Los Alamitos City Council
November 18, 2024

Preliminary Water Quality Management Plan (WQMP)
VTTM 19263
MJW Investments Section V

Modular Trough
Diversion System
HOA
HOA to inspect
system and schedule
maintenance when
deficiencies are
noted. Area near
system to be kept
free of debris and
cleanings shall be
scheduled to remove
silt from trough as
needed
Inspections should
occur at least two
times per year and
one of the inspection
must be before the
start of the rainy
season (October 1st).

Preliminary Water Quality Management Plan (WQMP)
VTTM 19263
MJW Investments Section VII

Section VI Site Plan and Drainage Plan
VI.1 SITE PLAN AND DRAINAGE PLAN
Include a site plan and drainage plan sheet set containing the following minimum information:
• Project location
• Site boundary
• Land uses and land covers, as applicable
• Suitability/feasibility constraints
• Structural BMP locations
• Drainage delineations and flow information
• Drainage connections
• BMP details

Preliminary Water Quality Management Plan (WQMP)
VTTM 19263
MJW Investments Section VII

Section VII Educational Materials
Refer to the Orange County Stormwater Program (ocwatersheds.com) for a library of materials available. For the copy submitted to the Permittee, only attach the educational materials specifically applicable to the project. Other materials specific to the project may be included as well and must be attached.

Education Materials
Residential Material
(http://www.ocwatersheds.com)
Check If
Applicable
Business Material
(http://www.ocwatersheds.com)
Check If
Applicable
The Ocean Begins at Your Front Door Tips for the Automotive Industry Tips for Car Wash Fund-raisers Tips for Using Concrete and Mortar Tips for the Home Mechanic Tips for the Food Service Industry Homeowners Guide for Sustainable
Water Use
Proper Maintenance Practices for Your
Business
Household Tips
Other Material
Check If
Attached Proper Disposal of Household
Hazardous Waste
Recycle at Your Local Used Oil
Collection Center (North County)
Recycle at Your Local Used Oil
Collection Center (Central County)
Recycle at Your Local Used Oil
Collection Center (South County)
Tips for Maintaining a Septic Tank
System
Responsible Pest Control
Sewer Spill
Tips for the Home Improvement Projects
Tips for Horse Care
Tips for Landscaping and Gardening
Tips for Pet Care
Tips for Pool Maintenance
Tips for Residential Pool, Landscape and
Hardscape Drains
Tips for Projects Using Paint

Attachment A
Orange County Technical Guidance Document
Worksheets and Figures

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
Table 2.7: Infiltration BMP Feasibility Worksheet
Infeasibility Criteria Yes No
1 Would Infiltration BMPs pose significant risk for
groundwater related concerns? Refer to Appendix
VII (Worksheet I) for guidance on groundwater-related
infiltration feasibility criteria.

X
Provide basis:

Per the preliminary Geotechnical Evaluation and Design Recommendations Report prepared by LGC Geotechnical, Inc dated December 21, 2021: “Geotechnical stability and integrity of the project site is reliant upon appropriate handling of surface water. Due to the extremely low measured infiltration rate, low permeability fine-grained soils at depth, shallow groundwater and site liquefaction potential, we strongly recommend against the intentional infiltration of storm water into subsurface soils.”
2 Would Infiltration BMPs pose significant risk of
increasing risk of geotechnical hazards that cannot
be mitigated to an acceptable level? (Yes if the
answer to any of the following questions is yes, as
established by a geotechnical expert):
• The BMP can only be located less than 50 feet
away from slopes steeper than 15 percent
• The BMP can only be located less than eight feet
from building foundations or an alternative setback.
• A study prepared by a geotechnical professional or
an available watershed study substantiates that
stormwater infiltration would potentially result in
significantly increased risks of geotechnical hazards
that cannot be mitigated to an acceptable level.

X
Provide basis:
3 Would infiltration of the DCV from drainage area violate downstream water rights?
X
Provide basis:

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
Table 2.7: Infiltration BMP Feasibility Worksheet (continued) Partial Infeasibility Criteria Yes No
4 Is proposed infiltration facility located on HSG D soils or the site geotechnical investigation identifies presence of soil characteristics which support categorization as D soils? X
Provide basis:
5 Is measured infiltration rate below proposed facility less than 0.3 inches per hour? This calculation shall be based on the methods described in Appendix VII.

X
Provide basis:
6 Would reduction of over predeveloped conditions cause impairments to downstream beneficial uses, such as
change of seasonality of ephemeral washes or
increased discharge of contaminated groundwater to
surface waters?
X
Provide citation to applicable study and summarize findings relative to the amount of infiltration that is permissible:
7 Would an increase in infiltration over predeveloped
conditions cause impairments to downstream
beneficial uses, such as change of seasonality of
ephemeral washes or increased discharge of
contaminated groundwater to surface waters?
X
Provide citation to applicable study and summarize findings relative to the amount of infiltration that is permissible:

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
Table 2.7: Infiltration BMP Feasibility Worksheet (continued) Infiltration Screening Results (check box corresponding to result):
8 Is there substantial evidence that infiltration from the project would result in a significant increase in I&I to the sanitary sewer that cannot be sufficiently mitigated? (See Appendix XVII)
Provide narrative discussion and supporting evidence:

No
9 If any answer from row 1-3 is yes: infiltration of any volume is not feasible within the DMA or equivalent.

Provide basis: Yes
10 If any answer from row 4-7 is yes, infiltration is permissible but is not presumed to be feasible for the entire DCV.

Criteria for designing biotreatment BMPs to achieve the maximum feasible infiltration and ET shall apply.

Provide basis:

No
11 If all answers to rows 1 through 11 are no, infiltration of the full DCV is potentially feasible, BMPs must be designed to infiltrate the full DCV to the maximum extent practicable.

Infiltration is Infeasible

DMA 1
Worksheet B: Simple Design Capture Volume Sizing Method Step 1: Determine the design capture storm depth used for calculating volume 1 Enter design capture storm depth from Figure III.1, d (inches) d= 0.80 inches 2 Enter the effect of provided HSCs, dHSC (inches)
(Worksheet A) dHSC= 0 inches
3 Calculate the remainder of the design capture storm depth, dremainder (inches) (Line 1 – Line 2) dremainder= 0.80 inches Step 2: Calculate the DCV
1 Enter Project area tributary to BMP (s), A (acres) A= 2.862 acres 2 Enter Project Imperviousness, imp (unitless) imp= 0.9 3 Calculate runoff coefficient, C= (0.75 x imp) + 0.15 C= 0.83 4 Calculate runoff volume, Vdesign= (C x dremainder x A x 43560 x (1/12)) Vdesign= 6,856 cu-ft
Step 3: Design BMPs to ensure full retention of the DCV Step 3a: Determine design infiltration rate N/A
1 Enter measured infiltration rate, Kmeasured (in/hr)
(Appendix VII) Kmeasured= NA In/hr
2 Enter combined safety factor from Worksheet H, Sfinal (unitless) Sfinal= NA
3 Calculate design infiltration rate, Kdesign = Kmeasured / Sfinal Kdesign= NA In/hr
Step 3b: Determine minimum BMP footprint
4 Enter drawdown time, T (max 48 hours) T= NA Hours
5 Calculate max retention depth that can be drawn down within the drawdown time (feet), Dmax = Kdesign x T x (1/12) Dmax= NA feet 6 Calculate minimum area required for BMP (sq-ft), Amin = Vdesign/ dmax
Amin= NA sq-ft

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
DMA 2
Worksheet B: Simple Design Capture Volume Sizing Method Step 1: Determine the design capture storm depth used for calculating volume 1 Enter design capture storm depth from Figure III.1, d (inches) d= 0.8 inches 2 Enter the effect of provided HSCs, dHSC (inches)
(Worksheet A) dHSC= 0 inches
3 Calculate the remainder of the design capture storm depth, dremainder (inches) (Line 1 – Line 2) dremainder= 0.8 inches Step 2: Calculate the DCV
1 Enter Project area tributary to BMP (s), A (acres) A= 2.018 acres 2 Enter Project Imperviousness, imp (unitless) imp= 0.9 3 Calculate runoff coefficient, C= (0.75 x imp) + 0.15 C= 0.83 4 Calculate runoff volume, Vdesign= (C x dremainder x A x 43560 x (1/12)) Vdesign= 4,836 cu-ft
Step 3: Design BMPs to ensure full retention of the DCV Step 3a: Determine design infiltration rate N/A
1 Enter measured infiltration rate, Kmeasured (in/hr)
(Appendix VII) Kmeasured= NA In/hr
2 Enter combined safety factor from Worksheet H, Sfinal (unitless) Sfinal= NA
3 Calculate design infiltration rate, Kdesign = Kmeasured / Sfinal Kdesign= NA In/hr
Step 3b: Determine minimum BMP footprint
4 Enter drawdown time, T (max 48 hours) T= NA Hours
5 Calculate max retention depth that can be drawn down within the drawdown time (feet), Dmax = Kdesign x T x (1/12) Dmax= NA feet 6 Calculate minimum area required for BMP (sq-ft), Amin = Vdesign/ dmax
Amin= NA sq-ft

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
DMA 3
Worksheet B: Simple Design Capture Volume Sizing Method Step 1: Determine the design capture storm depth used for calculating volume 1 Enter design capture storm depth from Figure III.1, d (inches) d= 0.8 inches 2 Enter the effect of provided HSCs, dHSC (inches)
(Worksheet A) dHSC= 0 inches
3 Calculate the remainder of the design capture storm depth, dremainder (inches) (Line 1 – Line 2) dremainder= 0.8 inches Step 2: Calculate the DCV
1 Enter Project area tributary to BMP (s), A (acres) A= 2.144 acres 2 Enter Project Imperviousness, imp (unitless) imp= 0.9 3 Calculate runoff coefficient, C= (0.75 x imp) + 0.15 C= 0.83 4 Calculate runoff volume, Vdesign= (C x dremainder x A x 43560 x (1/12)) Vdesign= 5,136 cu-ft
Step 3: Design BMPs to ensure full retention of the DCV Step 3a: Determine design infiltration rate N/A
1 Enter measured infiltration rate, Kmeasured (in/hr)
(Appendix VII) Kmeasured= NA In/hr
2 Enter combined safety factor from Worksheet H, Sfinal (unitless) Sfinal= NA
3 Calculate design infiltration rate, Kdesign = Kmeasured / Sfinal Kdesign= NA In/hr
Step 3b: Determine minimum BMP footprint
4 Enter drawdown time, T (max 48 hours) T= NA Hours
5 Calculate max retention depth that can be drawn down within the drawdown time (feet), Dmax = Kdesign x T x (1/12) Dmax= NA feet 6 Calculate minimum area required for BMP (sq-ft), Amin = Vdesign/ dmax
Amin= NA sq-ft

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
DMA 4
Worksheet B: Simple Design Capture Volume Sizing Method Step 1: Determine the design capture storm depth used for calculating volume 1 Enter design capture storm depth from Figure III.1, d (inches) d= 0.8 inches 2 Enter the effect of provided HSCs, dHSC (inches)
(Worksheet A) dHSC= 0 inches
3 Calculate the remainder of the design capture storm depth, dremainder (inches) (Line 1 – Line 2) dremainder= 0.8 inches Step 2: Calculate the DCV
1 Enter Project area tributary to BMP (s), A (acres) A= 1.935 acres 2 Enter Project Imperviousness, imp (unitless) imp= 0.9 3 Calculate runoff coefficient, C= (0.75 x imp) + 0.15 C= 0.83 4 Calculate runoff volume, Vdesign= (C x dremainder x A x 43560 x (1/12)) Vdesign= 4,637 cu-ft
Step 3: Design BMPs to ensure full retention of the DCV Step 3a: Determine design infiltration rate N/A
1 Enter measured infiltration rate, Kmeasured (in/hr)
(Appendix VII) Kmeasured= NA In/hr
2 Enter combined safety factor from Worksheet H, Sfinal (unitless) Sfinal= NA
3 Calculate design infiltration rate, Kdesign = Kmeasured / Sfinal Kdesign= NA In/hr
Step 3b: Determine minimum BMP footprint
4 Enter drawdown time, T (max 48 hours) T= NA Hours
5 Calculate max retention depth that can be drawn down within the drawdown time (feet), Dmax = Kdesign x T x (1/12) Dmax= NA feet 6 Calculate minimum area required for BMP (sq-ft), Amin = Vdesign/ dmax
Amin= NA sq-ft

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
DMA 5
Worksheet B: Simple Design Capture Volume Sizing Method Step 1: Determine the design capture storm depth used for calculating volume 1 Enter design capture storm depth from Figure III.1, d (inches) d= 0.8 inches 2 Enter the effect of provided HSCs, dHSC (inches)
(Worksheet A) dHSC= 0 inches
3 Calculate the remainder of the design capture storm depth, dremainder (inches) (Line 1 – Line 2) dremainder= 0.8 inches Step 2: Calculate the DCV
1 Enter Project area tributary to BMP (s), A (acres) A= 0.476 acres 2 Enter Project Imperviousness, imp (unitless) imp= 0.9 3 Calculate runoff coefficient, C= (0.75 x imp) + 0.15 C= 0.83 4 Calculate runoff volume, Vdesign= (C x dremainder x A x 43560 x (1/12)) Vdesign= 1,140 cu-ft
Step 3: Design BMPs to ensure full retention of the DCV Step 3a: Determine design infiltration rate N/A
1 Enter measured infiltration rate, Kmeasured (in/hr)
(Appendix VII) Kmeasured= NA In/hr
2 Enter combined safety factor from Worksheet H, Sfinal (unitless) Sfinal= NA
3 Calculate design infiltration rate, Kdesign = Kmeasured / Sfinal Kdesign= NA In/hr
Step 3b: Determine minimum BMP footprint
4 Enter drawdown time, T (max 48 hours) T= NA Hours
5 Calculate max retention depth that can be drawn down within the drawdown time (feet), Dmax = Kdesign x T x (1/12) Dmax= NA feet 6 Calculate minimum area required for BMP (sq-ft), Amin = Vdesign/ dmax
Amin= NA sq-ft

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
DMA 6
Worksheet B: Simple Design Capture Volume Sizing Method Step 1: Determine the design capture storm depth used for calculating volume 1 Enter design capture storm depth from Figure III.1, d (inches) d= 0.8 inches 2 Enter the effect of provided HSCs, dHSC (inches)
(Worksheet A) dHSC= 0 inches
3 Calculate the remainder of the design capture storm depth, dremainder (inches) (Line 1 – Line 2) dremainder= 0.8 inches Step 2: Calculate the DCV
1 Enter Project area tributary to BMP (s), A (acres) A= 0.439 acres 2 Enter Project Imperviousness, imp (unitless) imp= 0.9 3 Calculate runoff coefficient, C= (0.75 x imp) + 0.15 C= 0.83 4 Calculate runoff volume, Vdesign= (C x dremainder x A x 43560 x (1/12)) Vdesign= 1,052 cu-ft
Step 3: Design BMPs to ensure full retention of the DCV Step 3a: Determine design infiltration rate N/A
1 Enter measured infiltration rate, Kmeasured (in/hr)
(Appendix VII) Kmeasured= NA In/hr
2 Enter combined safety factor from Worksheet H, Sfinal (unitless) Sfinal= NA
3 Calculate design infiltration rate, Kdesign = Kmeasured / Sfinal Kdesign= NA In/hr
Step 3b: Determine minimum BMP footprint
4 Enter drawdown time, T (max 48 hours) T= NA Hours
5 Calculate max retention depth that can be drawn down within the drawdown time (feet), Dmax = Kdesign x T x (1/12) Dmax= NA feet 6 Calculate minimum area required for BMP (sq-ft), Amin = Vdesign/ dmax
Amin= NA sq-ft

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
DMA 7
Worksheet B: Simple Design Capture Volume Sizing Method Step 1: Determine the design capture storm depth used for calculating volume 1 Enter design capture storm depth from Figure III.1, d (inches) d= 0.8 inches 2 Enter the effect of provided HSCs, dHSC (inches)
(Worksheet A) dHSC= 0 inches
3 Calculate the remainder of the design capture storm depth, dremainder (inches) (Line 1 – Line 2) dremainder= 0.8 inches Step 2: Calculate the DCV
1 Enter Project area tributary to BMP (s), A (acres) A= 2.246 acres 2 Enter Project Imperviousness, imp (unitless) imp= 0.9 3 Calculate runoff coefficient, C= (0.75 x imp) + 0.15 C= 0.83 4 Calculate runoff volume, Vdesign= (C x dremainder x A x 43560 x (1/12)) Vdesign= 5,381 cu-ft
Step 3: Design BMPs to ensure full retention of the DCV Step 3a: Determine design infiltration rate N/A
1 Enter measured infiltration rate, Kmeasured (in/hr)
(Appendix VII) Kmeasured= NA In/hr
2 Enter combined safety factor from Worksheet H, Sfinal (unitless) Sfinal= NA
3 Calculate design infiltration rate, Kdesign = Kmeasured / Sfinal Kdesign= NA In/hr
Step 3b: Determine minimum BMP footprint
4 Enter drawdown time, T (max 48 hours) T= NA Hours
5 Calculate max retention depth that can be drawn down within the drawdown time (feet), Dmax = Kdesign x T x (1/12) Dmax= NA feet 6 Calculate minimum area required for BMP (sq-ft), Amin = Vdesign/ dmax
Amin= NA sq-ft

DMA 1
Worksheet D: Capture Efficiency Method for Flow-Based BMPs Step 1: Determine the design capture storm depth used for calculating volume 1 Enter the time of concentration, Tc (min) (See Appendix IV.2) Tc= 5.00 2 Using Figure III.4, determine the design intensity at which the estimated time of concentration (Tc) achieves 80% capture efficiency, I1
I1= 0.26 in/hr
3 Enter the effect depth of provided HSCs upstream, dHSC (inches) (Worksheet A) dHSC= 0 inches
4 Enter capture efficiency corresponding to dHSC, Y2
(Worksheet A) Y2= 0 %
5 Using Figure III.4, determine the design intensity at which the time of concentration (Tc) achieves the upstream capture efficiency(Y2), I2
I2= 0 in/hr
6 Determine the design intensity that must be provided by BMP, Idesign= I1-I2
Idesign= 0.26 in/hr
Step 2: Calculate the design flowrate
1 Enter Project area tributary to BMP (s), A (acres) A= 2.862 acres 2 Enter Project Imperviousness, imp (unitless) imp= 0.9 * 3 Calculate runoff coefficient, C= (0.75 x imp) + 0.15 C= 0.83 4 Calculate design flowrate, Qdesign= (C x idesign x A) Qdesign= 0.614 cfs Supporting Calculations
Describe system:

Surface runoff will be conveyed through the private street to proposed curb inlet Biofiltration Vaults for water quality treatment.
*Assumed 90% impervious coverage utilized for preliminary calculations. Actual impervious coverage will be calculated in final engineering.

Provide time of concentration assumptions:

The time of concentration was assumed to be 5 minutes for conservative purposes.

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
Worksheet D: Capture Efficiency Method for Flow-Based BMPs Graphical Operations
Provide supporting graphical operations. See Example III.7.

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
DMA 2
Worksheet D: Capture Efficiency Method for Flow-Based BMPs Step 1: Determine the design capture storm depth used for calculating volume 1 Enter the time of concentration, Tc (min) (See Appendix IV.2) Tc= 5.00 2 Using Figure III.4, determine the design intensity at which the estimated time of concentration (Tc) achieves 80% capture efficiency, I1
I1= 0.26 in/hr
3 Enter the effect depth of provided HSCs upstream, dHSC (inches) (Worksheet A) dHSC= 0 inches
4 Enter capture efficiency corresponding to dHSC, Y2
(Worksheet A) Y2= 0 %
5 Using Figure III.4, determine the design intensity at which the time of concentration (Tc) achieves the upstream capture efficiency(Y2), I2
I2= 0 in/hr
6 Determine the design intensity that must be provided by BMP, Idesign= I1-I2
Idesign= 0.26 in/hr
Step 2: Calculate the design flowrate
1 Enter Project area tributary to BMP (s), A (acres) A= 2.018 acres 2 Enter Project Imperviousness, imp (unitless) imp= 0.9 * 3 Calculate runoff coefficient, C= (0.75 x imp) + 0.15 C= 0.83 4 Calculate design flowrate, Qdesign= (C x idesign x A) Qdesign= 0.433 cfs Supporting Calculations
Describe system:

Surface runoff will be conveyed through the private street to proposed curb inlet Biofiltration Vaults for water quality treatment.
*Assumed 90% impervious coverage utilized for preliminary calculations. Actual impervious coverage will be calculated in final engineering.

Provide time of concentration assumptions:

The time of concentration was assumed to be 5 minutes for conservative purposes.

