5.92
935.00 6.08
940.00 6.69
945.00 7.56
950.00 8.85
955.00 10.71
960.00 14.26
965.00 23.26
970.00 42.54
975.00 37.19
980.00 17.67
985.00 9.58
990.00 7.41
995.00 6.08
1000.00 5.34
1005.00 4.74
1010.00 4.27
1015.00 3.91
1020.00 3.65
1025.00 3.45
1030.00 3.28
1035.00 3.13
1040.00 3.00
1045.00 2.89
1050.00 2.78
1055.00 2.69
1060.00 2.61
1065.00 2.53
1070.00 2.46
1075.00 2.40
1080.00 2.34
1085.00 2.25
1090.00 2.01
1095.00 1.79
1100.00 1.70
1105.00 1.65
1110.00 1.61
1115.00 1.58
1120.00 1.54
1125.00 1.51
1130.00 1.48
1135.00 1.45
1140.00 1.43

Page 2360 of 3005 ends

1145.00 1.40
1150.00 1.37
1155.00 1.35
1160.00 1.33
1165.00 1.31
1170.00 1.29
1175.00 1.27
1180.00 1.25
1185.00 1.23
1190.00 1.21
1195.00 1.19
1200.00 1.18
1205.00 1.16
1210.00 1.14
1215.00 1.13
1220.00 1.12
1225.00 1.10
1230.00 1.09
1235.00 1.08
1240.00 1.06
1245.00 1.05
1250.00 1.04
1255.00 1.03
1260.00 1.02
1265.00 1.00
1270.00 0.99
1275.00 0.98
1280.00 0.97
1285.00 0.96
1290.00 0.95
1295.00 0.94
1300.00 0.94
1305.00 0.93
1310.00 0.92
1315.00 0.91
1320.00 0.90
1325.00 0.89
1330.00 0.89
1335.00 0.88
1340.00 0.87
1345.00 0.86
1350.00 0.86
1355.00 0.85
1360.00 0.84
1365.00 0.84
1370.00 0.83
1375.00 0.82
1380.00 0.82
1385.00 0.81
1390.00 0.80

Page 2361 of 3005 ends

1395.00 0.80
1400.00 0.79
1405.00 0.79
1410.00 0.78
1415.00 0.77
1420.00 0.77
1425.00 0.76
1430.00 0.76
1435.00 0.75
1440.00 0.75
1445.00 0.69
1450.00 0.38
1455.00 0.10
1460.00 0.02
1465.00 0.01
Initial Storage = 0.0000 acre-ft
Detention Basin Result Parameters
Routed Hydrograph
Peak Outflow Discharge: 8.900 cfs, Time to Peak: 960.00 (min), Total Outflow Volume:
185892.73 ft^3
Time min Discharge cfs Storage acre-ft

0.00 0.00 0.000000

10.00 0.10 0.001770

15.00 0.30 0.004129

20.00 0.49 0.005747

25.00 0.61 0.006676

30.00 0.67 0.007202

35.00 0.71 0.007542

40.00 0.73 0.007745

45.00 0.74 0.007848

50.00 0.75 0.007935

55.00 0.75 0.007992

60.00 0.76 0.008026

65.00 0.76 0.008043

70.00 0.76 0.008101

75.00 0.77 0.008131

80.00 0.77 0.008146

85.00 0.77 0.008155

90.00 0.77 0.008211

95.00 0.78 0.008240
100.00 0.78 0.008254
105.00 0.78 0.008314
110.00 0.79 0.008344
115.00 0.79 0.008359
120.00 0.79 0.008367
125.00 0.79 0.008423

Page 2362 of 3005 ends

130.00 0.80 0.008452
135.00 0.80 0.008466
140.00 0.80 0.008526
145.00 0.81 0.008556
150.00 0.81 0.008572
155.00 0.81 0.008579
160.00 0.81 0.008635
165.00 0.82 0.008664
170.00 0.82 0.008679
175.00 0.82 0.008738
180.00 0.83 0.008768
185.00 0.83 0.008784
190.00 0.83 0.008844
195.00 0.84 0.008874
200.00 0.84 0.008890
205.00 0.84 0.008950
210.00 0.85 0.008980
215.00 0.85 0.008996
220.00 0.85 0.009056
225.00 0.86 0.009086
230.00 0.86 0.009154
235.00 0.86 0.009188
240.00 0.87 0.009206
245.00 0.87 0.009267
250.00 0.88 0.009298
255.00 0.88 0.009314
260.00 0.88 0.009374
265.00 0.89 0.009404
270.00 0.89 0.009472
275.00 0.89 0.009506
280.00 0.90 0.009524
285.00 0.90 0.009585
290.00 0.91 0.009616
295.00 0.91 0.009684
300.00 0.91 0.009718
305.00 0.92 0.009788
310.00 0.92 0.009824
315.00 0.93 0.009842
320.00 0.93 0.009903
325.00 0.94 0.009934
330.00 0.94 0.010002
335.00 0.94 0.010037
340.00 0.95 0.010106
345.00 0.95 0.010142
350.00 0.96 0.010212
355.00 0.96 0.010248
360.00 0.97 0.010318
365.00 0.97 0.010354
370.00 0.98 0.010424
375.00 0.98 0.010460

Page 2363 of 3005 ends

380.00 0.99 0.010530
385.00 0.99 0.010566
390.00 1.00 0.010636
395.00 1.00 0.010672
400.00 1.01 0.010742
405.00 1.01 0.010778
410.00 1.02 0.010848
415.00 1.03 0.010936
420.00 1.03 0.010981
425.00 1.04 0.011055
430.00 1.04 0.011094
435.00 1.05 0.011165
440.00 1.06 0.011253
445.00 1.06 0.011298
450.00 1.07 0.011373
455.00 1.08 0.011464
460.00 1.08 0.011510
465.00 1.09 0.011585
470.00 1.10 0.011676
475.00 1.10 0.011722
480.00 1.11 0.011797
485.00 1.12 0.011888
490.00 1.12 0.011934
495.00 1.13 0.012009
500.00 1.14 0.012100
505.00 1.15 0.012198
510.00 1.16 0.012300
515.00 1.16 0.012352
520.00 1.17 0.012430
525.00 1.18 0.012522
530.00 1.19 0.012621
535.00 1.20 0.012724
540.00 1.20 0.012828
545.00 1.21 0.012881
550.00 1.22 0.012960
555.00 1.23 0.013053
560.00 1.24 0.013152
565.00 1.25 0.013254
570.00 1.25 0.013358
575.00 1.26 0.013463
580.00 1.27 0.013569
585.00 1.28 0.013675
590.00 1.29 0.013781
595.00 1.30 0.013887
600.00 1.32 0.014045
605.00 1.33 0.014177
610.00 1.34 0.014297
615.00 1.35 0.014410
620.00 1.36 0.014519
625.00 1.37 0.014627

Page 2364 of 3005 ends

630.00 1.39 0.014786
635.00 1.40 0.014919
640.00 1.41 0.015039
645.00 1.43 0.015204
650.00 1.44 0.015340
655.00 1.45 0.015514
660.00 1.47 0.015654
665.00 1.48 0.015830
670.00 1.50 0.015971
675.00 1.51 0.016147
680.00 1.53 0.016289
685.00 1.54 0.016465
690.00 1.56 0.016659
695.00 1.58 0.016862
700.00 1.60 0.017069
705.00 1.62 0.017227
710.00 1.63 0.017412
715.00 1.65 0.017610
720.00 1.67 0.017814
725.00 1.70 0.018231
730.00 1.78 0.019535
735.00 1.92 0.021188
740.00 2.06 0.022446
745.00 2.15 0.023244
750.00 2.22 0.023806
755.00 2.27 0.024249
760.00 2.30 0.024631
765.00 2.34 0.024982
770.00 2.37 0.025316
775.00 2.40 0.025643
780.00 2.44 0.026017
785.00 2.47 0.026364
790.00 2.50 0.026749
795.00 2.54 0.027153
800.00 2.58 0.027567
805.00 2.62 0.027986
810.00 2.66 0.028408
815.00 2.70 0.028883
820.00 2.75 0.029385
825.00 2.80 0.029901
830.00 2.84 0.030424
835.00 2.89 0.030950
840.00 2.95 0.031583
845.00 3.01 0.032217
850.00 3.07 0.032957
855.00 3.14 0.033697
860.00 3.21 0.034491
865.00 3.29 0.035312
870.00 3.37 0.036198
875.00 3.46 0.037170

Page 2365 of 3005 ends

880.00 3.55 0.038185
885.00 3.65 0.039327
890.00 3.78 0.040792
895.00 3.93 0.042476
900.00 4.10 0.044478
905.00 4.30 0.046694
910.00 4.52 0.049280
915.00 4.78 0.052106
920.00 5.07 0.055418
925.00 5.38 0.058719
930.00 5.63 0.060713
935.00 5.81 0.062562
940.00 6.09 0.066676
945.00 6.60 0.073297
950.00 7.39 0.083379
955.00 8.56 0.098190
960.00 8.90 0.755600
965.00 8.90 0.854498
970.00 8.90 1.086177
975.00 8.90 1.281011
980.00 8.90 1.341410
985.00 8.90 1.346094
990.00 8.90 1.335832
995.00 8.90 1.316410
1000.00 8.90 1.291893
1005.00 8.90 1.263243
1010.00 8.90 1.231356
1015.00 8.90 1.196989
1020.00 8.90 1.160833
1025.00 8.90 1.123298
1030.00 8.90 1.084593
1035.00 8.90 1.044855
1040.00 8.90 1.004222
1045.00 8.90 0.962831
1050.00 8.90 0.920682
1055.00 8.90 0.877914
1060.00 8.90 0.834594
1065.00 8.90 0.790724
1070.00 8.90 0.755600
1075.00 8.90 0.755600
1080.00 6.35 0.728006
1085.00 4.36 0.713470
1090.00 3.27 0.704812
1095.00 2.60 0.699253
1100.00 2.18 0.695952
1105.00 1.93 0.694008
1110.00 1.78 0.692810
1115.00 1.69 0.692043
1120.00 1.63 0.691444
1125.00 1.58 0.690982

Page 2366 of 3005 ends

1130.00 1.54 0.690591
1135.00 1.50 0.690236
1140.00 1.47 0.689950
1145.00 1.44 0.689649
1150.00 1.41 0.689339
1155.00 1.39 0.689078
1160.00 1.36 0.688840
1165.00 1.34 0.688615
1170.00 1.32 0.688396
1175.00 1.30 0.688181
1180.00 1.28 0.687967
1185.00 1.26 0.687754
1190.00 1.24 0.687541
1195.00 1.22 0.687329
1200.00 1.20 0.687169
1205.00 1.19 0.686983
1210.00 1.17 0.686784
1215.00 1.15 0.686631
1220.00 1.14 0.686501
1225.00 1.12 0.686331
1230.00 1.11 0.686192
1235.00 1.10 0.686069
1240.00 1.08 0.685903
1245.00 1.07 0.685766
1250.00 1.06 0.685644
1255.00 1.05 0.685530
1260.00 1.04 0.685420
1265.00 1.02 0.685259
1270.00 1.01 0.685126
1275.00 1.00 0.685006
1280.00 0.99 0.684893
1285.00 0.98 0.684783
1290.00 0.97 0.684675
1295.00 0.96 0.684568
1300.00 0.95 0.684513
1305.00 0.94 0.684433
1310.00 0.93 0.684341
1315.00 0.92 0.684242
1320.00 0.91 0.684139
1325.00 0.91 0.684035
1330.00 0.90 0.683981
1335.00 0.89 0.683902
1340.00 0.88 0.683810
1345.00 0.87 0.683711
1350.00 0.87 0.683661
1355.00 0.86 0.683583
1360.00 0.85 0.683491
1365.00 0.85 0.683444
1370.00 0.84 0.683369
1375.00 0.83 0.683278

Page 2367 of 3005 ends

1380.00 0.83 0.683232
1385.00 0.82 0.683156
1390.00 0.81 0.683066
1395.00 0.81 0.683020
1400.00 0.80 0.682944
1405.00 0.80 0.682906
1410.00 0.79 0.682834
1415.00 0.78 0.682745
1420.00 0.78 0.682700
1425.00 0.77 0.682625
1430.00 0.77 0.682587
1435.00 0.76 0.682516
1440.00 0.76 0.682479
1445.00 0.74 0.682149
1450.00 0.64 0.680368
1455.00 0.44 0.678005
1460.00 0.26 0.676384
1465.00 0.14 0.675506
1470.00 0.07 0.675006
1475.00 0.04 0.674751
1480.00 0.02 0.674621

Page 2368 of 3005 ends

Inflow Runoff (peak=42.54cfs)
Routed Runoff (peak=8.90cfs) Page 2369 of 3005
C.4 Outlet Pipe Orifice Calculations

Page 2370 of 3005 ends

Orifice 1 diameter = 24 IN
Invert elevation of orifice = 19.7 FT
Tailwater EGL = 21.7 FT
Q = flow [CFS] = KA(2gh)^0.5
K = orifice flow coefficient = 0.62
A = cross sectional area of orifice [SF] = 3.14 * r^2 3.140 SF g = gravitational constant = 32.2 [FT/S^2]
h = hydraulic head [FT] = Headwater elev - Tailwater water surface elevation Headwater Surface Elevation Orifice Outflow
[FT] [CFS]

21.7 0.00

22.2 11.05

22.7 15.62

23.2 19.13
Submerged Outlet Pipe Analyzed as Orifice
Total System Outflow Table

Page 2371 of 3005 ends

C.5 Existing Lampson Avenue Street
Capacity Calculations

Page 2372 of 3005 ends

Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Wednesday, Jul 10 2024 Q100 Street Flow - SECTION B-B
Gutter
Cross Sl, Sx (ft/ft) = 0.020
Cross Sl, Sw (ft/ft) = 0.083
Gutter Width (ft) = 2.00
Invert Elev (ft) = 17.30
Slope (%) = 0.20
N-Value = 0.015
Calculations
Compute by: Known Q
Known Q (cfs) = 6.26
Highlighted
Depth (ft) = 0.49
Q (cfs) = 6.260
Area (sqft) = 3.51
Velocity (ft/s) = 1.78
Wetted Perim (ft) = 18.90
Crit Depth, Yc (ft) = 0.45
Spread Width (ft) = 18.40
EGL (ft) = 0.54
0 2 4 6 8 10 12 14 16 18 20 22 24
Elev (ft) Depth (ft) Section

17.00 -0.30

17.25 -0.05

17.50 0.20

17.75 0.45

18.00 0.70
Reach (ft)

Page 2373 of 3005 ends

Inlet Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Tuesday, Jul 9 2024Offsite InletCurb InletLocation = SagCurb Length (ft) = 4.00Throat Height (in) = 6.00Grate Area (sqft) = -0-Grate Width (ft) = -0-Grate Length (ft) = -0-GutterSlope, Sw (ft/ft) = 0.083Slope, Sx (ft/ft) = 0.020Local Depr (in) = 2.00Gutter Width (ft) = 2.00Gutter Slope (%) = -0-Gutter n-value = -0- CalculationsCompute by: Known QQ (cfs) = 6.26HighlightedQ Total (cfs) = 6.26Q Capt (cfs) = 6.26Q Bypass (cfs) = -0-Depth at Inlet (in) = 9.56Efficiency (%) = 100Gutter Spread (ft) = 25.21Gutter Vel (ft/s) = -0-Bypass Spread (ft) = -0-Bypass Depth (in) = -0-

Page 2374 of 3005 ends

Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Tuesday, Mar 12 2024 Q2 Street Flow Depth on North Side of Lampson Ave (Per X4+X5) Section A-AUser-definedInvert Elev (ft) = 20.61Slope (%) = 0.20N-Value = 0.015CalculationsCompute by: Known QKnown Q (cfs) = 1.55(Sta, El, n)-(Sta, El, n)...( 0.00, 21.28)-(0.17, 20.61, 0.015)-(1.83, 20.78, 0.015)-(29.00, 21.31, 0.015) HighlightedDepth (ft) = 0.37Q (cfs) = 1.550
Area (sqft) = 1.52
Velocity (ft/s) = 1.02Wetted Perim (ft) = 12.31Crit Depth, Yc (ft) = 0.31Top Width (ft) = 12.01EGL (ft) = 0.39 -5 0 5 10 15 20 25 30 35
Elev (ft) Depth (ft) Section

20.00 -0.6120.50 -0.1121.00 0.3921.50 0.8922.00 1.39
Sta (ft)

16.99 ft
travel lane
free of
inundation
Per DMA X4 + X5 contributing flows,street flooded 12.01 ft, leaving 16.99 fttravel lane free of flooding.

0.37' 12.01 ft floodedQ2 WSE=20.98

Page 2375 of 3005 ends

Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Tuesday, Mar 12 2024 Q25 Street Flow Depth on North Side of Lampson Ave (Per X4+X5) Section A-A User-defined
Invert Elev (ft) = 20.61
Slope (%) = 0.20
N-Value = 0.015
Calculations
Compute by: Known Q
Known Q (cfs) = 3.84
(Sta, El, n)-(Sta, El, n)...
( 0.00, 21.28)-(0.17, 20.61, 0.015)-(1.83, 20.78, 0.015)-(29.00, 21.31, 0.015) Highlighted
Depth (ft) = 0.47
Q (cfs) = 3.840
Area (sqft) = 2.97
Velocity (ft/s) = 1.29
Wetted Perim (ft) = 17.54
Crit Depth, Yc (ft) = 0.40
Top Width (ft) = 17.16
EGL (ft) = 0.50
-5 0 5 10 15 20 25 30 35
Elev (ft) Depth (ft) Section

20.00 -0.61

20.50 -0.11

21.00 0.39

21.50 0.89

22.00 1.39
Sta (ft)

11.84 ft
travel lane
free of
inundation
Per DMA X4 + X5 contributing flows,
street flooded 17.16 ft, leaving 11.84 ft
travel lane free of flooding. 0.47'

17.16 ft
flooded
Q25 WSE=21.08

Page 2376 of 3005 ends

Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Tuesday, Mar 12 2024 Q100 Street Flow Depth on North Side of Lampson Ave (Per X4+X5) Section A-A User-defined
Invert Elev (ft) = 20.61
Slope (%) = 0.20
N-Value = 0.015
Calculations
Compute by: Known Q
Known Q (cfs) = 5.03
(Sta, El, n)-(Sta, El, n)...
( 0.00, 21.28)-(0.17, 20.61, 0.015)-(1.83, 20.78, 0.015)-(29.00, 21.31, 0.015) Highlighted
Depth (ft) = 0.50
Q (cfs) = 5.030
Area (sqft) = 3.51
Velocity (ft/s) = 1.43
Wetted Perim (ft) = 19.10
Crit Depth, Yc (ft) = 0.43
Top Width (ft) = 18.70
EGL (ft) = 0.53
-5 0 5 10 15 20 25 30 35
Elev (ft) Depth (ft) Section

20.00 -0.61

20.50 -0.11

21.00 0.39

21.50 0.89

22.00 1.39
Sta (ft)

10.30 ft
travel lane
free of
inundation
Per DMA X4 + X5 contributing flows,
street flooded 18.70 ft, leaving 10.30 ft
travel lane free of flooding. 0.50'

18.70 ft
flooded
Q100 WSE=21.11

Page 2377 of 3005 ends

APPENDIX D

REFERENCE MATERIALS

Page 2378 of 3005 ends

D.1 - Orange County Drainage Facilities Maps

Page 2379 of 3005 ends

SITE OLD RANCH

COUNTRY CLUB

LAMPSON AVE JOINT FORCES

TRAINING BASE

Page 2380 of 3005 ends

SITE

Page 2381 of 3005 ends

Page 2382 of 3005 ends

D.2 - City of Seal Beach Master Plan of Drainage
Update: Figure 1-3

Page 2383 of 3005 ends

Storm Drain BC 2A
$0.21 M
Storm
Drain
BC
2B
$0.48
M
Storm
Drain
BC 1-1
$0.51 M
Storm
Drain
B
C 1A
$

0.5 9
M
Storm Drain BC 1B
$0.53 M
Storm
Drain CPE
1A
$0.54 M
Storm Drain CPE 1B
$4.43 M Storm Drain CPE 1C
$3.17 M
Storm Drain CPE 1-1
$1.57 M
Storm
Drain CPE 2A
$0.54 M
Storm Drain CPE 2B
$4.14 M
Storm Drain CPE 2C
$3..00 M
Storm Drain CPE 3-1A
Storm D
$4
ra
.1
in CPE 3-1B
0 M
Storm Drain CPE 3-1C
$2.43 M
Storm Drain CPE 3-4A
Storm D
$2
ra
.4
in CPE 3-4B
9 M
Storm Drain CPE3-4C
$1.16 M
Storm Drain CPE 4A
$1.11 M
Storm Drain CPE 4B
$2.07 M
Storm
Drain
L
A 1
$

5.0 9
M
G
O
L
D
E
N
R
O
D
CIR
F
E
R
N
CIR

HAZELNUT AV

ALMOND AV
C
OLU
M
BIN
E
S
T
CLO
V
E
R
CIR
C
A
R
N
ATIO
N
CIR

CAMELIA ST

BIRCHWOOD AV

CANDLEBERRY AV

BASSWOOD ST

LAMPSON AV
FEDERAL STORM CHANNEL (C01S06)
BIXBY STORM CHANNEL (C01S04)
BOLSA
CHICA

CHANNEL
(C02)
Storm Drain CPE5
$0.07 M
5 6
7 8
9 LAMPSON AV

SAN DIEGO FREEWAY
D
A
F
F
O

DIL CIR

ELDER AV

BIRCHWOOD AV

HAZELNUT AV

CANDLEBERRY AV
FIR AV
A
L
L
E
Y

ASTER ST

GUAVA AV
PIN
E
S
T

YELLOWTAIL DR

ROWENA DR

DOGWOOD AV
R
O
S
E
S
T
H
E
AT
H
E
R
S
T

IRONWOOD AV

DRUID LN

ST CLOUD DR
R
E
A
G
A
N
S
T

WISTERIA
ST
S
E
A
L
B
E
A
C
H
B
LV
D

BLUEBELL ST

KEMPTON DR
C
H
E
R
RY
S
T
PA
S
E
O
B
O
NITA

OLYMPIC DR
L
U
N
A
R
D
R
MANLEY
ST
F
U
C
H
SIA
S
T
VIO
L
E
T
S
T
A
C
HIC
A
R
D

BANYAN AV

ROSSMOOR CENTER WY

ACACIA AV
S
AT
E
L
LIT
E
D
R

CHRISTAL AV

PARK AV

ANTHONY AV
R
O
S
E
CIR

BARTLETT
ST

OLD RANCH PKWY
S
U
N
F
L
O
W
E
R
S
T
PA
N
S
Y
CIR

BRADBURY RD
M
A
RIG
O
L
D
S
T
IRIS
S
T
OLE
A
N
D
E
R
S
T

MARIETTA AV
G
O
L
D
E
N
R
O
D
S
T
HIL
L
R
O
S
E
D
R
D
AIS
Y
CIR
D
AIS
Y
S
T

LAMPSON AV
P
RIM
R
O
S
E
CIR
T
E
A
B
E
R
RY
CIR
S
U
N
F
L
O
W
E
R
C
RI
PAN
SY
ST
IRIS
CIR
F
U
C
H
SIA
CIR
RAINIE
R
CIR
T
U
LIP
S
T
IN
T
E
RIO
R
CIR
P
RIM
R
O
S
E
S
T
D
A
H
LIA
CIR
JA
S
MIN
CIR
H
E
AT
H
E
R
CIR
FIR
CIR

BRADBURY RD

HAZELNUT AV
D
AIS
Y
CIR

ALMOND AV

IRONWOOD AV
O
L
E
A
N
D
E
R
S
T

DOGWOOD AV

CANDLEBERRY AV

GUAVA AV

DOGWOOD AV
FIR AV

BARTLETT
ST

IRONWOOD AV

ELDER AV
FIR AV

BARTLETT
ST
0 200 400 800 1,200
Feet
1" = 400'
Legend
High Priority
Medium Priority
Low Priority
2008 Budgeted Planned Improvements
Existing City Storm Drain (Protect in Place)
County Facility
Parcel
City Boundary
2005 AD - HOC Committee Report Recommendations
High Priority Project
Moderate Priority Project
5 High Priority Rank
PROJECT NO: 0800810.00
DATE: August 2008

CITY OF SEAL BEACH

MASTER PLAN OF DRAINAGE UPDATE
Northeast Region Capital Improvement
Projects (Alternative No. 1) Figure 1-3
High
Priority
Rank
Storm
Drain Downstream Location Upstream Location Size Length Total Cost Total ProjectCost Westerly extension of Guava Avenue
and Old Ranch Golf Course
Lampson Avenue Crossing, near
Guava Avenue
Double 6'(W) x 3'(H)
RCB 120 339,733
Lampson Avenue Crossing, near
Guava Avenue
Guava Avenue and Ironwood
Avenue R/W (N) 6'(W) x 3'(H) RCB 120 191,644
Westerly extension of Elder Avenue
and Old Ranch Golf Course Lampson Avenue Crossing
Double 6'(W) x 3'(H)
RCB 120 339,733
Lampson Avenue Crsossing
Elder Avenue and Ironwood
Avenue R/W (N) 6'(W) x 3'(H) RCB 120 191,644
Westerly extension of Basswood
Avenue and Old Ranch Golf Course West of Lampson Avenue 9'(W) x 2'9"(H) RCB 31 61,885 West of Lampson Avenue Lampson Avenue Crossing, near
Basswood Street 9'(W) x 2'9"(H) RCB 95 189,648
Lampson Avenue Crossing, near
Basswood Street
Basswood Avenue and Aster
Street 9'(W) x 2'9"(H) RCB 430 858,407
Bolsa Chica Channel 250' north of
freeway
Wisteria Street 6'(W) x 3'(H) RCB 103 164,495
Wisteria Street Violet Street north of Almond
Avenue 42" RCP 314 424,654
9 BC 2A Bolsa Chica Channel and easterly
extension of Fir Avenue Wisteria Street and Fir Avenue 48" RCP 130 200,928 200,928 High Priority Totals 1,583 2,962,773 2,962,773
Priority
Storm
Drain Downstream Location Upstream Location Size Length Total Cost Total ProjectCost Medium BC 1-1 Wisteria Lane 250' north of freeway
Wisteria Lane and Candleberry
Avenue 30" RCP 485 509,250 509,250
Violet Street north of Almond Avenue Almond Avenue, east at Teaberry Circle 36" RCP 300 347,760
Almond Avenue, east at Teaberry
Circle
Almond Avenue east of Sunflower
Circle 30" RCP 170 178,500
Wisteria Street and Fir Avenue Wisteria Street at Hazelnut Avenue 3'(W) x2'(H) RCB 250 254,074
Wisteria Street at Hazelnut Avenue
Wisteria Street and Ironwood
Avenue 2'6"(W) x 1'6"(H) RCB 250 217,778
Guava Avenue and Ironwood Avenue

R/W (N)
Guava Avenue and Hazelnut
Avenue
Double 6'(W) x 2'3"(H)
RCB 370 987,078
Hazelnut Avenue and Guava Avenue Hazelnut Avenue and Heather Street
Double 6'(W) x 2'3"(H)
RCB 1,290 3,441,433
Medium CPE 2B
Alt 1
Elder Avenue and Ironwood Avenue
R/W (N) Elder Avenue and Fuchsia Street Double 6'(W) x 2'3"(H)RCB 1,550 4,135,056 4,135,056 Medium CPE 3-1B
Alt 1 Candleberry Avenue and Aster Street Candleberry Avenue and FuschiaStreet 10'8"(W) x 3'(H) RCB 1,800 4,095,093 4,095,093 Birchwood and Aster Street Birchwood Avenue and Bluebell Street 7'(W) x 2'3"(H) RCB 200 326,667
Birchwood Avenue and Bluebell Street
Birchwood Avenue and Daisy
Circle 6'(W) x 2'3"(H) RCB 1,450 2,157,815
Medium CPE 5
Alt 1 Cal Trans Open Channel Lampson Avenue 24" RCP 75 63,000 63,000 Medium Priority Totals 8,190 16,713,503 16,713,503
High Priority Improvement Projects
Medium Priority Improvement Projects
8 BC 1A
Medium CPE 3-4B
Alt 1
Medium BC 2B
Medium CPE 1B
Alt 1
5 CPE 1A
Alt 1
6 CPE 2A
Alt 1
7 CPE 4A
Alt 1
526,260
589,148
4,428,511
2,484,481
Medium BC 1B
531,378
531,378
1,109,941
471,852
Priority
Storm
Drain Downstream Location Upstream Location Size Length Total Cost Total ProjectCost Ironwood Avenue and Guava Avenue Fir Avenue , east of Ironwood Avenue 5'(W) x 2'(H) RCB 450 588,000
Fir Avenue , east of Ironwood Avenue Fir Avenue , West of Daisy Circle 4'6"(W) x2'(H) RCB 640 789,807 Fir Avenue , West of Daisy Circle Fir Avenue and Daisy Circle 4'(W) x 2'(H) RCB 160 185,837 Hazlenut Avenue and Heather Street Havelnut Avenue and Iris Street 8'(W) x 2'3"(H) RCB 270 480,200 Havelnut Avenue and Iris Street Hazelnut Avenue, east of Iris Street 8'(W) x 2'3"(H) RCB 340 604,696
Hazelnut Avenue, east of Iris Street Hazelnut Avenue and Rose Street 5'(W) x 2'3"(H) RCB 1,010 1,356,393 Hazelnut Avenue and Rose Street Rose Street and Fir Avenue 30" RCP 340 357,000 Rose Street and Fir Avenue Fir Avenue and Sunflower Street 30" RCP 250 262,500 Fir Avenue and Sunflower Street Sunflower Street north of Fir Avenue 30" RCP 100 105,000
Elder Avenue and Fuchsia Street Elder Avenue and Heather Street 8'(W) x 2'3"(H) RCB 500 889,259 Elder Avenue and Heather Street Elder Avenue west of Oleander Street 8'(W) x 2'3"(H) RCB 750 1,116,111
Elder Avenue west of Oleander Street Elder Avenue and Oldeander Street 36" RCP 350 405,720
Elder Avenue and Oldeander Street Oleander Street and Dogwood Avenue 36" RCP 250 289,800
Oleander Street and Dogwood Avenue Dogwood Avenue and Primrose Street 36" RCP 250 289,800
Fuchsia Street and Candleberry
Avenue
Fuchsia Street and Birchwood
Avenue 5'(W) x 3'(H) RCB 200 290,370
Fuchsia Street and Birchwood Avenue
Birchwood Avenue , east of Fuchia
Street 5'(W) x 3'(H) RCB 500 725,926
Birchwood Avenue , east of Fuchia
Street
Birchwood Avenue, west of
Marigold Street 4'(W) x 3'(H) RCB 500 653,333
Birchwood Avenue, west of Marigold
Street
Birchwood Avenue and Oleander
Street 36" RCP 650 753,480
Daisy Circle and Birchwood Avenue Daisy Circle and Birchwood Avenue 36" RCP 400 463,680
Daisy Circle and Birchwood Avenue Almond Avenue east of Goldenrod Circle 36" RCP 600 695,520
Aster Street and Basswood Avenue Aster Street and Almond Avenue 7'(W) x 2'9"(H) RCB 370 631,193 Aster Street and Almond Avenue Almond Avenue, east of Buebell Street 6'6"(W) x 2'9"(H) RCB 350 571,667
Almond Avenue, east of Buebell Street Almond Avenue and Carnation Circle 6'(W) x 2'9"(H) RCB 330 515,044
Almond Avenue and Carnation Circle Almond Avenue and Clover Circle 4'(W) 2'9"(H) RCB 270 343,000 Bixby Storm Channel and Seal Beach
Boulevard
Seal Beach Boulevard, north of
Bixby Storm Channel 60" RCP 254 469,392
Seal Beach Boulevard, north of Bixby
Storm Channel
Seal Beach Boulevard and
Rossmoor Center Way
60" RCP 2,500 4,620,000
Low Priority Totals 12,584 18,452,729 18,452,729
Low Priority Improvement Projects
Low LA 1
Low CPE 3-4C
Alt 1
Low CPE 4B
Alt 1
Low CPE 2C
Alt 1
Low CPE 3-1C
Alt 1
Low CPE 1-1
Alt 1
Low CPE 1C
Alt 1
1,159,200
2,060,904
5,089,392
1,563,644
3,165,789
2,990,690
2,423,110

Page 2384 of 3005 ends

D.3 - Infeasible Drainage System Outlets 1 and 2
Exhibits

Page 2385 of 3005 ends

Page 2386 of 3005 ends

To
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AVE SHT

DWG DESCRIPTION SHT

DWG DESCRIPTION
NO.

N0. N0. N0. 1.

G - 1 TITLE SHEET 10. C - 6 CONNECTION DETAILS AT STA. 22 +37. 87, STA. 23 + 72. 79, STA. 49 + 55. 56 AND STA. 59 + 33. 66 2.

G - 2 GENERAL NOTES 11.

C - 7 8 - INCH SEWER PLAN AND PROFILE 3.

G - 3 WATERLINE SHEET INDEX STA. 10 +00. 00 TO STA. 18 + 00. 00 4.

G- 4 GRAVITY SEWER SHEET INDEX 12. C- 8 8 - INCH SEWER PLAN AND PROFILE STA. 18 + 00. 00 TO STA. 24 + 09. 00 5.

C - 1 16 - INCH WATERMAIN PLAN AND PROFILE
STA. 9 + 94. 48 TO STA. 20 + 00. 00 13. C - 9 CITY OF SEAL BEACH STANDARD DETAILS S - 11 S -2, S - 3, S- 4, S - 6, 'S - 8, S - 9 AND S -14 6.

C - 2 16 - INCH WATERMAIN PLAN AND PROFILE
STA. 20 + 00. 00 TO STA. 30 + 00. 00 14. C - 10 CITY OF SEAL REACH STANDARD DETAILS S - 12, S -15a, S -15b, S -16, S- 17, 133 - 1 AND 182 7.

C - 3 16 - INCH AND 12 -INCH WATERMAIN PLAN AND PROFILE STA. 30 + 00. 00 TO STA. 40 + 00. 00 15. C - 11 CITY OF SEAL REACH STANDARD DETAILS 705, 706, 707, 710, 711 AND 712 8.

C- 4 12 - INCH AND 8 -INCH WATERMAIN PLAN AND PROFILE
STA. 40 + 00. 00 TO STA 50 + 50. 00 9.

C - 5 8 - INCH WATERMAIN PLAN AND PROFILE
STA. 50 + 50. 00 TO STA. 59 + 33. 66 1MPSON

AVE ONWOOD
AVE 1ZELNUT
AVE tn
GUAVA

AVE FIR
AVE a
I.--
id
GARDEN
GROVE FWY m
Drawn
By: I Checked By: I SHEET 1
OF 1 . J N1 \
0800 Seat Leach \ 700 LamDann Avenue Well \_Offslfa Paakade \ 01_6- 1 _ title_ sht. don 8/ 3/ 2009

Page 2387 of 3005 ends

200 / 00 0 200 400

SCALE IN FEET
Inch - 200ft.

J. A. LOAGUE
DATE:

JULY 2009
T.

No. C71422
Exp. 12/ 3V09
CIVIL
F
CA`s
APPROVED BY:

AKM Consulting Engineers
Aw 553 Wald
AF Eq Irvine, Ca. 92618
949) 753 - 7333
f

REVISIONS
TITLE:

DATE BY

WATERLINE SHEET INDEX
F--j

AS BUILT
Approved:

FIELD BOOK REF.

SEE COVER S H E E T
MICHAEL HO, CITY ENGINEER RCE NO. 70299 DATE
Recommended:

SEE COVER SHEET
Drawn By: Checked By=
N. \ 0800 Seal Beach \700 Lampson Avenue Well\ - Offs to P a 1 PROJECT NO.

DRAWING NO.

G - 3
SHEET 3 OF 15
3 C- 3- w9terline- index_ map. dgn 8/ 3/ 2009

Page 2388 of 3005 ends

30+ 00 31+ 00 32+ 00 33+ 00 34+ 00 35+ 00 36+ 00 37+ 00 38+ 00 39+ 00 40+ 00 T
CONSTRUCT 63-0- L- F,------16- INCi----CML--,DUGTILE- IRO- CL S35 ft- EMS Co STRUCT 37G- L.r, NCH - CML DUGT1LE IROW- CC, A SS3 0 ___1&- 1NCf+_ PVC- C ASa- 23 ,___AWWA -- C905-- W A-TER-- --PIO ,E h INE- (SE NOTE- -4y — R- 1 27 INC H__P__V-C - -- dLASS- 200r---AWW --- C900- ---WATER- PIPELINE SEE- NO-TE- 4)-
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J/ WELL FACILITY

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R,1W 0
OLD RAN CA LOS ALAJMJTOS 4301
COUNTRY CL U10' OLAMPSON AIR STATION
y tig wg L

PROPOSED
15— STEEL WELL DISCHARIGF, 37-82M
PIPE ( BY OTHERS) j - h?,*
4V
60 TU ra I mowg
23 24
0 ExlST/ - 4 -
AND ff&RW ASSEMBLY RIW r
56+29.27 8C
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PROPOSED 8-INCH W/ 2 -16' BUTTERFLY
SHEETS 18 SD EXISTING
twi, EXISTlkeLu? SEWER SEE fEET VALVES AND I- 5TING
C-7 AND C-8
IS

RESILIENT WEDGE
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CURB AND
88 26
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17 7t
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MEDIAN 25 EXISTING L 1xi IVV CURB AND 1
2 STA 35 85

TRAFFIC
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14221 4225 4233 4241 4249 4253 425'7 4265 4273 4281 4289 4291 A' 430j
431

CURB AND
33 ERR

CONSTRUCTION NOTES,
lO CONSTRUCT / 2 /NCH CLASS 350 CUL DUCTILE LAMPSON AVENUE IRON OR 1.2-INCH PVC CLASS 200, AWWA C900
WATERMAIN. TRENCH, BACKFILL AND
CONSTRUCT 161 CLASS 150 BUTTERFLY VALVE
PLAN

PAVEMENT
71 / AND
PER
133.

CITY

RUBBERIZED

OF SEAL BEACH

ASPHALT (
STD. @ FLG x MJ) PER CITY OF SEAL BEACH STD.

IS REQUIRED FOR TRENCH REPAIR ( SEE NOTE 4) PLAN 707•

CURVE DATA

A R L T
04' 4458' 977' 80.99' 40.52'
1 30`34" 1022' 2:7:8:.7:2:'
tQ
10 PROFILE SCALE:

HORIZ. P 40'
VERT. 4'
5 CONSTRUCT 16-INCH CLASS 350 CYL DUCTILE @ CONSTRUCT 10x 6' TEE ( PO x FLG) WITH 6-INCH DESIGNED BY: PROJECT:

IRON OR 16 INCH PVC CLASS 200, AWWA C900 ( FLG x PO) RESILIENT WEDGE GATE VALVE. FOR CITY OF SEAL BEACH SE FUTURE FIRE HYDRANT ASSEMBLY. INSTALL SHEET NOTES: - WATERMAIN. TRENCH, BACKFILL AND T.

I'/ j,
PUBLIC LAMPSON AVENUE WELL, PHASE 11- PAVEMENT PER CITY OF SEAL BEACH STD. THRUST BLOCKS PER CITY OF SEAL BEACH J. T. LEE A% PLAN 711AND 133. RUBBERIZED ASPHALT STD. PLANS 7/2. I. CONTRACTOR SHALL POTHOLE TO VERIFY DEPTH, AND LOCATION IS REQUIRED FOR TRENCH REPAIR OF ALL CONNECTION POINTS AND CROSSING UTILITIES PRIOR TO DRAWN BY:

WORKS WATER TRANSMISSION MAIN
SEE NOTE 4) @ CONSTRUCT 6-1NCHPVC CLASS 200o, AWWA SUBMISSION OF SHOP DRAWINGS. = No. 071422 DEPARTMENT AND GRAVITY SEWER,
C900 STUB OUT PER CITY OF SEAL BEACH CADD
OCONSTRUCT 0RESAJENT WEDGE GATE VALVE STD. PLAN 711. INSTALL END CAP AND 2. WORK IN LAMPSON AVE. REQUIRES A NO FEE ENCROACHMENT CHECKED BY:

Exp. 12/ 31/ 09 PROJECT NO. WT0903 W
FLG x FLG) PER CITY OF SEAL BEACH Sm. THRUST BLOCK 5-FEET BEYOND RIGHT-OF-WAY PERMIT FROM THE CITY OF SEAL BEACH. THE CONTRACTOR SHALL CIVIL REVISIONS TITLE:

PLAIN 706. ON WELL SITE. REPAIR PAVEMENT PER CITY BE REQUIRED TO PREPARE AND SUBMIT A TRAFFIC CONTROL PLAIN 12- INCH AND 16- INCH WATERMAIN STD. PLAN 133. SIGNED AND SEALED BY A REGISTERED TRAFFIC CONTROL ENGINEER J. A. LOAGUE OF C DATE BY

PLAN AND PROFILE

CONSTRUCT FIRE HYDRANT ASSEMBLY PER

REMOVE AND REPLACE EXISTING MEDIAN CURB TO

TO THE CITY OF SEAL BEACH FOR REVIEW AND APPROVAL
DATE:

APPROVED BY: STA. 30 + 00.00 TO STA. 40 + 00. 00
CITY OF SEAL BEACH STD. PLAIN 705. @ NEAREST JOINT AS REQUIRED FOR CONSTRUCTION. 3. THE CONTRACTOR SHALL EMPLOY HAND EXCAVATION ONLY WITHIN REPLACE EXISTING LANDSCAPING AND IRRIGATION 3 -FEET OF SCIG FACILITIES. A REPRESENTATIVE OF THE GAS COMPANY JULY 2009 Approved. PROJECT NO.

CONSTRUCT 160 90" ELBOW AND THRUST BLOCK
SYSTEM IN KIND. MUST INSPECT ALL EXCAVATIONS NEAR EXISTING SCIG FACILITIES. I TARqWTLEE RGM. C71422 DATE AS BUILT PER CITY OF SEAL BEACH STD. PLAN 7/2, CONTRACTOR SHALL CONTACT SCIG 2 WORKING DAYS PRIOR TO SEE COVER SHEET FIELD BOOK REF.

CONSTRUCT 16' x / 2' DUCTILE IRON TEE @ CONSTRUCT 20 LF. OF 24-INCH X %2' WALL EXCAVATION TO COORDINATE INSPECTION. MZWE RU, -CITY ENGINEER RCE NO. 70299 DATE FLG x FLG) WITH THRUST BLOCK PER C17-( OF STEEL CASING PER C17Y OF SEAL BEACH STD.

A111111FIIIIIIIIII AKM Consulting Engineers
Recommended: DRAWING NO.

SEAL BEACH STD. PLAIN 7/2. DWG. S-12 FILL CASING ANNULAR SPACE WITH 4. CONTRACTOR BASE BID SHALL BE FOR FURNISHING AND INSTALLING 553 Wald LOW DENSITY GROVT. CENTER CASING UNDER DUCTILE IRON PIPE. PVC PIPE SHALL ONLY BE PROPOSED AS A BID Irvine, Ca. 92618

SEE COVER SHEET
C- 3
SEWER. ALTERNATIVE AND MAY BE IMPLEMENTED AT THE SOLE DISCRETION DAVID L. SPITZ, ASSOCIATE ENGINEER RCE N0. 69804 DATE CONSTRUCT 16646 ELBOW ( PO x PO) WITH THRUST
OF THE C17-(. (
949) 753- 7333
BLOCK PER Clr( OF SEAL BEACH STD. PLAIN 712.

Drawn By: Checked By: SHEET 7 OF
No \ 0800 Seal Beach\ 700 Lampson Avenue Well\- 6ffs1tePockoge\ 07- C- 3- pnpsht- wtr- 03. dgn 8/ 312009 REPLACE 100 LF EX. 18"
RCP W/ PROP. 36" RCP
PROP. 30" RCP

CONNECT TO
EX. 36" RCP
PROP. MH
250'
100' STA 37+15 2" WATER XING STA 37+07 8" SEWER XINGSTA 36+09 16" WATER XING PROP. 30" RCP
CONFLICTS WITH EX.

WATER AND SEWER
@ 0.2% PIPE SLOPE

Page 2389 of 3005 ends

40 +00 41 + 00 42 +00 43 +00 44 +00 45 +00 46 +00 47 +00 48 +00 49 +00 50 +00 I CON --ST lCT 94. 44- .. E. 8 INCH CMS. D! TILE .I. E50 50-; _ O R. -- 8 INCH - P-V £ - -- C LAS, -- _ 00 _
AWWA C900- WATER - -- PIP LINE--tSE €_ NOT € - -41 t.: ____ 1 1NCt=fi--- CMt-- -OtJC- 1tE 1RON _- _Ot aB_._ __ - - - - -- .__ 2 5 OR- 12-- 1 . CH PVC CLASS ' 12-00 AW A C9001 WATER PIPELINEi 2 5
srA. 49
XISTING GROUND - SURFACE 4,- - - _____ _._____ _..____________._ ` _ _.._ _ .___ ___ _____. _- ____._.._ _ _..____.. _. _ _ _ .__ -_ —_._ -._ - -- a FIRE- HYDR
OF PROPOSED_
I C I
I
LO
I EX
15 _ 15
Oda004
LQ LU
10 _ _ _ _ -._ _____ __ __
T _ _ _ cam__ _. _ _______- 10
1 s I 1
t __ W
I
I
I
v
i
1 3
r W
I
I
I W fit
CC
I V !
1 AW i!
t
I I
S PROFILE SCALE:

HORIZ.
l' _
40'
O
d
Uj
ZN
ti
SHEET NOTES:
h CONTRACTOR SHALL POTHOLE TO VERIFY DEPTH, ANO LOCATION

OF ALL CONNECTION POINTS AND CROSSING UTILITIES PRIOR TO SUBMISSION OF SHOP DRAWINGS.

2. WORK IN LAMPSON AVE. REQUIRES A NO FEE ENCROACHMENT
PERMIT FROM THE CRY OF SEAL BEACH. THE CONTRACTOR SHALL

BE REQUIRED TO PREPARE AND
SUBMIT

A TRAFFIC CONTROL PLAN

SIGNED AND SEALED BY A REGISTERED TRAFFIC CONTROL ENGINEER TO THE CITY OF SEAL BEACH FOR REVIEW AND APPROVAL.

J. THE CONTRACTOR SHALL EMPLOY HAND EXCAVATION ONLY WITHIN 3FEET OF SCG FACILITIES. A REPRESENTATIVE OF THE GAS

COMPANY MUST INSPECT ALL EXCAVATIONS NEAR EXISTING SCG
FACILITIES. CONTRACTOR SHALL CONTACT SCG 2 WORKING DAYS PRIOR TO EXCAVATION TO COORDINATE INSPECTION.