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
DMA 3
Worksheet D: Capture Efficiency Method for Flow-Based BMPs Step 1: Determine the design capture storm depth used for calculating volume 1 Enter the time of concentration, Tc (min) (See Appendix IV.2) Tc= 5.00 2 Using Figure III.4, determine the design intensity at which the estimated time of concentration (Tc) achieves 80% capture efficiency, I1
I1= 0.26 in/hr
3 Enter the effect depth of provided HSCs upstream, dHSC (inches) (Worksheet A) dHSC= 0 inches
4 Enter capture efficiency corresponding to dHSC, Y2
(Worksheet A) Y2= 0 %
5 Using Figure III.4, determine the design intensity at which the time of concentration (Tc) achieves the upstream capture efficiency(Y2), I2
I2= 0 in/hr
6 Determine the design intensity that must be provided by BMP, Idesign= I1-I2
Idesign= 0.26 in/hr
Step 2: Calculate the design flowrate
1 Enter Project area tributary to BMP (s), A (acres) A= 2.144 acres 2 Enter Project Imperviousness, imp (unitless) imp= 0.9 * 3 Calculate runoff coefficient, C= (0.75 x imp) + 0.15 C= 0.83 4 Calculate design flowrate, Qdesign= (C x idesign x A) Qdesign= 0.460 cfs Supporting Calculations
Describe system:

Surface runoff will be conveyed through the private street to proposed curb inlet Biofiltration Vaults for water quality treatment.
*Assumed 90% impervious coverage utilized for preliminary calculations. Actual impervious coverage will be calculated in final engineering.

Provide time of concentration assumptions:

The time of concentration was assumed to be 5 minutes for conservative purposes.

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
DMA 4
Worksheet D: Capture Efficiency Method for Flow-Based BMPs Step 1: Determine the design capture storm depth used for calculating volume 1 Enter the time of concentration, Tc (min) (See Appendix IV.2) Tc= 5.00 2 Using Figure III.4, determine the design intensity at which the estimated time of concentration (Tc) achieves 80% capture efficiency, I1
I1= 0.26 in/hr
3 Enter the effect depth of provided HSCs upstream, dHSC (inches) (Worksheet A) dHSC= 0 inches
4 Enter capture efficiency corresponding to dHSC, Y2
(Worksheet A) Y2= 0 %
5 Using Figure III.4, determine the design intensity at which the time of concentration (Tc) achieves the upstream capture efficiency(Y2), I2
I2= 0 in/hr
6 Determine the design intensity that must be provided by BMP, Idesign= I1-I2
Idesign= 0.26 in/hr
Step 2: Calculate the design flowrate
1 Enter Project area tributary to BMP (s), A (acres) A= 1.935 acres 2 Enter Project Imperviousness, imp (unitless) imp= 0.9 * 3 Calculate runoff coefficient, C= (0.75 x imp) + 0.15 C= 0.83 4 Calculate design flowrate, Qdesign= (C x idesign x A) Qdesign= 0.415 cfs Supporting Calculations
Describe system:

Surface runoff will be conveyed through the private street to proposed curb inlet Biofiltration Vaults for water quality treatment.
*Assumed 90% impervious coverage utilized for preliminary calculations. Actual impervious coverage will be calculated in final engineering.

Provide time of concentration assumptions:

The time of concentration was assumed to be 5 minutes for conservative purposes.

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
DMA 5
Worksheet D: Capture Efficiency Method for Flow-Based BMPs Step 1: Determine the design capture storm depth used for calculating volume 1 Enter the time of concentration, Tc (min) (See Appendix IV.2) Tc= 5.00 2 Using Figure III.4, determine the design intensity at which the estimated time of concentration (Tc) achieves 80% capture efficiency, I1
I1= 0.26 in/hr
3 Enter the effect depth of provided HSCs upstream, dHSC (inches) (Worksheet A) dHSC= 0 inches
4 Enter capture efficiency corresponding to dHSC, Y2
(Worksheet A) Y2= 0 %
5 Using Figure III.4, determine the design intensity at which the time of concentration (Tc) achieves the upstream capture efficiency(Y2), I2
I2= 0 in/hr
6 Determine the design intensity that must be provided by BMP, Idesign= I1-I2
Idesign= 0.26 in/hr
Step 2: Calculate the design flowrate
1 Enter Project area tributary to BMP (s), A (acres) A= 0.476 acres 2 Enter Project Imperviousness, imp (unitless) imp= 0.9 * 3 Calculate runoff coefficient, C= (0.75 x imp) + 0.15 C= 0.83 4 Calculate design flowrate, Qdesign= (C x idesign x A) Qdesign= 0.102 cfs Supporting Calculations
Describe system:

Surface runoff will be conveyed through the private street to proposed curb inlet Biofiltration Vaults for water quality treatment.
*Assumed 90% impervious coverage utilized for preliminary calculations. Actual impervious coverage will be calculated in final engineering.

Provide time of concentration assumptions:

The time of concentration was assumed to be 5 minutes for conservative purposes.

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
DMA 6
Worksheet D: Capture Efficiency Method for Flow-Based BMPs Step 1: Determine the design capture storm depth used for calculating volume 1 Enter the time of concentration, Tc (min) (See Appendix IV.2) Tc= 5.00 2 Using Figure III.4, determine the design intensity at which the estimated time of concentration (Tc) achieves 80% capture efficiency, I1
I1= 0.26 in/hr
3 Enter the effect depth of provided HSCs upstream, dHSC (inches) (Worksheet A) dHSC= 0 inches
4 Enter capture efficiency corresponding to dHSC, Y2
(Worksheet A) Y2= 0 %
5 Using Figure III.4, determine the design intensity at which the time of concentration (Tc) achieves the upstream capture efficiency(Y2), I2
I2= 0 in/hr
6 Determine the design intensity that must be provided by BMP, Idesign= I1-I2
Idesign= 0.26 in/hr
Step 2: Calculate the design flowrate
1 Enter Project area tributary to BMP (s), A (acres) A= 0.439 acres 2 Enter Project Imperviousness, imp (unitless) imp= 0.9 * 3 Calculate runoff coefficient, C= (0.75 x imp) + 0.15 C= 0.83 4 Calculate design flowrate, Qdesign= (C x idesign x A) Qdesign= 0.094 cfs Supporting Calculations
Describe system:

Surface runoff will be conveyed through the private street to proposed curb inlet Biofiltration Vaults for water quality treatment.
*Assumed 90% impervious coverage utilized for preliminary calculations. Actual impervious coverage will be calculated in final engineering.

Provide time of concentration assumptions:

The time of concentration was assumed to be 5 minutes for conservative purposes.

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
DMA 7
Worksheet D: Capture Efficiency Method for Flow-Based BMPs Step 1: Determine the design capture storm depth used for calculating volume 1 Enter the time of concentration, Tc (min) (See Appendix IV.2) Tc= 5.00 2 Using Figure III.4, determine the design intensity at which the estimated time of concentration (Tc) achieves 80% capture efficiency, I1
I1= 0.26 in/hr
3 Enter the effect depth of provided HSCs upstream, dHSC (inches) (Worksheet A) dHSC= 0 inches
4 Enter capture efficiency corresponding to dHSC, Y2
(Worksheet A) Y2= 0 %
5 Using Figure III.4, determine the design intensity at which the time of concentration (Tc) achieves the upstream capture efficiency(Y2), I2
I2= 0 in/hr
6 Determine the design intensity that must be provided by BMP, Idesign= I1-I2
Idesign= 0.26 in/hr
Step 2: Calculate the design flowrate
1 Enter Project area tributary to BMP (s), A (acres) A= 2.246 acres 2 Enter Project Imperviousness, imp (unitless) imp= 0.9 * 3 Calculate runoff coefficient, C= (0.75 x imp) + 0.15 C= 0.83 4 Calculate design flowrate, Qdesign= (C x idesign x A) Qdesign= 0.482 cfs Supporting Calculations
Describe system:

Surface runoff will be conveyed through the private street to proposed curb inlet Biofiltration Vaults for water quality treatment.
*Assumed 90% impervious coverage utilized for preliminary calculations. Actual impervious coverage will be calculated in final engineering.

Provide time of concentration assumptions:

The time of concentration was assumed to be 5 minutes for conservative purposes.

Worksheet I: Summary of Groundwater-related Feasibility Criteria 1 Is project large or small? (as defined by Table VIII.2) circle one
Large Small
2 What is the tributary area to the BMP? A 12.12 acres
3 What type of BMP is proposed? Underground infiltration 4 What is the infiltrating surface area of the proposed BMP? ABMP sq-ft 5 What land use activities are present in the tributary area (list all) Multi-Family Residential
6 What land use-based risk category is applicable? L M H 7 If M or H, what pretreatment and source isolation BMPs have been considered and are proposed (describe all):

Proposed MWS System Biofiltration Vaults will provide treatment for the required design flow rate. 8 What minimum separation to mounded seasonally high
groundwater applies to the proposed BMP?
See Section VIII.2 (circle one)
5 ft 10 ft
9 Provide rationale for selection of applicable minimum separation to seasonally high mounded groundwater:

Per the TGD Section VIII.2, the following applies to a subsurface infiltration gallery:
“Separation to mounded seasonally high groundwater shall be at least 10 feet for infiltration devices that inject water below the subsurface and surface infiltration BMPs with tributary area and land use activities that are considered to pose a more significant risk to groundwater quality.”
10 What is separation from the infiltrating surface to seasonally high groundwater? SHGWT <10 ft
11 What is separation from the infiltrating surface to mounded seasonally high groundwater?
Mounded
SHGWT n/a ft
12 Describe assumptions and methods used for mounding analysis:

Groundwater was encountered at 11-13 feet below existing grade 13 Is the site within a plume protection boundary (See Figure VIII.2)? Y N N/A
14 Is the site within a selenium source area or other natural plume area (See Figure VIII.2)? Y N N/A
15 Is the site within 250 feet of a contaminated site? Y N N/A

Worksheets from Orange County Technical Guidance Document (5-19-2011) See TGD for instructions and/or examples related to these worksheets www.ocwatersheds.com/WQMP.aspx
Worksheet I: Summary of Groundwater-related Feasibility Criteria 16 If site-specific study has been prepared, provide citation and briefly summarize relevant findings:
n/a
17 Is the site within 100 feet of a water supply well, spring, septic system?

Y N N/A
18 Is infiltration feasible on the site relative to groundwaterrelated criteria? Y N Provide rationale for feasibility determination:

Per the preliminary Geotechnical Evaluation and Design Recommendations Report prepared by LGC Geotechnical, Inc dated December 21, 2021: “Geotechnical stability and integrity of the project site is reliant upon appropriate handling of surface water. Due to the extremely low measured infiltration rate, low permeability fine-grained soils at depth, shallow groundwater and site liquefaction potential, we strongly recommend against the intentional infiltration of storm water into subsurface soils.” Note: if a single criterion or group of criteria would render infiltration infeasible, it is not necessary to evaluate every question in this worksheet.

Worksheet J: Summary of Harvested Water Demand and Feasibility Entire Site 1 What demands for harvested water exist in the tributary area (check all that apply):
2 Toilet and urinal flushing □
3 Landscape irrigation ✓
4 Other:_______________________________________________________ □ 5 What is the design capture storm depth? (Figure III.1) d 0.8 inches 6 What is the project size? A 12.12 ac
7 What is the acreage of impervious area? * IA 10.91 ac For projects with multiple types of demand (toilet flushing, irrigation demand, and/or other demand) 8 What is the minimum use required for partial capture? (Table X.6) gpd
9 What is the project estimated wet season total daily use (Section X.2)?
gpd
10 Is partial capture potentially feasible? (Line 9 > Line 8?) For projects with only toilet flushing demand
11 What is the minimum TUTIA for partial capture? (Table X.7) 12 What is the project estimated TUTIA?
13 Is partial capture potentially feasible? (Line 12 > Line 11?) For projects with only irrigation demand
14 What is the minimum irrigation area required based on conservation landscape design? (Table X.8) [10.91x0.9]

9.82 ac
15 What is the proposed project irrigated area? (multiply conservation landscaping by 1; multiply active turf by 2) 0.9 ac 16 Is partial capture potentially feasible? (Line 15 > Line 14?) No Provide supporting assumptions and citations for controlling demand calculation:

Due to the proposed development type, density and amount of available landscaping, Harvest and Use BMPs for irrigation purposes will not be feasible.
* For preliminary purposes, an assumed 90% impervious coverage based on development type was utilized for these calculations.

ORANGE COUNTY ORANGE COUNTY

RIVERSIDE COUNTY RIVERSIDE COUNTY

ORANGE COUNTY

ORANGE COUNTY

SAN BERNARDINO COUNTY SAN BERNARDINO COUNTY

ORANGE COUNTY

LOS ANGELES COUNTY

ORANGE COUNTY

LOS ANGELES COUNTY

1.05 0.7

0.95 1

0.9 0.85

0.8 0.75

0.7 0.65

0.95 0.7

0.9 0.9

0.75 P:\9526E\6-GIS\Mxds\Reports\InfiltrationFeasability_20110215\9526E_FigureXVI-1_RainfallZones_20110215.mxd FIGURE

JOB TITLE SCALE
1" = 1.8 miles

DESIGNED

DRAWING

CHECKED
BMP
04/22/10
DATE
JOB NO.

TH
TH
9526-E

ORANGE COUNTY

TECHNICAL GUIDANCE

DOCUMENT
ORANGE CO. CA

RAINFALL ZONES

SUBJECT TO FURTHER REVISION
0 3.6 7.2 1.8
Miles
0 6 12 3
Kilometers
LEGEND
Orange County Precipitation Stations24 Hour, 85th Percentile Rainfall (Inches)24 Hour, 85th Percentile Rainfall (Inches) - ExtrapolatedCity Boundaries Rainfall ZonesDesign Capture Storm Depth (inches)

0.65"0.70.750.800.850.900.951.001.10"
Note: Events defined as 24-hour periods (calendar days) with greater than 0.1 inches of rainfall. For areas outside of available data coverage, professional judgment shall be applied.

XVI-1

PROJECT SITE

ORANGE COUNTY ORANGE COUNTY

RIVERSIDE COUNTY RIVERSIDE COUNTY

ORANGE COUNTY

ORANGE COUNTY

SAN BERNARDINO COUNTY SAN BERNARDINO COUNTY

ORANGE COUNTY

LOS ANGELES COUNTY

ORANGE COUNTY

LOS ANGELES COUNTY
P:\9526E\6-GIS\Mxds\Reports\InfiltrationFeasability_20110215\9526E_FigureXVI-2a_HydroSoils_20110215.mxd FIGURE XVI-2a

JOB TITLE SCALE
1" = 1.8 miles

DESIGNED

DRAWING

CHECKED
BMP
02/09/11
DATE
JOB NO.

TH
TH
9526-E

ORANGE COUNTY

INFILTRATION STUDY
ORANGE CO. CA

NRCS HYDROLOGIC

SOILS GROUPS

SUBJECT TO FURTHER REVISION
Source: Soils: Natural Resources Conservation Service (NRCS)Soil Survey - soil_ca678, Orange County & Western RiversideDate of publication: 2006-02-08 I!
0 3.6 7.2 1.8
Miles
0 5 10 2.5
Kilometers
LEGEND
City Boundaries
Hydrologic Soil Groups
A SoilsB SoilsC SoilsD Soils
http://websoilsurvey.nrcs.usda.gov/app/HomePage.htm

PROJECT SITE

ORANGE COUNTY ORANGE COUNTY

RIVERSIDE COUNTY RIVERSIDE COUNTY

ORANGE COUNTY

ORANGE COUNTY

SAN BERNARDINO COUNTY SAN BERNARDINO COUNTY

ORANGE COUNTY

LOS ANGELES COUNTY

ORANGE COUNTY

LOS ANGELES COUNTY
10 10
3 5
10 30
10 30
10 20
10 10
5 50
3 30
30 30
30 20
5 10
20 30
50 10
30 20
P:\9526E\6-GIS\Mxds\Reports\InfiltrationFeasability_20110215\9526E_FigureXVI-2d_DepthToGroundwaterOverview_20110215.mxd FIGURE XVI-2d

JOB TITLE SCALE
1" = 1.25 miles

DESIGNED

DRAWING

CHECKED
BMP
02/09/11
DATE
JOB NO.

TH
TH
9526-E

ORANGE COUNTY

INFILTRATION STUDY
ORANGE CO. CA

NORTH ORANGE COUNTY

MAPPED DEPTH TO FIRST

GROUNDWATER

SUBJECT TO FURTHER REVISION
Note: Data are not available for South Orange County at this time.Source:Sprotte, Fuller and Greenwood, 1980.California Division of Mines and Geology;California Geological Survey I!
0 2.5 5 1.25
Miles
048 2
Kilometers
LEGEND
Depth To First Groundwater ContoursCity BoundariesOCWD Groundwater Basin Protection Boundary

PROJECT SITE

ORANGE COUNTY RIVERSIDE COUNTY

ORANGE COUNTY SAN BERNARDINO COUNTY

ORANGE COUNTY

LOS ANGELES COUNTY

ORANGE COUNTY ORANGE COUNTY LOS ANGELES COUNTY LOS ANGELES COUNTY P:\9526E\6-GIS\Mxds\Reports\InfiltrationFeasability_20110215\9526E_FigureXVI-2f_NorthOCGroundwaterProtectionAreasStreetMap_20110215.mxd FIGURE
XVI-2f JOB TITLE SCALE 1" = 1.25 miles DESIGNED DRAWING CHECKED BMP 04/22/10 DATE JOB NO. THTH 9526-E

ORANGE COUNTY

INFILTRATION STUDY
ORANGE CO. CA

NORTH ORANGE COUNTY

GROUNDWATER PROTECTION
AREAS

SUBJECT TO FURTHER REVISION
Note: Individual contamination sites are not plotted.

See State Water Resources Control Board Geotracker database (http://geotracker.waterboards.ca.gov),
Department of Toxic Substance Control Envirostor database (http://www.envirostor.dtsc.ca.gov) and other applicable sources for current listing of active contaminated sites.

Groundwater basin and plume protection boundaries for
South Orange County are not shown on this exhibit
at this time
I!
0 1.25 2.55
Miles
0248
Kilometers
LEGEND
City Boundaries
OCWD Groundwater Basin Protection Boundary
Plume Protection Boundaries
North Basin Groundwater Protection Project
South Basin Groundwater Protection Project
El Toro Marine Base
Tustin Marine Air Base
Approximate Selenium Contamination Area

PROJECT SITE

P:\9526E\6-GIS\Mxds\SuceptabilityMaps_20100505\9526E_SanGabrielCoyoteCreekSusceptibility_20100430.mxd Anaheim Bay-Huntington Harbor
Watershed
Newport BayNewport Coastal
Streams Watershed
Santa River Watershed
Los Angeles County
Channel in
Retarding Basin
Los Alamitos
Naval Air
Station
Seal Beach
Naval Weapons
Station
Fullerton
Airport
Hillcrest
Park
Reservoir
Orange
County
La Jolla
Recharge
Basin Kraemer
Basin
Fullerton
Reservoir
Fullerton
Reservoir Brea Creek
Reservior
Humble
Reservoir
Valencia
Reservoir
Fullerton
Reservoir
Miller
Retarding
Basin
Cypress
Retarding
Basin
Los Alamitos
Retarding
Basin
Placentia
Retarding
Basin
Raymond
Retarding
Basin
Gilbert
Retarding
Basin
Crescent
Retarding
Basin
Loftus Diversion
Channel
Desilting Basin
Rossmoor
Retarding
Basin
1 JOB TITLE SCALE 1" = 8000'

DESIGNEDDRAWINGCHECKED
BMP
04/30/10
DATEJOB NO.

THTH9526-E

ORANGE COUNTY

WATERSHED

MASTER PLANNING
ORANGE CO. CA

SUSCEPTIBILITY ANALYIS

SAN GABRIEL-COYOTE CREEK
I!
0 8,000 16,000
Feet
Susceptibility
Potential Areas of Erosion, Habitat, &
Physical Structure Susceptibility
Channel Type
Earth (Unstable)
Earth (Stabilized)
Stabilized
Tidel Influence
<= Mean High Water Line (4.28')
Water Body
Basin
Lake
Reservoir
Other Lands
Airport/Military
SUSCEPTIBILITY MAP UPATE (FEB 2013)
Project Site

Attachment B
Preliminary WQMP Exhibit

DWG: P:\K\KBHO-007\dwg\Sheets\Exhibits\EH_PE-WQMP.dwg BY: jhendricks Aug 19, 2024 - 10:47:39am PROJ: KBHO-007 REVISIONS 0 1" = 40' 20 40 80 WQMP EXHIBIT TENTATIVE TRACT MAP NO. 19263 4665 LAMPSON AVENUE CITY OF LOS ALAMITOS, COUNTY OF ORANGE, STATE OF CALIFORNIA 38%/I&:OR.S$*EN&< T T T T T T NO PARKING Trans.