4. CONTRACTOR BASE BID SHALL BE FOR FURNISHING AND INSTALLING DUCTILE IRON PIPE. PVC PIPE SHALL ONLY BE PROPOSED AS A BID

ALTERNATIVE AND MAY BE IMPLEMENTED AT THE SOLE DISCRETION OF THE CITY.

CONSTRUCTION NOTES:
lO CONSTRUCT 10CLASS 350 CML DUCTILE IRON OR l2' PVC
CLASS 200 AWWA C9P0 WATERMAIN. TRENCH, BACKF/LL
AND PAVEMENT PER CITY OF SEAL BEACH STD. PLAN 711
AND 133. RUBBERIZED ASPHALT IS REIXIIRED FOR TRENCH
REPAIR. ( SEE NOTE 4)
O5 CONSTRUCT 0RESIUENT WEDGE GATE VALVE ( FLG x FLG) PER CITY OF SEAL BEACH STD. PLAN 706.

O9 REMOVE AND SALVAGE FIRE HYDRANT. REMOVE HYDRANT BURY, VALVE BOX AND COVER, AND BACKF /LL AND REPLACE IN KIND.

O CONSTRUCT FIRE HYDRANT ASSEMBLY PER CITY OF SEAL BEACH STD. PLAN 705.
l3 CAP AND SEAL EXISTING WATERLINE. INSTALL THRUST BLOCK PER CITY OF SEAL BEACH STD. PLAN 7/2
O CONSTRUCT 8' RES/IJENT WEDGE GATE VALVE ( FLG x FLG) PER CITY OF SEAL BEACH STD. PLAN 706.

Q2 CONSTRUCT l2' x 8' DUCTILE IRON TEE ( FLG x FLG) WITH THRUST BLOCK PER CITY OF SEAL BEACH STD. PLAN 712
Q CONSTRUCT 8' CLASS 350 CML IX/ CT/LE IRON OR 90PVC CLASS 200 AWWA L500 WATERMAIN. TRENCH, BACKF/LL AND PAVEMENT PER
CITY OF SEAL BEACH STD. 7/l AND 133. RUBBER /ZED ASPHALT IS REWIRED FOR TRENCH REPAIR. ( SEE NOTE 4)

LAMPSON AVENUE

CURVE DATA

D R L T
Q 30'3034° 1022' 544.21' 1278.72'
DESIGNED BY:

J. T. LEE
T.

IFS,
DRAWN BY: y LU
C AD D
o:

No. C71422
XP,
12/ 3U09
CHECKED BY :
9r
CIVIL \ P
J. A. LOAGUE OF
DATE:

APPROVED BY:

JULY 2009 ` °
9 JARED L LEE RGE NU. C7142Z 3ATf
10 0 40
1 AKM Consulting Engineers
553 Wald
Irvine, Ca. 92618

SCALE IN FEET
l 949 J 153 - 7333
Inch - 40 ft.

PUBLIC
WORKS

DEPARTMENT

REVISIONS
DA

I I AS BUILT
FIELD BOOK REF.
a
d
j(n
v
Q

HEATHER STREET
PROJECT: CITY OF SEAL BEACH oF• SEA(•••
LAMPSON AVENUE WELL, PHASE 11- ° RgFoFgy

WATER TRANSMISSION MAIN
AND GRAVITY SEWER.,
PROJECT NO. WT0903 • oU T :'
TITLE:
12 -INCH AND 8 -INCH WATERMAIN

PLAN AND PROFILE
STA. 40 + 00.00 TO STA. 50 + 50. 00
Approved: PROJECT NO.

SEE COVER SHEET
MICHAEL H0, CITY ENGINEER RCE NO. 70299 DATE
Recommended: DRAWING NO.

SEE COVER SHEET
C- 4
DAVID L. SPITZ, ASSOCIATE ENGINEER RCE NO. 69800 DATE
Drawn By: Checked By: — SHEET 8 OF 15
Ns \ 0800 Seal Beach \ 700 Lampson Avenue Well \_ 0:' a Package \08- C- 4_ pnpsht- wtr- 04. dgn 8/ 3/ 2009 PROP. 30" RCP
877' 175' STA 49+56 8" WATER XING STA 49+41 3" GAS XING STA 43+95 ELEC XING STA 40+97 ELEC XING PROP. MH
PROP. MH
PROP. MH

Page 2390 of 3005 ends

51+ 00 52+ 00 53+ 00 54+ 00 55+ 00 56+ 00 57+ 00 58+ 00 59+ 00 60+ 00 CML-- DUC' TILE- IROU- CLASSk-35G---
R- 8--INC- P_VC-- CL ASS- 200--- AW-WA,__C900-- PIPELINE---- t--_____
25 T
56+96DO STA. 59#JIB7
IF
20 AC WATERMAIN
20 AS
tz Q
cr
10 10
PROFILE SCALE:

HORIZ. 40'

REMOVE AND REPLACE
STA a41_]P_4q
EXISTING CONCRETE CROSS EN PIPELINE CONSTRUCTION.

F
SIGN
2 4
A_2 GUTTER 710 JOE N

20. 4 _ 221

REMOVE EXISTING PLUG AND
CONNECT TO NEW ff RESILIENT
X 21EXISTING ) H
CURB
DE
TREES
X '24. 2
X 24. 4
X 24. 5 X 24. 5 X 24. 5
x 24. 4
ASPH PROPOSED 8-INCH
n ? 110 8
@ X 21 8 -------- —
EXISTING X 22. 4 /
0 FIRE . HYDR x

RIW CURB AND ASSEMBLY'
0 WEDGE GATE VALVE PER
CONNECTION DETAIL 4
t 22. 7 jR
LO 00

EXISTING
MEDIAN
X 21. 3

LOPSON AVENUE
59+
I X_
23 X 21. 3 _ X 21. 3 VCV 1'
X 21. 3
XE91ATIN
I
STA
8- 45' ELBOW
x x
R/ W
x
SE G
EXISTING POOL x
TREES
1 TREE OBSUUNt- L 22. 3
N/ yy x
X 2j.

GUTTER
DENSE 23, 2-, x
POOL
X 22. 5 3. 2

BRUSH POOL EXISTING

22. 8 CURB AND
x 22. 7
352J DENS. 4509
TREE
45JI 4225 4533 4541 4549 455-7 4565 45-13 4581 4589 4601 4609 461 4625 4633 1 12N 2 . 7
j
6 x ------ 1- 1 J" I t F_' J f r _ e- 9

LAMPSON AVENUE
SHEET NOTES.-
CONSTRUCTION NOTES:

T. J. T. LEE '
re,
PUBLIC
PROJECT: CITY OF SEAL BEACH
LAMPSON AVENUE WELL, PHASE 11-
CONTRXTOR SHALL POTHOLE TO VERIFY DEPTH, AND LOCATION REMOVE AND SALVAGE FIRE HYDRANT. REMOVE WORMT BURY, DRAWN BY: WORKS WATER TRANSMISSION MAIN OF ALL CONNECTION POINTS AND CROSSING UTILITIES PRIOR TO VALVE BOX AND COVER, AND BACKFILL AND REPLACE IN KIND.

C71422 DEPARTMENT AND GRAVITY SEWER SUBMISSION OF SHOP DRAWINGS.

CONSTRUCT FIRE HYDRANT ASSEMBLY PER CITY OF SEAL
CADD
No
Exp. 1213VO9
I
PROJECT NO. WT0903 W,
WORK IN LMPSON AVE.REOUIRES A NO FEE
PERMIT FROM THE CITY OF SEAL BEACH.

ENCROACHMENT

THE CONTRACTOR SHALL
BEACH STD. PLAN 705. CHECKED BY:

CIVI REVISIONS
TITLE:

BE REOUIRED TO PREPARE AND SUBMIT A TRAFFIC CONTROL PLAN CONSTRUCT 8RESIUENT WEDGE GATE VALVE ( FLG x FLG) J. A. LOAGUE DATE BY 8- INCH WATERMAIN PLAN AND PROFILE
SIGNED AND SEALED BY A REGISTERED TRAFFIC CONTROL ENGINEER PER CITY OF SEAL BEACH STD. PLAN 706. STA. 50 + 50.00 TO STA. 59 + 33. 66 TO THE CITY OF SEAL BEACH FOR REVIEW AND APPfWAL
CONSTRUCT 80 CLASS 350 CML DUCTILE IRON OR
80 DATE:

APPROVED BY:

J. THE CONTRACTOR SHAU EMPLOY HAND EXCAVATION ONLY WITHIN PIC CLASS " AWWA C*9019 WATERMAIN. TRENCH. JULY 2009 AS
Approved:

BUILT
PROJECT NO.
3-FEET OF SCIG FACILITIES. A REPRESENTATIVE OF THE GAS BACKFILL AND PAVEMENT PER CITY OF SEAL EE RGE NU. C71422 DATE
COMPANY MUST INSPECT ALL EXCAVATIONS NEAR EXISTING SCG BEACH STD. 711AND 03. RUBBERIZED ASPHALT IS SEE COVER SHEET FIELD BOOK REF.

FACILITIES. CONTRACTOR SHALL CONTACT SCIG 2 WORKING DAYS REOUIRED FOR TRENCH REPAIR. ( SEE NOTE 4) MICHAEL HO, CITY ENGINEER RCE NO. 70299 DATE
PRIOR TO EXCAVATION TO COORDINATE INSPECTION.

4. CONTRACTOR BASE BID SHALL BE FOR FURNISHING AND INST" NG 20 / 0 0 20 40
CONSTRUCT 8' 46 ELBOW ( PO x PO) WITH THRUST BLOCK
I I
i
I AKM Consulting Engineers
OEM=
i a
553 Wald
PER CITY OF SEAL BEACH STD. PLAN 71Z I
I
Irvine. Co. 92618
Recommended:

SEE COVER SHEET
DRAWING NO.

C- 5
DUCTILE IRON P/Pf. PVC PIPE SHALL ONLY

ALTERNATIVE AND MAY BE IMPLEMENTED

BE PROPOSED AS A BID
AT THE SOLE DISCRE71ON
AN=
SCALE IN FEET AV M ( 949) 753- 7333
CONSTRUCT 8645* ELBOW ( FLG x PIO) WITH THRUST BLOCK / inch - 40 ft.

DAVID L. SPITZ, ASSOCIATE ENGINEER- RCE NO. 69800 DATE
OF THE CITY. PER CITY OF SEAL BEACH STD. PLAN 7121
Drawn By: Checked By: SHEET 9 OF 15
Ns \ 0800 See 000ch\ rou Lvm» son * o//\- orrmto povxoom` oy- o- s_ pnnu» t-wtr- os' unn o/ n/ uooy r
PROP. 30" RCP
645' SITE

POINT OF CONNECTION

TO PROPOSED
PARKWAY CULVERT STA 50+94 ELEC XING 34" GAS XING
PROP. MH
PROP. MH
PROP. MH

Page 2391 of 3005 ends

APPENDIX E

SOILS MAP

Page 2392 of 3005 ends

Soil Map—Orange County and Part of Riverside County, California (KBHO-007 Soil Map)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
3/13/2024

Page 1 of 3 ends

3738370 3738410 3738450 3738490 3738530 3738570 3738610 3738330 3738370 3738410 3738450 3738490 3738530 3738570 3738610 402630 402670 402710 402750 402790 402830 402870 402910 402950 402990 403030 403070 402630 402670 402710 402750 402790 402830 402870 402910 402950 402990 403030 403070 33° 46' 59'' N
118° 3' 6'' W
33° 46' 59'' N
118° 2' 48'' W
33° 46' 50'' N
118° 3' 6'' W
33° 46' 50'' N N 118° 2' 48'' W
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 11N WGS84 0 50 100 200 300
Feet
0 30 60 120 180
Meters
Map Scale: 1:2,050 if printed on A landscape (11" x 8.5") sheet.

Soil Map may not be valid at this scale.

Page 2393 of 3005 ends

MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Map Unit Polygons
Soil Map Unit Lines
Soil Map Unit Points
Special Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
Gravelly Spot
Landfill
Lava Flow
Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
Sodic Spot
Spoil Area
Stony Spot
Very Stony Spot
Wet Spot
Other
Special Line Features
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.

Warning: Soil Map may not be valid at this scale.

Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale.

Please rely on the bar scale on each map sheet for map
measurements.

Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:

Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required.

This product is generated from the USDA-NRCS certified data as of the version date(s) listed below.

Soil Survey Area: Orange County and Part of Riverside County, California
Survey Area Data: Version 17, Aug 30, 2023
Soil map units are labeled (as space allows) for map scales 1:50,000 or larger.

Date(s) aerial images were photographed: Apr 14, 2022—Apr 23, 2022
The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident.

Soil Map—Orange County and Part of Riverside County, California (KBHO-007 Soil Map)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
3/13/2024

Page 2 of 3 ends

Page 2394 of 3005 ends

Map Unit Legend
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 158 Hueneme fine sandy loam,
drained

19.3 100.0%
Totals for Area of Interest 19.3 100.0%
Soil Map—Orange County and Part of Riverside County, California KBHO-007 Soil Map Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
3/13/2024

Page 3 of 3 ends

Page 2395 of 3005 ends

Orange County and Part of Riverside County,
California
158—Hueneme fine sandy loam, drained
Map Unit Setting
National map unit symbol: hcn3
Elevation: 0 to 430 feet
Mean annual precipitation: 15 inches
Mean annual air temperature: 64 degrees F
Frost-free period: 300 to 350 days
Farmland classification: Prime farmland if irrigated
Map Unit Composition
Hueneme and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions, and transects of the mapunit.

Description of Hueneme
Setting
Landform: Alluvial fans
Landform position (two-dimensional): Toeslope
Landform position (three-dimensional): Rise
Down-slope shape: Linear
Across-slope shape: Convex
Parent material: Stratified alluvium derived from sedimentary rock Typical profile
H1 - 0 to 27 inches: fine sandy loam
H2 - 27 to 60 inches: stratified sand to silt loam
Properties and qualities
Slope: 0 to 2 percent
Depth to restrictive feature: More than 80 inches
Drainage class: Poorly drained
Capacity of the most limiting layer to transmit water (Ksat): High (1.98 to 5.95 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum content: 1 percent
Maximum salinity: Very slightly saline to slightly saline (2.0 to 4.0 mmhos/cm)
Available water supply, 0 to 60 inches: Moderate (about 9.0 inches)
Interpretive groups
Land capability classification (irrigated): 1
Land capability classification (nonirrigated): 3c
Hydrologic Soil Group: A
Map Unit Description: Hueneme fine sandy loam, drained---Orange County and Part of Riverside County, California
KBHO-007 Soil Map_158
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
3/13/2024

Page 1 of 2 ends

Page 2396 of 3005 ends

Ecological site: R019XG911CA - Loamy Fan
Hydric soil rating: Yes
Minor Components
San emigdio, fine sandy loam
Percent of map unit: 5 percent
Hydric soil rating: No
Hueneme, fine sandy loam
Percent of map unit: 5 percent
Hydric soil rating: No
Bolsa, silt loam, drained
Percent of map unit: 5 percent
Hydric soil rating: No
Data Source Information
Soil Survey Area: Orange County and Part of Riverside County, California Survey Area Data: Version 17, Aug 30, 2023
Map Unit Description: Hueneme fine sandy loam, drained---Orange County and Part of Riverside County, California
KBHO-007 Soil Map_158
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
3/13/2024

Page 2 of 2 ends

Page 2397 of 3005 ends

4665 Lampson Avenue

NOISE IMPACT ANALYSIS

CITY OF LOS ALAMITOS
PREPARED BY:

Bill Maddux
[email protected]
(619) 788-1971
JULY 12, 2024
14501-11 Noise Study.docx

Page 2398 of 3005 ends

Page 2399 of 3005 ends

4665 Lampson Avenue
14501-11 Noise Study.docx
i

TABLE OF CONTENTS
TABLE OF CONTENTS ............................................................................................................................. I APPENDICES ......................................................................................................................................... II LIST OF EXHIBITS ................................................................................................................................. III LIST OF TABLES ................................................................................................................................... III LIST OF ABBREVIATED TERMS ............................................................................................................. IV EXECUTIVE SUMMARY ......................................................................................................................... 1 On-Site Traffic Noise Analysis .................................................................................................................. 1 Off-Site Traffic Noise Analysis .................................................................................................................. 4 Operational Noise Analysis ...................................................................................................................... 4 Construction Noise Analysis .................................................................................................................... 4 Construction Vibration Analysis .............................................................................................................. 5 Aircraft Noise Abatement ........................................................................................................................ 5 Summary of Significance Findings ........................................................................................................... 5 1 INTRODUCTION ........................................................................................................................... 7

1.1 Site Location .................................................................................................................................. 7

1.2 Project Description ........................................................................................................................ 7 2 FUNDAMENTALS ....................................................................................................................... 11

2.1 Range of Noise ............................................................................................................................ 11

2.2 Noise Descriptors ........................................................................................................................ 12

2.3 Sound Propagation ...................................................................................................................... 13

2.4 Noise Control .............................................................................................................................. 14

2.5 Noise Barrier Attenuation ........................................................................................................... 14

2.6 Land Use Compatibility With Noise ............................................................................................ 14

2.7 Vibration ..................................................................................................................................... 14 3 REGULATORY SETTING .............................................................................................................. 17

3.1 State of California Noise Requirements ...................................................................................... 17

3.2 State of California Building Code ................................................................................................ 17

3.3 City of Los Alamitos Noise Standards .......................................................................................... 17

3.4 Construction Noise Standards..................................................................................................... 20

3.5 Construction Vibration Standards ............................................................................................... 21

3.6 Airport Land Use Compatibility ................................................................................................... 22 4 SIGNIFICANCE CRITERIA ............................................................................................................ 27

4.1 Noise Level Increases (Threshold A) ........................................................................................... 27

4.2 Vibration (Threshold B) ............................................................................................................... 28

4.3 Aircraft/Airport (Threshold C) ..................................................................................................... 28

4.4 Significance Criteria Summary .................................................................................................... 29 5 EXISTING NOISE LEVEL MEASUREMENTS ................................................................................... 31

5.1 Measurement Procedure and Criteria ........................................................................................ 31

5.2 Noise Measurement Locations ................................................................................................... 31

5.3 Noise Measurement Results ....................................................................................................... 33 6 TRAFFIC NOISE METHODS AND PROCEDURES ............................................................................ 35

6.1 FHWA Traffic Noise Prediction Model ........................................................................................ 35

Page 2400 of 3005 ends

4665 Lampson Avenue
14501-11 Noise Study.docx
ii
7 ON-SITE TRAFFIC NOISE IMPACTS .............................................................................................. 39

7.1 On-Site Exterior Traffic Noise Analysis ........................................................................................ 39

7.2 On-Site Interior Traffic Noise Analysis ........................................................................................ 40 8 OFF-SITE TRAFFIC NOISE IMPACTS ............................................................................................. 43

8.1 Traffic Noise level contours ........................................................................................................ 43

8.2 Existing 2023 Condition Project Traffic Noise Levels .................................................................. 49

8.3 OY 2026 Traffic Noise Level Increases ........................................................................................ 49

8.4 GPBO 2045 Traffic Noise Level Increases .................................................................................... 50

8.5 Cumulative Traffic Noise Level Increases .................................................................................... 50 9 RECEIVER LOCATIONS................................................................................................................ 55 10 OPERATIONAL NOISE IMPACTS ................................................................................................. 59

10.1 Operational Noise Sources .......................................................................................................... 59

10.2 Reference Noise Levels ............................................................................................................... 61

10.3 CadnaA Noise Prediction Model ................................................................................................. 62

10.4 Project Operational Noise Levels ................................................................................................ 62

10.5 Project Operational Noise Level Compliance .............................................................................. 63

10.6 Project Operational Noise Level Increases ................................................................................. 64 11 CONSTRUCTION IMPACTS ......................................................................................................... 67

11.1 Construction Noise Levels ........................................................................................................... 67

11.2 Construction Reference Noise Levels ......................................................................................... 67

11.3 Construction Noise Analysis ........................................................................................................ 69

11.4 Construction Noise Level Compliance ........................................................................................ 70

11.5 Construction Vibration Impacts .................................................................................................. 70 12 ON-SITE AIRCRAFT NOISE IMPACTS ........................................................................................... 73 13 REFERENCES .............................................................................................................................. 75 14 CERTIFICATION .......................................................................................................................... 77

APPENDICES
APPENDIX 3.1: CITY OF LOS ALAMITOS MUNICIPAL CODE
APPENDIX 5.1: STUDY AREA PHOTOS
APPENDIX 5.2: NOISE LEVEL MEASUREMENTS
APPENDIX 6.1: SITE PLAN
APPENDIX 7.1: ON-SITE TRAFFIC NOISE LEVEL CALCULATIONS
APPENDIX 8.1: OFF-SITE TRANSPORTATION NOISE LEVEL CONTOURS APPENDIX 10.1: CARRIER 25HBC5 AIR CONDITIONING UNIT
APPENDIX 10.2: OPERATIONAL NOISE LEVEL CALCULATIONS
APPENDIX 11.1: CONSTRUCTION NOISE LEVEL CALCULATIONS

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LIST OF EXHIBITS
EXHIBIT ES-A: NOISE CONTROL MEASURE SUMMARY .......................................................................... 2 EXHIBIT 1-A: LOCATION MAP .............................................................................................................. 8 EXHIBIT 1-B: CONCEPTUAL SITE PLAN .................................................................................................. 9 EXHIBIT 2-A: TYPICAL NOISE LEVELS .................................................................................................. 11 EXHIBIT 2-B: TYPICAL LEVELS OF GROUND-BORNE VIBRATION .......................................................... 16 EXHIBIT 3-A: LAND USE AND NOISE COMPATIBILITY MATRIX ............................................................ 19 EXHIBIT 3-B: AELUP AIRPORT NOISE LEVEL CONTOUR BOUNDARIES .................................................. 24 EXHIBIT 3-C: APHC 2020 AIRPORT NOISE LEVEL CONTOUR BOUNDARIES ........................................... 25 EXHIBIT 3-D: LIMITATIONS ON LAND USE DUE TO AIRCRAFT NOISE ................................................... 26 EXHIBIT 5-A: AMBIENT NOISE MEASUREMENT LOCATIONS ............................................................... 32 EXHIBIT 9-A: RECEIVER LOCATIONS ................................................................................................... 57 EXHIBIT 10-A: OPERATIONAL NOISE SOURCE LOCATIONS .................................................................. 60 EXHIBIT 11-A: CONSTRUCTION ACTIVITY AND RECEIVER LOCATIONS ................................................. 68 TABLE 11-2: CONSTRUCTION EQUIPMENT NOISE LEVEL SUMMARY ................................................... 70 EXHIBIT 12-A: ON-SITE AIRCRAFT NOISE LEVEL CONTOURS ................................................................ 74