METERS DATA METERS DATA

Attachment C
Site BMPs

1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.65 3.70 3.75 3.80 3.85 3.90 3.95 MWS‐L‐4‐4 6.70 1.0 0.022 0.023 0.025 0.026 0.028 0.029 0.031 0.032 0.034 0.035 0.037 0.038 0.040 0.042 0.043 0.045 0.046 0.048 0.049 0.051 0.052 0.054 0.055 0.056 0.057 0.058 0.058 0.059 0.060 0.061 MWS‐L‐3‐6 10.06 1.0 0.032 0.035 0.037 0.039 0.042 0.044 0.046 0.048 0.051 0.053 0.055 0.058 0.060 0.062 0.065 0.067 0.069 0.072 0.074 0.076 0.078 0.081 0.083 0.084 0.085 0.087 0.088 0.089 0.090 0.091MWS‐L‐4‐6 9.30 1.0 0.030 0.032 0.034 0.036 0.038 0.041 0.043 0.045 0.047 0.049 0.051 0.053 0.055 0.058 0.060 0.062 0.064 0.066 0.068 0.070 0.073 0.075 0.077 0.078 0.079 0.080 0.081 0.082 0.083 0.084MWS‐L‐4‐8 14.80 1.0 0.048 0.051 0.054 0.058 0.061 0.065 0.068 0.071 0.075 0.078 0.082 0.085 0.088 0.092 0.095 0.099 0.102 0.105 0.109 0.112 0.115 0.119 0.122 0.124 0.126 0.127 0.129 0.131 0.132 0.134 MWS‐L‐4‐13 18.40 1.0 0.059 0.063 0.068 0.072 0.076 0.080 0.084 0.089 0.093 0.097 0.101 0.106 0.110 0.114 0.118 0.122 0.127 0.131 0.135 0.139 0.144 0.148 0.152 0.154 0.156 0.158 0.160 0.163 0.165 0.167MWS‐L‐4‐15 22.40 1.0 0.072 0.077 0.082 0.087 0.093 0.098 0.103 0.108 0.113 0.118 0.123 0.129 0.134 0.139 0.144 0.149 0.154 0.159 0.165 0.170 0.175 0.180 0.185 0.188 0.190 0.193 0.195 0.198 0.200 0.203MWS‐L‐4‐17 26.40 1.0 0.085 0.091 0.097 0.103 0.109 0.115 0.121 0.127 0.133 0.139 0.145 0.151 0.158 0.164 0.170 0.176 0.182 0.188 0.194 0.200 0.206 0.212 0.218 0.221 0.224 0.227 0.230 0.233 0.236 0.239MWS‐L‐4‐19 30.40 1.0 0.098 0.105 0.112 0.119 0.126 0.133 0.140 0.147 0.153 0.160 0.167 0.174 0.181 0.188 0.195 0.202 0.209 0.216 0.223 0.230 0.237 0.244 0.251 0.255 0.258 0.262 0.265 0.269 0.272 0.276MWS‐L‐4‐21 34.40 1.0 0.111 0.118 0.126 0.134 0.142 0.150 0.158 0.166 0.174 0.182 0.189 0.197 0.205 0.213 0.221 0.229 0.237 0.245 0.253 0.261 0.268 0.276 0.284 0.288 0.292 0.296 0.300 0.304 0.308 0.312 MWS‐L‐6‐8 18.80 1.0 0.060 0.065 0.069 0.073 0.078 0.082 0.086 0.091 0.095 0.099 0.104 0.108 0.112 0.116 0.121 0.125 0.129 0.134 0.138 0.142 0.147 0.151 0.155 0.157 0.160 0.162 0.164 0.166 0.168 0.170MWS‐L‐8‐8 29.60 1.0 0.095 0.102 0.109 0.115 0.122 0.129 0.136 0.143 0.149 0.156 0.163 0.170 0.177 0.183 0.190 0.197 0.204 0.211 0.217 0.224 0.231 0.238 0.245 0.248 0.251 0.255 0.258 0.262 0.265 0.268 MWS‐L‐8‐12 44.40 1.0 0.143 0.153 0.163 0.173 0.183 0.194 0.204 0.214 0.224 0.234 0.245 0.255 0.265 0.275 0.285 0.296 0.306 0.316 0.326 0.336 0.346 0.357 0.367 0.372 0.377 0.382 0.387 0.392 0.397 0.402MWS‐L‐8‐16 59.20 1.0 0.190 0.204 0.217 0.231 0.245 0.258 0.272 0.285 0.299 0.312 0.326 0.340 0.353 0.367 0.380 0.394 0.408 0.421 0.435 0.448 0.462 0.476 0.489 0.496 0.503 0.509 0.516 0.523 0.530 0.537MWS‐L‐8‐20 74.00 1.0 0.238 0.255 0.272 0.289 0.306 0.323 0.340 0.357 0.374 0.391 0.408 0.425 0.442 0.459 0.476 0.493 0.509 0.526 0.543 0.560 0.577 0.594 0.611 0.620 0.628 0.637 0.645 0.654 0.662 0.671 MWS‐L‐10‐20 or
MWS‐L‐8‐24

88.80 1.0 0.285 0.306 0.326 0.346 0.367 0.387 0.408 0.428 0.448 0.469 0.489 0.509 0.530 0.550 0.571 0.591 0.611 0.632 0.652 0.673 0.693 0.713 0.734 0.744 0.754 0.764 0.774 0.785 0.795 0.805 4'x'4 media cage 14.80 1.0 0.048 0.051 0.054 0.058 0.061 0.065 0.068 0.071 0.075 0.078 0.082 0.085 0.088 0.092 0.095 0.099 0.102 0.105 0.109 0.112 0.115 0.119 0.122 0.124

MWS MODEL SIZE

WETLAND

PERMITER
LENGTH

LOADING
RATE
GPM/SF

HGL HEIGHT

SHALLOW MODELS STANDARD HEIGHT MODEL HIGH CAPACITY MODELS MWS Linear 2.0 HGL Sizing Calculations

MWS Linear
Advanced Stormwater Biofiltration

Contents
1 Introduction
2 Applications
3 Configurations
4 Advantages
5 Operation
6 Orientations | Bypass
7 Performance | Approvals
8 Sizing
9 Installation | Maintenance | Plants

www.ModularWetlands.com
The Urban Impact
For hundreds of years natural wetlands surrounding our shores have played an integral role as nature’s stormwater treatment system. But as our cities grow and develop, these natural wetlands have perished under countless roads, rooftops, and parking lots.

Plant A Wetland
Without natural wetlands our cities are deprived of water purification, flood control, and land stability. Modular Wetlands and the MWS Linear re-establish nature’s presence and rejuvenate water ways in urban areas.

MWS Linear
The Modular Wetland System Linear represents a pioneering breakthrough in stormwater technology as the only biofiltration system to utilize patented horizontal flow, allowing for a smaller footprint and higher treatment capacity. While most biofilters use little or no pre-treatment, the MWS Linear incorporates an advanced pre-treatment chamber that includes separation and prefilter cartridges. In this chamber sediment and hydrocarbons are removed from runoff before it enters the biofiltration chamber, in turn reducing maintenance costs and improving performance.

Parking Lots
Parking lots are designed to maximize space and
the MWS Linear’s 4 ft. standard planter width allows for easy integration into parking lot islands and other landscape medians.

Mixed Use
The MWS Linear can be installed as a raised planter to treat runoff from rooftops or patios, making it perfect for sustainable “live-work” spaces.

Industrial
Many states enforce strict regulations for discharges from industrial sites. The MWS Linear has helped various sites meet difficult EPA mandated
effluent limits for dissolved metals and other pollutants.

Residential
Low to high density developments can benefit
from the versatile design of the MWS Linear. The
system can be used in both decentralized LID design and cost-effective end-of-the-line configurations.

Streets
Street applications can be challenging due to
limited space. The MWS Linear is very adaptable,
and offers the smallest footprint to work around
the constraints of existing utilities on retrofit projects.

Commercial
Compared to bioretention systems, the MWS Linear can treat far more area in less space - meeting treatment and volume control requirements.

Applications
The MWS Linear has been successfully used on numerous new construction and retrofit projects. The system’s superior versatility makes it beneficial for a wide range of stormwater and waste water applications - treating rooftops, streetscapes, parking lots, and industrial sites.

More applications are available on our website: www.ModularWetlands.com/Applications • Agriculture
• Reuse
• Low Impact Development
• Waste Water

www.ModularWetlands.com
Configurations
The MWS Linear is the preferred biofiltration system of Civil Engineers across the country due to its versatile design. This highly versatile system has available “pipe-in” options on most models, along with built-in curb or grated inlets for simple integration into your stormdrain design.

Curb Type
The Curb Type configuration accepts sheet flow through a curb opening and is commonly used along road ways and parking lots. It can be used in sump or flow by conditions. Length of curb opening varies based on model and size.

Grate Type
The Grate Type configuration offers the same features and benefits as the Curb Type but with a grated/drop inlet above the systems pre-treatment chamber.

It has the added benefit of allowing for pedestrian access over the inlet. ADA compliant grates are available to assure easy and safe access. The Grate Type can also be used in scenarios where runoff needs to be intercepted on both sides of landscape islands.

Downspout Type
The Downspout Type is a variation of the Vault Type and is designed to accept a vertical downspout pipe from roof top and podium areas. Some models have the option of utilizing an internal bypass, simplifying the overall design. The system can be installed as a raised planter and the exterior can be stuccoed or covered with other finishes to match the look of adjacent buildings.

Vault Type
The system’s patented horizontal flow biofilter is able to accept inflow pipes directly into the pre-treatment chamber, meaning the MWS Linear can be used in end-of-the-line installations. This greatly improves feasibility over typical decentralized designs that are required with other biofiltration/bioretention systems. Another benefit of the “pipe in” design is the ability to install the system downstream of underground detention systems to meet water quality volume requirements.

Cartridge Housing
Pre-filter Cartridge
Curb Inlet
Individual Media Filters
Advantages & Operation
The MWS Linear is the most efficient and versatile biofiltration system on the market, and the only system with horizontal flow which improves performance, reduces footprint, and minimizes maintenance. Figure-1 and Figure-2 illustrate the invaluable benefits of horizontal flow and the multiple treatment stages. • Horizontal Flow Biofiltration
• Greater Filter Surface Area
• Pre-Treatment Chamber
• Patented Perimeter Void Area
• Flow Control
• No Depressed Planter Area
Separation
• Trash, sediment, and debris are separated before
entering the pre-filter cartridges
• Designed for easy maintenance access
Pre-Filter Cartridges
• Over 25 ft2 of surface area per cartridge
• Utilizes BioMediaGREEN filter material
• Removes over 80% of TSS & 90% of hydrocarbons
• Prevents pollutants that cause clogging from
migrating to the biofiltration chamber
1 Pre-Treatment
1 2
Drain-
1 2 Vertical Underdrain
Manifold
Featured Advantages

www.ModularWetlands.com
Fig. 1
Horizontal Flow
• Less clogging than downward flow biofilters
• Water flow is subsurface
• Improves biological filtration
Patented Perimeter Void Area
• Vertically extends void area between the walls
and the WetlandMEDIA on all four sides.
• Maximizes surface area of the media for higher
treatment capacity
WetlandMEDIA
• Contains no organics and removes phosphorus
• Greater surface area and 48% void space
• Maximum evapotranspiration
• High ion exchange capacity and light weight
Flow Control
• Orifice plate controls flow of water through
WetlandMEDIA to a level lower than the
media’s capacity.
• Extends the life of the media and improves
performance
Drain-Down Filter
• The Drain-Down is an optional feature that
completely drains the pre-treatment
chamber
• Water that drains from the pre-treatment
chamber between storm events will be
treated
Fig. 2 - Top View 2x to 3x More Surface Area Than Traditional Downward Flow Bioretention Systems. 2 Biofiltration
3 Discharge
Perimeter Void Area
3 4
3 Flow Control Riser
-Down Line
Outlet Pipe Page 5

Orientations
Bypass
Internal Bypass Weir (Side-by-Side Only)
The Side-By-Side orientation places the pre-treatment and discharge chambers adjacent to one another allowing for integration of internal bypass.

The wall between these chambers can act as a bypass weir when flows exceed the system’s treatment capacity, thus allowing bypass from the pre-treatment chamber directly to the discharge chamber.

External Diversion Weir Structure
This traditional offline diversion method can be
used with the MWS Linear in scenarios where runoff is being piped to the system. These simple and effective structures are generally configured with
two outflow pipes. The first is a smaller pipe on the
upstream side of the diversion weir - to divert low
flows over to the MWS Linear for treatment. The
second is the main pipe that receives water once the
system has exceeded treatment capacity and water
flows over the weir.

Flow By Design
This method is one in which the system is placed
just upstream of a standard curb or grate inlet to
intercept the first flush. Higher flows simply pass by
the MWS Linear and into the standard inlet downstream.

End-To-End
The End-To-End orientation places the pre-treatment and discharge chambers on opposite ends of the biofiltration chamber therefore minimizing the
width of the system to 5 ft (outside dimension). This
orientation is perfect for linear projects and street
retrofits where existing utilities and sidewalks limit
the amount of space available for installation. One
limitation of this orientation is bypass must be external.

Side-By-Side
The Side-By-Side orientation places the pre-treatment and discharge chamber adjacent to one another with the biofiltration chamber running parallel on either side. This minimizes the system length, providing a highly compact footprint. It has been
proven useful in situations such as streets with directly adjacent sidewalks, as half of the system can be placed under that sidewalk. This orientation also
offers internal bypass options as discussed below.

This simple yet innovative diversion trough can be
installed in existing or new curb and grate inlets to
divert the first flush to the MWS Linear via pipe. It
works similar to a rain gutter and is installed just
below the opening into the inlet. It captures the low
flows and channels them over to a connecting pipe
exiting out the wall of the inlet and leading to the
MWS Linear. The DVERT is perfect for retrofit and
green street applications that allows the MWS Linear to be installed anywhere space is available.

DVERT Low Flow Diversion
DVERT Trough

www.ModularWetlands.com
Rhode Island DEM Approved
Approved as an authorized BMP and noted to achieve the following minimum removal efficiencies: 85% TSS, 60% Pathogens, 30% Total Phosphorus for discharges to freshwater systems, and 30% Total Nitrogen for discharges to saltwater or tidal systems.

MASTEP Evaluation
The University of Massachusetts at Amherst – Water Resources Research Center, issued a technical evaluation report noting removal rates up to 84% TSS, 70% Total Phosphorus,

68.5% Total Zinc, and more.

Washington State DOE Approved
The MWS Linear is approved for General Use Level Designation (GULD) for Basic, Enhanced, and Phosphorus treatment at 1 gpm/ft2 loading rate. The highest performing BMP on the market for all main pollutant categories.

Approvals
The MWS Linear has successfully met years of challenging technical reviews and testing from some of the most prestigious and demanding agencies in the nation, and perhaps the world.

DEQ Assignment
The Virginia Department of Environmental Quality assigned the MWS Linear, the highest phosphorus removal rating for manufactured treatment devices to meet the new Virginia Stormwater Management Program (VSMP) Technical Criteria.

VA
TSS Total
Phosphorus
Ortho
Phosphorus Nitrogen Dissolved Zinc Dissolved Copper Total Zinc Total Copper Motor Oil 85% 64% 67% 45% 66% 38% 69% 50% 95%
Performance
The MWS Linear continues to outperform other treatment methods with superior pollutant removal for TSS, heavy metals, nutrients, hydrocarbons and bacteria. Since 2007 the MWS Linear has been field tested on numerous sites across the country. With it’s advanced pre-treatment chamber and innovative horizontal flow biofilter, the system is able to effectively remove pollutants through a combination of physical, chemical, and biological filtration processes. With the same biological processes found in natural wetlands, the MWS Linear harnesses natures ability to process, transform, and remove even the most harmful pollutants.

Treatment Flow Sizing Table
Model # Dimensions WetlandMedia
Surface Area
Treatment Flow
Rate (cfs)
MWS-L-4-4 4’ x 4’ 23 ft2 0.052
MWS-L-4-6 4’ x 6’ 32 ft2 0.073
MWS-L-4-8 4’ x 8’ 50 ft2 0.115
MWS-L-4-13 4’ x 13’ 63 ft2 0.144
MWS-L-4-15 4’ x 15’ 76 ft2 0.175
MWS-L-4-17 4’ x 17’ 90 ft2 0.206
MWS-L-4-19 4’ x 19’ 103 ft2 0.237
MWS-L-4-21 4’ x 21’ 117 ft2 0.268
MWS-L-8-8 8’ x 8’ 100 ft2 0.230
MWS-L-8-12 8’ x 12’ 151 ft2 0.346
MWS-L-8-16 8’ x 16’ 201 ft2 0.462
Flow Based Sizing
The MWS Linear can be used in stand alone applications to meet treatment flow requirements. Since the MWS Linear is the only biofiltration system that can accept inflow pipes several feet below the surface it can be used not only in decentralized design applications
but also as a large central end-of-the-line application for maximum feasibility.

Volume Based Sizing
Many states require treatment of a water quality volume and do not offer the option of flow based design. The MWS Linear and its unique horizontal flow makes it the only biofilter that can be used in volume based design installed downstream of ponds, detention basins, and underground storage systems.

Treatment Volume Sizing Table
Model # Treatment Capacity (cu. ft.)
@ 24-Hour Drain Down
Treatment Capacity (cu. ft.)
@ 48-Hour Drain Down
MWS-L-4-4 1140 2280
MWS-L-4-6 1600 3200
MWS-L-4-8 2518 5036
MWS-L-4-13 3131 6261
MWS-L-4-15 3811 7623
MWS-L-4-17 4492 8984
MWS-L-4-19 5172 10345
MWS-L-4-21 5853 11706
MWS-L-8-8 5036 10072
MWS-L-8-12 7554 15109
MWS-L-8-16 10073 20145

www.ModularWetlands.com
Installation
The MWS Linear is simple, easy to install, and has a space efficient design that offers lower excavation and installation costs compared to traditional tree-box type systems. The structure of the system resembles pre-cast catch basin or utility vaults and is installed in a similar fashion.

The system is delivered fully assembled for quick installation. Generally, the structure can be unloaded and set in place in 15 minutes. Our experienced
team of field technicians are available to supervise
installations and provide technical support.

Plant Selection
Abundant plants, trees, and grasses bring value and an aesthetic benefit to any urban setting, but those in the MWS Linear do even more - they increase pollutant removal. What’s not seen, but very important, is that below grade the stormwater runoff/flow is being subjected to nature’s secret weapon: a dynamic physical, chemical, and biological process working to break down and remove non-point source pollutants. The flow rate is controlled in the MWS Linear, giving the plants more “contact time” so that pollutants are more successfully decomposed, volatilized and incorporated into the biomass of The MWS Linear’s micro/macro flora and fauna.

A wide range of plants are suitable for use in the MWS Linear, but selections vary by location and climate. View suitable plants by selecting the list relative to your project location’s hardy zone.

Please visit www.ModularWetlands.com/Plants for more information and various plant lists.

Maintenance
Reduce your maintenance costs, man hours, and materials with the MWS Linear. Unlike other biofiltration systems that provide no pre-treatment, the MWS Linear is a self-contained treatment train which incorporates simple and effective pre-treatment.

Maintenance requirements for the biofilter itself are almost completely eliminated, as the pre-treatment chamber removes and isolates trash, sediments, and hydrocarbons. What’s left is the simple maintenance of an easily accessible pre-treatment chamber that can be cleaned by hand or with a standard vac truck. Only periodic replacement of lowcost media in the pre-filter cartridges is required for long term operation and there is absolutely no need to replace expensive biofiltration media.

MWS – Linear
Hybrid Stormwater Filtration System

SPECIFICATIONS

Modular Wetland Systems, Inc. www.modularwetlands.com
P.O. Box 869 P 760-433-7640
Oceanside, CA 92049 F 760-433-3179

MWS – Linear
Hybrid Stormwater Filtration System
Save valuable space with small
otprint for urban sites.
d tropical
ndscape plants.
er and
ss expensive maintenance
ystem
unoff is
in
d
ischarge chamber the rate of discharge is controlled by valves set to a desired rate”. ested Pollutant Removal Efficiencies:
fo
Improve BMP aesthetics with
attractive native an
la
Reduce lifetime costs with saf
le
“The MWS – Linear hybrid stormwater
treatment system is described as a self contained treatment train. This system utilizes an innovative combination of l treatment processes. Stormwater runoff flows into the s via pipe or curb/grate type catch basin opening. Polluted runoff first encounters a screening device to remove larger pollutants and then enters a hydrodynamic separation chamber which settles out the sediments and larger suspended solids. Next the r treated by a revolutionary filter media, BioMediaGREEN that removes fines and associated pollutants, including bacteria. From there runoff enters of bioretention filter the form of a subsurface flow vegetated gravel wetland. Within the wetland physical, chemical, and biological mechanisms remove the remaining particulate and dissolve pollutants. The purified runoff leaves the system via the discharge chamber. In the d
T
Removal
Di d
Removal
D
Removal
TPH Removal Removal
TSS ssolve
Lead
issolved
Copper E. coli Turbidity
98% 81% 92% 99% 60.2% 92%

“Nature and Harmony Working Together in Perfect Harmony”

SPECIFICATIONS – MWS- LINEAR
gaged in the engineering design and
roduction of treatment systems for stormwater.
treat the entire water quality
olume when used with pre-storage and properly sized.
ls.
g
¾” x 1
nels are
g
ted of UV protected/marine grade
berglass and stainless steel hinge and mount.
uires
tails of this are provided in the installation section of the WS-Linear Design Kit.

Track Record: The MWS- Linear Hybrid Stormwater Treatment System is manufactured by a company whom is regularly en
p
Coverage: The MWS- Linear is designed to treat the water quality volume or water quality flow. For flow based design, high flow bypass is internal, for volume based design, high flow bypass is external and prior to pre-detention system. For offline volume based designs the MWS - Linear has the ability to v
Non-Corrosive Materials: The MWS – Linear is designed with non-corrosive materia All internal piping is SD35 PVC. Catch basin filter components, including mountin hardware, fasteners, support brackets, filtration material, and support frame are constructed of non-corrosive materials (316 stainless steel, and UV protected/marine grade fiberglass). Fasteners are stainless steel. Primary filter mesh is 316 stainless steel welded screens. Filtration basket screens for coarse, medium and fine filtration is ¾“expanded, 10 x 10 mesh, and 35 x 35 mesh, respectively. No polypropylene, monofilament netting or fabrics shall be used in this system. Media Protective Pa constructed of UV protected/marine grade fiberglass. Mounts are constructed of stainless steel. BioMediaGREEN is an inert rock substrate and is non-corrosive.

Perimeter filter structure is constructed of lightweight injection molded plastic. Mountin brackets are constructed of SD40 PVC and are mounted with 3/8” diameter stainless steel redheads. Drain down filter cover is construc
fi
Weight: Each complete unit weighs approximately 29,000 to 40,000 pounds and req a boom crane to install. De
M

Transportation: The Modular Wetland System – Linear is designed to be transported a standard flat bed t
on
ruck. The unit easily fits on a flat bed truck without the need of pecial permitting.
d
noff can enter the system through a pipe, and/or a
uilt in curb or grate type opening.
etland System – Linear is completely passive and
quires no external energy sources.
he
tation. As a precaution a footing can
lso be built into the systems concrete structure.
re
o slippage, breaking, or tearing. All filters are warranted for a minimum of five (5) years. e
hydrocarbon removal abilities. Within the wetland filter biological processes capture and s
Alternative Technology Configurations: The Modular Wetland System – Linear is modular is design. Each module will be up to 22 feet long and 5 feet wide. The system can be made in lengths varying from 13 to 100s of feet long. For lengths longer than 22 feet the system will shipped in modules and assembled on site. The Modular Wetlan System – Linear has many alternative configurations. This allows the system to be adapted to many site conditions. Ru
b
Energy Requirements: The Modular W
re
Buoyancy Issues: Buoyancy is only a an issue when ground water levels rise above t bottom of the Modular Wetland System – Linear’s concrete structure. With 8.5 cubic yards of wetland media there is no concern of floa
a
Durability: The structure of the box will be precast concrete. The concrete will be 28 day compressive strength fc = 5,000 psi. Steel reinforcing will be ASTM A – C857. Structu will support an H20 loading as indicted by AASHTO. The joint between the concrete sections will ship lap and joint sealed with ram-nek. Filter (excluding oil absorbent media) and support structures are of proven durability. The filter and mounting structures are of sufficient strength to support water, sediment, and debris loads when the filter is full, with n
Oil Absorbent Media: The MWS – Linear utilizes both physical and biological mechanisms to capture and filter oil and grease. A skimmer and boom system will b positioned on the internal perimeter of the catch basin insert. The primary filtration media, BioMediaGreen, utilized in the perimeter and drain down filters, has excellent

break down oil and grease. Much of the breakdown and transformation of oil and grease performed by natural occurring bacteria.
n system. For
eak flows that exceed internal bypass capacity, external bypass is use. for internally bypassed flows. External bypass will bypass of eatment processes.
ze. Annual
een and quarter-scale
boratory tests on the MWS – Linear flow based system.

POLLUTANT

FICIENCY
is
Overflow Protection: The grate and curb type MWS – Linear are designed with an internal bypass consisting of two SD PVC pipes which direct high flows around the perimeter and wetland filter, directly into the discharge chamber. For the volume based vault type configuration, bypass should be located prior to the pre-detentio p
Filter Bypass: Runoff will bypass filtration (BioMediaGREEN and wetland filter) components of the MWS - Linear. The system will still provide screening and settling during higher flow rates
tr
Pollutant Removal Efficiency: The MWS - Linear is capable of removing over 90% of the net annual total suspended solids (TSS) load based on a 20-micron particle si TSS removal efficiency models are based on documented removal efficiency performance from full-scale laboratory tests on BioMediaGr la

REMOVAL
EF
Trash & Litter 99%
TPH (mg/L) 99%
TSS (mg/L) 98%
E. Coli (MPN/100ml) 60%
Turbidity (NTU) 92%
Dissolved Metals (mg/L) 76%
Non-Scouring: During heavy storm events the runoff bypasses perimeter and wetland lter components. The system will not re-suspend solids at design flows. rticle
diameter = 19 microns
Sil-Co-Sil 106. Mean pa
fi

Uniqueness: The Modular Wetland System – Linear is a complete self contain treatment train that incorporates capture, screening, sedimentation, filtration, bioretention, high flow bypass, and flow control into a single modular structure. This system provides four stages of treatment making it the only 4 stage treatment train stormwater filtration system, therefore making it unique to the industry. Other s not incorporate all the necessary attributes to make it a complete stormwater management device as
ed
ystems do
with the Modular Wetland System – Linear. Therefore, no equal xists for this system.
ter management system no external
retreatment of preconditioning is necessary.

PECIFICATIONS – BioMediaGREEN
se
nd is also biodegradable. It is stable with no
nown adverse environmental effects.
injection) studies have
hown that the products disappear very rapidly from the lung. dies that show no relation between inhalation exposure
nd the development of tumors.
e
Pretreatment & Preconditioning: Since the Modular Wetland System – Linear is a complete capture and treatment train stormwa
p
S

BioMediaGREEN is a proprietary engineered filter media. Made of a unique combination of the inert naturally occurring material this product is non-combustible and do not po a fire hazard, stable and non-reactive, a
k
This product has been tested in long-term carcinogenicity studies [inhalation and intraperitoneal injection (i.p.)] with no significant increase in lung tumors or abdominal tumors. Short-term biopersistent (inhalation and intra-tracheal s
In October 2001, IARC classified this product as Group 3, "not classifiable as to its carcinogenicity to humans". The 2001 decision was based on the latest epidemiological studies and animal inhalation stu
a

The product can typically be disposed of in an ordinary landfill (local regulations may apply). If you are unsure of the regulations, contact your local Public Health Department r the local office of the Environmental Protection Agency (EPA). nt
REEN
ut
ut filters, catch basin inserts,
ater polishing units, and hydrodynamic separators.
ve Materials: The BioMediaGreen material is made of non-corrosive aterials.

MediaGREEN material has been tested through
gorous flow and loading conditions.
has been proven to capture and
tain hydrocarbons.
and
liage, sediments, TSS, particulate and dissolved
etals, nutrients, and bacteria.
le
o
Coverage: When properly installed BioMediaGREEN Filter Blocks provide sufficie contact time, at rated flows, of passing contaminate water. The BioMediaG material will capture and retain most pollutants that pass through it. The BioMediaGREEN material is made of a proprietary blend of inert substances. The BioMediaGREEN Filter Blocks can be used in different treatment devices, including b not limited to flume filters, trench drain filters, downspo w
Non-Corrosi
m
Durability: The BioMediaGREEN material has been chosen for its proven durability, with an expected life of 2 plus years. The BioMediaGREEN material is of sufficient strength to support water, sediment, and debris loads when the media is at maximum flow; with no slippage, breaking, or tearing. The Bio
ri
Oil Absorbent Media: The BioMediaGREEN material
re
Pollutant Removal Efficiency: The BioMediaGREEN Filter Blocks are designed to capture high levels of Hydrocarbons including but not limited to oils & grease, gasoline, diesel, and PAHs. BioMediaGREEN Filter Blocks have the physical ability to block filter trash and litter, grass and fo
m
BioMediaGREEN technology is based on a proprietary blend of synthetic inert natural substances aimed at removal of various stormwater pollutants. BioMediaGREEN was created to have a very porous structure capable of selectively removing pollutants whi

allowing high flow through rates for water. As pollutants are captured by its structure, ioMediaGREEN captures most pollutants and maintains porosity and filtering rge percentage of TSS, hydrocarbons, nutrients, and heavy metals. Microbial reduction ary depending on colony size, flow rates and site specific conditions.

REMOVAL

EFFICIENCY
B
capabilities.

Field and laboratory tests have confirmed the BioMediaGREEN capability to capture la
efficiency will v

POLLUTANT
Oil & Grease (mg/L) 90%
TPH (mg/L) 99%
TSS (mg/L) 85%
Turbidity (NTU) 99%
Total Phosphorus (mg/L) 69.6%
Dissolved Metals (mg/L) 75.6%
Replacement: Removal and replacement of the blocks is simple. Remove blocks from ltration system. Replace with new block of equal size.

Sil-Co-Sil 106. Mean particle
diameter = 19 microns
fi

TECHNICAL GUIDANCE DOCUMENT APPENDICES
XIV-69 December 20, 2013
BIO-7: Proprietary Biotreatment
Proprietary biotreatment devices are devices that are
manufactured to mimic natural systems such as bioretention areas by incorporating plants, soil, and microbes engineered to provide treatment at higher flow rates or volumes and with smaller footprints than their natural counterparts.

Incoming flows are typically filtered through a planting media (mulch, compost, soil, plants, microbes, etc.) and either infiltrated or collected by an underdrain and delivered to the storm water conveyance system. Tree box filters are an
increasingly common type of proprietary biotreatment device that are installed at curb level and filled with a bioretention type soil. For low to moderate flows they operate similarly to bioretention systems and are bypassed during high flows.

Tree box filters are highly adaptable solutions that can be used in all types of development and in all types of soils but are especially applicable to dense urban parking lots, street, and roadways.

Feasibility Screening Considerations
x Proprietary biotreatment devices that are unlined may cause incidental infiltration. Therefore, an evaluation of site conditions should be conducted to evaluate whether the BMP should include an impermeable liner to avoid infiltration into the subsurface.

Opportunity Criteria
x Drainage areas of 0.25 to 1.0 acres.
x Land use may include commercial, residential, mixed use, institutional, and subdivisions.

Proprietary biotreatment facilities may also be applied in parking lot islands, traffic circles, road shoulders, and road medians.
x Must not adversely affect the level of flood protection provided by the drainage system.

OC-Specific Design Criteria and Considerations
□ Frequent maintenance and the use of screens and grates to keep trash out may decrease the likelihood of clogging and prevent obstruction and bypass of incoming flows. □ Consult proprietors for specific criteria concerning the design and performance. □
Proprietary biotreatment may include specific media to address pollutants of concern. However, for proprietary device to be considered a biotreatment device the media must be capable of supporting rigorous growth of vegetation.
□
Proprietary systems must be acceptable to the reviewing agency. Reviewing agencies shall have the discretion to request performance information. Reviewing agencies shall have the discretion to deny the use of a proprietary BMP on the grounds of performance, maintenance considerations, or other relevant factors.

Also known as:
¾ Catch basin planter box
¾ Bioretention vault
¾ Tree box filter
Proprietary biotreatment
Source:
http://www.americastusa.com
/index.php/filterra/

TECHNICAL GUIDANCE DOCUMENT APPENDICES
XIV-70 December 20, 2013
□ In right of way areas, plant selection should not impair traffic lines of site. Local jurisdictions may also limit plant selection in keeping with landscaping themes.

Computing Sizing Criteria for Proprietary Biotreatment Device x Proprietary biotreatment devices can be volume based or flow-based BMPs. x Volume-based proprietary devices should be sized using the Simple Design Capture Volume Sizing Method described in Appendix III.3.1 or the Capture Efficiency Method for Volume-Based, Constant Drawdown BMPs described in Appendix III.3.2.
x The required design flowrate for flow-based proprietary devices should be computed using the Capture Efficiency Method for Flow-based BMPs described in Appendix III.3.3).

In South Orange County, the provided ponding plus pore volume must be checked to demonstrate that it is greater than 0.75 of the remaining DCV that this BMP is designed to address. Many propretary biotreatment BMPs will not be able to meet the definition of “biofiltration” that applies in South Orange County. See Section III.7 and Worksheet SOC-1.

Additional References for Design Guidance
x Los Angeles Unified School District (LAUSD) Stormwater Technical Manual, Chapter 4:
http://www.laschools.org/employee/design/fs-studies-andreports/download/white_paper_report_material/Storm_Water_Technical_Manual_2009-optred.pdf?version_id=76975850 x Los Angeles County Stormwater BMP Design and Maintenance Manual, Chapter 9:
http://dpw.lacounty.gov/DES/design_manuals/StormwaterBMPDesignandMaintenance.pdf x Santa Barbara BMP Guidance Manual, Chapter 6:
http://www.santabarbaraca.gov/NR/rdonlyres/91D1FA75-C185-491E-A882- 49EE17789DF8/0/Manual_071008_Final.pdf

Attachment D
Reference Materials

Attachment E
Operations and Maintenance Plan
(to be completed during final engineering)

Bio Clean ARS
A Stormwater Trash Capture Solution
A Forterra Company

OPERATION & MAINTENANCE
MANUAL
5796 Armada Drive Suite 250 | Carlsbad, CA 92008 | 855.566.3938 [email protected] | biocleanenvironmental.com

1 | P a g e

MAINTENANCE
The Bio Clean ARS requires minimal preventative maintenance. Regular street sweeping will prevent debris from building up in front of the unit thereby obstructing storm water from entering the catch basin curb opening. The Bio Clean ARS is specially designed with flow control blades that will open during larger rain events to prevent flooding regardless of trash build up in front of the unit.

Pressure-washing the unit may be necessary if street sweeping is unavailable.

Yearly Maintenance Schedule:

Inspections consist of visually inspecting the unit from street level and performing an openingclosing function check.

Visual Inspection:

1. Built-up debris and foreign object debris can hinder the unit’s operation. Remove any visible debris that may be on, in front of, and nearby the unit.

2. Look for any visible signs of vandalism or damage that may compromise the unit’s ability to properly function. Attempted vandalism and slight damage should be inspected closely to ensure no future damage may result.

2 | P a g e
Opening-Closing Function Check:

1. Manually push on the blades at the bottom from the front of the catch basin. Perform this at the center and at each end of the device Please ensure all appropriate traffic control has been set up and all appropriate safety procedures are followed based on local and state regulations, if required.

2. Observe if the tension is appropriate on the blades and that the return to the close position. Note if any or all of the blades to not return to the close position.

3. Observe if the blades which are interconnecting work together. The blade being pushed on should open the most and the adjacent blades should open slight less in an outward pattern as shown below. Please note if any blades are moving or not moving outside of this pattern.

5. Check to see if the tensioner and cable/spring is properly connected behind each blade. Note any issues related to the cable/spring not being connected.

Blades Maintenance/Adjustment/Replacement:

1. Verify which Blade is damaged and plan which faceplate is easiest and most efficient to remove.

2. Remove Faceplate from brackets and remove tension spring from back of unit.

3. Slide each blade off until damaged blade has been reached. Replace damaged blade or blades.

4. Feed tensioner spring through all the back clips and attach faceplate to top bar.

5. Secure tensioner spring on back of unit and secure faceplate to mounted bracket

LA-ARS Locking Screen: Torsion Spring and Adjustment Knob System Maintenance

1. Verify unit does not have damage blades and working properly

2. Check the status of the locking system making sure the system can tighten by first releasing the unit by pressing on the releases on each side of the unit. If unit releases, proceed to next step

3. Check the status of the tension knob by clicking it tighter to make sure the unit tightens with each click of the tightening knob. If unit tightens, maintenance is complete.

4. If unit does not tighten or release, remove faceplates from bracket and remove torsion spring system. Both Torsion Spring and Adjustment knob units will need to be replaced.

5. Screw new torsion spring and adjustment knob system into place and place metal wire into plastic holding system on back of each blade.

6. Test unit by tightening and releasing the locking system. If unit is working properly, reinstall unit.

3 | P a g e

Replacement Schedule:

All components on the on the Bio Clean ARS are made from 304 or 316 stainless steel parts with the exception of the flow control blades which are made of structural polymer. Replacement of individual blades is quick and easy. If during maintenance inspection it is observed the unit is damaged or vandalized to the point at which the opening-closing function is not operating correctly, the unit should be repaired. Bio Clean Environmental should be notified if a replacement parts or repair work is needed.

For Maintenance Services
Please Contact Us At:
760-433-7640
[email protected]

ENGINEERED SOLUTIONS
Modular Wetlands® Linear
Operation & Maintenance Manual

2 MODULAR WETLANDS® LINEAR

OPERATION & MAINTENANCE MANUAL

TABLE OF CONTENTS
Overview........................................................................................................3 Inspection Summary....................................................................................... 4 Inspection Process..........................................................................................5 Maintenance Indicators.................................................................................. 6 Inspection Process..........................................................................................7 Maintenance Summary .................................................................................. 8 Pretreatment Chamber ................................................................ 9 Prefilter Cartridge ...................................................................... 10 Biofiltration Chamber ................................................................ 11 Discharge Chamber ................................................................... 12 Inspection Report.........................................................................................13 Cleaning and Maintenance Report................................................................ 14

3 OVERVIEW
The Modular Wetlands® Linear Biofilter is designed to remove high levels of trash, debris, sediments, nutrients, metals, and hydrocarbons. Its simple design allows for quick and easy installation. The system is housed in a standard precast structure and can be installed at various depths to meet site-specific conditions.

INTRODUCTION
This is the Modular Wetlands Linear Biofilter operation and maintenance manual. Before starting, read the instructions and equipment lists closely. It is important to follow all necessary safety procedures associated with state and local regulations. Some steps required confined space entry. Please contact Contech for more information on pre-authorized third party contractors who can provide installation services in your area. For a list of service providers in your area please visit: www.conteches.com/maintenance.

Pretreatment
Chamber
Biofiltration
Chamber
Discharger
Chamber
Prefilter Box
Biofiltration
Media
Flow
Control
Riser
Vertical
Underdrain
Outflow
Inflow

4 INSTRUCTIONS

INSPECTION SUMMARY
Stormwater regulations require BMPs be inspected and maintained to ensure they are operating as designed to allow for effective pollutant removal and provide protection to receiving water bodies. It is recommended that inspections be performed multiple times during the first year to assess the site specific loading conditions. The first year of inspections can be used to set inspection and maintenance intervals for subsequent years to ensure appropriate maintenance is provided.
• Inspect pre-treatment, biofiltration, and discharge chambers an average of once every six to twelve months. Varies based on site specific and local conditions.
• Average inspection time is approximately 15 minutes. Always ensure appropriate safety protocol and procedures are followed.

The following is a list of equipment required to allow for simple and effective inspection of the Modular Wetlands Linear:
• Modular Wetlands Linear Inspection Form
• Flashlight
• Manhole hook or appropriate tools to remove access hatches and covers • Appropriate traffic control signage and procedures
• Measuring pole and/or tape measure
• Protective clothing and eye protection
• 7/16” open or closed ended wrench
• Large permanent black marker (initial inspections only - first year) Note: entering a confined space requires appropriate safety and certification. It is generally not required for routine inspections of the system

INSPECTION AND MAINTENANCE NOTES

1. Following maintenance and/or inspection, it is recommended that the maintenance operator prepare a maintenance/inspection record. The record should include any maintenance activities performed, amount and description of debris collected, and condition of the system and its various filter mechanisms.

2. The owner should keep maintenance/inspection record(s) for a minimum of five years from the date of maintenance. These records should be made available to the governing municipality for inspection upon request at any time.