LIST OF TABLES
TABLE ES-1: SUMMARY OF SIGNIFICANCE FINDINGS ........................................................................... 6 TABLE 3-1: LOS ALAMITOS MUNICIPAL CODE EXTERIOR NOISE STANDARDS ...................................... 20 TABLE 3-2: BUILDING DAMAGE VIBRATION CRITERIA ........................................................................ 21 TABLE 4-1: SIGNIFICANCE CRITERIA SUMMARY .................................................................................. 29 TABLE 5-1: 24 HOUR AMBIENT NOISE LEVEL MEASUREMENTS .......................................................... 33 TABLE 6-1: ON SITE ROADWAY PARAMATERS ................................................................................... 36 TABLE 6-2: TIME OF DAY VEHICLE SPLITS ........................................................................................... 36 TABLE 6-3: DISTRIBUTION OF FLOW BY VEHICLE TYPE (VEHICLE MIX) ................................................ 36 TABLE 6-4: OFF-SITE ROADWAY PARAMETERS................................................................................... 37 TABLE 6-5: AVERAGE DAILY TRAFFIC VOLUMES ................................................................................. 38 TABLE 7-1: EXTERIOR NOISE LEVELS (DBA CNEL) ................................................................................ 39 TABLE 7-2: FIRST FLOOR INTERIOR TRAFFIC NOISE LEVELS ................................................................. 40 TABLE 7-3: SECOND FLOOR INTERIOR TRAFFIC NOISE LEVELS ............................................................ 41 TABLE 8-1: EXISTING 2023 WITHOUT PROJECT CONDITIONS NOISE LEVEL CONTOURS ....................... 44 TABLE 8-2: EXISTING 2023 WITH PROJECT CONDITIONS NOISE LEVEL CONTOURS .............................. 45 TABLE 8-3: OY 2026 WITHOUT PROJECT CONDITIONS NOISE LEVEL CONTOURS ................................. 46 TABLE 8-4: OY 2026 WITH PROJECT CONDITIONS NOISE LEVEL CONTOURS ........................................ 47 TABLE 8-5: GPBO 2045 WITHOUT PROJECT CONDITIONS NOISE LEVEL CONTOURS ............................ 48 TABLE 8-6: GPBO 2045 WITH PROJECT CONDITIONS NOISE LEVEL CONTOURS ................................... 49 TABLE 8-7: EXISTING 2023 OFF-SITE PROJECT-RELATED TRAFFIC NOISE IMPACTS............................... 51 TABLE 8-8: OY 2026 OFF-SITE PROJECT-RELATED TRAFFIC NOISE IMPACTS ........................................ 52 TABLE 8-9: GPBO 2045 OFF-SITE PROJECT-RELATED TRAFFIC NOISE IMPACTS .................................... 53 TABLE 8-10: CUMULATIVE PROJECT TRAFFIC NOISE INCREASES ......................................................... 54 TABLE 10-1: REFERENCE NOISE LEVELS ............................................................................................... 62 TABLE 10-2: PROJECT DAYTIME OPERATIONAL NOISE LEVELS ............................................................ 63 TABLE 10-3: PROJECT NIGHTTIME OPERATIONAL NOISE LEVELS ......................................................... 63

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TABLE 10-4: OPERATIONAL NOISE LEVEL COMPLIANCE ...................................................................... 64 TABLE 10-5: DAYTIME PROJECT OPERATIONAL NOISE LEVEL INCREASES ............................................ 65 TABLE 10-6: NIGHTTIME OPERATIONAL NOISE LEVEL INCREASES ....................................................... 65 TABLE 11-3: CONSTRUCTION NOISE LEVEL COMPLIANCE ................................................................... 70 TABLE 11-4: VIBRATION SOURCE LEVELS FOR CONSTRUCTION EQUIPMENT ...................................... 71 TABLE 11-5: PROJECT CONSTRUCTION VIBRATION LEVELS ................................................................. 72

LIST OF ABBREVIATED TERMS
(1) Reference
ADT Average Daily Traffic
AELUP Airport Environs Land Use Plan
ANSI American National Standards Institute
Calveno California Vehicle Noise
CEQA California Environmental Quality Act
CNEL Community Noise Equivalent Level
dBA A-weighted decibels
EIR Environmental Impact Report
EPA Environmental Protection Agency
FHWA Federal Highway Administration
FTA Federal Transit Administration
INCE Institute of Noise Control Engineering
Leq Equivalent continuous (average) sound level
Lmax Maximum level measured over the time interval
Lmin Minimum level measured over the time interval
MM Mitigation Measure
mph Miles per hour
OCTA Orange County Transportation Agency
PPV Peak Particle Velocity
Project 4665 Lampson Avenue
REMEL Reference Energy Mean Emission Level
RMS Root-mean-square
VdB Vibration Decibels

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1 EXECUTIVE SUMMARY
Urban Crossroads, Inc. has prepared this noise study to evaluate potential noise associated with proposed development at 4665 Lampson Avenue (“Project”) in the City of Los Alamitos. The Project is proposed to include the development of 55 single family detached residential dwelling units (cluster homes), 114 multifamily (low-rise) residential dwelling units, and 77 affordable apartment dwelling units (total of 246 dwelling units) and demolition of the existing 88,000 square foot commercial office building. This study has been prepared to evaluate the Project’s potential noise impacts in light of the thresholds of significance identified in Appendix G of the California Environmental Quality Act (CEQA) Guidelines. (1)

ON-SITE TRAFFIC NOISE ANALYSIS
An on-site exterior and interior noise impact analysis has been completed to determine the traffic-related noise levels and to identify potential necessary abatement measures for the proposed Project. It is expected that the primary source of traffic-related noise impacts to the Project site will be from Lampson Avenue.

EXTERIOR TRAFFIC NOISE ANALYSIS
The on-site traffic noise level impacts indicate that noise levels at the Project buildings adjacent to Lampson Avenue would experience exterior noise levels ranging from 64.6 to 72.8 dBA CNEL.

Therefore, to reduce noise levels to 65 dBA CNEL or less in compliance with the City of Los Alamitos exterior noise level noise and land use compatibility policies, the Project would include Noise 1 in the Project design and construct a seven (7) foot-high noise barrier along Lampson Avenue, shown in Exhibit ES-A. With the barrier, exterior noise levels will range from 58.3 to

63.8 dBA CNEL at backyards of residential units and common outdoor activity areas of multifamily residential units. This noise analysis shows that with the proposed noise barrier the Project will satisfy the City of Los Alamitos 65 dBA CNEL normally acceptable exterior noise level standards for residential land uses. The identified noise barrier heights represent the minimum wall and/or berm combination height required to satisfy the City of Los Alamitos exterior noise level standards.

Noise 1 The Project will construct a 7-foot-high noise barrier along Lampson Avenue, as shown in Exhibit ES-A. The noise control barrier will be constructed so that the top of each wall and /or berm combination extends to the planned height above the pad elevation of the lot it is shielding. When the roadway or terrain is elevated above the pad elevation, the barrier shall extend to the recommended height above the highest point between the residential home and the roadway. The barrier shall be built with a material surface weight of at least 4 pounds per square foot, with no decorative cutouts, perforations, or line-of-sight openings between residences and Lampson Avenue. (2) The noise barrier shall be constructed using the following materials:

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2 EXHIBIT ES-A: NOISE CONTROL MEASURE SUMMARY

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3  masonry block;
 stucco veneer over wood framing (or foam core), or 1-inch-thick tongue and groove wood of sufficient weight per square foot;
 glass (1/4-inch-thick),
 material with sufficient weight per square foot capable of providing a minimum transmission loss of 20 dBA;
 earthen berm; or,
 any combination of these construction materials.

INTERIOR TRAFFIC NOISE ABATEMENT
Typical building construction will provide a Noise Reduction (NR) of approximately 12 dBA with "windows open" and a minimum 25 dBA noise reduction with "windows closed." (3) (4) The Project will provide mechanical ventilation (e.g. air conditioning) for all units which would allow a windows-closed condition. Based on predicted exterior noise levels, to satisfy the State of California and the City of Los Alamitos 45 dBA CNEL interior noise level criteria, first-floor units are being designed to meet a Noise Reduction (NR) of 20.3 dBA at first floors and 26.3 dBA at second floors for units adjacent to Lampson Avenue. Therefore, the Project will provide second floor units with windows that have an STC rating of 29. The Project includes the following Project design feature:

Noise: 2 To comply with the State of California and City of Los Alamitos 45 dBA CNEL interior noise standards for residential land use the Project will provide the following or equivalent noise abatement measures on building plans:
 Windows & Glass Doors: At a minimum the Project will provide windows and glass doors that are well-fitted, well-weather-stripped assemblies with minimum sound transmission class (STC) ratings of 27. Additionally, all second floor facades adjacent to Lampson Avenue will be provided windows and glass doors that are well-fitted, well-weather-stripped assemblies with minimum sound transmission class (STC) ratings of 29.
 Doors (Non-Glass): All exterior doors shall be well weather-stripped and have. Wellsealed perimeter gaps around the doors are essential to achieve the optimal STC rating. (5)
 Walls: At any penetrations of exterior walls by pipes, ducts, or conduits, the space between the wall and pipes, ducts, or conduits shall be caulked or filled with mortar to form an airtight seal.
 Roof: Roof sheathing of wood construction shall be per manufacturer’s specification or caulked plywood of at least one-half inch thick. Ceilings shall be per manufacturer’s specification or well-sealed gypsum board of at least one-half inch thick. Insulation with at least a rating of R-19 shall be used in the attic space.  Ventilation: Arrangements for any habitable room shall be such that any exterior door or window can be kept closed when the room is in use and still receive circulated air. A forced air circulation system (e.g. air conditioning) or active ventilation system

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4 (e.g. fresh air supply) shall be provided which satisfies the requirements of the Uniform Building Code.

OFF-SITE TRAFFIC NOISE ANALYSIS
Traffic generated by the operation of the proposed Project will influence the traffic noise levels in surrounding off-site areas. To quantify the traffic noise increases on the surrounding off-site areas, the changes in traffic noise levels on sixteen roadway segments surrounding the Project site were calculated based on the change in the average daily traffic (ADT) volumes. The traffic noise levels provided in this analysis are based on the traffic forecasts found in 4665 Lampson Avenue Traffic Impact Analysis prepared by Urban Crossroads, Inc. (6) To assess the off-site noise level impacts associated with the proposed Project, noise level contour boundaries were developed for Existing 2023, Opening Year 2026 (OY 2026), and General Plan Buildout 2045(GBPO 2045) without and with Project traffic conditions. Land uses along roadway segments analyzed would experience Project related traffic noise level increases of up to 1.0 dBA CNEL. Therefore, the analysis shows that the Project-related traffic noise level increases under all scenarios would be less than significant.

OPERATIONAL NOISE ANALYSIS
The Project would include specific type of operational noise attributable to the Project, including roof-top and ground-mounted air conditioning units, parking lot vehicle movements, outdoor activity, and trash enclosure activities. Project operational noise levels during the daytime hours at off-site receiver locations are expected to range from 20.4 to 46.9 dBA Leq. Project operational noise levels during the nighttime hours at off-site receiver locations are expected to range from

16.8 to 43.7 dBA Leq. Project operational noise levels will satisfy Section 17.20.050 of the City of Los Alamitos Municipal Code daytime and nighttime noise standards of 55 dBA and 50 dBA Leq, respectively, at all residential receivers. Therefore, potential operational noise impacts for the residential land use are anticipated to result in less than significant impacts.

CONSTRUCTION NOISE ANALYSIS
Construction noise levels are expected to create temporary and intermittent high-level noise conditions at receivers surrounding the Project site when certain activities occur at the closest point to the nearby receiver locations from the edge of primary Project construction activity.

Using sample reference noise levels to represent the construction activities at the Project site, this analysis estimates the Project-related construction noise levels at nearby sensitive receiver locations. The results of the analysis show the highest construction noise levels at the potentially impacted receiver locations are expected to approach 63.2 dBA Leq.

The Project related construction equipment noise levels are anticipated to satisfy the FTA construction noise level standards of 80 dBA Leq for mobile equipment during typical Project construction activities at all receiver locations. Additionally, construction activities are planned to typically occur between 7:00 a.m. and 6:00 p.m. and would comply with the City of Los Alamitos limitation on allowable hours of construction per Section 17.20.020. Therefore, based

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5 on the results of this analysis, all nearby sensitive receiver locations will experience less than significant impacts due to Project construction noise levels.

CONSTRUCTION VIBRATION ANALYSIS
Construction activity can result in varying degrees of ground vibration, depending on the equipment and methods used, distance to the affected structures and soil type. It is expected that ground-borne vibration from Project construction activities would cause only intermittent, localized intrusion. Ground-borne vibration levels resulting from typical construction activities occurring within the Project site were estimated by data published by the Federal Transit Administration (FTA). At the nearest receivers Project construction vibration velocity levels are estimated to range from less than 0.00 to 0.02 in/sec PPV. Based on maximum acceptable continuous vibration threshold of 0.3 PPV (in/sec), the typical Project construction vibration levels will not exceed the City of Los Alamitos thresholds at properties located adjacent to the Project site. Therefore, vibration impacts due to Project construction activities would be less than significant.

AIRCRAFT NOISE ABATEMENT
Based on a review of noise level contours for the Joint Forces Training Base (JFTB) Los Alamitos, a portion of the proposed residential uses would be located within the conditionally consistent 60-65 dBA noise contour under projected conditions. As discussed under the on-site traffic noise traffic noise analysis, typical modern residential construction can achieve a noise level reduction of 25 dBA with windows closed. Thus, with the Project design feature Noise-1, a windows closed condition is evaluated, which indicates maximum interior noise levels would range from 35 to 40 dBA CNEL from aircraft noise exposure. As discussed, in the following analysis, exposure of exterior use areas to noise levels in excess of 70 dBA CNEL would be considered significant, and exposure of residential land uses to noise levels in excess of 65 dBA CNEL would be significant unless noise levels in interior habitable rooms are reduced to 45 dBA CNEL. Therefore, the Project would not expose people residing or working in the project area to excessive interior noise levels from airport or aircraft operations, and impacts would be less than significant.

SUMMARY OF SIGNIFICANCE FINDINGS
The results of 4665 Lampson Avenue Noise Impact Analysis are summarized below based on the significance criteria in Section 4 of this report consistent with Appendix G of the California Environmental Quality Act (CEQA) Guidelines. (7). Table ES-1 shows the findings of significance for each potential noise and/or vibration impact under CEQA before and after any required mitigation measures.

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6 TABLE ES-1: SUMMARY OF SIGNIFICANCE FINDINGS
Analysis Report
Section
Significance Findings
Unmitigated Mitigated Mitigated Measure
On-Site Traffic Noise 7 Less Than Significant1 - -
Off-Site Traffic Noise 8 Less Than Significant - -
Operational Noise 10 Less Than Significant - -
Construction Noise
11 Less Than Significant - -
Construction Vibration Less Than Significant - -
On-Site Aircraft Noise 12 Less Than Significant - -
1 Less than significant with Project Design Features (Noise -1 and Noise -2)

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7 1 INTRODUCTION
This noise analysis has been completed to evaluate the noise impacts associated with the development of the proposed 4665 Lampson Avenue project (“Project”). This noise study describes the Project, provides information regarding noise and vibration fundamentals, outlines the local regulatory setting, provides the study methods and procedures for performing noise analysis, evaluates potential noise impacts from the project, and identifies mitigation measures to reduce impacts, as necessary.

1.1 SITE LOCATION
The proposed Project is located at 4665 Lampson Avenue in the City of Los Alamitos. The Project’s location in relation to the surrounding area is shown on Exhibit 1-A. The surrounding land use designations are Residential to the south, JFTB Los Alamitos to the north, the Navy Golf Course to the east, and Arbor Park (Community Facilities) to the west. Interstate 405 (I-405) is located approximately 0.48 miles south of the Project site.

1.2 PROJECT DESCRIPTION
The Project consists of the development of 55 single family detached residential dwelling units (cluster homes), 114 multifamily (low-rise) residential dwelling units, and 77 affordable apartment dwelling units (total of 246 dwelling units). A preliminary site plan for the proposed Project is shown on Exhibit 1-B. The site is currently occupied by a two-story, 88,000 square foot commercial office building and parking lot. Access to the Project site will be accommodated to Lampson Avenue via two proposed driveways. The Project is anticipated to generate an increase of 1,658 two-way trip-ends per day with 112 AM peak hour trips and 147 PM peak hour trips.

The Project is anticipated to have an opening year of 2026.

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8 EXHIBIT 1-A: LOCATION MAP

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9 EXHIBIT 1-B: CONCEPTUAL SITE PLAN

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11 2 FUNDAMENTALS
Noise has been simply defined as “unwanted sound.” Sound becomes unwanted when it interferes with normal activities, when it causes actual physical harm or when it has adverse effects on health. Noise is measured on a logarithmic scale of sound pressure level known as a decibel (dB). A-weighted decibels (dBA) approximate the subjective response of the human ear to broad frequency noise source by discriminating against very low and very high frequencies of the audible spectrum. They are adjusted to reflect only those frequencies which are audible to the human ear. Exhibit 2-A presents a summary of the typical noise levels and their subjective loudness and effects that are described in more detail below.

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

2.1 RANGE OF NOISE
Since the range of intensities that the human ear can detect is so large, the scale frequently used to measure intensity is a scale based on multiples of 10, the logarithmic scale. The scale for measuring intensity is the decibel scale. Human perception of noise has no simple correlation with acoustical energy. The perception of noise is not linear in terms of dBA or in terms of acoustical energy. Two equivalent noise sources result in a 3 dBA increase. However, it is widely accepted that the average healthy ear can barely perceive changes of 3 dBA, increase or decrease; that a change of 5 dBA is readily perceptible; and that an increase (decrease) of 10 dBA

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12 sounds twice (half) as loud (Caltrans 2009). The most common sounds vary between 40 dBA (very quiet) to 100 dBA (very loud). Normal conversation at three feet is roughly at 60 dBA, while loud jet engine noises equate to 110 dBA at approximately 100 feet, which can cause serious discomfort. (8) Another important aspect of noise is the duration of the sound and the way it is described and distributed in time.

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

To describe the time-varying character of environmental noise, the statistical or percentile noise descriptors L50, L25, L8 and L2, are commonly used. The percentile noise descriptors are the noise levels equaled or exceeded during 50 percent, 25 percent, 8 percent, and 2 percent of a stated time. Sound levels associated with the L2 and L8 typically describe transient or short-term events, while levels associated with the L50 describe the steady state (or median) noise conditions. While the L50 describes the median noise levels occurring 50 percent of the time, the Leq accounts for the total energy (average) observed for the entire hour. Therefore, the Leq noise descriptor is generally 1-2 dBA higher than the L50 noise level.

Peak hour or average noise levels, while useful, do not completely describe a given noise environment. Noise levels lower than peak hour may be disturbing if they occur during times when quiet is most desirable, namely evening and nighttime (sleeping) hours. To account for this, the Community Noise Equivalent Level (CNEL), representing a composite 24-hour noise level is utilized. The CNEL is the weighted average of the intensity of a sound, with corrections for time of day, and averaged over 24 hours. The time-of-day corrections require the addition of 5 decibels to dBA Leq sound levels in the evening from 7:00 p.m. to 10:00 p.m., and the addition of 10 decibels to dBA Leq sound levels at night between 10:00 p.m. and 7:00 a.m. These additions are made to account for the noise sensitive time periods during the evening and night hours when sound appears louder. CNEL does not represent the actual sound level heard at any time, but rather represents the total sound exposure. The City of Los Alamitos relies on the 24-hour CNEL level to assess land use compatibility with transportation related noise sources.

Sound levels used for compliance modeling, sound level limitations on equipment, and product labeling use another descriptor, are known as the sound power level (Lw). Sound power is the rate at which sound energy is emitted from a source per unit time. Knowing the sound power level of a device allows for the objective comparison of the sound output of different devices, without any knowledge of the environment in which they were tested or the distance at which measurements were taken. This makes sound power levels ideal for verifying compliance with property line noise level limits.

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13 2.3 SOUND PROPAGATION
When sound propagates over a distance, it changes in level and frequency content. The way noise reduces with distance depends on the following factors.

2.3.1 GEOMETRIC SPREADING
Sound from a localized source (i.e., a stationary point source) propagates uniformly outward in a spherical pattern. The sound level attenuates (or decreases) at a rate of 6 dB for each doubling of distance from a point source. Highways consist of several localized noise sources on a defined path and hence can be treated as a line source, which approximates the effect of several point sources. Noise from a line source propagates outward in a cylindrical pattern, often referred to as cylindrical spreading. Sound levels attenuate at a rate of 3 dB for each doubling of distance from a line source. (9)

2.3.2 GROUND ABSORPTION
The propagation path of noise from a highway to a receptor is usually very close to the ground.

Noise attenuation from ground absorption and reflective wave canceling adds to the attenuation associated with geometric spreading. Traditionally, the excess attenuation has also been expressed in terms of attenuation per doubling of distance. This approximation is usually sufficiently accurate for distances of less than 200 ft. For acoustically hard sites (i.e., sites with a reflective surface between the source and the receptor, such as a parking lot or body of water), no excess ground attenuation is assumed. For acoustically absorptive or soft sites (i.e., those sites with an absorptive ground surface between the source and the receptor such as soft dirt, grass, or scattered bushes and trees), an excess ground attenuation value of 1.5 dB per doubling of distance is normally assumed. When added to the cylindrical spreading, the excess ground attenuation results in an overall drop-off rate of 4.5 dB per doubling of distance from a line source. (3)

2.3.3 ATMOSPHERIC EFFECTS
Receptors located downwind from a source can be exposed to increased noise levels relative to calm conditions, whereas locations upwind can have lowered noise levels. Sound levels can be increased at large distances (e.g., more than 500 feet) due to atmospheric temperature inversion (i.e., increasing temperature with elevation). Other factors such as air temperature, humidity, and turbulence can also have significant effects. (9)

2.3.4 SHIELDING
A large object or barrier in the path between a noise source and a receptor can substantially attenuate noise levels at the receptor. The amount of attenuation provided by shielding depends on the size of the object and the frequency content of the noise source. Shielding by trees and other such vegetation typically only has an “out of sight, out of mind” effect. That is, the perception of noise impact tends to decrease when vegetation blocks the line-of-sight to nearby resident. However, for vegetation to provide a substantial, or even noticeable, noise reduction, the vegetation area must be at least 15 feet in height, 100 feet wide and dense enough to

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14 completely obstruct the line-of sight between the source and the receiver. This size of vegetation may provide up to 5 dBA of noise reduction. The FHWA does not consider the planting of vegetation to be a noise abatement measure. (3)

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

2.5 NOISE BARRIER ATTENUATION
Effective noise barriers can reduce noise levels by 10 to 15 dBA, cutting the loudness of traffic noise in half. A noise barrier is most effective when placed close to the noise source or receptor.

Noise barriers, however, do have limitations. For a noise barrier to work, it must be high enough and long enough to block the path of the noise source. (3)

2.6 LAND USE COMPATIBILITY WITH NOISE
Some land uses are more tolerant of noise than others. For example, schools, hospitals, churches, and residences are more sensitive to noise intrusion than are commercial or industrial developments and related activities. As ambient noise levels affect the perceived amenity or livability of a development, so too can the mismanagement of noise impacts impair the economic health and growth potential of a community by reducing the area’s desirability as a place to live, shop and work. For this reason, land use compatibility with the noise environment is an important consideration in the planning and design process. The FHWA encourages State and Local government to regulate land development in such a way that noise-sensitive land uses are either prohibited from being located adjacent to a highway, or that the developments are planned, designed, and constructed in such a way that noise impacts are minimized. (10)

2.7 VIBRATION
Per the Federal Transit Administration (FTA) Transit Noise and Vibration Impact Assessment Manual, (7) vibration is the periodic oscillation of a medium or object. The rumbling sound caused by the vibration of room surfaces is called structure-borne noise. Sources of groundborne vibrations include natural phenomena (e.g., earthquakes, volcanic eruptions, sea waves, landslides) or human-made causes (e.g., explosions, machinery, traffic, trains, construction equipment). Vibration sources may be continuous, such as factory machinery, or transient, such as explosions. As is the case with airborne sound, ground-borne vibrations may be described by amplitude and frequency.