3. Transport all debris, trash, organics, and sediments to approved facility for disposal in accordance with local and state requirements.

4. Entry into chambers may require confined space training based on state and local regulations.

5. No fertilizer shall be used in the biofiltration chamber.

6. Irrigation should be provided as recommended by manufacturer and/or landscape architect. Amount of irrigation required is dependent on plant species. Some plants may not require irrigation after initial establishment.

5 INSPECTION PROCESS

1. Prepare the inspection form by writing in the necessary information including project name, location, date & time, unit number and other information (see inspection form).

2. Observe the inside of the system through the access covers. If minimal light is available and vision into the unit is impaired, utilize a flashlight to see inside the system and all of its chambers.

3. Look for any out of the ordinary obstructions in the inflow pipe, pre-treatment chamber, biofiltration chamber, discharge chamber or outflow pipe. Write down any observations on the inspection form.

4. Through observation and/or digital photographs, estimate the amount of trash, debris accumulated in the pre-treatment chamber. Utilizing a tape measure or measuring stick, estimate the amount of sediment in this chamber. Record this depth on the inspection form.

5. Through visual observation, inspect the condition of the pre-filter cartridges. Look for excessive build-up of sediment on the cartridges, any build-up on the tops of the cartridges, or clogging of the holes. Record this information on the inspection form. The prefilter cartridges can be further inspected by removing the cartridge tops and assessing the color of the BioMediaGREEN filter cubes (requires entry into pre-treatment chamber - see notes previous notes regarding confined space entry). Record the color of the material. New material is a light green color. As the media becomes clogged, it will turn darker in color, eventually becoming dark brown or black.

The closer to black the media is the higher percentage that the media is exhausted and is in need of replacement.

6. The biofiltration chamber is generally maintenance-free due to the system’s advanced pre-treatment chamber. For units which have open planters with vegetation, it is recommended that the vegetation be inspected. Look for any plants that are dead or showing signs of disease or other negative stressors. Record the general health of the plants on the inspection form and indicate through visual observation or digital photographs if trimming of the vegetation is required.

7. The discharge chamber houses the orifice control structure, drain down filter (only in California - older models), and is connected to the outflow pipe. It is important to check to ensure the orifice is in proper operating conditions and free of any obstructions. It is also important to assess the condition of the drain down filter media which utilizes a block form of the BioMediaGREEN. Assess in the same manner as the cubes in the prefilter cartridge as mentioned above. Generally, the discharge chamber will be clean and free of debris. Inspect the water marks on the side walls. If possible, inspect the discharge chamber during a rain event to assess the amount of flow leaving the system while it is at 100% capacity (pre-treatment chamber water level at peak HGL - top of bypass weir). The water level of the flowing water should be compared to the watermark level on the side walls, which is an indicator of the highest discharge rate the system achieved when initially installed. Record on the form if there is any difference in level from the watermark in inches.

INSPECTION
• Excessive accumulation of sediment in the pre-treatment chamber of more than 6" in depth.
• Excessive accumulation of sediment on the BioMediaGREEN media housed within the pretreatment cartridges. The following chart shows photos of the condition of the BioMediaGREEN contained within the pre-filter cartridges. When media is more than 85% clogged, replacement is required.
7 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS

INSPECTION
• Excessive accumulation of sediment in the pre-treatment chamber of more than 6" in depth.
• Excessive accumulation of sediment on the BioMediaGREEN media housed within the pretreatment cartridges. The following chart shows photos of the condition of the BioMediaGREEN contained within the pre-filter cartridges. When media is more than 85% clogged, replacement is required.
7 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS
New
BioMediaGREEN
0%
Exhausted
BioMediaGREEN
85% 100%

6 MAINTENANCE INDICATORS
Based upon the observations made during inspection,
maintenance of the system may be required based on the
following indicators:
• Missing or damaged internal components or
cartridges
• Obstructions in the system or its inlet and/or outlet pipes
• Excessive accumulation of floatables in the
pretreatment chamber in which the length and
width of the chamber is fully impacted more than
18”. See photo below.
• Excessive accumulation of sediment in the
pretreatment chamber of more than 6” in depth.
• Excessive accumulation of sediment on the
BioMediaGREEN media housed within the
pretreatment cartridges. The following chart shows
photos of the condition of the BioMediaGREEN
contained within the pre-filter cartridges. When
media is more than 85% clogged, replacement is
required.
• Excessive accumulation of sediment on the
BioMediaGREEN media housed within the
pretreatment cartridges. When media is more than
85% clogged, replacement is required. The darker
the BioMediaGREEN, the more clogged it is and in
need of replacement.

MAINTENANCE INDICATORS
Based upon the observations made during inspection, maintenance of the system may b required based on the following indicators:
• Missing or damaged internal components or cartridges
• Obstructions in the system or its inlet and/or outlet pipes • Excessive accumulation of floatables in the pre-treatment chamber in which the leng of the chamber is fully impacted more than 18". See photo below.

8. Finalize the inspection report for analysis by the maintenance manager t determine if maintenance is required.
6 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS

INSPECTION
• Excessive accumulation of sediment in the pre-treatment chamber of more than 6" i depth.

INSPECTION

MAINTENANCE INDICATORS
Based upon the observations made during inspection, maintenance of the system may be required based on the following indicators:
• Missing or damaged internal components or cartridges
• Obstructions in the system or its inlet and/or outlet pipes • Excessive accumulation of floatables in the pre-treatment chamber in which the length and width of the chamber is fully impacted more than 18". See photo below.

8. Finalize the inspection report for analysis by the maintenance manager to determine if maintenance is required.
6 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS

INSPECTION

MAINTENANCE INDICATORS
Based upon the observations made during inspection
required based on the following indicators:
• Missing or damaged internal components or cartr
• Obstructions in the system or its inlet and/or outle
• Excessive accumulation of floatables in the pre-tr
of the chamber is fully impacted more than 18". S

8. Finalize the inspection report for analysis
determine if maintenance is required.
6 ©2022 COPYRIGHT | CONTECH ENG
NOTE: During the first few storms, the water level in the outflow chamber should be observed and a 6” long horizontal watermark line drawn (using a large permanent marker) at the water level in the discharge chamber while the system is operating at 100% capacity. The diagram below illustrates where the line should be drawn. This line is a reference point for future inspections of the system.

Water level in the discharge chamber is a function of flow rate and pipe size. Observation of the water level during the first few months of operation can be used as a benchmark level for future inspections. The initial mark and all future observations shall be made when the system is at 100% capacity (water level at maximum level in the pre-treatment chamber). If future water levels are below this mark when the system is at 100% capacity, this is an indicator that maintenance to the pre-filter cartridges may be needed.

8. Finalize the inspection report for analysis by the maintenance manager to determine if maintenance is required.

7 INSPECTION PROCESS
• Excessive accumulation of sediment on the BioMediaGREEN media housed within the drain down filter (California only - older models). The following photos show the condition of the BioMediaGREEN contained within the drain down filter. When media is more than 85% clogged, replacement is required. • Overgrown vegetation.
• Water level in the discharge chamber during 100% operating capacity (pretreatment chamber water level at max height) is lower than the water mark by 20%.

INSPECTION
• Excessive accumulation of sediment on the BioMediaGREEN media housed within the drain down filter (California only - older models). The following photos show the condition of the BioMediaGREEN contained within the drain down filter. When media is more than 85% clogged, replacement is required.
• Overgrown vegetation.
• Water level in the discharge chamber during 100% operating capacity (pre-treatment chamber water level at max height) is lower than the watermark by 20%. 8 INSPECTION
• Excessive accumulation of sediment on the BioMediaGREEN media housed within the drain down filter (California only - older models). The following photos show the condition of the BioMediaGREEN contained within the drain down filter. When media is more than 85% clogged, replacement is required.
• Overgrown vegetation.
• Water level in the discharge chamber during 100% operating capacity (pre-treatment chamber water level at max height) is lower than the watermark by 20%.

8 MAINTENANCE SUMMARY
The time has come to maintain your Modular Wetlands® Linear. All necessary pre-maintenance steps must be carried out before maintenance occurs. Once traffic control has been set up per local and state regulations and access covers have been safely opened, the maintenance process can begin. It should be noted that some maintenance activities require confined space entry. All confined space requirements must be strictly followed before entry into the system. In addition, the following is recommended:
• Prepare the maintenance form by writing in the necessary information including project name, location, date & time, unit number and other info (see maintenance form). • Set up all appropriate safety and cleaning equipment. • Ensure traffic control is set up and properly positioned. • Prepared pre-checks (OSHA, safety, confined space entry) are performed.

The following is a list of equipment to required for maintenance of the Modular Wetlands® Linear:
• Modular Wetlands Linear Maintenance Form
• Manhole hook or appropriate tools to access hatches and covers • Protective clothing, flashlight, and eye protection
• 7/16” open or closed ended wrench
• Vacuum assisted truck with pressure washer
• Replacement BioMediaGREEN for pre-filter cartridges if required (order from one of Contech’s Maintenance Team members at https://www.conteches.com/maintenance).

9 MAINTENANCE | PRETREATMENT CHAMBER

1. Remove access cover over pre-treatment chamber and position vacuum truck accordingly.

2. With a pressure washer, spray down pollutants accumulated on walls and pre-filter cartridges.

3. Vacuum out pre-treatment chamber and remove all accumulated pollutants including trash, debris, and sediments. Be sure to vacuum the floor until the pervious pavers are visible and clean.

4. If pre-filter cartridges require media replacement, continue to step 5. If not, replace access cover and move to step 11.
cartridges.

3. Vacuum out pre-treatment chamber and remove all accumulated pollutants including trash, debris, and sediments. Be sure to vacuum the floor until the pervious pavers are visible and clean.

4. If pre-filter cartridges require media replacement, move on to next page. If not, replace access cover.
11 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS
cartridges.

3. Vacuum out pre-treatment chamber and remove all accumulated pollutants including trash, debris, and sediments. Be sure to vacuum the floor until the pervious pavers are visible and clean.

4. If pre-filter cartridges require media replacement, move on to next page. If not, replace access cover.
11 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS

2. With a pressure washer, spray down pollutants accumulated on walls and pre-filter cartridges.

3. Vacuum out pre-treatment chamber and remove all accumulated pollutants including trash, debris, and sediments. Be sure to vacuum the floor until the pervious pavers are visible and clean.

4. If pre-filter cartridges require media replacement, move on to next page. If not, replace access cover.
11 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS

2. With a pressure washer, spray down pollutants accumulated on walls and pre-filter cartridges.

3. Vacuum out pre-treatment chamber and remove all accumulated pollutants including trash, debris, and sediments. Be sure to vacuum the floor until the pervious pavers are visible and clean.

4. If pre-filter cartridges require media replacement, move on to next page. If not, replace access cover.
11 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS

10 MAINTENANCE | PREFILTER CARTRIDGES

5. After successfully cleaning out the pre-treatment chamber (previous page) enter the pre-treatment chamber.

6. Unscrew the two bolts (circles shown below) holding the lid on each cartridge filter and remove lid.

7. Place the vacuum hose over each individual media filter to suck out filter media.

8. Once filter media has been sucked out, use a pressure washer to spray down the inside of the cartridge and it’s media cages. Remove cleaned media cages and place to the side. Once removed, the vacuum hose can be inserted into the cartridge to vacuum out any remaining material near the bottom of the cartridge.

9. Reinstall media cages and fill with new media from the manufacturer or outside supplier. Manufacturer will provide specification of media and sources to purchase. Utilize the manufacture-provided refilling tray and place on top of the cartridge. Fill the tray with new bulk media and shake down into place. Using your hands, lightly compact the media into each filter cage. Once the cages are full, remove the refilling tray and replace the cartridge top, ensuring bolts are properly tightened.

10. Exit the pre-treatment chamber. Replace access hatch or manhole cover.

1. After successfully cleaning out the pre-treatment chamber (previous page) enter the pre-treatment chamber.

2. Unscrew the two bolts (red circles) holding the lid on each cartridge filter and remove lid.

3. Place the vacuum hose over each individual media filter to suck out filter media.

4. Once filter media has been sucked out, use a pressure washer to spray down the inside of the cartridge and it's media cages. Remove cleaned media cages and place to the side. Once removed, the vacuum hose can be inserted into the cartridge to vacuum out any remaining material near the bottom of the cartridge.
12 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS
0 0

1. After successfully cleaning out the pre-treatment chamber (previous page) enter the pre-treatment chamber.

2. Unscrew the two bolts (red circles) holding the lid on each cartridge filter and remove lid.

3. Place the vacuum hose over each individual media filter to suck out filter media.

4. Once filter media has been sucked out, use a pressure washer to spray down the inside of the cartridge and it's media cages. Remove cleaned media cages and place to the side. Once removed, the vacuum hose can be inserted into the cartridge to vacuum out any remaining material near the bottom of the cartridge.
12 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS
0 0

1. After successfully cleaning out the pre-treatment chamber (previous page) enter the pre-treatment chamber.

2. Unscrew the two bolts (red circles) holding the lid on each cartridge filter and remove lid.

3. Place the vacuum hose over each individual media filter to suck out filter media.

4. Once filter media has been sucked out, use a pressure washer to spray down the inside of the cartridge and it's media cages. Remove cleaned media cages and place to the side. Once removed, the vacuum hose can be inserted into the cartridge to vacuum out any remaining material near the bottom of the cartridge.
12 ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS
0 0

5. MAINTENANCE (PRE-FILTER CARTRIDGES)
Reinstall media cages and fill with new media from the manufacturer or outside supplier. Manufacturer will provide specification of media and sources to purchase. utilize the manufacture-provided refilling tray and place on top of the cartridge. Fill the tray with new bulk media and shake down into place. using your hands, lightly compact the media into each filter cage. Once the cages are full, remove the refilling tray and replace the cartridge top, ensuring bolts are properly tightened.

6. Exit the pre-treatment chamber. Replace access hatch or manhole cover.

5. MAINTENANCE (PRE-FILTER CARTRIDGES)
Reinstall media cages and fill with new media from the manufacturer or outside supplier. Manufacturer will provide specification of media and sources to purchase. utilize the manufacture-provided refilling tray and place on top of the cartridge. Fill the tray with new bulk media and shake down into place. using your hands, lightly compact the media into each filter cage. Once the cages are full, remove the refilling tray and replace the cartridge top, ensuring bolts are properly tightened.

6. Exit the pre-treatment chamber. Replace access hatch or manhole cover.

5. MAINTENANCE (PRE-FILTER CARTRIDGES)
Reinstall media cages and fill with new media from the manufacturer or outside supplier. Manufacturer will provide specification of media and sources to purchase. utilize the manufacture-provided refilling tray and place on top of the cartridge. Fill the tray with new bulk media and shake down into place. using your hands, lightly compact the media into each filter cage. Once the cages are full, remove the refilling tray and replace the cartridge top, ensuring bolts are properly tightened.

6. Exit the pre-treatment chamber. Replace access hatch or manhole cover.

11 MAINTENANCE | BIOFILTRATION CHAMBER

11. In general, the biofiltration chamber is maintenance-free with the exception of maintaining the vegetation. The Modular Wetlands Linear utilizes vegetation similar to surrounding landscape areas, therefore trim vegetation to match surrounding vegetation. If any plants have died, replace them with new ones.

12. Each vertical under drain on the biofiltration chamber has a removable (threaded cap) that can be taken off to check any blockages or root growth. Once removed, a jetting attachment can be used to clean out the under drain and orifice riser.

13. As with all biofilter systems, at some point the biofiltration media (WetlandMedia) will need to be replaced. Either because of physical clogging of sorptive exhaustion of the media ion exchange capacity (to remove dissolved metals and phosphorous). The general life of this media is 10 to 20 years based on site specific conditions and pollutant loading. Utilize the vacuum truck to vacuum out the media by placing the hose into the chamber. Once all the media is removed use the power washer to spray down all the netting on the outer metal cage. Inspect the netting for any damage or holes. If the netting is damaged it can be repaired or replaced with guidance by the manufacturer.

14. Contact one of Contech’s Maintenance Team members at https://www.conteches.com/maintenance to order new WetlandMedia. The quantity of media needed can be determined by providing the model number and unit depth. Media will be provided in super sacks for easy installation. Each sack will weigh between 1000 and 2000 lbs. A lifting apparatus (backhoe, boom truck, or other) is recommended to position the super sack over the biofiltration chamber. Fill the media cages up to the same level as the old media. Replant with vegetation. ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS

3. As with all biofilter systems, at some point the biofiltration media (WetlandMedia) will need to be replaced. Either because of physical clogging of sorptive exhaustion of the media ion exchange capacity (to remove dissolved metals and phosphorous).

The general life of this media is 10 to 20 years based on site specific conditions and pollutant loading. Utilize the vacuum truck to vacuum out the media by placing the hose into the chamber. Once all the media is removed use the power washer to spray down all the netting on the outer metal cage. Inspect the netting for any damage or holes. If the netting is damaged it can be repaired or replaced with guidance by the manufacturer.

4. The first step is to contact the manufacturer and order new WetlandMedia. The quantity of media needed can be determined by providing the model number and unit depth. Media will be provided in super sacks for easy installation. Each sack will weigh between 1000 and 2000 lbs. A lifting apparatus (backhoe, boom truck, or other) is rec-ommended to position the super sack over the biofiltration chamber.

Fill the media cages up to the same level as the old media. Replant with vegetation.

2. Each vertical under drain on the biofiltration chamber has a removable (threaded) that can be taken off to check any blockages or root growth. Once removed a a jetting attachment can be used to clean out the under drain and orifice riser. ©2022 COPYRIGHT | CONTECH ENGINEERED SOLUTIONS
all biofilter systems, at some point the biofiltration media (WetlandMedia) ed to be replaced. Either because of physical clogging of sorptive exhaustion media ion exchange capacity (to remove dissolved metals and phosphorous). neral life of this media is 10 to 20 years based on site specific conditions and nt loading. Utilize the vacuum truck to vacuum out the media by placing the to the chamber. Once all the media is removed use the
washer to spray down all the netting on the outer metal cage. Inspect the for any damage or holes. If the netting is damaged it can be repaired or re with guidance by the manufacturer.
st step is to contact the manufacturer and order new WetlandMedia. The y of media needed can be determined by providing the model number and pth. Media will be provided in super sacks for easy installation. Each sack gh between 1000 and 2000 lbs. A lifting apparatus (backhoe, boom truck, or s rec-ommended to position the super sack over the biofiltration chamber. media cages up to the same level as the old media. Replant with vegetation. vertical under drain on the biofiltration chamber has a removable (threaded) an be taken off to check any blockages or root growth. Once removed a g attachment can be used to clean out the under drain and 1 orifice riser. .

MAINTENANCE (BIOFILTRATION CHAMBER)
In general, the biofiltration chamber is maintenance-free with the exception of maintaining the vegetation. Using standard gardening tools, properly trim back the vegetation to healthy levels. The MW Linear™ utilizes vegetation similar to surrounding landscape areas, therefore trim vegetation to match surrounding vegetation. If any plants have died, replace them with new ones.

3. As with all biofilter systems, at some point the biofiltration media (WetlandMedia) will need to be replaced. Either because of physical clogging of sorptive exhaustion of the media ion exchange capacity (to remove dissolved metals and phosphorous).

The general life of this media is 10 to 20 years based on site specific conditions and pollutant loading. Utilize the vacuum truck to vacuum out the media by placing the hose into the chamber. Once all the media is removed use the power washer to spray down all the netting on the outer metal cage. Inspect the netting for any damage or holes. If the netting is damaged it can be repaired or replaced with guidance by the manufacturer.

4. The first step is to contact the manufacturer and order new WetlandMedia. The quantity of media needed can be determined by providing the model number and unit depth. Media will be provided in super sacks for easy installation. Each sack will weigh between 1000 and 2000 lbs. A lifting apparatus (backhoe, boom truck, or other) is rec-ommended to position the super sack over the biofiltration chamber.

Fill the media cages up to the same level as the old media. Replant with vegetation.

2. Each vertical under drain on the biofiltration chamber has a removable (threaded) that can be taken off to check any blockages or root growth. Once removed a a jetting attachment can be used to clean out the under drain and orifice riser.

12 MAINTENANCE | DISCHARGE CHAMBER

15. Remove access hatch or manhole cover over discharge chamber.

16. Enter chamber to gain access to the drain down filter. Unlock the locking mechanism and lift up drain down filter housing to remove used BioMediaGREEN filter block as shown below. NOTE: Drain down filter is only found on units installed in California prior to 2023. If no drain down filter is present, skip steps 16 and 17.

17. Insert a new BioMediaGREEN filter block and lock drain down filter housing back in place.

18. Replace access hatch or manhole cover over discharge chamber.

INSPECTION
• Excessive accumulation of sediment on the BioMediaGREEN media housed within the drain down filter (California only - older models). The following photos show the condition of the BioMediaGREEN contained within the drain down filter. When media is more than 85% clogged, replacement is required.
• Overgrown vegetation.
• Water level in the discharge chamber during 100% operating capacity (pre-treatment chamber water level at max height) is lower than the watermark by 20%.

INSPECTION
• Excessive accumulation of sediment on the BioMediaGREEN media housed within the drain down filter (California only - older models). The following photos show the condition of the BioMediaGREEN contained within the drain down filter. When media is more than 85% clogged, replacement is required.
• Overgrown vegetation.
• Water level in the discharge chamber during 100% operating capacity (pre-treatment chamber water level at max height) is lower than the watermark by 20%.

13 NOTES
_______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________ _______________________________________________________________________________________________________

14 For Office Use Only
(city) (Zip Code) (Reviewed By)
Owner / Management Company
(Date)
Contact Phone ( ) _
Inspector Name Date / / Time AM / PM
Weather Condition Additional Notes
Yes
Depth:

Yes No
Modular Wetland System Type (Curb, Grate or UG Vault): Size (22', 14' or etc.):

Other Inspection Items:

Type of Inspection Routine Follow Up Complaint Storm Storm Event in Last 72-hours? No Yes Office personnel to complete section to
the left.

Inspection Report
Modular Wetlands Linear
Is the filter insert (if applicable) at capacity and/or is there an accumulation of debris/trash on the shelf system? Does the cartridge filter media need replacement in pre-treatment chamber and/or discharge chamber? Any signs of improper functioning in the discharge chamber? Note issues in comments section.

Chamber:

Is the inlet/outlet pipe or drain down pipe damaged or otherwise not functioning properly? Structural Integrity:

Working Condition:

Is there evidence of illicit discharge or excessive oil, grease, or other automobile fluids entering and clogging the unit?
Is there standing water in inappropriate areas after a dry period? Damage to pre-treatment access cover (manhole cover/grate) or cannot be opened using normal lifting pressure?
Damage to discharge chamber access cover (manhole cover/grate) or cannot be opened using normal lifting pressure?
Does the MWS unit show signs of structural deterioration (cracks in the wall, damage to frame)? Project Name
Project Address
Inspection Checklist
No Comments
Does the depth of sediment/trash/debris suggest a blockage of the inflow pipe, bypass or cartridge filter? If yes, specify which one in the comments section. Note depth of accumulation in in pre-treatment chamber.

Is there a septic or foul odor coming from inside the system? Is there an accumulation of sediment/trash/debris in the wetland media (if applicable)? Is it evident that the plants are alive and healthy (if applicable)? Please note Plant Information below.

Sediment / Silt / Clay
Trash / Bags / Bottles
Green Waste / Leaves / Foliage
Waste: Plant Information
No Cleaning Needed
Recommended Maintenance
Additional Notes:

Damage to Plants
Plant Replacement
Plant Trimming
Schedule Maintenance as Planned
Needs Immediate Maintenance

ENGINEERED SOLUTIONS

15 For Office Use Only
(city) (Zip Code) (Reviewed By)
Owner / Management Company
(Date)
Contact Phone ( ) _
Inspector Name Date / / Time AM / PM
Weather Condition Additional Notes
Site
Map #
Comments:

Inlet and Outlet
Pipe Condition
Drain Down Pipe
Condition
Discharge Chamber
Condition
Drain Down Media
Condition
Plant Condition
Media Filter
Condition
Long:

MWS
Sedimentation
Basin
Total Debris
Accumulation
Condition of Media
25/50/75/100
(will be changed
@ 75%)
Operational Per
Manufactures'
Specifications
(If not, why?)
Lat: MWS
Catch Basins
GPS Coordinates
of Insert
Manufacturer /
Description / Sizing
Trash
Accumulation
Foliage
Accumulation
Sediment
Accumulation
Type of Inspection Routine Follow Up Complaint Storm Storm Event in Last 72-hours? No Yes Office personnel to complete section to
the left.

Project Address
Project Name
Cleaning and Maintenance Report
Modular Wetlands Linear ENGINEERED SOLUTIONS

SUPPORT
DRAWINGS AND SPECIFICATIONS ARE AVAILABLE AT WWW.CONTECHES.COM © 2023 CONTECH ENGINEERED SOLUTIONS LLC, A QUIKRETE COMPANY 800-338-1122
WWW.CONTECHES.COM
ALL RIGHTS RESERVED. PRINTED IN THE USA.

CONTECH ENGINEERED SOLUTIONS LLC PROVIDES SITE SOLUTIONS FOR THE CIVIL ENGINEERING INDUSTRY. CONTECH’S PORTFOLIO INCLUDES BRIDGES, DRAINAGE, SANITARY SEWER, STORMWATER AND EARTH STABILIZATION PRODUCTS. FOR INFORMATION ON OTHER CONTECH DIVISION OFFERINGS, VISIT CONTECHES.COM OR CALL 800-338-1122.

Modular Wetlands Maintenance Guide 1/2023
NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS

SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS

AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED

WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION.

ENGINEERED SOLUTIONS

Modular Wetland System (MWS) – LINEAR
Maintenance Cost (per acre)
MWS - LINEAR Cleaning Required
Yearly
Maintenance
Cost
Year 1
1) Clean Inlet Filter (6 Month Intervals)
2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media
$80 / each (x2)
$350 / year
$500 / year
Year 2
1) Clean Inlet Filter (6 Month Intervals)
2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media
$80 / each (x2)
$350 / year
$500 / year
Year 3
1) Clean Inlet Filter (6 Month Intervals)
2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media
$80 / each (x2)
$350 / year
$500 / year
Year 4
1) Clean Inlet Filter (6 Month Intervals)
2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media
$80 / each (x2)
$350 / year
$500 / year
Year 5
1) Clean Inlet Filter (6 Month Intervals)
2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media
$80 / each (x2)
$350 / year
$500 / year
Year 6
1) Clean Inlet Filter (6 Month Intervals)
2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media
$80 / each (x2)
$350 / year
$500 / year
Year 7
1) Clean Inlet Filter (6 Month Intervals)
2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media
$80 / each (x2)
$350 / year
$500 / year
Year 8
1) Clean Inlet Filter (6 Month Intervals)
2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media
$80 / each (x2)
$350 / year
$500 / year
Year 9
1) Clean Inlet Filter (6 Month Intervals)
2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media
$80 / each (x2)
$350 / year
$500 / year
Year 10
1) Clean Inlet Filter (6 Month Intervals)
2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media
4) Remove & Replace Wetland Plants & Media
$80 / each (x2)
$350/ year
$500 / year
$2,500
Total 1 - 10 Total Maintenance Cost Over 10 Years $11,800 Average Yearly Cost Assumes 10 Year Replacement of Wetland Media. $1,180 / Year
WWW.MODULARWETLANDS.COM P: 760-433-7640

Modular Wetland System - Linear (MWS-Linear)
Maintenance Schedule
MWS - LINEAR Cleaning Required Est. Cleaning
Time
Year 1 1) Clean Inlet Filter (6 Month Intervals) (does not apply to vault type) 2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media (12 month Intervals) 10 Minutes
25 Minutes
45 Minutes
Year 2 1) Clean Inlet Filter (6 Month Intervals) (does not apply to vault type) 2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media (12 month Intervals) 10 Minutes
25 Minutes
45 Minutes
Year 3 1) Clean Inlet Filter (6 Month Intervals) (does not apply to vault type) 2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media (12 month Intervals) 10 Minutes
25 Minutes
45 Minutes
Year 4 1) Clean Inlet Filter (6 Month Intervals) (does not apply to vault type) 2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media (12 month Intervals) 10 Minutes
25 Minutes
45 Minutes
Year 5 1) Clean Inlet Filter (6 Month Intervals) (does not apply to vault type) 2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media (12 month Intervals) 10 Minutes
25 Minutes
45 Minutes
Year 6 1) Clean Inlet Filter (6 Month Intervals) (does not apply to vault type) 2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media (12 month Intervals) 10 Minutes
25 Minutes
45 Minutes
Year 7 1) Clean Inlet Filter (6 Month Intervals) (does not apply to vault type) 2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media (12 month Intervals) 10 Minutes
25 Minutes
45 Minutes
Year 8 1) Clean Inlet Filter (6 Month Intervals) (does not apply to vault type) 2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media (12 month Intervals) 10 Minutes
25 Minutes
45 Minutes
Year 9… 1) Clean Inlet Filter (6 Month Intervals) (does not apply to vault type) 2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media (12 month Intervals) 10 Minutes
25 Minutes
45 Minutes
Year 15
1) Clean Inlet Filter (6 Month Intervals) (does not apply to vault type) 2) Vacuum Catch Basin (12 Month Intervals)
3) Replace BioMedia Green Filter Media (12 month Intervals) 4) Remove & Replace Wetland Plants & Media (every 10-20 years) 10 Minutes
25 Minutes
45 Minutes
6 to 8 Hours
Procedure 1
Clean Inlet Filter
(does not apply to vault type)
Modular Wetland Systems, Inc. recommends the catch basin filter be inspected and cleaned a minimum of once every six months and replacement of hydrocarbon booms once a year. The procedure is easily done with the use of any standard vacuum truck. Before doing maintenance please use proper safety and traffic control. 1) Remove grate or manhole, remove the deflector shield (grate type only). Note: entry into an underground stormwater vault such as an inlet vault requires certification in confined space training. 2) Remove all trash, debris, organics, and sediments collected by the inlet filter insert either manually or with the use of a vactor truck.
3) Evaluate hydrocarbon boom. If the boom is filled with hydrocarbons and oils it should be replaced. Attach new boom to basket with plastic ties through pre-drilled holes in basket. Place the deflector shield (grate type only) back into the filter.

Hydrocarbon boom should be replaced annually. (The hydrocarbon boom may be classified as hazardous material and will have to be picked up and disposed of as hazardous waste). 10 Minutes

Procedure 2
Vacuum Catch Basin
Modular Wetland Systems, Inc. recommends the separation chamber be inspected and cleaned a minimum of once a year. The procedure is easily done with the use of any standard vacuum truck. Before doing maintenance please use proper safety and traffic control.
1) Remove grate or manhole.
2) Remove catch basin filter.
3) Spray down pollutants accumulated on cartridge filters and catch basin walls. 4) Vacuum out sediments and debris accumulated on catch basin floor. 5) Replace catch basin filter, and replace grate or manhole cover. 25 Minutes
Procedure 3
Replace BioMedia
Green Media Filter
Modular Wetland Systems, Inc. recommends the BioMediaGREEN Cartridge Filters be inspected and cleaned a minimum of once a year. The procedure will require prior maintenance of catch basin. Before doing maintenance please use proper safety and traffic control.
1) Remove grate, remove catch basin filter.
2) Perform maintenance activities on catch basin.
3) Enter separation chamber, unscrew the two bolts holding the lid on the cartridge filter. This will expose the 14 pieces of BioMediaGREEN in each cartridge. 4) Evaluate media condition, replace if necessary. If the spaces between the media are filled with sediment and the surface of the media is dark brown or black the media should be replaced. The old media can be removed by hand by pulling the media pieces up out of the cartridge and taking them out of the catch basin. 5) Once all old media is removed, spray down the interior of the cartridge and vacuum out accumulated debris.
6) Use new pieces of BioMediaGREEN and slide down over the perforated PVC risers. The media will only go in one way for easy installation. Replace media over all risers.
5) Replace cartridge filter lid, replace catch basin filter, and replace grate or manhole cover.

Modular Wetland Systems, Inc. recommends the drain down filter be inspected and maintained a minimum of once a year.
1) Open hatch of discharge chamber, enter chamber.
2) Unlatch fiberglass cover, remove media block, replace with new block, replace and latch cover.
3) Exit chamber, close and lock down the hatch.
45 Minutes
Procedure 4
Replace Wetland
Media
Modular Wetland Systems, Inc. recommends the wetland media be evaluated every 3 to 5 years to test flow rate. The media life is approximately 15 to 20 years. The wetland media is an expanded shale that can be ordered from the manufacturer or independent supplier. If the flow through the wetland filter is decreasing the internal inflow and outflow pipes leading to and from the wetland chamber can be jetted. If the flow through the wetland is still minimal then the media may need to be replaced. To replace the media the following steps are required. Before doing maintenance please use proper safety and traffic control.
1) Remove plants and dispose. Have new plants standing ready to plant. 2) Use a larger vacuum truck to remove the media from the wetland chamber. 3) Spray down the chamber walls and remove all sediment and water. 4) Replace with new wetland media and plant plants.
6 to 8 Hours
WWW.MODULARWETLANDS.COM P: 760-433-7640

Attachment F
Geotechnical Report

131 Calle Iglesia, Suite 200, San Clemente, CA 92672 (949) 369-6141 www.lgcgeotechnical.com December 21, 2021 Project No. 21198-01
Mr. Matthew J. Waken
MW Investment Group, LLC
27702 Crown Valley Parkway, Suite D-4-197
Ladera Ranch, CA 92694
Subject: Preliminary Geotechnical Evaluation and Design Recommendations for Proposed Single‐Family and Multi‐Family Residential Development, 4665 Lampson Avenue, Los Alamitos, California
In accordance with your request and authorization, LGC Geotechnical, Inc. has performed a preliminary geotechnical evaluation for the proposed single-family and multi-family residential development located at 4665 Lampson Avenue in the City of Los Alamitos, California. The purpose of our study was to evaluate the existing onsite geotechnical conditions and to provide preliminary geotechnical recommendations relative to the proposed residential development.

Should you have any questions regarding this report, please do not hesitate to contact our office. We appreciate this opportunity to be of service.

Respectfully Submitted,
LGC Geotechnical, Inc.

Ryan Douglas, PE, GE 3147
Project Engineer
RLD/BPP/amm
Distribution: (1) Addressee (electronic copy)

Project No. 21198‐01 Page i December 21, 2021

TABLE OF CONTENTS
Section Page

1.0 INTRODUCTION ......................................................................................................................................1

1.1 Purpose and Scope of Services ............................................................................................................... 1

1.2 Project Description ..................................................................................................................................... 1

1.3 Existing Conditions ..................................................................................................................................... 1

1.4 Background ................................................................................................................................................... 2

1.5 Subsurface Geotechnical Evaluation .................................................................................................. 4

1.6 Laboratory Testing ..................................................................................................................................... 4

2.0 GEOTECHNICAL CONDITIONS.............................................................................................................6

2.1 Geologic Geology ......................................................................................................................................... 6

2.2 Site Specific Geology .................................................................................................................................. 6

2.3 Groundwater ................................................................................................................................................. 6

2.4 Field Infiltration Testing ......................................................................................................................... 7

2.5 Seismic Design Criteria ............................................................................................................................ 7

2.6 Faulting ........................................................................................................................................................... 9

2.6.1 Liquefaction and Dynamic Settlement ................................................................................. 9

2.6.2 Liquefaction Surface Effects .................................................................................................. 10

2.6.3 Lateral Spreading ...................................................................................................................... 10

2.7 Static Settlement ....................................................................................................................................... 10

2.8 Expansion Potential ................................................................................................................................ 11

3.0 CONCLUSIONS........................................................................................................................................12

4.0 PRELIMINARY RECOMMENDATIONS ............................................................................................13

4.1 Site Earthwork .......................................................................................................................................... 13

4.1.1 Site Preparation ......................................................................................................................... 13

4.1.2 Removal and Recompaction Depths and Limits ........................................................... 14

4.1.3 Temporary Excavations ......................................................................................................... 15

4.1.4 Removal Bottoms and Subgrade Preparation ................................................................ 15

4.1.5 Material for Fill .......................................................................................................................... 16

4.1.6 Placement and Compaction of Fills .................................................................................... 17

4.1.7 Trench and Retaining Wall Backfill and Compaction .................................................. 17

4.1.8 Shrinkage and Subsidence .................................................................................................... 18

4.2 Preliminary Foundation Recommendations ................................................................................. 18

4.2.1 Provisional Post-Tensioned Foundation Design Parameters ................................ 19

4.2.2 Post-Tensioned Foundation Subgrade Preparation and Maintenance ............. 20

4.2.3 Slab Underlayment Guidelines ............................................................................................ 21

4.3 Soil Bearing and Lateral Resistance ................................................................................................ 22

4.4 Lateral Earth Pressures for Retaining Walls ............................................................................... 22

4.5 Soil Corrosivity .......................................................................................................................................... 24

4.6 Control of Surface Water and Drainage Control .......................................................................... 24

4.7 Subsurface Water and Infiltration ..................................................................................................... 25

4.8 Preliminary Asphalt Concrete Pavement Sections .................................................................. 25

TABLE OF CONTENTS (Cont’d)
Project No. 21198‐01 Page ii December 21, 2021

4.9 Nonstructural Concrete Flatwork ...................................................................................................... 26

4.10 Geotechnical Plan Review ..................................................................................................................... 27

4.11 Geotechnical Observation and Testing During Construction ................................................. 27

5.0 LIMITATIONS.........................................................................................................................................29

LIST OF ILLUSTRATIONS, TABLES, AND APPENDICES
Figures
Figure 1 – Site Location Map (Page 3)
Figure 2 – Geotechnical Exploration Location Map (Rear of Text) Figure 3 – Retaining Wall Backfill Detail (Rear of Text) Tables
Table 1 – Groundwater Summary (Page 6)
Table 2 – Summary of Field Infiltration Testing (Page 7) Table 3 – Seismic Design Parameters (Page 8)
Table 4 – Provisional Geotechnical Parameters for Post-Tensioned Foundation Slab Design (Page 20) Table 5 – Lateral Earth Pressures – Imported Sandy Soils (Page 23) Table 6 – Preliminary Pavement Section Options (Page 26) Table 7 – Nonstructural Concrete Flatwork for Low Expansion Potential (Page 27) Appendices
Appendix A – References
Appendix B – Boring and CPT Logs
Appendix C – Laboratory Test Results
Appendix D – Infiltration Test Data
Appendix E – General Earthwork and Grading Specifications

Project No. 21198‐01 Page 1 December 21, 2021

1.0 INTRODUCTION

1.1 Purpose and Scope of Services
This report presents the results of our preliminary geotechnical evaluation for the proposed single-family and multi-family residential development located at 4665 Lampson Avenue in the City of Los Alamitos, California. Refer to the Site Location Map (Figure 1).

The purpose of our study was to provide a preliminary geotechnical evaluation relative to the proposed residential development. As part of our scope of work, we have: 1) reviewed available geotechnical background information including in-house regional geologic maps and published geotechnical literature pertinent to the site (Appendix A); 2) performed a limited subsurface geotechnical evaluation of the site consisting of the excavation of seven small-diameter borings ranging in depth from approximately 5 to 46.5 feet below existing ground surface; 3) performed two field infiltration tests; 4) performed laboratory testing of select soil samples obtained during our subsurface evaluation; and 5) prepared this preliminary geotechnical summary report presenting our findings, preliminary conclusions and recommendations for the development of the proposed residential project.

It should be noted that our evaluation and this report only address geotechnical issues associated with the site and do not address any environmental issues.

1.2 Project Description
Based on the preliminary site plan (KTGY, 2021), the proposed development includes the construction of 102 single-family residential lots and 90 affordable multi-family units. Proposed site improvements include a park and a series of internal streets. Design cuts and fills (not including required remedial grading) are anticipated to be on the order of 1 to 3 feet. The proposed building structures are anticipated to be relatively light-weight at-grade structures with maximum column and wall loads of approximately 30 kips and 2 kips per linear foot, respectively. Please note no grading plans or structural loads were provided to us at the time of this report.

The recommendations given in this report are based upon the estimated structural loading, grading and layout information above. We understand that the project plans are currently being developed at this time; LGC Geotechnical should be provided with updated project plans and any changes to structural loads when they become available, in order to either confirm or modify the recommendations provided herein. Additional field work and/or laboratory testing may be necessary.

1.3 Existing Conditions
The site is approximately 12 acres and is bound to the south by Lampson Avenue, to the east by a golf course, to the north by a park and to the west by vacant land. The site is currently occupied by the California Department of Fish and Wildlife with an associated parking lot and open space.

Project No. 21198‐01 Page 2 December 21, 2021
The site has minor relief, with the highest being the northern side of the site and gently slopes gently from north to south.

1.4 Background
Review of historical aerials indicates that the building and associated improvements were constructed after 1963, but prior to 1972 and remained relatively unchanged since (Historic Aerials, 2021). Aerial photos from 1952 and 1963 indicate the site was previously raw land.

Site Location
FIGURE 1
Site Location Map
DATE December 2021
ENG. / GEOL.

PROJECT NO.