Additionally, in contrast to airborne noise, ground-borne vibration outdoors is not a common environmental problem and annoyance from ground-borne vibration is almost exclusively an indoor phenomenon. (7) Therefore, the effects of vibrations should only be evaluated at a structure and the effects of the building structure on the vibration should be considered. WoodPage 2417 of 3005 4665 Lampson Avenue
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15 frame buildings, such as typical residential structures, are more easily excited by ground vibration than heavier buildings. In contrast, large masonry buildings with spread footings have a low response to ground vibration. (7) In general, the heavier a building is, the lower the response will be to the incident vibration energy. However, all structurers reduce vibration levels due to the coupling of the building to the soil.

There are several different methods that are used to quantify vibration. The peak particle velocity (PPV) is defined as the maximum instantaneous peak of the vibration signal. (7) The PPV is most frequently used to describe vibration impacts to buildings but is not always suitable for evaluating human response (annoyance) because it takes some time for the human body to respond to vibration signals. Instead, the human body responds to average vibration amplitude often described as the root mean square (RMS). The RMS amplitude is defined as the average of the squared amplitude of the signal and is most frequently used to describe the effect of vibration on the human body. (7) However, the RMS amplitude and PPV are related mathematically, and the RMS amplitude of equipment is typically calculated from the PPV reference level. The RMS amplitude is approximately 70% of the PPV (11). Thus, thus either can be used on the description of vibration impacts.

Vibration decibel notation (VdB) is another vibration notation developed and used by the FTA in their guidance manual to describe vibration levels and provide a background of common vibration levels and set vibration limits. (7) Decibel notation (VdB) serves to reduce the range of numbers used to describe vibration levels and is used in this report to describe vibration levels.

As stated in the FTA guidance manual, the background vibration-velocity level in residential areas is generally 50 VdB. Ground-borne vibration is normally perceptible to humans at approximately 65 VdB. For most people, a vibration-velocity level of 75 VdB is the approximate dividing line between barely perceptible and distinctly perceptible levels. (7) Typical outdoor sources of perceptible ground-borne vibration are construction equipment, steel-wheeled trains, and traffic on rough roads. If a roadway is smooth, the ground-borne vibration is rarely perceptible. The range of interest is from approximately 50 VdB, which is the typical background vibration-velocity level, to 100 VdB, which is the general threshold where minor damage can occur in fragile buildings. Exhibit 2-B illustrates common vibration sources and the human and structural response to ground-borne vibration.

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

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17 3 REGULATORY SETTING
To limit population exposure to physically and/or psychologically damaging as well as intrusive noise levels, the federal government, the State of California, various county governments, and most municipalities in the state have established standards and ordinances to control noise. In most areas, automobile and truck traffic is the major source of environmental noise. Traffic activity generally produces an average sound level that remains constant with time. Air and rail traffic, and commercial and industrial activities are also major sources of noise in some areas.

Federal, state, and local agencies regulate different aspects of environmental noise. Federal and state agencies generally set noise standards for mobile sources such as aircraft and motor vehicles, while regulation of stationary sources is left to local agencies.

3.1 STATE OF CALIFORNIA NOISE REQUIREMENTS
The State of California regulates freeway noise, sets standards for sound transmission, provides occupational noise control criteria, identifies noise standards, and provides guidance for local land use compatibility. State law requires that each county and city adopt a General Plan that includes an element that addresses noise issues per guidelines adopted by the Governor’s Office of Planning and Research. (12) The purpose of this element is to ensure a local planning area limits the exposure of the community to excessive noise levels. State law allows jurisdictions to organize their general plan in any format, including by consolidating elements. Here, noise issues are addressed in the City of Los Alamitos’ Public Facilities and Safety Element of its General Plan.

In addition, the California Environmental Quality Act (CEQA) requires that reasonably foreseeable environmental effects of a project be analyzed, including environmental noise impacts.

3.2 STATE OF CALIFORNIA BUILDING CODE
The State of California’s Green Building Standards Code contains mandatory measures for nonresidential building construction in Section 5.507 on Environmental Comfort. (13) These noise standards are applied to new construction in California for controlling interior noise levels resulting from exterior noise sources. The regulations specify that acoustical studies must be prepared when non-residential structures are developed in areas where a general plan or airport plan provide contours that show exterior noise levels exceed 65 dBA CNEL, such as within a noise level contour of an airport, freeway, or railroad; or if contours are unavailable, buildings exposed to a noise level of 65 dBA Leq-1-hr during any hour of operation; shall be constructed to provide an interior noise level environment attributable to exterior sources that does not exceed an hourly equivalent level of 50 dBA Leq in occupied areas during any hour of operation.

3.3 CITY OF LOS ALAMITOS NOISE STANDARDS
The General Plan is a tool for managing noise by planning for and maintaining compatibility between sensitive land uses and noise sources. (14) The City of Los Alamitos has identified two separate types of noise sources: (1) transportation, and (2) stationary. To control transportation related noise sources such as arterial roads, freeways, airports, and railroads, the City of Los Alamitos has established guidelines for acceptable community noise levels in the Public Facilities

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18 and Safety Element of the General Plan. Noise from stationary sources is regulated through specific standards in Chapter 17.20 of the Los Alamitos Municipal Code. and Division 6 of the Orange County Municipal Code (Rossmoor). The Public Facilities and Safety Element of the General Plan includes the following Noise Hazards goal and policies:
 Goal 4: An environment in which minimized noise contributes to the public's health, safety, and welfare.
 Policy 4.1 Land use compatibility. Approve development and require mitigation measures to ensure existing and future land use compatibility as shown in the City’s Noise Ordinance, the Land Use and Noise Compatibility Matrix, the State Interior and Exterior Noise Standards, and the Airport Environs Land Use Plan for the JFTB.
 Policy 4.2 New residential. When new residential development is proposed adjacent to land designated for industrial or commercial uses, require the proposed development to assess potential noise impacts and fund feasible noise-related mitigation measures.  Policy 4.3 Control sound at the source. Prioritize noise mitigation measures to control sound at the source over buffers, soundwalls, and other perimeter measures.  Policy 4.4 Noise impacts. Minimize or eliminate persistent, periodic, or impulsive noise impacts of business operations.
 Policy 4.6 Aircraft noise. Work with the JFTB and Long Beach Airport to minimize the noise impact of small aircraft and helicopters on residential neighborhoods.

3.3.1 LAND USE COMPATIBILITY
The noise criteria identified in the City of Los Alamitos Public Facilities and Safety Element (Table 4) are guidelines to evaluate the land use compatibility of transportation-related noise. The compatibility criteria, shown on Exhibit 3-A, provides the City with a planning tool to gauge the compatibility of land uses relative to existing and future exterior noise levels.

The Land Use and Noise Compatibility Matrix describes categories of compatibility and not specific noise standards. The residential land uses of the Project are considered clearly compatible with unmitigated exterior noise levels of less than 60 dBA CNEL and normally compatible with unmitigated exterior noise levels approaching 70 dBA CNEL, new construction or development should be undertaken only after detailed analysis of the noise reduction requirements are made and needed noise insulation features in the design are determined.

Conventional construction, with closed windows and fresh air supply systems or air conditioning, will normally suffice. For normally incompatible exterior noise levels, exceeding 70 dBA CNEL, new construction or development should be discouraged. If new construction or development does proceed, a detailed analysis of the noise reduction requirements are made and needed noise insulation features must be included in the design.

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19 EXHIBIT 3-A: LAND USE AND NOISE COMPATIBILITY MATRIX Source: City of Los Alamitos General Plan Public Facilities and Safety Element, Table 4.

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20 3.3.2 CITY OF LOS ALAMITOS OPERATIONAL NOISE STANDARDS To control transportation-related noise sources such as arterial roads, freeways, airports, and railroads, the City of Los Alamitos has established the standards provided in Table 4 of General Plan Public Facilities and Safety Element for compatible community noise levels.

To analyze noise impacts originating from a designated fixed location or private property such as the Project, stationary-source (operational) noise such as the expected roof-top and groundmounted air conditioning units, parking lot vehicle movements, outdoor activity, and trash enclosure activities are typically evaluated against standards established under a City’s Municipal Code. Table 3-1 summarizes the City of Los Alamitos Municipal Code, Section 17.20.050 exterior noise standards that may be received at nearby land use uses. The City of Los Alamitos noise ordinance is included in Appendix 3.1.

TABLE 3-1: LOS ALAMITOS MUNICIPAL CODE EXTERIOR NOISE STANDARDS Noise District Maximum Noise Level1 Time Period
1 (Residential) day 55 dB(A) 7:00 a.m. to 10:00 p.m.
1 (Residential) night 50 dB(A) 10:00 p.m. to 7:00 a.m.
2 (Professional and Institutional) 55 dB(A) Anytime
3 (Commercial) 60 dB(A) Anytime
4 (Industrial) 70 dB(A) Anytime
Notes: The noise levels at the affected property shall not exceed:
-The noise standard for a cumulative period of more than 30 minutes in any hour; or -The noise standard plus 5 dBA for a cumulative period of more than 15 minutes in any hour; or -The noise standard plus 10 dBA for a cumulative period of more than 5 minutes in any hour; or -The noise standard plus 15 dBA for a cumulative period of more than one minute in any hour; or -The noise standard plus 20 dBA for any period of time. 1 Los Alamitos Municipal Code Chapter 17.20.050, Noise. (Appendix 3.1).

3.4 CONSTRUCTION NOISE STANDARDS
To control noise impacts associated with the construction of the Project, noise from construction activities are typically limited to the hours of operation established under a City’s Municipal Code.

The City of Los Alamitos Municipal Code, Section 17.20.020, states that construction activities are exempted from the noise ordinance if it occurs between the hours of 7:00 a.m. to 8:00 p.m. on weekdays and on Saturdays. Construction is not allowed at any time on Sundays or Federal holidays. (15) Neither the City’s General Plan nor Municipal Code establish numeric maximum acceptable construction source noise levels at potentially affected receivers for CEQA analysis purposes. Therefore, a numerical construction threshold based on Federal Transit Administration (FTA) Transit Noise and Vibration Impact Assessment Manual is used for analysis of daytime construction impacts, as discussed below.

According to the FTA, local noise ordinances are typically not very useful in evaluating construction noise. They usually relate to nuisance and hours of allowed activity, and sometimes specify limits in terms of maximum levels, but are generally not practical for assessing the impact of a construction project. Project construction noise criteria should account for the existing noise

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21 environment, the absolute noise levels during construction activities, the duration of the construction, and the adjacent land use. Due to the lack of standardized construction noise thresholds, the FTA provides guidelines that can be considered reasonable criteria for construction noise assessment. The FTA considers a daytime exterior construction noise level of 80 dBA Leq as a reasonable threshold for noise sensitive residential land use. (7 p. 179)

3.5 CONSTRUCTION VIBRATION STANDARDS
Construction activity can result in varying degrees of ground-borne vibration, depending on the equipment and methods used, distance to the affected structures and soil type. Construction vibration is generally associated with pile driving and rock blasting. Other construction equipment such as air compressors, light trucks, hydraulic loaders, etc., generates little or no ground vibration. Occasionally large bulldozers and loaded trucks can cause perceptible vibration levels at close proximity.

To analyze vibration impacts originating from the operation and construction of 4665 Lampson Avenue, vibration-generating activities are appropriately evaluated against standards established under a City’s Municipal Code, if such standards exist. However, the City of Los Alamitos does not identify specific vibration level limits. Therefore, for analysis purposes, the Caltrans Transportation and Construction Vibration Guidance Manual, (11 p. 38) Table 19, vibration damage are used in this noise study to assess potential temporary construction-related impacts at adjacent building locations.

The construction vibration damage potential criteria include consideration of the building conditions. (8 p. 182) Table 3-2 describes the maximum acceptable transient and continuous vibration building damage potential levels by structure type and condition. The existing buildings adjacent to the Project site can best be described as “older residential structures” with a maximum acceptable continuous vibration threshold of 0.3 PPV (in/sec).

TABLE 3-2: BUILDING DAMAGE VIBRATION CRITERIA
Structure and Condition Maximum Transient
Vibration Levels PPV (in/sec)
Maximum Continuous
Vibration Levels PPV (in/sec)
Extremely fragile historic buildings 0.12 0.08
Fragile buildings 0.2 0.1
Historic and some old buildings 0.5 0.25
Older residential structures 0.5 0.3
New residential structures 1.0 0.5
Modern industrial/commercial buildings 2.0 0.5
Caltrans Transportation and Construction Vibration Guidance Manual, April 2020, Tables 19, p. 38.

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22 3.6 AIRPORT LAND USE COMPATIBILITY
The JFTB Los Alamitos is located adjacent to, and northwest of the Project site. The Project site is located within the Airport Environs Land Use Plan Airport Planning Area (16).

Exhibit 3-B shows the Project site in relation to the airport’s noise level contour boundaries, as provided by the Airport Environs Land Use Plan (AELUP) for Joint Forces Training Base Los Alamitos (16). The AELUP noise level contours are based on a 1987 U.S. Army Environmental Hygiene Agency (USAEHA) assessment that was published in 1994 as part of the Air Installation Compatible Use Zone (AICUZ) Study, Armed Forces Reserve Center Los Alamitos Airfield (17). The 1994 ACUIZ noise level contours were based on 55,000 aircraft operations. The noise level contours shown on Exhibit 3-B are a modified version of the 1994 ACUIZ Noise Level Contours published by the ALUC in 1995. Based on the AELUP noise level contours, shown on Exhibit 3-B, the majority of the Project site sits within the 60 dBA CNEL but outside the 65 dBA CNEL noise level contour boundary of the JFTB Los Alamitos.

Exhibit 3-C shows the Project site in relation to the airport’s noise level contour boundaries, as more recently published in 2020 by the US Army Public Health Center in the Noise Assessment for Los Alamitos Airfield, Joint Forces Training Base Los Alamitos (18). The more recent 2020 noise level contours are based on 46,235 aircraft operations. As shown on Exhibit 3-C, a portion of the northwestern portion of the Project site is within the 60 dBA CNEL noise level contour boundary of the JFTB Los Alamitos.

This analysis relies on the more recent 2020 noise level contours developed by the US Army Public Health Center. The reliance on this more recent information is justified because the noise level contours included in the AELUP were originally established based on data collected almost four decades ago in 1987 as part of an earlier US Army USAEHA assessment published in 1994. The 2020 noise level contours reflect the most current data and analysis as to existing and projected noise environments at the Project site. In addition, the 2020 noise level contours were generated based on current background information using the Department of Defense aircraft noise model NoiseMap, which is a suite of computer programs and components developed by the US Air Force to predict noise exposure near an airfield/runway due to aircraft flight, maintenance, and ground run-up operations. The 1994 report was based on information available at that time related to airfield and heliport planning criteria, air installation compatible use zone study documents from other military installations, environmental noise assessments for the Los Alamitos Armed Forces Reserve Center, then-existing and proposed airfield operations, and other information. By comparison, the 2020 noise level contours are more current, reflecting more recent existing and proposed airfield operations as well as other information.

The noise criteria identified in the Airport Environs Land Use Plan (AELUP) for Joint Forces Training Base Los Alamitos (16) are guidelines to evaluate the land use compatibility of aircraft-related noise. The compatibility criteria, shown on Exhibit 3-D, provides a planning tool to gauge the compatibility of land uses relative to existing and future exterior noise levels. Residential land uses located outside the 60 dBA contour are considered normally consistent, residential land uses located within the 60 dBA contour are considered conditionally consistent and are required to

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23 ensure that the interior CNEL does not exceed 45 dBA CNEL. Residential land uses located within the 65 dBA contour are considered normally inconsistent.

This is consistent with the City of Los Alamitos noise compatibility standards which states residential land uses exposed to noise levels ranging from 60-65 dBA CNEL are considered “Normally Compatible”, and requires new construction or development to conduct a detailed analysis of the noise reduction requirements to verify any needed noise insulation features are included in the design. The City General Plan states, “conventional construction, with closed windows and fresh air supply systems or air conditioning, will normally suffice.” Relative to noise from JFTB Los Alamitos, the General Plan states, “homes within the moderate noise impact zone (between 60 and 65 dBA CNEL) could be seriously disturbed by single noise events, but are still considered compatible by the AELUP.”

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24 EXHIBIT 3-B: AELUP AIRPORT NOISE LEVEL CONTOUR BOUNDARIES

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25 EXHIBIT 3-C: APHC 2020 AIRPORT NOISE LEVEL CONTOUR BOUNDARIES

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26 EXHIBIT 3-D: LIMITATIONS ON LAND USE DUE TO AIRCRAFT NOISE

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27 4 SIGNIFICANCE CRITERIA
The following significance criteria are based on currently adopted guidance provided by Appendix G of the California Environmental Quality Act (CEQA) Guidelines. (1) For the purposes of this report, impacts would be potentially significant if the Project results in or causes:

A. Generation of a substantial temporary or permanent increase in ambient noise levels in the vicinity of the project in excess of standards established in the local general plan or noise ordinance, or applicable standards of other agencies?
B. Generation of excessive ground-borne vibration or ground-borne noise levels? C. For a project located within the vicinity of a private airstrip or an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project expose people residing or working in the project area to excessive noise levels? While the City of Los Alamitos General Plan Guidelines provide direction on noise compatibility and establish noise standards by land use type that are sufficient to assess the significance of noise impacts, they do not define the levels at which increases are considered substantial for use under Threshold A. Similarly, the City of Los Alamitos General Plan Guidelines do not define the vibration levels at which temporary or constant vibrations are considered substantial for use under Threshold B. CEQA Appendix G Threshold C applies to nearby public and private airports, if any, and the Project’s land use compatibility. Table 4-1 shows the significance criteria summary matrix.

4.1 NOISE LEVEL INCREASES (THRESHOLD A)
Noise level increases resulting from the Project are evaluated based on the Appendix G CEQA Guidelines described above at the closest sensitive receiver locations. Under CEQA, consideration must be given to the magnitude of the increase, the existing baseline ambient noise levels, and the location of noise-sensitive receivers to determine if a noise increase represents a significant environmental impact. This approach recognizes that there is no single noise increase that renders the noise impact significant. (19) This is primarily because of the wide variation in individual thresholds of annoyance and differing individual experiences with noise.

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

In general, the more a new noise exceeds the previously existing ambient noise level, the less acceptable the new noise will typically be judged. The Federal Interagency Committee on Noise (FICON) (20) developed guidance to be used for the assessment of project-generated increases in noise levels that consider the ambient noise level. The FICON recommendations are based on studies that relate aircraft noise levels to the percentage of persons highly annoyed by aircraft noise. Although the FICON recommendations were specifically developed to assess aircraft noise impacts, these recommendations are often used in environmental noise impact assessments involving the use of cumulative noise exposure metrics, such as the average-daily noise level (CNEL) and equivalent continuous noise level (Leq).

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28 The FICON guidance provides an established source of criteria to assess the impacts of substantial temporary or permanent increase in baseline ambient noise levels. Based on the FICON criteria, the amount to which a given noise level increase is considered acceptable is reduced when the without Project (baseline) noise levels are already shown to exceed certain land-use specific exterior noise level criteria. The specific levels are based on typical responses to noise level increases of 5 dBA or readily perceptible, 3 dBA or barely perceptible, and 1.5 dBA depending on the underlying without Project noise levels for noise-sensitive uses. These levels of increases and their perceived acceptance are consistent with guidance provided by both the Federal Highway Administration (3 p. 9) and Caltrans (21 p. 2_48).

4.2 VIBRATION (THRESHOLD B)
As described in Section 3.6 the vibration impacts originating from the construction of 4665 Lampson Avenue, vibration-generating activities are appropriately evaluated the thresholds of significance outlined in the Caltrans Transportation and Construction Vibration Guidance Manual, (11 p. 38). These guidelines identify the maximum acceptable continuous vibration building damage threshold of 0.3 PPV (in/sec) for “older residential structures” which is used in this noise study to assess potential impacts due to Project construction vibration levels.

4.3 AIRCRAFT/AIRPORT (THRESHOLD C)
The City provides policies regarding compatibility with JFTB Los Alamitos in Policy 4.1, Land use compatibility.

The noise compatibility criteria identified in the AELUP are guidelines to evaluate the land use compatibility of aircraft-related noise. The compatibility criteria, shown on Exhibit 3-D, indicates residential land uses exposed to noise levels less than 65 dBA CNEL are “normally consistent” and no special noise reduction requirements are identified. Residential land uses exposed to noise levels less than 70 dBA CNEL are considered “conditionally consistent” with the ALEUP and would be required to ensure that the interior CNEL does not exceed 45 dBA CNEL. For noise levels greater than 70 dBA CNEL, the ALUEP considers residential land use inconsistent, unless interior noise levels are reduced to 45 dBA CNEL and that all units are interior oriented to preclude impacts on exterior use areas. The ALEUP does not require any additional considerations for exterior locations exposed to noise levels below 70 dBA CNEL.

The AELUP compatibility criteria are generally consistent with the City of Los Alamitos General Plan Policy 4.1, where the residential land uses of the Project are considered clearly compatible with unmitigated exterior noise levels of less than 60 dBA CNEL and normally compatible with unmitigated exterior noise levels approaching 70 dBA CNEL, new construction or development should be undertaken only after detailed analysis of the noise reduction requirements are made and needed noise insulation features in the design are determined. Conventional construction, with closed windows and fresh air supply systems or air conditioning, will normally suffice. For normally incompatible exterior noise levels, exceeding 70 dBA CNEL, new construction or development should be discouraged. If new construction or development does proceed, a detailed analysis of the noise reduction requirements are made and needed noise insulation features must be included in the design.

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29 Therefore, for purposes of this analysis, exposure of exterior use areas to noise levels in excess of 70 dBA CNEL would be considered significant, and exposure of residential land uses to noise levels in excess of 65 dBA CNEL would be significant unless noise levels in interior habitable rooms are reduced to 45 dBA CNEL.

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

TABLE 4-1: SIGNIFICANCE CRITERIA SUMMARY
Analysis Condition(s)
Significance Criteria
Daytime Nighttime
On-Site
Traffic1
Exterior Noise Level Criteria1 See Exhibit 3A
Interior Noise Level Standard1 45 dBA CNEL
On-Site
Aircraft2
Exterior Noise Level Criteria1,2 See Exhibits 3A and 3D Interior Noise Level Standard2 45 dBA CNEL
Off-Site
Traffic3
If ambient is < 60 dBA CNEL3 ≥ 5 dBA CNEL Project increase If ambient is 60 - 65 dBA CNE3L ≥ 3 dBA CNEL Project increase If ambient is > 65 dBA CNEL3 ≥ 1.5 dBA CNEL Project increase Operational
Exterior Noise Level Standards4
55 dBA Leq 50 dBA Leq
If ambient is < 60 dBA Leq3 ≥ 5 dBA Leq Project increase If ambient is 60 - 65 dBA Leq3 ≥ 3 dBA Leq Project increase If ambient is > 65 dBA Leq3 ≥ 1.5 dBA Leq Project increase Construction
Noise Level Threshold5
80 dBA Leq
Vibration Level Threshold6 0.30 in/sec PPV
1 City of Los Alamitos General Plan Public Facilities and Safety Element. 2 Orange County ALUC, Airport Environs Land Use Plan for Joint Forces Training Base Los Alamitos, August 2017. 3 FICON, 1992 4 City of Los Alamitos Municipal Code, Section 17.20.050 5 Federal Transit Administration, Transit Noise and Vibration Impact Assessment Manual. 6 Caltrans Transportation and Construction Vibration Manual, April 2020 Table 19. "Daytime" = 7:00 a.m. to 10:00 p.m.; "Nighttime" = 10:00 p.m. to 7:00 a.m.

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31 5 EXISTING NOISE LEVEL MEASUREMENTS
To assess the existing noise level environment, four 24-hour noise level measurements were taken at sensitive receiver locations in the Project study area. The receiver locations were selected to describe and document the existing noise environment within the Project study area.

Exhibit 5-A provides the boundaries of the Project study area and the noise level measurement locations. To fully describe the existing noise conditions, noise level measurements were collected by Urban Crossroads, Inc. on Monday, May 23rd, 2022. Appendix 5.1 includes study area photos.

5.1 MEASUREMENT PROCEDURE AND CRITERIA
To describe the existing noise environment, the hourly noise levels were measured during typical weekday conditions over a 24-hour period. By collecting individual hourly noise level measurements, it is possible to describe the daytime and nighttime hourly noise levels and calculate the 24-hour CNEL. The long-term noise readings were recorded using Piccolo Type 2 integrating sound level meter and dataloggers. The Piccolo sound level meters were calibrated using a Larson-Davis calibrator, Model CAL 150. All noise meters were programmed in "slow" mode to record noise levels in "A" weighted form. The sound level meters and microphones were equipped with a windscreen during all measurements. All noise level measurement equipment satisfies the American National Standards Institute (ANSI) standard specifications for sound level meters ANSI S1.4-2014/IEC 61672-1:2013. (22)

5.2 NOISE MEASUREMENT LOCATIONS
The long-term noise level measurements were positioned as close to the nearest sensitive receiver locations as possible to assess the existing ambient hourly noise levels surrounding the Project site. Actual measurement locations may be affected by location access, equipment security, and proximity to noise sources or solid objects that would affect the measurement and thus may be located at locations that have similar acoustic conditions as the desired locations.

Both Caltrans and the FTA recognize that it is not reasonable to collect noise level measurements that can fully represent any part of a private yard, patio, deck, or balcony normally used for human activity when estimating impacts for new development projects. This is demonstrated in the Caltrans general site location guidelines which indicate that, sites must be free of noise contamination by sources other than sources of interest. Avoid sites located near sources such as barking dogs, lawnmowers, pool pumps, and air conditioners unless it is the express intent of the analyst to measure these sources. (9) Further, FTA guidance states, that it is not necessary nor recommended that existing noise exposure be determined by measuring at every noise-sensitive location in the project area. Rather, the recommended approach is to characterize the noise environment for clusters of sites based on measurements or estimates at representative locations in the community. (7)

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32 EXHIBIT 5-A: AMBIENT NOISE MEASUREMENT LOCATIONS

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33 Based on recommendations of Caltrans and the FTA, it is not necessary to collect measurements at each individual building or residence, because each measurement represents a group of locations that share acoustical equivalence. (7) In other words, the area represented by the measurement location shares similar shielding, terrain, and geometric relationship to the reference noise source as the receiver location. Receivers represent a location of noise sensitive areas and are used to estimate the future noise level impacts. Collecting reference ambient noise level measurements at the nearby sensitive receiver locations allows for a comparison of the before and after Project noise levels and is necessary to assess potential noise impacts due to the Project’s contribution to the ambient noise levels.

5.3 NOISE MEASUREMENT RESULTS
The noise measurements presented below focus on the average or equivalent sound levels (Leq).

The equivalent sound level (Leq) represents a steady state sound level containing the same total energy as a time varying signal over a given sample period. Table 5-1 identifies the hourly daytime (7:00 a.m. to 10:00 p.m.) and nighttime (10:00 p.m. to 7:00 a.m.) noise levels at each noise level measurement location. Appendix 5.2 provides a summary of the existing hourly ambient noise levels.

TABLE 5-1: 24 HOUR AMBIENT NOISE LEVEL MEASUREMENTS
Location1 Description
Energy Average
Noise Level
(dBA Leq)
2 Daytime Nighttime
L1 Located north of the Project site near Arbor Dog
Park at 4665 Lampson Avenue. 49.9 42.4
L2 Located east of the Project site near single-family
residence at 5001 Lunar Drive. 60.8 52.4
L3 Located southwest of the Project site near singlefamily residence at 4701 Ironwood Avenue. 68.7 60.7 L4
Located west of the Project site near Old Ranch
Country Club Golf Course at 3901 Lampson
Avenue.

56.5 55.1
1 See Exhibit 5-A for the noise level measurement locations. 2 Energy (logarithmic) average levels. The long-term 24-hour measurement worksheets are included in Appendix 5.2. "Daytime" = 7:00 a.m. to 10:00 p.m.; "Nighttime" = 10:00 p.m. to 7:00 a.m.

Table 5-1 provides the (energy average) noise levels used to describe the daytime and nighttime ambient conditions. These daytime and nighttime energy average noise levels represent the average of all hourly noise levels observed during these time periods expressed as a single number. Appendix 5.2 provides summary worksheets of the noise levels for each hour as well as

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34 the minimum, maximum, L1, L2, L5, L8, L25, L50, L90, L95, and L99 percentile noise levels observed during the daytime and nighttime periods.

The background ambient noise levels in the Project study area are dominated by the transportation-related noise associated with the arterial roadway network and the nearby community facility land uses, including but not limited to JFTB Los Alamitos, Navy Golf Course, and Arbor Park located adjacent to the northern, eastern, western Project site boundaries. This includes the auto and truck activities on Lampson Avenue adjacent to the Project site and near the noise level measurement locations. The 24-hour existing noise level measurements shown on Table 5-1 present the worst-case existing unmitigated ambient noise conditions.

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35 6 TRAFFIC NOISE METHODS AND PROCEDURES
The following section outlines the methods and procedures used to estimate and analyze the future traffic noise environment. Consistent with the City of Los Alamitos General Plan Policies for residential land use, all transportation related noise levels are presented in terms of the 24-hour CNEL.

6.1 FHWA TRAFFIC NOISE PREDICTION MODEL
The estimated roadway noise impacts from vehicular traffic were calculated using a computer program that replicates the Federal Highway Administration (FHWA) Traffic Noise Prediction Model- FHWA-RD-77-108. (23) The FHWA Model arrives at a predicted noise level through a series of adjustments to the Reference Energy Mean Emission Level (REMEL). In California the national REMELs are substituted with the California Vehicle Noise (Calveno) Emission Levels. (24) Adjustments are then made to the REMEL to account for: the roadway classification (e.g., collector, secondary, major or arterial), the roadway active width (i.e., the distance between the center of the outermost travel lanes on each side of the roadway), the total average daily traffic (ADT), the travel speed, the percentages of automobiles, medium trucks, and heavy trucks in the traffic volume, the roadway grade, the angle of view (e.g., whether the roadway view is blocked), the site conditions ("hard" or "soft" relates to the absorption of the ground, pavement, or landscaping), and the percentage of total ADT which flows each hour throughout a 24-hour period.

6.1.2 ON-SITE TRAFFIC NOISE PREDICTION MODEL INPUTS
The on-site roadway parameters including the average daily traffic (ADT) volumes used for this study are presented on Table 6-1. Although the Project site is located within the City of Los Alamitos, the majority of the roadways lies within the City of Seal Beach. Based on the City of Seal Beach General Plan Circulation Element, Lampson Avenue is classified as 4-lane Secondary Arterial. (25) Future average daily traffic volumes needed to assess the future on-site traffic noise environment and to identify the appropriate noise abatement measures that address the worstcase future noise conditions, shown on Table 6-1, were obtained from the 4665 Lampson Avenue Traffic Analysis prepared by Urban Crossroads on February 3, 2023 (6). The vehicle speed is based on the posted speed limit for Lampson Avenue. Soft site conditions were used to analyze the traffic noise impacts within the Project study area which account for the sound propagation loss over natural surfaces such as normal earth and ground vegetation. Research conducted by Caltrans has shown that due to the mix of ground types in actual situations, the hard site condition over predicted traffic noise levels and the use of soft site conditions is more appropriate for the application of the FHWA traffic noise prediction model . (26)

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36 TABLE 6-1: ON SITE ROADWAY PARAMATERS
Roadway
Segment Lanes Classification1
Roadway
Capacity
Volume1
Speed
Limit
(mph)2
Site
Conditions
Lampson
Avenue 4 Secondary Arterial 15,150 45 Soft
1 Source: 4665 Lampson Avenue Traffic Analysis Urban Crossroads, Inc. February 2023. 2 Posted speed limits.

Table 6-2 presents the time-of-day vehicle splits by vehicle type, and Table 6-3 presents the total traffic flow distributions (vehicle mixes) used for this analysis. The vehicle mix provides the hourly distribution percentages of automobile, medium trucks, and heavy trucks for input into the FHWA Model based on roadway types. To predict the future noise environment at each building within the Project site, coordinate information was collected to identify the noise transmission path between the noise source and receiver. The coordinate information is based on the Project site plan showing the plotting of each Project building in relationship to Lampson Avenue, as shown in Exhibit 1-B and in Appendix 6.1.

TABLE 6-2: TIME OF DAY VEHICLE SPLITS
Time Period
Vehicle Type
Autos Medium
Trucks
Heavy
Trucks
Daytime (7:00 a.m. - 7:00 p.m.) 77.5% 84.8% 86.5%
Evening (7:00 p.m. - 10:00 p.m.) 12.9% 4.9% 2.7%
Nighttime (10:00 p.m. - 7:00 a.m.) 9.6% 10.3% 10.8%
Total: 100.0% 100.0% 100.0%
Source: Typical Southern California vehicle mix.

TABLE 6-3: DISTRIBUTION OF FLOW BY VEHICLE TYPE (VEHICLE MIX) Roadway
Total % Traffic Flow
Total
Autos Medium Trucks Heavy Trucks
All Roadways 97.42% 1.84% 0.74% 100.00%
Source: Typical Southern California vehicle mix.

6.1.2 OFF-SITE TRAFFIC NOISE PREDICTION MODEL INPUTS
Table 6-4 presents the roadway parameters used to assess the Project’s off-site transportation noise impacts for Existing, Opening Year (2026) and General Plan Buildout (2045) Conditions, with and without Project Conditions. Table 6-4 identifies the fourteen (14) study area roadway segments, the distance from the centerline to adjacent land use based on the functional roadway classifications per the City of Los Alamitos General Plan Circulation Element, and the posted vehicle speeds.

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37 TABLE 6-4: OFF-SITE ROADWAY PARAMETERS
ID Roadway Segment Receiving
Land Use1
Distance from
Centerline to
Nearest Adjacent
Land Use (Feet)2
Vehicle
Speed
(mph)3
1 Lampson Ave. e/o Los Alamitos Blvd. Sensitive 40' 45
2 Lampson Ave. e/o Old Ranch Plaza Sensitive 40' 45
3 Lampson Ave. e/o Basswood St. Sensitive 40' 45
4 Lampson Ave. e/o Candleberry St. Sensitive 40' 45
5 Lampson Ave. e/o Heather St. Sensitive 40' 45
6 Lampson Ave. e/o Driveway 1 Sensitive 40' 45
7 Lampson Ave. e/o Driveway 2 Sensitive 40' 45
8 Lampson Ave. e/o Rose St. Sensitive 40' 45
9 Lampson Ave. e/o Tulip St. Sensitive 40' 45
10 Lampson Ave. e/o Valley View St. Sensitive 40' 45
11 Los Alamitos Blvd. n/o Lampson Ave. Sensitive 73' 40 12 Los Alamitos Blvd. s/o Lampson Ave. Non-Sensitive 73' 40 13 Valley View St. n/o Lampson Ave. Sensitive 73' 45
14 Valley View St. s/o Lampson Ave. Sensitive 73' 45 1
Source: City of Los Alamitos Land Use Element Figure 1, City of Seal Beach General Plan Land Use Element, Figure 4. 2 Distance to adjacent land use is based upon the right-of-way distances for each functional roadway classification provided in the City of Seal Beach Circulation Element.
3 Posted speed limits in the Project study area.

The average daily traffic volumes used for this study are presented on Table 6-5 and are based on 4665 Lampson Avenue Traffic Analysis prepared by Urban Crossroads, Inc. (6) Table 6-2 presents the time of day vehicle splits and Table 6-3 presents the traffic flow distributions (vehicle mix) used for this analysis. The vehicle mix provides the hourly distribution percentages of automobile, medium trucks, and heavy trucks for input into the FHWA noise prediction model.

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38 TABLE 6-5: AVERAGE DAILY TRAFFIC VOLUMES
ID Roadway Segment
Existing OY 2026 GBPO 2045
Without
Project
With
Project
Without
Project
With
Project
Without
Project
With
Project
1 Lampson Ave. e/o Los Alamitos Blvd. 17,350 18,250 20,350 21,250 22,350 23,300 2 Lampson Ave. e/o Old Ranch Plaza 16,550 17,450 19,050 19,950 20,000 20,900 3 Lampson Ave. e/o Basswood St. 13,150 14,100 15,200 16,150 16,000 16,900 4 Lampson Ave. e/o Candleberry St. 11,450 12,350 13,500 14,400 14,150 15,100 5 Lampson Ave. e/o Heather St. 11,650 12,600 13,750 14,700 14,450 15,350 6 Lampson Ave. e/o Driveway 1 11,450 12,350 13,600 14,500 14,250 15,150 7 Lampson Ave. e/o Driveway 2 11,450 12,200 13,600 14,350 14,250 15,000 8 Lampson Ave. e/o Rose St. 12,050 12,800 14,300 15,050 15,000 15,750 9 Lampson Ave. e/o Tulip St. 13,000 13,750 15,450 16,200 16,200 16,950 10 Lampson Ave. e/o Valley View St. 10,200 10,450 11,400 11,650 12,700 12,950 11 Los Alamitos Blvd. n/o Lampson Ave. 38,350 41,650 41,150 44,450 48,550 48,900 12 Los Alamitos Blvd. s/o Lampson Ave. 36,650 37,250 42,250 42,850 46,500 47,050 13 Valley View St. n/o Lampson Ave. 41,500 41,700 46,100 46,300 50,750 50,900 14 Valley View St. s/o Lampson Ave. 40,850 41,200 45,150 45,500 49,650 50,000 1 4665 Lampson Traffic Analysis, Urban Crossroads, Inc.

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39 7 ON-SITE TRAFFIC NOISE IMPACTS
An on-site exterior traffic noise impact analysis has been completed to determine the noise exposure levels that would result from adjacent traffic noise sources in the Project study area, and to identify potential noise abatement measures for the proposed Project that would achieve acceptable Project exterior and interior noise levels in compliance with the City of Los Alamitos land use and noise compatibility policies. The primary source of traffic noise affecting the Project site is from Lampson Avenue. The Project will also experience some background traffic noise from the Project’s internal local streets, however, due to low traffic volume/speed, traffic noise from these roads will not make a significant contribution to the noise environment.

7.1 ON-SITE EXTERIOR TRAFFIC NOISE ANALYSIS
Using the FHWA and FTA noise prediction methodologies and the parameters outlined in Tables 6-1 thru 6-3, the expected future exterior noise levels at the Project buildings facing Lampson Avenue were calculated. Table 8-1 presents a summary of future exterior noise levels at the building façade of each floor. The on-site traffic noise level impacts indicate that noise levels at the Project buildings adjacent to Lampson Avenue would experience unmitigated exterior noise levels of ranging from 64.6 to 72.8 dBA CNEL. The on-site traffic noise analysis calculations are provided in Appendix 7.1.

To satisfy the City of Los Alamitos normally acceptable exterior noise level standard for residential land uses construction of a seven-foot-high noise barrier along Lampson Avenue, as shown on the Exhibit ES-A. With construction of this barrier, common outdoor activity areas with exposure to Lampson Avenue traffic noise would be exposed to noise levels less than 65 dBA CNEL which would satisfy the City of Los Alamitos clearly acceptable exterior noise level standard for multifamily residential land uses. With the proposed noise barrier shown on Exhibit ES-A, the future exterior noise levels at the single-family backyards and multi-family common outdoor activity areas will range from 58.3 to 63.6 dBA CNEL. This noise analysis shows that the recommended noise barrier will satisfy the City of Los Alamitos normally acceptable exterior noise level standard for single-family and clearly acceptable exterior noise level standard for multi-family residential land uses.

TABLE 7-1: EXTERIOR NOISE LEVELS (DBA CNEL)
Receiver Location
(Land Use Type) Source
Unmitigated
Noise Level
(dBA CNEL)
Mitigated
Noise Level
(dBA CNEL)
Barrier
Height
(Feet)
Land Use
Compatibility3
Apartments Lampson Avenue 72.8 63.8 7.0 Clearly Acceptable Single Family Lampson Avenue 72.8 63.8 7.0 Clearly Acceptable Park Lampson Avenue 64.6 58.3 7.0 Clearly Acceptable 1
Exterior noise level calculations are included in Appendix 7.1. 2 Barrier heights are based on the Project site plan included in Appendix 6.1. 3 City of Los Alamitos General Plan Public Facilities and Safety Element (Table 4).

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40 7.2 ON-SITE INTERIOR TRAFFIC NOISE ANALYSIS
To ensure that the interior traffic noise levels comply with the City of Los Alamitos interior noise level standards, future noise levels were calculated at the first and second-floor building facades.

7.2.1 NOISE REDUCTION METHODOLOGY
The interior noise level is the difference between the predicted exterior noise level at the building facade and the noise reduction of the structure. Typical building construction will provide a Noise Reduction (NR) of approximately 12 dBA with "windows open" and a minimum 25 dBA noise reduction with "windows closed." However, sound leaks, cracks and openings within the window assembly can greatly diminish its effectiveness in reducing noise. Several methods are used to improve interior noise reduction, including: (1) weather-stripped solid core exterior doors; (2) upgraded dual glazed windows; (3) mechanical ventilation/air conditioning; and (4) exterior wall/roof assembles free of cut outs or openings.

7.2.2 INTERIOR NOISE LEVEL ASSESSMENT
It is our understanding that the Project will provide mechanical ventilation (e.g. air conditioning) in all units. Therefore, Tables 7-2 and 7-3 present interior noise levels based on a windows-closed condition. Table 7-2 shows that the future noise levels at the first-floor building façades adjacent to Lampson Avenue are estimated to be 63.6 dBA CNEL with interior noise levels of

38.6 dBA CNEL. The first-floor interior noise level analysis shows that the City of Los Alamitos 45 dBA CNEL interior noise standards can be satisfied using standard construction for all firstfloor units. The on-site traffic interior noise analysis calculations are provided in Appendix 7.1.

TABLE 7-2: FIRST FLOOR INTERIOR TRAFFIC NOISE LEVELS
Receiver Location
(Land Use Type)
Noise
Level
at Façade1
Required
Interior
NR2
Estimated
Interior
NR3
Upgraded
Windows4
Interior
Noise
Level5
Threshold Threshold
Exceeded?
Apartments 63.6 18.6 25.0 No 38.6 45 No
Single Family 63.6 18.6 25.0 No 38.6 45 No 1
Exterior noise level at the facade with a windows closed condition requiring a means of mechanical ventilation (e.g. air conditioning). 2 Noise reduction required to satisfy the 45 dBA CNEL interior noise standards. 3 Estimated minimum interior noise reduction.
4 Does the required interior noise reduction trigger upgraded with a minimum STC rating of greater than 27? 5 Estimated interior noise level with minimum STC rating for all windows. "NR" = Noise reduction
Table 7-3 shows the future noise levels at the second-floor building façades adjacent to Lampson Avenue are estimated to be 71.3 dBA CNEL with interior noise levels of 46.3 dBA CNEL. Based on the second-floor interior noise level analysis, to comply with the City of Los Alamitos 45 dBA CNEL interior noise standards second floor units and habitable rooms would require windows with an STC rating of 29.

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41 TABLE 7-3: SECOND FLOOR INTERIOR TRAFFIC NOISE LEVELS Receiver Location
(Land Use Type)
Noise
Level
at Façade1
Required
Interior
NR2
Estimated
Interior
NR3
Upgraded
Windows4
Interior
Noise
Level5
Threshold Threshold
Exceeded?
Apartments 71.3 26.3 25.0 No 46.3 45 Yes
Single Family 71.3 26.3 25.0 No 46.3 45 Yes 1
Exterior noise level at the facade with a windows closed condition requiring a means of mechanical ventilation (e.g. air conditioning). 2 Noise reduction required to satisfy the 45 dBA CNEL interior noise standards. 3 Estimated minimum interior noise reduction.
4 Does the required interior noise reduction trigger upgraded with a minimum STC rating of greater than 27? 5 Estimated interior noise level with minimum STC rating for all windows. "NR" = Noise reduction

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43 8 OFF-SITE TRAFFIC NOISE IMPACTS
To assess the off-site traffic CNEL noise level impacts associated with development of the proposed Project, noise level contours were developed based on 4665 Lampson Avenue Traffic Impact Analysis. (6) Noise level contour boundaries represent the equal levels of noise exposure and are measured in CNEL from the center of the roadway. Noise level contours were developed for the following traffic scenarios:
 Existing Conditions (2023): This scenario refers to existing traffic conditions.  Existing Plus Project Conditions (2023+P): This scenario refers to existing traffic conditions plus project traffic increases.
 Opening Year (2026) Conditions (OY 2026): This scenario includes Existing traffic volumes plus an ambient growth factor of 8.24% plus traffic from pending and approved but not yet constructed known development projects in the area.
 Opening Year (2026) Plus Project Conditions (OY 2026+P): This scenario includes Opening Year Cumulative (2026) Without Project volumes plus Project traffic increases.  General Plan Buildout (2045) Without Project Conditions (GBPO): This scenario includes Existing traffic volumes plus an ambient growth factor of 14% plus traffic from pending and approved but not yet constructed known development projects in the area.  General Plan Buildout (2045) With Project Conditions (GBPO+P): This scenario includes General Plan Buildout Without Project volumes plus Project traffic increases.

8.1 TRAFFIC NOISE LEVEL CONTOURS
Noise contours were used to assess the Project's incremental 24-hour dBA CNEL traffic-related noise impacts at land uses adjacent to roadways conveying Project traffic. The noise contours represent the distance to noise levels of a constant value and are measured from the center of the roadway for the 70, 65, and 60 dBA CNEL noise levels. The noise contours do not consider the effect of any existing noise barriers or topography that may attenuate ambient noise levels.

In addition, because the noise contours reflect modeling of vehicular noise on area roadways, they appropriately do not reflect noise contributions from the surrounding stationary noise sources within the Project study area.

Tables 8-1 through 8-6 present a summary of the exterior dBA CNEL traffic noise levels. Roadway segments are analyzed in each of the following timeframes: Existing, Opening Year 2022 with and without Project Buildout, General Plan Buildout (2045) with and without Project conditions.

Appendix 8.1 includes a summary of the dBA CNEL traffic noise level contours for each of the traffic scenarios.