PROJECT NAME
SCALE
RLD
Not to Scale
MWIG - Los Alamitos
21198-01

Project No. 21198‐01 Page 4 December 21, 2021

1.5 Subsurface Geotechnical Evaluation
LGC Geotechnical performed a subsurface geotechnical evaluation of the site consisting of the excavation of five hollow-stem auger borings and two hand-auger borings to evaluate onsite geotechnical conditions.

Five hollow-stem borings (HS-1 through HS-3, I-1, and I-2) were drilled to depths ranging from approximately 5 to 46.5 feet below existing grade. An LGC Geotechnical staff engineer observed the drilling operations, logged the borings, and collected soil samples for laboratory testing. The borings were excavated by Cal Pac Drilling, Inc. under subcontract to LGC Geotechnical using a truck-mounted drill rig equipped with 6 and 8-inch-diameter hollow-stem augers. Driven soil samples were collected by means of the Standard Penetration Test (SPT) and Modified California Drive (MCD) sampler generally obtained at 2.5 to 5-foot vertical increments. The MCD is a split-barrel sampler with a tapered cutting tip and lined with a series of 1-inch-tall brass rings. The SPT sampler (1.4-inch ID) and MCD sampler (2.4-inch ID, 3.0-inch OD) were driven using a 140-pound automatic hammer falling 30 inches to advance the sampler a total depth of 18 inches. The raw blow counts for each 6-inch increment of penetration were recorded on the boring logs. Bulk samples of the near-surface soils were also collected and logged at select borings for laboratory testing. At the completion of drilling, the borings were backfilled with the native soil cuttings and tamped. Some settlement of the backfill soils may occur over time.

Two hand auger borings (HA-1 and HA-2) were excavated to approximately 5 feet below the existing surface, sampled, logged, and backfilled. The approximate locations of our hand auger borings are presented on our Boring Location Map (Figure 2). The boring logs are presented in Appendix B.

Infiltration testing was performed within two of the borings (I-1 and I-2) to depths of approximately 5 feet below existing grade. An LGC Geotechnical geologist installed standpipes, backfilled the borings with crushed rock and pre-soaked the infiltration holes prior to testing.

Infiltration testing was performed per the County of Orange testing guidelines. Standpipes were removed and the locations were subsequently backfilled with native soils at the completion of testing. Some settlement of the backfill soils may occur over time.

The approximate locations of our subsurface explorations are provided on the Boring Location Map (Figure 2). The boring logs are provided in Appendix B.

1.6 Laboratory Testing
Representative bulk and driven (relatively undisturbed) samples were obtained for laboratory testing during our field evaluation. Laboratory testing included in-situ moisture content and insitu dry density, fines content, Atterberg Limits, expansion index, consolidation, direct shear, laboratory compaction and corrosion (sulfate, chloride, pH and minimum resistivity).

The following is a summary of the laboratory test results:
 Dry density of the samples collected ranged from approximately 87 pounds per cubic foot (pcf) to 111 pcf, with an average of 99 pcf. Field moisture contents ranged from approximately 9 to 35 percent, with an average of 25 percent.

Project No. 21198‐01 Page 5 December 21, 2021
 Two fines content tests were performed and indicated a fines content (passing No. 200 sieve) of approximately 15 and 16.5 percent. Based on the Unified Soils Classification System (USCS), the tested samples would be classified as “coarse-grained.”  Four Atterberg Limit (liquid limit and plastic limit) tests were performed. Results indicated a Plasticity Index (PI) value ranging from 12 to 24.
 Two consolidation tests were performed. The load versus deformation plots are provided in Appendix C.
 One remolded direct shear test was performed. The plot is provided in Appendix C.  One laboratory compaction test of a near surface sample indicated a maximum dry density of 116.0 pcf with an optimum moisture content of 13.0 percent.  Two Expansion potential tests were performed and indicated an expansion index value of 30 and 32, corresponding to “Low” expansion potential.
 Corrosion testing indicated soluble sulfate contents ranging from approximately 0.032 to

0.254 percent, a chloride content ranging from 140 to 600 parts per million (ppm), pH of

8.92, and a minimum resistivity of 210 ohm-centimeters.

A summary of the laboratory test results is presented in Appendix C. The moisture and dry density results are presented on the boring logs in Appendix B.

Project No. 21198‐01 Page 6 December 21, 2021

2.0 GEOTECHNICAL CONDITIONS

2.1 Geologic Conditions
The subject site is located within the Orange County coastal plain, more generally located on the broad southern margin of the Los Angeles Basin. The site is located more specifically within the Santa Ana River drainage basin, and it is underlain at depth by poorly consolidated alluvial sediments mapped as Quaternary Young Alluvial Fan deposits “Unit 2” (Qya2) (USGS, 2016).

2.2 Site‐Specific Geology
Based on the results of our subsurface investigation, the site is underlain by a thin veneer of topsoil and older artificial fill over young alluvial deposits of Holocene age, per regional geologic mapping (USGS, 2016). The materials are described on the boring logs presented in Appendix B.

The young alluvial sediments encountered during our subsurface exploration generally consist of interbedded layers of gray and brown, silty clay, clay, silty sand, and clayey sand. The materials were observed to be very moist to wet with depth, soft to very stiff and medium dense to dense.

2.3 Groundwater
Groundwater was encountered in three of our borings (HS-1 through HS-3) at depths of approximately 11 to 13 feet below existing grade. Additionally, historic high groundwater is estimated to be about 10 feet below existing grade (CDMG, 1998). The location and approximate depth of groundwater is summarized in Table 1 below.

TABLE 1
Groundwater Summary
Boring
Number
Total Drilled
Depth of Boring
(ft)
Groundwater Depth
Below Existing Grade
(ft)
HS-1 21.5 13
HS-2 46.5 11.5
HS-3 21.5 11
Seasonal fluctuations of groundwater elevations should be expected over time. In general, groundwater levels fluctuate with the seasons and local zones of perched groundwater may be present due to local seepage caused by irrigation and/or recent precipitation. Local perched groundwater conditions or surface seepage may develop once site development is completed.

Project No. 21198‐01 Page 7 December 21, 2021

2.4 Field Infiltration Testing
Two field percolation tests were performed in locations and depths per the direction of the project civil engineer, the location is depicted on Figure 2 – Boring Location Map. Test well installation consisted of placing a 3-inch diameter perforated PVC pipe in the excavated 8-inch diameter borehole and backfilling the annulus with crushed rock including the placement of approximately 2 inches of crushed rock at the bottom of the borehole. The infiltration test wells were presoaked the day of installation and testing took place within 24 hours of presoaking.

During the pre-test, the water level was observed to drop less than 6 inches in 25 minutes for two consecutive readings. Therefore, the test procedure for fine-grained soils or “slow test” was followed. Test well installation and the estimation of infiltration rates were accomplished in general accordance with the guidelines set forth by the County of Orange (2013). In general, three-dimensional flow out of the test well (percolation), as observed in the field, is mathematically reduced to one-dimensional flow out of the bottom of the test well (infiltration). Infiltration tests are performed using relatively clean water, free of particulates, silt, etc. The results of our recent field infiltration testing are presented in Appendix D and summarized below.

TABLE 2
Summary of Field Infiltration Testing
Infiltration Test
Identification
Approx. Depth
Below Existing
Grade (ft)
Observed
Infiltration Rate*
(in./hr.)
I-1 5 0.03
I-2 5 0.04
*Observed Infiltration Rates Do Not Include Factor of Safety.

The tested infiltration rates provided in this report are considered a general representation of the infiltration rates at the location of the proposed infiltration boring. Please note, the testing of infiltration rates is highly dependent upon the materials encountered at the point of testing (i.e., location and depth of testing). Varying subsurface conditions may exist outside of the test location which could alter the calculated infiltration rate. Please refer to Section 4.7 for subsurface water infiltration recommendations.

2.5 Seismic Design Criteria
The site seismic characteristics were evaluated per the guidelines set forth in Chapter 16, Section 1613 of the 2019 California Building Code (CBC). Since the site contains soils that are susceptible to liquefaction (refer to below Section “Liquefaction and Dynamic Settlement”), ASCE 7-16 which has been adopted by the CBC requires that site soils be assigned Site Class “F” and a site-specific response spectrum be performed. However, in accordance with Section

20.3.1 of ASCE 7-16, if the fundamental periods of vibration of the planned structure are equal to or less than 0.5 second, a site-specific response spectrum is not required and ASCE 7- 16/2019 CBC site class and seismic parameters may be used in lieu of a site-specific response

Project No. 21198‐01 Page 8 December 21, 2021
spectrum. It should be noted that the seismic parameters provided herein are not applicable for any structure having a fundamental period of vibration greater than 0.5 second. Please note that the following seismic parameters are only applicable for code‐based acceleration response spectra and are not applicable for where site‐specific ground motion procedures are required by ASCE 7‐16. Representative site coordinates of latitude

33.7815 degrees north and longitude -118.0510 degrees west were utilized in our analyses.

The maximum considered earthquake (MCE) spectral response accelerations (SMS and SM1) and adjusted design spectral response acceleration parameters (SDS and SD1) for Site Class D are provided in Table 3 below. The structural designer should contact the geotechnical consultant if structural conditions (e.g., number of stories, seismically isolated structures, etc.) require site-specific ground motions.

TABLE 3
Seismic Design Parameters
Selected Parameters from 2019 CBC,
Section 1613 ‐ Earthquake Loads
Seismic
Design
Values
Notes/Exceptions
Distance to applicable faults classifies the site as a
“Near-Fault” site. Section 11.4.1 of ASCE 7
Site Class D* Chapter 20 of ASCE 7
Ss (Risk-Targeted Spectral Acceleration
for Short Periods) 1.467g From SEAOC, 2021
S1 (Risk-Targeted Spectral
Accelerations for 1-Second Periods) 0.524g From SEAOC, 2021 Fa (per Table 1613.2.3(1)) 1.000
For Simplified Design Procedure
of Section 12.14 of ASCE 7, Fa
shall be taken as 1.4 (Section

12.14.8.1)
Fv (per Table 1613.2.3(2)) 1.776
Value is only applicable per
requirements/exceptions per
Section 11.4.8 of ASCE 7
SMS for Site Class D
[Note: SMS = FaSS] 1.467g -
SM1 for Site Class D
[Note: SM1 = FvS1] 0.931g
Value is only applicable per
requirements/exceptions per
Section 11.4.8 of ASCE 7
SDS for Site Class D
[Note: SDS = (2/3)SMS] 0.978g -
SD1 for Site Class D
[Note: SD1 = (2/3)SM1] 0.620g
Value is only applicable per
requirements/exceptions per
Section 11.4.8 of ASCE 7
CRS (Mapped Risk Coefficient at 0.2 sec) 0.908 ASCE 7 Chapter 22 CR1 (Mapped Risk Coefficient at 1 sec) 0.913 ASCE 7 Chapter 22 *Since site soils are Site Class D and S1 is greater than or equal to 0.2, the seismic response coefficient Cs is determined by Eq. 12.8-2 for values of T ≤ 1.5Ts and taken equal to 1.5 times the value calculated in accordance with either Eq. 12.8-3 for TL ≥ T > Ts, or Eq. 12.8-4 for T > TL. Refer to ASCE 7-16.

Project No. 21198‐01 Page 9 December 21, 2021
Section 1803.5.12 of the 2019 CBC (per Section 11.8.3 of ASCE 7) states that the maximum considered earthquake geometric mean (MCEG) Peak Ground Acceleration (PGA) should be used for liquefaction potential. The PGAM for the site is equal to 0.696g (SEAOC, 2021).

A deaggregation of the PGA based on a 2,475-year average return period indicates that an earthquake magnitude of 6.8 at a distance of approximately 10.6 km from the site would contribute the most to this ground motion (USGS, 2014).

2.6 Faulting
Prompted by damaging earthquakes in Northern and Southern California, State legislation and policies concerning the classification and land-use criteria associated with faults have been developed. Their purpose was to prevent the construction of urban developments across the trace of active faults, resulting in the Alquist-Priolo Earthquake Fault Zoning Act. Earthquake Fault Zones have been delineated along the traces of active faults within California. Where developments for human occupation are proposed within these zones, the state requires detailed fault evaluations be performed so that engineering geologists can mitigate the hazards associated with active faulting by identifying the location of active faults and allowing for a setback from the zone of previous ground rupture.

The subject site is not located within a State of California Earthquake Fault Zone (AlquistPriolo) and no faults were identified on the site during our site evaluation (CGS, 2018). The possibility of damage due to ground rupture is considered low since no active faults are known to cross the site. The closest known active faults to the subject site are the Newport-Inglewood, Puente Hills, Palos Verdes and Elsinore Fault Zones (USGS 2016).

Secondary effects of seismic shaking resulting from large earthquakes on the major faults in the Southern California region, which may affect the site, include ground lurching and shallow ground rupture, soil liquefaction, and dynamic settlement. These secondary effects of seismic shaking are a possibility throughout the Southern California region and are dependent on the distance between the site and causative fault and the onsite geology. A discussion of these secondary effects is provided in the following sections.

2.6.1 Liquefaction and Dynamic Settlement
Liquefaction is a seismic phenomenon in which loose, saturated, granular soils behave similarly to a fluid when subject to high-intensity ground shaking. Liquefaction occurs when three general conditions coexist: 1) shallow groundwater; 2) low density noncohesive (granular) soils; and 3) high-intensity ground motion. Studies indicate that saturated, loose near-surface cohesionless soils exhibit the highest liquefaction potential, while dry, dense, cohesionless soils and cohesive soils exhibit low to negligible liquefaction potential. In general, cohesive soils are not considered susceptible to liquefaction, depending on their plasticity and moisture content (Bray & Sancio, 2006).

Effects of liquefaction on level ground include settlement, sand boils, and bearing capacity failures below structures. Dynamic settlement of dry loose sands can occur as the sand particles tend to settle and densify as a result of a seismic event.

Project No. 21198‐01 Page 10 December 21, 2021
Based on our review of the State of California Seismic Hazard Zone for liquefaction potential (CDMG, 1999), the site is located within a liquefaction hazard zone. Subsurface field data indicates that the site contains isolated sandy layers susceptible to liquefaction interfingered with fine-grained non-liquefiable soils and dense sands. The recent explored groundwater elevation of 11 feet below existing grade and historic high groundwater elevation of 10 feet below existing grade were both used in the liquefaction analysis. Liquefaction potential was evaluated using the procedures outlined by Special Publication 117A (SCEC, 1999 & CGS, 2008) and the applicable seismic criteria (e.g., 2019 CBC). Liquefaction induced settlement was estimated using the PGAM per the 2019 CBC and a moment magnitude of 6.80 (USGS, 2014).

Results indicate total seismic settlement on the order of 2 inches. Differential seismic settlement can be estimated as half of the total estimated seismic settlement over a horizontal span of about 40 feet. This can be mitigated using a post-tensioned slab and interconnecting isolated pad footings with grade beams.

2.6.2 Liquefaction Surface Effects
Liquefaction induced surface effects, such as sand boils, can occur when shallow liquefiable soil layers trigger during a seismic event and are not contained deep enough below a non-liquefiable cap (i.e., non-liquefiable soils such as artificial fill or fine-grained soil). Based on analysis of the subsurface data, surface effects due to liquefaction are not anticipated to significantly affect the proposed surface improvements.

2.6.3 Lateral Spreading
Lateral spreading is a type of liquefaction-induced ground failure associated with the lateral displacement of surficial blocks of sediment resulting from liquefaction in a subsurface layer. Once liquefaction transforms the subsurface layer into a fluid mass, gravity plus the earthquake inertial forces may cause the mass to move downslope towards a free face (such as a river channel or an embankment). Lateral spreading may cause large horizontal displacements and such movement typically damages pipelines, utilities, bridges, and structures.

Due to the lack of a nearby “free face” condition and non-continuous nature of the subsurface layers, the potential for lateral spreading is considered very low.

2.7 Static Settlement
Although no grading plans were available during the preparation of this report, the subject site is sensitive to static settlement and grade changes. Static settlement would be induced by raising the planned grades and subjecting the new grades to building loads. Moderate increases in grades up to approximately 2 to 3 feet are estimated at this time.

The underlying soils were found to be generally stiff to very stiff silts and clays. Based on laboratory test data consisting of in-situ moisture content, consolidation tests, and blow counts,

Project No. 21198‐01 Page 11 December 21, 2021
fine-grained soils are considered generally normally consolidated. Based upon in-situ testing, visual examination, lab data, geotechnical evaluation and the proposed corrective grading and fill placement recommendations, static settlement induced by raising grades 1 to 3 feet is estimated to be on the order of 1-inch. LGC Geotechnical should be provided with the grading plans to for review to confirm or modify the recommendations for static settlement.

2.8 Expansion Potential
Based on the results of our laboratory testing, site soils are anticipated to have a “Low” expansion potential. Final expansion potential of site soils should be determined at the completion of grading. Results of expansion testing at finish grades will be utilized to confirm final foundation design.

Project No. 21198‐01 Page 12 December 21, 2021

3.0 CONCLUSIONS
Based on the results of our geotechnical evaluation, it is our opinion that the proposed development is feasible from a geotechnical standpoint, provided the following conclusions and recommendations are implemented.

The following is a summary of the primary geotechnical factors that may affect future development of the site:
 In general, our borings indicate the site is underlain by young alluvial fan deposits to the maximum explored depth of approximately 46.5 feet below existing grade. The material consists of clay, clayey sand, silty clay, and silty sand. The material was observed to be very moist to wet with depth and soft to stiff and medium dense to dense.
 Groundwater was encountered during our subsurface evaluation at depths of approximately 11 to 13 feet below existing grade. Historic high groundwater is estimated to be about 10 feet below existing grade (CDMG, 1998).
 The subject site is not located within a State of California Earthquake Fault Zone (Alquist-Priolo).

The main seismic hazard that may affect the site is ground shaking from one of the active regional faults. The subject site will likely experience strong seismic ground shaking during its design life.  Site soils are considered susceptible to liquefaction. The site is located in a State of California Seismic Hazard Zone for liquefaction (CDMG, 1999). Total seismic settlement is estimated to be on the order of 2.0 inches. Differential seismic settlement can be estimated at half of the total seismic settlement over a horizontal span of 40 feet for design of foundations.  Based on the results of preliminary laboratory testing, site soils are anticipated to have “Low” expansion potential. Mitigation measures are required for foundations and site improvements like concrete flatwork to minimize the impacts of expansive site soils. Final design expansion potential must be determined at the completion of grading.
 Pre-soaking of the subgrade for building slabs will be required due to site expansive soils. The duration of this process varies greatly based on the chosen method and is also dependent on factors such as soil type and weather conditions. Time duration for presoaking from completion of rough grading to trenching of foundations should be accounted for in the construction schedule (typically 1 to 2 weeks).
 From a geotechnical perspective, the existing onsite soils are suitable material for use as general fill (not retaining wall backfill), provided that they are relatively free from rocks (larger than 8 inches in maximum dimension), construction debris, and significant organic material.  The site contains soils that are not suitable for retaining wall backfill due to their fines content and expansion potential, therefore import of sandy soils will be required by the contractor for obtaining suitable backfill soil for planned site retaining walls.  Excavations into the existing site soils should be feasible with heavy construction equipment in good working order.
 Due to the relatively shallow site groundwater (about 11 feet below existing ground surface) and soils above the groundwater table with high moisture contents, dewatering or stabilization of subgrade for removal bottoms or deep utility trenches may be locally required, prior to subsequent fill placement.

Project No. 21198‐01 Page 13 December 21, 2021

4.0 PRELIMINARY RECOMMENDATIONS
The following recommendations are to be considered preliminary and should be confirmed upon completion of grading and earthwork operations. In addition, they should be considered minimal from a geotechnical viewpoint, as there may be more restrictive requirements from the architect, structural engineer, building codes, governing agencies, or the owner.

It should be noted that the following geotechnical recommendations are intended to provide sufficient information to develop the site in general accordance with the 2019 CBC requirements. With regard to the potential occurrence of potentially catastrophic geotechnical hazards such as fault rupture, earthquake-induced landslides, liquefaction, etc. the following geotechnical recommendations should provide adequate protection for the proposed development to the extent required to reduce seismic risk to an “acceptable level.” The “acceptable level” of risk is defined by the California Code of Regulations as “that level that provides reasonable protection of the public safety, though it does not necessarily ensure continued structural integrity and functionality of the project” [Section 3721(a)].

Therefore, repair and remedial work of the proposed improvements may be required after a significant seismic event. With regards to the potential for less significant geologic hazards to the proposed development, the recommendations contained herein are intended as a reasonable protection against the potential damaging effects of geotechnical phenomena such as expansive soils, fill settlement, groundwater seepage, etc. It should be understood, however, that although our recommendations are intended to maintain the structural integrity of the proposed development and structures given the site geotechnical conditions, they cannot preclude the potential for some cosmetic distress or nuisance issues to develop as a result of the site geotechnical conditions.