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44 TABLE 8-1: EXISTING 2023 WITHOUT PROJECT CONDITIONS NOISE LEVEL CONTOURS ID Road Segment Receiving
Land Use1
CNEL at
Nearest
Receiving
Land Use
(dBA)2
Distance to Contour from
Centerline (Feet)
70 dBA
CNEL
65 dBA
CNEL
60 dBA
CNEL
1 Lampson Ave. e/o Los Alamitos Blvd. Sensitive 71.6 RW 110 236 2 Lampson Ave. e/o Old Ranch Plaza Sensitive 71.4 RW 107 230 3 Lampson Ave. e/o Basswood St. Sensitive 70.4 RW 91 196 4 Lampson Ave. e/o Candleberry St. Sensitive 69.8 RW 83 179 5 Lampson Ave. e/o Heather St. Sensitive 69.8 RW 84 181 6 Lampson Ave. e/o Driveway 1 Sensitive 69.8 RW 83 179
7 Lampson Ave. e/o Driveway 2 Sensitive 69.8 RW 83 179
8 Lampson Ave. e/o Rose St. Sensitive 70.0 RW 86 185
9 Lampson Ave. e/o Tulip St. Sensitive 70.3 RW 90 195
10 Lampson Ave. e/o Valley View St. Sensitive 69.3 RW RW 166 11 Los Alamitos Blvd. n/o Lampson Ave. Sensitive 69.1 RW RW 296 12 Los Alamitos Blvd. s/o Lampson Ave. Non-Sensitive 68.9 RW RW 287 13 Valley View St. n/o Lampson Ave. Sensitive 70.7 RW 176 379 14 Valley View St. s/o Lampson Ave. Sensitive 70.7 RW 174 375 1 Based on a review of existing aerial imagery. Noise sensitive uses limited to existing residential land uses. 2 The CNEL is calculated at the boundary of the right-of-way of each roadway and the property line of the nearest receiving land use. "RW" = Location of the respective noise contour falls within the right-of-way of the road.

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45 TABLE 8-2: EXISTING 2023 WITH PROJECT CONDITIONS NOISE LEVEL CONTOURS ID Road Segment Receiving
Land Use1
CNEL at
Nearest
Receiving
Land Use
(dBA)2
Distance to Contour from
Centerline (Feet)
70 dBA
CNEL
65 dBA
CNEL
60 dBA
CNEL
1 Lampson Ave. e/o Los Alamitos Blvd. Sensitive 71.8 RW 113 244 2 Lampson Ave. e/o Old Ranch Plaza Sensitive 71.6 RW 110 238 3 Lampson Ave. e/o Basswood St. Sensitive 70.6 RW 95 204 4 Lampson Ave. e/o Candleberry St. Sensitive 70.1 RW 87 188 5 Lampson Ave. e/o Heather St. Sensitive 70.1 RW 88 190 6 Lampson Ave. e/o Driveway 1 Sensitive 70.1 RW 87 188
7 Lampson Ave. e/o Driveway 2 Sensitive 70.0 RW 86 186
8 Lampson Ave. e/o Rose St. Sensitive 70.2 RW 89 192
9 Lampson Ave. e/o Tulip St. Sensitive 70.5 RW 94 202
10 Lampson Ave. e/o Valley View St. Sensitive 69.3 RW RW 168 11 Los Alamitos Blvd. n/o Lampson Ave. Sensitive 69.2 RW RW 298 12 Los Alamitos Blvd. s/o Lampson Ave. Non-Sensitive 69.0 RW RW 290 13 Valley View St. n/o Lampson Ave. Sensitive 70.7 RW 176 380 14 Valley View St. s/o Lampson Ave. Sensitive 70.7 RW 175 377 1 Based on a review of existing aerial imagery. Noise sensitive uses limited to existing residential land uses. 2 The CNEL is calculated at the boundary of the right-of-way of each roadway and the property line of the nearest receiving land use. "RW" = Location of the respective noise contour falls within the right-of-way of the road.

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46 TABLE 8-3: OY 2026 WITHOUT PROJECT CONDITIONS NOISE LEVEL CONTOURS ID Road Segment Receiving
Land Use1
CNEL at
Nearest
Receiving
Land Use
(dBA)2
Distance to Contour from
Centerline (Feet)
70 dBA
CNEL
65 dBA
CNEL
60 dBA
CNEL
1 Lampson Ave. e/o Los Alamitos Blvd. Sensitive 72.6 RW 129 277 2 Lampson Ave. e/o Old Ranch Plaza Sensitive 72.0 RW 118 254 3 Lampson Ave. e/o Basswood St. Sensitive 71.1 RW 102 219 4 Lampson Ave. e/o Candleberry St. Sensitive 70.6 RW 94 203 5 Lampson Ave. e/o Heather St. Sensitive 70.7 RW 95 205 6 Lampson Ave. e/o Driveway 1 Sensitive 70.6 RW 94 204
7 Lampson Ave. e/o Driveway 2 Sensitive 70.6 RW 94 204
8 Lampson Ave. e/o Rose St. Sensitive 70.8 RW 98 210
9 Lampson Ave. e/o Tulip St. Sensitive 71.1 RW 103 221
10 Lampson Ave. e/o Valley View St. Sensitive 69.8 RW 83 180 11 Los Alamitos Blvd. n/o Lampson Ave. Sensitive 69.8 RW 152 328 12 Los Alamitos Blvd. s/o Lampson Ave. Non-Sensitive 69.6 RW 149 321 13 Valley View St. n/o Lampson Ave. Sensitive 71.2 RW 189 407 14 Valley View St. s/o Lampson Ave. Sensitive 71.1 RW 186 401 1 Based on a review of existing aerial imagery. Noise sensitive uses limited to existing residential land uses. 2 The CNEL is calculated at the boundary of the right-of-way of each roadway and the property line of the nearest receiving land use. "RW" = Location of the respective noise contour falls within the right-of-way of the road.

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47 TABLE 8-4: OY 2026 WITH PROJECT CONDITIONS NOISE LEVEL CONTOURS ID Road Segment Receiving
Land Use1
CNEL at
Nearest
Receiving
Land Use
(dBA)2
Distance to Contour from
Centerline (Feet)
70 dBA
CNEL
65 dBA
CNEL
60 dBA
CNEL
1 Lampson Ave. e/o Los Alamitos Blvd. Sensitive 72.8 RW 132 284 2 Lampson Ave. e/o Old Ranch Plaza Sensitive 72.2 RW 121 261 3 Lampson Ave. e/o Basswood St. Sensitive 71.3 RW 105 227 4 Lampson Ave. e/o Candleberry St. Sensitive 70.8 RW 98 211 5 Lampson Ave. e/o Heather St. Sensitive 70.9 RW 99 213 6 Lampson Ave. e/o Driveway 1 Sensitive 70.9 RW 98 212
7 Lampson Ave. e/o Driveway 2 Sensitive 70.8 RW 98 210
8 Lampson Ave. e/o Rose St. Sensitive 71.0 RW 101 217
9 Lampson Ave. e/o Tulip St. Sensitive 71.3 RW 106 228
10 Lampson Ave. e/o Valley View St. Sensitive 69.9 RW 84 182 11 Los Alamitos Blvd. n/o Lampson Ave. Sensitive 69.8 RW 153 329 12 Los Alamitos Blvd. s/o Lampson Ave. Non-Sensitive 69.7 RW 150 324 13 Valley View St. n/o Lampson Ave. Sensitive 71.2 RW 189 408 14 Valley View St. s/o Lampson Ave. Sensitive 71.1 RW 187 403 1 Based on a review of existing aerial imagery. Noise sensitive uses limited to existing residential land uses. 2 The CNEL is calculated at the boundary of the right-of-way of each roadway and the property line of the nearest receiving land use. "RW" = Location of the respective noise contour falls within the right-of-way of the road.

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48 TABLE 8-5: GPBO 2045 WITHOUT PROJECT CONDITIONS NOISE LEVEL CONTOURS ID Road Segment Receiving
Land Use1
CNEL at
Nearest
Receiving
Land Use
(dBA)2
Distance to Contour from
Centerline (Feet)
70 dBA
CNEL
65 dBA
CNEL
60 dBA
CNEL
1 Lampson Ave. e/o Los Alamitos Blvd. Sensitive 73.0 RW 137 295 2 Lampson Ave. e/o Old Ranch Plaza Sensitive 72.2 RW 122 262 3 Lampson Ave. e/o Basswood St. Sensitive 71.3 RW 105 226 4 Lampson Ave. e/o Candleberry St. Sensitive 70.8 RW 97 209 5 Lampson Ave. e/o Heather St. Sensitive 70.9 RW 98 212 6 Lampson Ave. e/o Driveway 1 Sensitive 70.8 RW 97 210
7 Lampson Ave. e/o Driveway 2 Sensitive 70.8 RW 97 210
8 Lampson Ave. e/o Rose St. Sensitive 71.0 RW 101 217
9 Lampson Ave. e/o Tulip St. Sensitive 71.3 RW 106 228
10 Lampson Ave. e/o Valley View St. Sensitive 70.2 RW 89 192 11 Los Alamitos Blvd. n/o Lampson Ave. Sensitive 70.2 RW 162 349 12 Los Alamitos Blvd. s/o Lampson Ave. Non-Sensitive 70.1 RW 159 342 13 Valley View St. n/o Lampson Ave. Sensitive 71.6 RW 201 434 14 Valley View St. s/o Lampson Ave. Sensitive 71.5 RW 199 428 1 Based on a review of existing aerial imagery. Noise sensitive uses limited to existing residential land uses. 2 The CNEL is calculated at the boundary of the right-of-way of each roadway and the property line of the nearest receiving land use. "RW" = Location of the respective noise contour falls within the right-of-way of the road.

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49 TABLE 8-6: GPBO 2045 WITH PROJECT CONDITIONS NOISE LEVEL CONTOURS ID Road Segment Receiving
Land Use1
CNEL at
Nearest
Receiving
Land Use
(dBA)2
Distance to Contour from
Centerline (Feet)
70 dBA
CNEL
65 dBA
CNEL
60 dBA
CNEL
1 Lampson Ave. e/o Los Alamitos Blvd. Sensitive 73.2 RW 140 302 2 Lampson Ave. e/o Old Ranch Plaza Sensitive 72.4 RW 125 269 3 Lampson Ave. e/o Basswood St. Sensitive 71.5 RW 109 234 4 Lampson Ave. e/o Candleberry St. Sensitive 71.0 RW 101 217 5 Lampson Ave. e/o Heather St. Sensitive 71.1 RW 102 220 6 Lampson Ave. e/o Driveway 1 Sensitive 71.0 RW 101 218 7 Lampson Ave. e/o Driveway 2 Sensitive 71.0 RW 101 217 8 Lampson Ave. e/o Rose St. Sensitive 71.2 RW 104 224
9 Lampson Ave. e/o Tulip St. Sensitive 71.5 RW 109 235
10 Lampson Ave. e/o Valley View St. Sensitive 70.3 RW 90 194 11 Los Alamitos Blvd. n/o Lampson Ave. Sensitive 70.2 RW 163 351 12 Los Alamitos Blvd. s/o Lampson Ave. Non-Sensitive 70.1 RW 160 345 13 Valley View St. n/o Lampson Ave. Sensitive 71.6 RW 202 435 14 Valley View St. s/o Lampson Ave. Sensitive 71.5 RW 199 430 1 Based on a review of existing aerial imagery. Noise sensitive uses limited to existing residential land uses. 2 The CNEL is calculated at the boundary of the right-of-way of each roadway and the property line of the nearest receiving land use. "RW" = Location of the respective noise contour falls within the right-of-way of the road.

8.2 EXISTING 2023 CONDITION PROJECT TRAFFIC NOISE LEVELS Table 8-1 presents the Existing 2023 without Project conditions CNEL noise levels, which are expected to range from 68.9 to 71.6 dBA CNEL, without accounting for any noise attenuation features such as noise barriers or topography. Table 8-2 shows the Existing 2023 with Project conditions will range from 69.0 to 71.8 dBA CNEL. As shown on Table 8-7 the Existing 2023 with Project will generate a noise level increase of up to 0.3 dBA CNEL on the study area roadway segments. Based on the significance criteria in Section 4.2 for off-site traffic noise impacts, the Project-related noise level increases are considered less than significant under Existing 2023 conditions at the land uses adjacent to roadways conveying Project traffic.

8.3 OY 2026 TRAFFIC NOISE LEVEL INCREASES
Table 8-3 presents the OY 2026 without Project conditions CNEL noise levels, which are expected to range from 69.6 to 72.6 dBA CNEL, without accounting for any noise attenuation features such as noise barriers or topography. Table 8-4 shows the OY 2026 with Project conditions will range from 69.7 to 72.8 dBA CNEL. Table 8-8 shows that the OY 2026 Project off-site traffic noise level increases of up to 0.3 dBA CNEL. Based on the significance criteria for off-site traffic noise presented in Section 4.2 for off-site traffic noise impacts, land uses adjacent to the study area roadway segments would experience less than significant noise level increases due to unmitigated OY 2026 Project-related traffic noise levels.

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50 8.4 GPBO2045 TRAFFIC NOISE LEVEL INCREASES
Table 8-5 presents the GPBO 2045 without Project conditions CNEL noise levels, which are expected to range from 70.1 to 73.0 dBA CNEL, without accounting for any noise attenuation features such as noise barriers or topography. Table 8-6 shows the GPBO 2045 with Project conditions will range from 70.1 to 73.2 dBA CNEL. Table 8-9 shows that the GPBO 2045 Project off-site traffic noise level increases of up to 0.2 dBA CNEL. Based on the significance criteria for off-site traffic noise presented in Section 4.2 for off-site traffic noise impacts, land uses adjacent to the study area roadway segments would experience less than significant noise level increases due to unmitigated GPBO 2045 Project-related traffic noise levels.

8.5 CUMULATIVE TRAFFIC NOISE LEVEL INCREASES
Table 8-10 shows that the Project off-site contribution to cumulative traffic noise level increases range from less than 0.1 to 0.2 dBA CNEL. Based on the significance criteria for off-site traffic noise presented in Section 4.2 for off-site traffic noise impacts, land uses adjacent to the study area roadway segments would not experience substantial noise level increases due to Projectrelated traffic noise level increases and would be considered a less than significant impact.

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51 TABLE 8-7: EXISTING 2023 OFF-SITE PROJECT-RELATED TRAFFIC NOISE IMPACTS ID Road Segment Receiving Land Use1
CNEL at Receiving
Land Use (dBA)2
NoiseSensitive
Land
Use?
Incremental Noise
Level Increase
Threshold3
No
Project
With
Project
Project
Addition Limit Exceeded?
1 Lampson Ave. e/o Los Alamitos Blvd. Sensitive 71.6 71.8 0.2 Yes 1.5 No 2 Lampson Ave. e/o Old Ranch Plaza Sensitive 71.4 71.6 0.2 Yes 1.5 No 3 Lampson Ave. e/o Basswood St. Sensitive 70.4 70.6 0.2 Yes 1.5 No 4 Lampson Ave. e/o Candleberry St. Sensitive 69.8 70.1 0.3 Yes 1.5 No 5 Lampson Ave. e/o Heather St. Sensitive 69.8 70.1 0.3 Yes 1.5 No 6 Lampson Ave. e/o Driveway 1 Sensitive 69.8 70.1 0.3 Yes 1.5 No 7 Lampson Ave. e/o Driveway 2 Sensitive 69.8 70.0 0.2 Yes 1.5 No 8 Lampson Ave. e/o Rose St. Sensitive 70.0 70.2 0.2 Yes 1.5 No 9 Lampson Ave. e/o Tulip St. Sensitive 70.3 70.5 0.2 Yes 1.5 No 10 Lampson Ave. e/o Valley View St. Sensitive 69.3 69.3 0.0 Yes 1.5 No 11 Los Alamitos Blvd. n/o Lampson Ave. Sensitive 69.1 69.2 0.1 Yes 1.5 No 12 Los Alamitos Blvd. s/o Lampson Ave. Non-Sensitive 68.9 69.0 0.1 No n/a No 13 Valley View St. n/o Lampson Ave. Sensitive 70.7 70.7 0.0 Yes 1.5 No 14 Valley View St. s/o Lampson Ave. Sensitive 70.7 70.7 0.0 Yes 1.5 No 1 Based on a review of existing aerial imagery. Noise sensitive uses limited to existing residential land uses. 2 The CNEL is calculated at the boundary of the right-of-way of each roadway and the property line of the receiving land use. 3 Does the Project create an incremental noise level increase exceeding the significance criteria (Table 4-1)?

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52 TABLE 8-8: OY 2026 OFF-SITE PROJECT-RELATED TRAFFIC NOISE IMPACTS ID Road Segment Receiving Land Use1
CNEL at Receiving
Land Use (dBA)2
NoiseSensitive
Land
Use?
Incremental Noise
Level Increase
Threshold3
No
Project
With
Project
Project
Addition Limit Exceeded?
1 Lampson Ave. e/o Los Alamitos Blvd. Sensitive 72.6 72.8 0.2 Yes 1.5 No 2 Lampson Ave. e/o Old Ranch Plaza Sensitive 72.0 72.2 0.2 Yes 1.5 No 3 Lampson Ave. e/o Basswood St. Sensitive 71.1 71.3 0.2 Yes 1.5 No 4 Lampson Ave. e/o Candleberry St. Sensitive 70.6 70.8 0.2 Yes 1.5 No 5 Lampson Ave. e/o Heather St. Sensitive 70.7 70.9 0.2 Yes 1.5 No 6 Lampson Ave. e/o Driveway 1 Sensitive 70.6 70.9 0.3 Yes 1.5 No 7 Lampson Ave. e/o Driveway 2 Sensitive 70.6 70.8 0.2 Yes 1.5 No 8 Lampson Ave. e/o Rose St. Sensitive 70.8 71.0 0.2 Yes 1.5 No 9 Lampson Ave. e/o Tulip St. Sensitive 71.1 71.3 0.2 Yes 1.5 No 10 Lampson Ave. e/o Valley View St. Sensitive 69.8 69.9 0.1 Yes 1.5 No 11 Los Alamitos Blvd. n/o Lampson Ave. Sensitive 69.8 69.8 0.0 Yes 1.5 No 12 Los Alamitos Blvd. s/o Lampson Ave. Non-Sensitive 69.6 69.7 0.1 No n/a No 13 Valley View St. n/o Lampson Ave. Sensitive 71.2 71.2 0.0 Yes 1.5 No 14 Valley View St. s/o Lampson Ave. Sensitive 71.1 71.1 0.0 Yes 1.5 No 1 Based on a review of existing aerial imagery. Noise sensitive uses limited to existing residential land uses. 2 The CNEL is calculated at the boundary of the right-of-way of each roadway and the property line of the receiving land use. 3 Does the Project create an incremental noise level increase exceeding the significance criteria (Table 4-1)?

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53 TABLE 8-9: GPBO 2045 OFF-SITE PROJECT-RELATED TRAFFIC NOISE IMPACTS ID Road Segment Receiving Land Use1
CNEL at Receiving
Land Use (dBA)2
NoiseSensitive
Land
Use?
Incremental Noise
Level Increase
Threshold3
No
Project
With
Project
Project
Addition Limit Exceeded?
1 Lampson Ave. e/o Los Alamitos Blvd. Sensitive 73.0 73.2 0.2 Yes 1.5 No 2 Lampson Ave. e/o Old Ranch Plaza Sensitive 72.2 72.4 0.2 Yes 1.5 No 3 Lampson Ave. e/o Basswood St. Sensitive 71.3 71.5 0.2 Yes 1.5 No 4 Lampson Ave. e/o Candleberry St. Sensitive 70.8 71.0 0.2 Yes 1.5 No 5 Lampson Ave. e/o Heather St. Sensitive 70.9 71.1 0.2 Yes 1.5 No 6 Lampson Ave. e/o Driveway 1 Sensitive 70.8 71.0 0.2 Yes 1.5 No 7 Lampson Ave. e/o Driveway 2 Sensitive 70.8 71.0 0.2 Yes 1.5 No 8 Lampson Ave. e/o Rose St. Sensitive 71.0 71.2 0.2 Yes 1.5 No 9 Lampson Ave. e/o Tulip St. Sensitive 71.3 71.5 0.2 Yes 1.5 No 10 Lampson Ave. e/o Valley View St. Sensitive 70.2 70.3 0.1 Yes 1.5 No 11 Los Alamitos Blvd. n/o Lampson Ave. Sensitive 70.2 70.2 0.0 Yes 1.5 No 12 Los Alamitos Blvd. s/o Lampson Ave. Non-Sensitive 70.1 70.1 0.0 No 3.0 No 13 Valley View St. n/o Lampson Ave. Sensitive 71.6 71.6 0.0 Yes 1.5 No 14 Valley View St. s/o Lampson Ave. Sensitive 71.5 71.5 0.0 Yes 1.5 No 1 Based on a review of existing aerial imagery. Noise sensitive uses limited to existing residential land uses. 2 The CNEL is calculated at the boundary of the right-of-way of each roadway and the property line of the receiving land use. 3 Does the Project create an incremental noise level increase exceeding the significance criteria (Table 4-1)?

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54 TABLE 8-10: CUMULATIVE PROJECT TRAFFIC NOISE INCREASES ID Road Segment Receiving Land Use1
CNEL at Receiving
Land Use (dBA)2 Noise- Sensitive
Land
Use?
Incremental Noise
Level Increase
Threshold3
Existing
GPBO 2045
Without
Project
GPBO
2045 With
Project
Cumulative
Increase
Cumulative
Contribution Limit Exceeded?
1 Lampson Ave. e/o Los Alamitos Blvd. Sensitive 71.6 73.0 73.2 1.6 0.2 Yes 1.5 No 2 Lampson Ave. e/o Old Ranch Plaza Sensitive 71.4 72.2 72.4 1.0 0.2 Yes 1.5 No 3 Lampson Ave. e/o Basswood St. Sensitive 70.4 71.3 71.5 1.1 0.2 Yes 1.5 No 4 Lampson Ave. e/o Candleberry St. Sensitive 69.8 70.8 71.0 1.2 0.2 Yes 1.5 No 5 Lampson Ave. e/o Heather St. Sensitive 69.8 70.9 71.1 1.3 0.2 Yes 1.5 No 6 Lampson Ave. e/o Driveway 1 Sensitive 69.8 70.8 71.0 1.2 0.2 Yes 1.5 No 7 Lampson Ave. e/o Driveway 2 Sensitive 69.8 70.8 71.0 1.2 0.2 Yes 1.5 No 8 Lampson Ave. e/o Rose St. Sensitive 70.0 71.0 71.2 1.2 0.2 Yes 1.5 No 9 Lampson Ave. e/o Tulip St. Sensitive 70.3 71.3 71.5 1.2 0.2 Yes 1.5 No 10 Lampson Ave. e/o Valley View St. Sensitive 69.3 70.2 70.3 1.0 0.1 Yes 1.5 No 11 Los Alamitos Blvd. n/o Lampson Ave. Sensitive 69.1 70.2 70.2 1.1 0.0 Yes 1.5 No 12 Los Alamitos Blvd. s/o Lampson Ave. Non-Sensitive 68.9 70.1 70.1 1.2 0.0 No n/a No 13 Valley View St. n/o Lampson Ave. Sensitive 70.7 71.6 71.6 0.9 0.0 Yes 1.5 No 14 Valley View St. s/o Lampson Ave. Sensitive 70.7 71.5 71.5 0.8 0.0 Yes 1.5 No 1 Based on a review of existing aerial imagery. Noise sensitive uses limited to existing residential land uses. 2 The CNEL is calculated at the boundary of the right-of-way of each roadway and the property line of the receiving land use. 3 Does the Project create an incremental noise level increase exceeding the significance criteria (Table 4-1)?

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55 9 RECEIVER LOCATIONS
To assess the potential for long-term operational and short-term construction noise impacts, the following sensitive receiver locations, as shown on Exhibit 9-A, were identified as representative locations for analysis. Receiver locations are modeled points used to assess impacts. The measurements shown on Exhibit 9-A are representative of receiver locations, because not all receiver locations are accessible (e.g., located on private property, unable to physically access, etc.) Thus, the receiver locations were chosen to be acoustically representative or similar in nature.

Sensitive receivers are generally defined as locations where people reside or where the presence of unwanted sound could otherwise adversely affect the use of the land. Noise-sensitive land uses are generally considered to include schools, hospitals, single-family dwellings, mobile home parks, churches, libraries, and recreation areas. Moderately noise-sensitive land uses typically include multi-family dwellings, hotels, motels, dormitories, out-patient clinics, cemeteries, golf courses, country clubs, athletic/tennis clubs, and equestrian clubs. Land uses that are considered relatively insensitive to noise include business, commercial, and professional developments.

Land uses that are typically not affected by noise include: industrial, manufacturing, utilities, agriculture, undeveloped land, parking lots, warehousing, liquid and solid waste facilities, salvage yards, and transit terminals.

To describe the potential off-site Project noise levels, four representative receiver locations in the vicinity of the Project site were identified. All distances are measured from the Project site boundary to the outdoor living areas (e.g., private backyards) or at the building façade, whichever is closer to the Project site. The selection of receiver locations is based on FHWA guidelines and is consistent with additional guidance provided by Caltrans and the FTA, as previously described in Section 5.2. Other sensitive land uses in the Project study area that are located at greater distances than those identified in this noise study will experience lower noise levels than those presented in this report due to the additional attenuation from distance and the shielding of intervening structures. Distance is measured in a straight line from the project boundary to each receiver location.

R1: Location R1 represents existing noise sensitive Arbor Dog Park at 4665 Lampson Avenue, approximately 173 feet north of the Project site. Receiver R1 is placed at the Park’s open space. A 24-hour noise measurement was taken near this location, L1, to describe the existing ambient noise environment.

R2: Location R2 represents the existing noise sensitive residence at 12462 Lunar Drive, approximately 887 feet east of the Project site. Since there are no private outdoor living areas (backyards) facing the Project site, receiver R2 is placed at the building façade. A 24-hour noise measurement was taken near this location, L2, to describe the existing ambient noise environment.

R3: Location R3 represents the existing noise sensitive residence at 4625 Ironwood Avenue, approximately 82 feet south of the Project site. Receiver R3 is placed at the private outdoor living areas (backyards) facing the Project site. A 24-hour noise measurement was taken near this location, L3, to describe the existing ambient noise environment.

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56 R4: Location R4 represents the existing noise sensitive residence at 12322 Provincetown Street, approximately 5,046 feet west of the Project site. Receiver R4 is placed at the private outdoor living areas (backyards) facing the Project site.

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57 EXHIBIT 9-A: RECEIVER LOCATIONS

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59 10 OPERATIONAL NOISE IMPACTS
This section analyzes the potential stationary-source operational noise impacts at the nearest receiver locations, identified in Section 9, resulting from the operation of the proposed 4665 Lampson Avenue Project. Exhibit 10-A identifies the representative noise source locations used to assess the operational noise levels. This section analyzes the potential operational noise impacts resulting from the operation of roof-top and ground-mounted air conditioning units, parking lot vehicle movements, outdoor activity, and trash enclosure activities associated with the Project.

10.1 OPERATIONAL NOISE SOURCES
This operational noise analysis is intended to describe noise level impacts associated with the expected typical of daytime and nighttime activities at the Project site. The proposed residential development is not expected to include any specific type of operational noise levels beyond the typical noise sources associated with residential land uses in the Project study area. However, to present a conservative approach, on-site Project-only operational noise sources are analyzed in this noise study and are expected to include: roof-top and ground-mounted air conditioning units, parking lot vehicle movements, outdoor activity, and trash enclosure activities.

AIR CONDITIONING UNITS
To assess the noise levels created by the roof-top and ground-mounted air conditioning units, reference noise levels were taken from equipment specifications for a 3- to 5-ton residential packaged air conditioning unit (Carrier 24ABC6). The air conditioning units were modeled as operating 45 minutes per hour during the daytime and 30 minutes at nighttime, which represents the typical maximum operating time for properly sized AC systems. For this noise analysis, 77 air conditioning units are expected to be located on the roof of the proposed affordable apartment buildings and 169 ground-mounted air conditioning units are located adjacent to single family detached residential units (cluster homes) and multifamily units (low-rise), as indicated on the Project site plan. The roof-top air conditioning units are anticipated to be located 3 feet above the roof and ground. At a uniform reference distance of 50 feet the units would generate a reference noise level of 44.4 dBA Leq.

PARKING LOT ACTIVITIES
To determine the noise levels associated with parking lot vehicle movements, Urban Crossroads collected reference noise level measurements over a 24-hour period, at the parking lot for the Panasonic Avionics Corporation in the City of Lake Forest. The peak hour of activity measured over the 24-hour noise level measurement period occurred between 12:00 p.m. to 1:00 p.m., or the typical lunch hour for employees working in the area. The measured reference noise level at 50 feet from parking lot vehicle movements was measured at 56.2 dBA Leq. The parking lot noise levels are mainly due to cars pulling in and out of spaces during peak lunch hour activity and employees talking. Noise associated with parking lot vehicle movements is expected to operate for the entire hour (60 minutes).

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60 EXHIBIT 10-A: OPERATIONAL NOISE SOURCE LOCATIONS

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61 OUTDOOR ACTIVITY AREAS
To describe the outdoor common area courtyards activity areas, a reference noise level measurement was taken by Urban Crossroads, Inc, at Washington Street Park in the City of Escondido. The 4.5-acre park was active during the measurement, and included a gazebo for gathering/parties, picnic tables, restrooms, two half-court basketball courts, two ageappropriate children's playgrounds, game tables, and walking paths. At 50 feet, the reference noise level is 59.9 dBA Leq at a noise source height of 5 feet. The reference noise level measurement includes outdoor eating, drinking, with patrons laughing and talking. Outdoor activities are limited to the daytime hours.

TRASH ENCLOSURE ACTIVITY
To describe the noise levels associated with a trash enclosure activity, Urban Crossroads collected a reference noise level measurement at an existing trash enclosure containing two dumpster bins, at the at the Old Town West Parking structure in the City of Orange. The trash enclosure noise levels describe metal gates opening and closing, metal scraping against concrete floor sounds, dumpster movement on metal wheels, trash dropping into the metal dumpster. The reference noise levels describe trash enclosure noise activities when trash is dropped into an empty metal dumpster, as would occur at the Project site. The measured reference noise level at the uniform 50-foot reference distance is 72.7 dBA Lmax and 57.4 dBA Leq for the trash enclosure activity. The reference noise level describes the expected noise source activities associated with the trash enclosures for each of the Project buildings. Typical trash enclosure activities are estimated to occur for 10 minutes per hour.

10.2 REFERENCE NOISE LEVELS
To estimate the operational noise impacts, reference noise level measurements were collected from similar types of activities to represent the noise levels expected with the development of the proposed Project. While sound pressure levels (e.g., Leq) quantify in decibels the intensity of given sound sources at a reference distance, sound power levels (Lw) are connected to the sound source and are independent of distance. Sound pressure levels vary substantially with distance from the source and diminish because of intervening obstacles and barriers, air absorption, wind, and other factors. Sound power is the acoustical energy emitted by the sound source and is an absolute value that is not affected by the environment. The reference project operational noise levels are based on the Project related noise sources shown on Exhibit 10-A. The reference Project operational sound power levels are summarized in Table 10-1.

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62 TABLE 10-1: REFERENCE NOISE LEVELS
Noise Source
Noise
Source
Height
(Feet)
Min./Hour2 Reference Noise
Level (dBA Leq)
Sound
Power
Level
(dBA) Day Night 6
@ Ref.

Dist.
@ 50
Feet
Air Conditioning Units1 5' 60 60 77.2 44.4 76.0
Parking Lot Movements 5' 60 60 66.6 56.1 87.8
Outdoor Activity 5' 60 0 62.8 59.9 91.5
Trash Enclosure Activity 5' 10 10 72.7 57.4 89.0 1
Carrier 25HBC5 air conditioning unit assumed for ground-mounted and roof-top units, see Appendix 10.1. 2 Anticipated duration (minutes within the hour) of noise activity during typical hourly conditions expected at the Project site. "Daytime" = 7:00 a.m. to 10:00 p.m.; "Nighttime" = 10:00 p.m. to 7:00 a.m.

10.3 CADNAANOISE PREDICTION MODEL
To fully describe the exterior operational noise levels from the Project, Urban Crossroads, Inc. developed a noise prediction model using the CadnaA (Computer Aided Noise Abatement) computer program. CadnaA can analyze multiple types of noise sources using the spatially accurate Project site plan, georeferenced Nearmap aerial imagery, topography, buildings, and barriers in its calculations to predict outdoor noise levels.

Using the ISO 9613 protocol, CadnaA will calculate the distance from each noise source to the noise receiver locations, using the ground absorption, distance, and barrier/building attenuation inputs to provide a summary of noise level at each receiver and the partial noise level contributions by noise source. Consistent with the ISO 9613 protocol, the CadnaA noise prediction model relies on the reference sound power level (Lw) to describe individual noise sources. While sound pressure levels (e.g., Leq) quantify in decibels the intensity of given sound sources at a reference distance, sound power levels (Lw) are connected to the sound source and are independent of distance. Sound pressure levels vary substantially with distance from the source and diminish because of intervening obstacles and barriers, air absorption, wind, and other factors. Sound power is the acoustical energy emitted by the sound source and is an absolute value that is not affected by the environment.

The operational noise level calculations provided in this noise study account for the distance attenuation provided due to geometric spreading, when sound from a localized stationary source (i.e., a point source) propagates uniformly outward in a spherical pattern. A default ground attenuation factor of 0.5 was used in the noise analysis to account for mixed ground representing a combination of hard and soft surfaces. Appendix 10.2 includes the detailed noise model inputs used to estimate the Project operational noise levels presented in this section.

10.4 PROJECT OPERATIONAL NOISE LEVELS
Using the reference noise levels to represent the proposed Project operations that include trash enclosure activity, air conditioning, a loading dock, and parking lot activity, Urban Crossroads, Inc. calculated the unmitigated operational source noise levels that are expected to be generated

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63 at the Project site and the Project-related noise level increases that would be experienced at each of the sensitive receiver locations. Table 10-2 shows the Project operational daytime noise levels.

The hourly noise levels at the off-site receiver locations are expected to range from 18.9 to

48.4 dBA Leq. Appendix 10.2 includes the detailed noise model inputs used to estimate the Project operational noise levels presented in this section.

TABLE 10-2: PROJECT DAYTIME OPERATIONAL NOISE LEVELS
Noise Source1
Operational Noise Levels by Receiver Location
(dBA Lmax)
R1 R2 R3 R4
Air Conditioning Units 40.8 30.8 42.5 16.3
Parking Lot Movements 38.5 31.1 41.7 11.7
Outdoor Activity 40.7 32.7 45.7 13.0
Trash Enclosure Activity 25.6 18.1 28.8 7.1
Total (All Noise Sources) 44.9 36.4 48.4 18.9
1 See Exhibit 10-A for the noise source locations. CadnaA noise model calculations are included in Appendix

10.2. Table 10-3 shows the Project operational noise levels during the nighttime hours of 10:00 p.m. to 7:00 a.m. The nighttime hourly noise levels at the off-site receiver locations are expected to range from 15.6 to 43.3 dBA Leq. Appendix 10.2 includes the detailed noise model inputs including the existing perimeter walls used to estimate the Project operational noise levels presented in this section.

TABLE 10-3: PROJECT NIGHTTIME OPERATIONAL NOISE LEVELS
Noise Source1
Operational Noise Levels by Receiver Location
(dBA Lmax)
R1 R2 R3 R4
Air Conditioning Units 38.1 28.1 39.8 13.6
Parking Lot Movements 37.6 30.2 40.8 10.8
Outdoor Activity 0.0 0.0 0.0 0.0
Trash Enclosure Activity 24.6 17.1 27.8 6.2
Total (All Noise Sources) 40.9 32.3 43.3 15.6
1 See Exhibit 10-A for the noise source locations. CadnaA noise model calculations are included in Appendix

10.2. 10.5 PROJECT OPERATIONAL NOISE LEVEL COMPLIANCE
Tables 10-4 shows the Project operational noise levels during the daytime and nighttime hours.

The daytime hourly noise levels at the off-site receiver locations are expected to range from 18.9 to 48.4 dBA Leq. The nighttime hourly noise levels at the off-site receiver locations are expected to range from 15.6 to 43.3 dBA Leq. Appendix 10.2 includes the detailed noise model inputs used to estimate the Project operational noise levels presented in this section.

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64 TABLE 10-4: OPERATIONAL NOISE LEVEL COMPLIANCE
Receiver
Location1
Project Operational Noise
Levels
(dBA Leq)2
Noise Level Standards
(dBA Leq)3
Noise Level Standards
Exceeded?4
Daytime Nighttime Daytime Nighttime Daytime Nighttime
R1 44.9 40.9 50 55 No No
R2 36.4 32.3 50 55 No No
R3 48.4 43.3 50 55 No No
R4 18.9 15.6 50 55 No No 1
See Exhibit 9-A for the receiver locations.
2 Proposed Project operational noise levels as shown on Table 10-1. 3 City of Los Alamitos Municipal Code, Section 17.20.050 (Appendix 3.1) 4 Do the estimated Project operational noise source activities exceed the noise level standards? "Daytime" = 7:00 a.m. to 10:00 p.m.; "Nighttime" = 10:00 p.m. to 7:00 a.m.

10.6 PROJECT OPERATIONAL NOISE LEVEL INCREASES
To describe the Project operational noise level increases, the Project operational noise levels are combined with the existing ambient noise levels measurements for the nearest receiver locations potentially impacted by Project operational noise sources. Since the units used to measure noise, decibels (dB), are logarithmic units, the Project-operational and existing ambient noise levels cannot be combined using standard arithmetic equations. (9) Instead, they must be logarithmically added using the following base equation:

SPLTotal = 10log10[10SPL1/10 + 10SPL2/10 + … 10SPLn/10] Where “SPL1,” “SPL2,” etc. are equal to the sound pressure levels being combined, or in this case, the Project-operational and existing ambient noise levels. The difference between the combined Project and ambient noise levels describes the Project noise level increases to the existing ambient noise environment. Noise levels that would be experienced at receiver locations when Project-source noise is added to the daytime and nighttime ambient conditions are presented on Tables 10-2 and 10-3, respectively.

As indicated on Tables 10-5 and 10-6, the Project will generate an unmitigated daytime and nighttime operational noise level increases ranging from less than 0.0 to 1.2 dBA Leq at the nearest receiver locations. In effect, the amount to which a given noise level increase is considered acceptable is reduced based on existing ambient noise conditions. Based on the operational noise level increase significance criteria presented in Section 4.2, the Project-related operational noise level increases will satisfy the operational noise level increase criteria at the nearest sensitive receiver locations and the impact will be less than significant.

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65 TABLE 10-5: DAYTIME PROJECT OPERATIONAL NOISE LEVEL INCREASES Receiver
Location1
Total Project
Operational
Noise Level2
Measurement
Location3
Reference
Ambient
Noise
Levels4
Combined
Project
and
Ambient5
Project
Increase6
Increase
Criteria
Increase
Criteria
Exceeded?
R1 38.5 L1 49.9 50.2 0.3 5.0 No R2 31.1 L2 60.8 60.8 0.0 3.0 No R3 41.7 L3 68.7 68.7 0.0 1.5 No R4 11.7 L4 56.5 56.5 0.0 5.0 No 1 See Exhibit 9-A for the receiver locations. 2 Total Project daytime operational noise levels as shown on Table 10-2. 3 Reference noise level measurement locations as shown on Exhibit 5-A. 4 Observed daytime ambient noise levels as shown on Table 5-1. 5 Represents the combined ambient conditions plus the Project activities. 6 The noise level increase expected with the addition of the proposed Project activities.

TABLE 10-6: NIGHTTIME OPERATIONAL NOISE LEVEL INCREASES Receiver
Location1
Total Project
Operational
Noise Level2
Measurement
Location3
Reference
Ambient
Noise
Levels4
Combined
Project
and
Ambient5
Project
Increase6
Increase
Criteria
Increase
Criteria
Exceeded?
R1 37.6 L1 42.4 43.6 1.2 5.0 No R2 30.2 L2 52.4 52.4 0.0 5.0 No R3 40.8 L3 60.7 60.7 0.0 3.0 No R4 10.8 L4 55.1 55.1 0.0 5.0 No 1 See Exhibit 9-A for the receiver locations. 2 Total Project nighttime operational noise levels as shown on Table 10-3. 3 Reference noise level measurement locations as shown on Exhibit 5-A. 4 Observed nighttime ambient noise levels as shown on Table 5-1. 5 Represents the combined ambient conditions plus the Project activities. 6 The noise level increase expected with the addition of the proposed Project activities.

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67 11 CONSTRUCTION IMPACTS
This section analyzes potential impacts resulting from the short-term construction activities associated with the development of the Project. Exhibit 11-A shows the construction noise source locations in relation to the nearest sensitive receiver locations previously described in Section 9. Section 17.20.020 of the City of Los Alamitos Code, construction activities are exempted from the noise ordinance if it occurs between the hours of 7:00 a.m. to 8:00 p.m. on weekdays and on Saturdays. No construction is allowed at any time on Sundays or Federal holidays.

In addition, since the City of Los Alamitos has not established a numeric maximum acceptable construction source noise levels at potentially affected receivers for CEQA analysis purposes, a numerical construction threshold based on Federal Transit Administration (FTA) Transit Noise and Vibration Impact Assessment Manual is used for analysis of daytime construction impacts.

The FTA considers a daytime exterior construction noise level of 80 dBA Leq as a reasonable threshold for noise sensitive residential land use. (7 p. 179)

11.1 CONSTRUCTION NOISE LEVELS
Noise generated by the Project construction equipment will include a combination of trucks, power tools, concrete mixers, and portable generators that when combined can reach high levels. The number and mix of construction equipment is expected to occur in the following stages:
 Demolition
 Site Preparation
 Grading
 Building Construction
 Paving
 Architectural Coating

11.2 CONSTRUCTION REFERENCE NOISE LEVELS
To describe construction noise activities, this construction noise analysis was prepared using reference construction equipment noise levels from the Federal Highway Administration (FHWA) published the Roadway Construction Noise Model (RCNM), which includes a national database of construction equipment reference noise emission levels. (27) The RCNM equipment database, provides a comprehensive list of the noise generating characteristics for specific types of construction equipment. In addition, the database provides an acoustical usage factor to estimate the fraction of time each piece of construction equipment is operating at full power (i.e., its loudest condition) during a construction operation.

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68 EXHIBIT 11-A: CONSTRUCTION ACTIVITY AND RECEIVER LOCATIONS

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4665 Lampson Avenue
14501-11 Noise Study.docx
69 TABLE 11-1: CONSTRUCTION REFERENCE NOISE LEVELS
Construction
Stage
Reference
Construction
Equipmnet1
Reference Noise
Level @ 50 Feet
(dBA Leq)
Composite Reference
Noise Level
(dBA Leq)
Reference
Power Level
(dBA Lw)
Demolition
Front End Loader 75.0
Gradall 83.0 84.5 116.1
Excavator 77.0
Site
Preparation
Dozer 78.0
Front End Loader 75.0 83.4 115.1
Grader 81.0
Grading
Excavator 77.0
Tractor 80.0 84.0 115.6
Scraper 80.0
Building
Construction
Crane 73.0
Backhoe 74.0 77.4 109.1
Generator (<25kVA) 70.0
Paving
Paver 74.0
Dump Truck 72.0 77.8 109.5
Roller 73.0
Architectural
Coating
Man Lift 68.0
Compressor (air) 74.0 76.2 107.8
Generator (<25kVA) 70.0 1
FHWA Road Construction Noise Model.

11.3 CONSTRUCTION NOISE ANALYSIS
Using the reference construction equipment noise levels and the CadnaA noise prediction model, calculations of the Project construction noise level impacts at the nearby sensitive receiver locations were completed. To assess a reasonable worst-case construction scenario and account for the dynamic nature of construction activities, the Project construction noise analysis models the equipment combination with the highest reference level as a moving point within the construction area (Project site boundary). Construction impacts are based on the highest noise level calculated at each receiver location. As shown on Table 11-2, the construction noise levels are expected to range from 26.8 to 63.6 dBA Leq, and the highest construction levels are expected to range from 35.1 to 63.6 dBA Leq at the nearby receiver locations. Appendix 11.1 includes the detailed CadnaA construction noise model inputs.

The construction noise analysis presents a conservative approach with the highest noise-levelproducing equipment for each stage of Project construction operating at the closest point from primary construction activity to the nearby sensitive receiver locations. This scenario is unlikely to occur during typical construction activities and likely overstates the construction noise levels which will be experienced at each receiver location.

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4665 Lampson Avenue
14501-11 Noise Study.docx
70 TABLE 11-2: CONSTRUCTION EQUIPMENT NOISE LEVEL SUMMARY Receiver
Location1
Construction Noise Levels (dBA Leq)
Demolition Site
Preparation Grading Building Construction Paving Architectural Coating Highest
Levels2
R1 59.1 58.0 58.6 52.0 52.5 50.8 58.6
R2 54.8 53.7 54.3 47.7 48.2 46.5 54.3
R3 63.6 62.5 63.1 56.5 57.0 55.3 63.1
R4 35.1 34.0 34.6 28.0 28.5 26.8 34.6 1
The nearest construction noise source and receiver locations are shown on Exhibit 11-A. All receivers are shown on Exhibit 9A 2 Construction noise level calculations based on distance from the project site boundaries (construction activity area) to nearby receiver locations. CadnaA construction noise model inputs are included in Appendix 11.1.

11.4 CONSTRUCTION NOISE LEVEL COMPLIANCE
To evaluate whether the Project will generate potentially significant short-term noise levels at nearest receiver locations, a construction-related daytime noise level threshold of 80 dBA Leq is used as a reasonable threshold to assess the daytime construction noise level impacts. The construction noise analysis shows that the nearest receiver locations will satisfy the reasonable daytime 80 dBA Leq significance threshold during Project construction activities as shown on Table 11-3. Therefore, the noise impacts due to Project construction noise are considered less than significant at all receiver locations.

TABLE 11-3: CONSTRUCTION NOISE LEVEL COMPLIANCE
Receiver
Location1
Construction Noise Levels (dBA Leq)
Highest Construction
Noise Levels2 Threshold3 Threshold Exceeded?4
R1 58.8 80 No
R2 54.4 80 No
R3 63.2 80 No
R4 35.6 80 No 1 Noise receiver locations are shown on Exhibit 11-A. 2 Highest construction noise level operating at the Project site boundary to nearby receiver locations (Table 11-2). 3 Federal Transit Administration, Transit Noise and Vibration Impact Assessment Manual. 4 Do the estimated Project construction noise levels exceed the construction noise level threshold?

11.5 CONSTRUCTION VIBRATION IMPACTS
Construction activity can result in varying degrees of ground vibration, depending on the equipment and methods used, distance to the affected structures and soil type. It is expected that ground-borne vibration from Project construction activities would cause only intermittent, localized intrusion. Ground-borne vibration levels resulting from typical construction activities occurring within the Project site were estimated by data published by the Federal Transit Administration (FTA). (7) However, while vehicular traffic is rarely perceptible, construction has

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Los Alamitos City CouncilNovember 18, 2024

Los Alamitos City Council
November 18, 2024