The geotechnical recommendations contained herein must be confirmed to be suitable or modified based on the actual as-graded conditions.

4.1 Site Earthwork
We anticipate that earthwork at the site will consist of demolition of the existing site improvements, required earthwork removals, subgrade preparation, precise grading and construction of the proposed new improvements, including the residential structures, neighborhood amenities, subsurface utilities, interior streets, etc.

We recommend that earthwork onsite be performed in accordance with the following recommendations, future grading plan review report(s), the 2019 CBC/City of Los Alamitos grading requirements, and the General Earthwork and Grading Specifications included in Appendix E. In case of conflict, the following recommendations shall supersede those included in Appendix E. The following recommendations should be considered preliminary and may be revised based upon future evaluation and review of the project plans and/or based on the actual conditions encountered during site grading/construction.

4.1.1 Site Preparation
Prior to grading of areas to receive structural fill or engineered improvements, the areas should be cleared of existing building structures, asphalt, surface obstructions, and

Project No. 21198‐01 Page 14 December 21, 2021
demolition debris. Vegetation and debris should be removed and properly disposed of offsite. Holes resulting from the removal of buried obstructions, which extend below proposed finish grades, should be replaced with suitable compacted fill material. Any abandoned sewer or storm drain lines should be completely removed and replaced with properly placed compacted fill. Deeper demolition may be required in order to remove existing foundations. We recommend the trenches associated with demolition which extend below the remedial grading depth of 5 feet be backfilled and properly compacted prior to the demolition contractor leaving the site.

If cesspools or septic systems are encountered, they should be removed in their entirety.

The resulting excavation should be backfilled with properly compacted fill soils. As an alternative, cesspools can be backfilled with lean sand-cement slurry. Any encountered wells should be properly abandoned in accordance with regulatory requirements. At the conclusion of the clearing operations, a representative of LGC Geotechnical should observe and accept the site prior to further grading.

4.1.2 Removal and Recompaction Depths and Limits
In order to provide a relatively uniform bearing condition for the planned residential building pads and improvements, we recommend the site soils be removed and recompacted according to the criteria outlined below.

Building Pads: We recommend that soils within building pads be removed and recompacted to a minimum depth of 5 feet below existing grade or 3 feet below the base of the foundations, whichever is deeper. Where space is available, the envelope for removal and recompaction should extend laterally a minimum distance equal to the depth of removal and recompaction below finish grade or 5 feet beyond the edges of the proposed building improvements, whichever is larger.

Minor Site Structures: For minor site structures such as free-standing walls, retaining walls, etc., removal and recompaction should extend at least 3 feet below existing grade or 2 feet below the base of foundations, whichever is deeper. Where space is available, the envelope for removal and recompaction should extend laterally a minimum distance of 3 feet beyond the edges of the proposed minor site structure improvements.

Pavement and Hardscape: Within pavement and hardscape areas, removal and recompaction should extend to a depth of at least 2 feet below the existing grade or 1-foot below finished subgrade (i.e., below planned aggregate base/asphalt concrete), whichever is deeper. In general, the envelope for removal and recompaction should extend laterally a minimum distance of 2 feet beyond the edges of the proposed pavement and hardscape improvements.

Based on our findings, the recommended removal and recompaction depths may extend to a depth in the proximity of the anticipated groundwater table and through clayey soils with high moisture contents. Care should be taken in order to avoid creating an unstable removal bottom during grading. Recommendations for subgrade stabilization are included in Section 4.1.4.

Project No. 21198‐01 Page 15 December 21, 2021
Local conditions may be encountered during excavation that could require additional over-excavation beyond the above noted minimum in order to obtain an acceptable subgrade. The actual depths and lateral extents of grading will be determined by the geotechnical consultant, based on subsurface conditions encountered during grading.

Removal areas and areas to be over-excavated should be accurately staked in the field by the Project Surveyor.

4.1.3 Temporary Excavations
Temporary excavations should be performed in accordance with project plans, specifications, and all Occupational Safety and Health Administration (OSHA) requirements. Excavations should be laid back or shored in accordance with OSHA requirements before personnel or equipment are allowed to enter. Based on our field investigation, the majority of site soils are anticipated to be OSHA Type “B” soils (refer to the attached boring logs). Minor amounts of sandy soils are present and should be considered susceptible to caving. Soil conditions should be regularly evaluated during construction to verify conditions are as anticipated. The contractor shall be responsible for providing the “competent person” required by OSHA standards to evaluate soil conditions. Close coordination with the geotechnical consultant should be maintained to facilitate construction while providing safe excavations. Excavation safety is the sole responsibility of the contractor.

Vehicular traffic, stockpiles, and equipment storage should be set back from the perimeter of excavations a minimum distance equivalent to a 1:1 projection from the bottom of the excavation or 5 feet, whichever is greater, unless the cut is shored and designed for applicable surcharge load. Once an excavation has been initiated, it should be backfilled as soon as practical. Prolonged exposure of temporary excavations may result in some localized instability. Excavations should be planned so that they are not initiated without sufficient time to shore/fill them prior to weekends, holidays, or forecasted rain.

It should be noted that any excavation that extends below a 1:1 (horizontal to vertical) projection of an existing foundation will remove existing support of the structure foundation. If requested, temporary shoring parameters will be provided.

4.1.4 Removal Bottoms and Subgrade Preparation
In general, removal bottoms, over-excavation bottoms and areas to receive compacted fill should be scarified to a minimum depth of 6 inches, brought to a near-optimum moisture condition (generally within optimum and 2 percent above optimum moisture content), and re-compacted per project recommendations.

Based on the presence of shallow groundwater, shallow soils with very high moisture contents, and the potential to encounter very moist/wet alluvial materials near/at the estimated removal bottoms and deep utility trenches, some of the removal bottoms are anticipated to be wet and unstable. Pumping subgrade is possible. We recommend all wet/unstable removal bottoms and pumping subgrade be stabilized by the placement

Project No. 21198‐01 Page 16 December 21, 2021
and “working in” of 1 to 3-inch nominal diameter crushed aggregate or an approved alternate stabilization method. Based on our experience with similar projects, we anticipate the thickness of crushed rock (stabilization aggregate) needed to stabilize the removal bottoms will be on the order to 6 to 18 inches thick. The actual thickness of aggregate required to stabilize the excavation bottom shall be determined in the field based on the actual conditions and equipment used. It should be anticipated that the first lift of crushed aggregate will be worked into the pumping subgrade. Subsequent lifts should be properly compacted and will help bridge the pumping conditions. Thickness of required aggregate stabilization may be reduced by placing a layer of biaxial geogrid reinforcement (e.g., Tensar TX140 or acceptable equivalent) directly on the subgrade prior to aggregate base placement. The contractor may have to minimize construction traffic on the removal bottom to reduce disturbance. Soft and yielding subgrade should be evaluated on a case-by-case basis during earthwork operations.

Removal bottoms, over-excavation bottoms and areas to receive fill should be observed and accepted by the geotechnical consultant prior to subsequent fill placement. Soil subgrade for planned footings and improvements (e.g., slabs, etc.) should be firm and competent.

4.1.5 Material for Fill
From a geotechnical perspective, the onsite soils are generally considered suitable for use as general compacted fill, provided they are screened of organic materials, construction debris and oversized material (8 inches in greatest dimension).

From a geotechnical viewpoint, any required import soils for general fill (i.e., nonretaining wall backfill) should consist of soils of “Very Low” to “Low” expansion potential (expansion index 50 or less based on American Society for Testing and Materials [ASTM] D 4829), and free of organic materials, construction debris and any material greater than 3 inches in maximum dimension. Import for any required retaining wall backfill should meet the criteria outlined in the following paragraph. Source samples should be provided to the geotechnical consultant for laboratory testing a minimum of four working days prior to any planned importation.

The onsite soils are not suitable for retaining wall backfill due to their fines content and expansion index; therefore, import of soils will be required by the contractor for obtaining suitable retaining wall backfill soil. These preliminary findings will be confirmed during grading. Retaining wall backfill should consist of imported sandy soils with a maximum of 35 percent fines (passing the No. 200 sieve) per ASTM Test Method D1140 (or ASTM D6913/D422) and a “Very Low” expansion potential (EI of 20 or less per ASTM D4829). Soils should also be screened of organic materials, construction debris, and any material greater than 3 inches in maximum dimension.

Aggregate base (crushed aggregate base or crushed miscellaneous base) should conform to the requirements of Section 200-2 of the most recent version of the Standard Specifications for Public Works Construction (“Greenbook”) for untreated base materials (except processed miscellaneous base) and/or City of Los Alamitos requirements.

Project No. 21198‐01 Page 17 December 21, 2021
The placement of demolition materials in compacted fill is acceptable from a geotechnical viewpoint provided the demolition material is broken up into pieces not larger than typically used for aggregate base (approximately 1-inch in maximum dimension) and well blended into fill soils with essentially no resulting voids. Demolition material placed in fills must be free of construction debris (wood, organics, etc.) and reinforcing steel. If asphalt concrete fragments will be incorporated into the demolition materials, approval from an environmental viewpoint may be required and is not the purview of the geotechnical consultant. From our previous experience, we recommend that asphalt concrete fragments be limited to fill areas within planned street areas (i.e., not within building pad areas).

4.1.6 Placement and Compaction of Fills
Material to be placed as fill should be brought to near-optimum moisture content (generally within optimum and 2 percent above optimum moisture content) and recompacted to at least 90 percent relative compaction (per ASTM D1557). Moisture conditioning of site soils will be required in order to achieve adequate compaction.

Significant drying and or mixing of very moist soils will be required prior to reusing the materials in compacted fills.

The optimum lift thickness to produce a uniformly compacted fill will depend on the type and size of compaction equipment used. In general, fill should be placed in uniform lifts not exceeding 8 inches in compacted thickness. Each lift should be thoroughly compacted and accepted prior to subsequent lifts. Generally, placement and compaction of fill should be performed in accordance with local grading ordinances and with observation and testing performed by the geotechnical consultant. Oversized material as previously defined should be removed from site fills.

During backfill of excavations, the fill should be properly benched into firm and competent soils of temporary backcut slopes as it is placed in lifts.

Aggregate base material should be compacted to at least 95 percent relative compaction at or slightly above optimum moisture content per ASTM D1557. Subgrade below aggregate base should be compacted to at least 90 percent relative compaction per ASTM D1557 at near-optimum moisture content (generally within optimum and 2 percent above optimum moisture content).

If gap-graded ¾-inch rock is used for backfill (around storm drain storage chambers, retaining wall backfill, etc.) it will require compaction. Rock shall be placed in thin lifts (typically not exceeding 6 inches) and mechanically compacted with observation by geotechnical consultant. Backfill rock shall meet the requirements of ASTM D2321. Gapgraded rock is required to be wrapped in filter fabric (Mirafi 140N or approved alternative) to prevent the migration of fines into the rock backfill.

4.1.7 Trench and Retaining Wall Backfill and Compaction The onsite soils may generally be suitable as trench backfill, provided the soils are screened of rocks and other material greater than 6 inches in diameter and organic

Project No. 21198‐01 Page 18 December 21, 2021
matter. If trenches are shallow or the use of conventional equipment may result in damage to the utilities, sand having a sand equivalent (SE) of 30 or greater (per California Test Method [CTM] 217) may be used to bed and shade the pipes. Based on our field evaluation, onsite soils will not meet this sand equivalent requirement. Sand backfill within the pipe bedding zone may be densified by jetting or flooding and then tamping to ensure adequate compaction. Subsequent trench backfill should be compacted in uniform thin lifts by mechanical means to at least the recommended minimum relative compaction (per ASTM D1557).

Retaining wall backfill should consist of sandy soils as outlined in preceding Section 4.1.5.

The limits of select sandy backfill should extend at minimum ½ the height of the retaining wall or the width of the heel (if applicable), whichever is greater (Figure 3). Retaining wall backfill soils should be compacted in relatively uniform thin lifts to at least 90 percent relative compaction (per ASTM D1557). Jetting or flooding of retaining wall backfill materials should not be permitted.

In backfill areas where mechanical compaction of soil backfill is impractical due to space constraints, typically sand-cement slurry may be substituted for compacted backfill. The slurry should contain about one sack of cement per cubic yard. When set, such a mix typically has the consistency of compacted soil. Sand cement slurry placed near the surface within landscape areas should be evaluated for potential impacts on planned improvements.

A representative from LGC Geotechnical should observe, probe, and test the backfill to verify compliance with the project recommendations.

4.1.8 Shrinkage and Subsidence
Allowance in the earthwork volumes budget should be made for an estimated 5 to 15 percent reduction in volume of near-surface (upper approximate 5 feet) soils. It should be stressed that these values are only estimates and that an actual shrinkage factor would be extremely difficult to predetermine. Subsidence, due to earthwork operations, is expected to be on the order of 0.1 feet. These values are estimates only and exclude losses due to removal of any vegetation or debris. The effective shrinkage of onsite soils will depend primarily on the type of compaction equipment and method of compaction used onsite by the contractor and accuracy of the topographic survey.

4.2 Preliminary Foundation Recommendations
Provided that the remedial grading recommendations provided herein are implemented, the site may be considered suitable for the support of the residential structures using a post-tensioned foundation system designed to resist the impacts of expansive soils and liquefaction induced differential settlement. Due to seismic settlement potential, we recommend isolated pad footings be interconnected with grade beams. The foundations designer should verify the foundation can accommodate the estimated settlement and differential settlement.

Project No. 21198‐01 Page 19 December 21, 2021
Site soils are anticipated to be “Low” expansion potential (EI of 50 or less per ASTM D4829) and special design considerations from a geotechnical perspective are required. Please note that the following foundation recommendations are preliminary and must be confirmed by LGC Geotechnical at the completion of grading. Recommended soil bearing and estimated settlement due to structural loads are provided in Section 4.3.

4.2.1 Provisional Post‐Tensioned Foundation Design Parameters The geotechnical parameters provided herein may be used for post-tensioned slab foundations. These parameters have been determined in general accordance with the Post-Tensioning Institute (PTI, 2012) Standard Requirements (PTI DC 10.5), referenced in Chapter 18 of the 2019 CBC. In utilizing these parameters, the foundation engineer should design the foundation system in accordance with the allowable deflection criteria of applicable codes and the requirements of the structural designer/architect.

Other types of stiff slabs may be used in place of the CBC post-tensioned slab design provided that, in the opinion of the foundation structural designer, the alternative type of slab is at least as stiff and strong as that designed by the CBC/PTI method to resist expansive soils.

Our design parameters are based on our experience with similar residential projects and the anticipated nature of the soil (with respect to expansion potential). Please note that implementation of our recommendations will not eliminate foundation movement (and related distress) should the moisture content of the subgrade soils fluctuate. It is the intent of these recommendations to help maintain the integrity of the proposed structures and reduce (not eliminate) movement, based upon the anticipated site soil conditions. Should future owners not properly maintain the areas surrounding the foundation, for example by overwatering, then we anticipate for highly expansive soils the maximum differential movement of the perimeter of the foundation to the center of the foundation to be on the order of a couple of inches. Soils of lower expansion potential are anticipated to show less movement.

Project No. 21198‐01 Page 20 December 21, 2021
TABLE 4
Provisional Geotechnical Parameters for Post‐Tensioned Foundation Slab Design Parameter PT Slab with
Perimeter Footing
PT Mat with
Thickened Edge
Expansion Index Low1 Low1
Thornthwaite Moisture Index -20 -20
Constant Soil Suction PF 3.9 PF 3.9
Center Lift
Edge moisture variation distance, em
Center lift, ym

9.0 feet

0.35 inch

9.0 feet

0.45 inch
Edge Lift
Edge moisture variation distance, em
Edge lift, ym

5.0 feet

0.75 inch

5.0 feet

0.85 inch
Modulus of Subgrade Reaction, k (assuming
presoaking as indicated below) 200 pci 200 pci
Minimum perimeter footing/thickened edge
embedment below finish grade 12 inches 6 inches
Perimeter foundation reinforcement N/A2 N/A2
Presoak (moisture conditioning) 100% optimum to
depth of 12 inches
100% optimum to
depth of 12 inches

1. Assumed for preliminary design purposes. Further evaluation is needed at the completion of grading. PT slab parameters are based on expansive soil conditions as well as seismic settlement findings.

2. Recommendations for foundation reinforcement and slab thickness are ultimately the purview of the foundation engineer/structural engineer based upon geotechnical criteria and structural engineering considerations.

3. Recommendations for sand below slabs have traditionally been included with geotechnical foundation recommendations, although they are not the purview of the geotechnical consultant. The sand layer requirements are the purview of the foundation engineer/structural engineer and should be provided in accordance with ACI Publication 302 “Guide for Concrete Floor and Slab Construction”.

4. Recommendations for vapor retarders below slabs are also the purview of the foundation engineer/structural engineer and should be provided in accordance with applicable code requirements.

4.2.2 Post‐Tensioned Foundation Subgrade Preparation and Maintenance Moisture conditioning (presoaking) of the subgrade soils is recommended prior to trenching the foundation. The duration of this process varies greatly based on the chosen method and is also dependent on factors such as soil type and weather conditions. Time duration for presoaking from completion of rough grading to trenching of foundations should be accounted for in the construction schedule (typically 1 to 2 weeks). The recommendations specific to the anticipated site soil conditions, including recommended presoak, are presented in Table 4. The subgrade moisture

Project No. 21198‐01 Page 21 December 21, 2021
condition of the building pad soils should be maintained at near-optimum moisture content up to the time of concrete placement. This moisture content should be maintained around the immediate perimeter of the slab during construction and up to occupancy of the homes.

The geotechnical parameters provided herein assume that if the areas adjacent to the foundation are planted and irrigated, these areas will be designed with proper drainage and adequately maintained so that ponding, which causes significant moisture changes below the foundation, does not occur. Our recommendations do not account for excessive irrigation and/or incorrect landscape design. Plants should only be provided with sufficient irrigation for life and not overwatered to saturate subgrade soils. Sunken planters placed adjacent to the foundation, should either be designed with an efficient drainage system or liners to prevent moisture infiltration below the foundation. Some lifting of the perimeter foundation beam should be expected even with properly constructed planters.

In addition to the factors mentioned above, future homeowners should be made aware of the potential negative influences of trees and/or other large vegetation. Roots that extend near the vicinity of foundations can cause distress to foundations. Future homeowners (and the owner’s landscape architect) should not plant trees/large shrubs closer to the foundations than a distance equal to half the mature height of the tree or 20 feet, whichever is more conservative unless specifically provided with root barriers to prevent root growth below the house foundation.

It is the homeowner’s responsibility to perform periodic maintenance during hot and dry periods to ensure that adequate watering has been provided to keep soils from separating or pulling back from the foundation. Future homeowners should be informed and educated regarding the importance of maintaining a constant level of soilmoisture. The homeowners should be made aware of the potential negative consequences of both excessive watering, as well as allowing potentially expansive soils to become too dry. Expansive soils can undergo shrinkage during drying and swelling during the rainy winter season or when irrigation is resumed. This can result in distress to building structures and hardscape improvements. The builder should provide these recommendations to future homeowners.

4.2.3 Slab Underlayment Guidelines
The following is for informational purposes only since slab underlayment (e.g., moisture retarder, sand or gravel layers for concrete curing and/or capillary break) is unrelated to the geotechnical performance of the foundation and thereby not the purview of the geotechnical consultant. Post-construction moisture migration should be expected below the foundation. The foundation engineer/architect should determine whether the use of a capillary break (sand or gravel layer), in conjunction with the vapor retarder, is necessary or required by code. Sand layer thickness and location (above and/or below vapor retarder) should also be determined by the foundation engineer/architect.

Project No. 21198‐01 Page 22 December 21, 2021

4.3 Soil Bearing and Lateral Resistance
Provided our earthwork recommendations are implemented, an allowable soil bearing pressure of 1,500 pounds per square foot (psf) may be used for the design of footings having a minimum width of 12 inches and minimum embedment of 12 inches below lowest adjacent ground surface.

This value may be increased by 300 psf for each additional foot of embedment and 150 psf for each additional foot of foundation width to a maximum value of 2,500 psf. A post-tensioned mat foundation a minimum of 6 inches below lowest adjacent grade may be designed for an allowable soil bearing pressure of 1,200 psf. These allowable bearing pressures are applicable for level (ground slope equal to or flatter than 5H:1V) conditions only. Bearing values indicated are for total dead loads and frequently applied live loads and may be increased by ⅓ for short duration loading (i.e., wind or seismic loads).

In utilizing the above-mentioned allowable bearing capacity and provided our earthwork recommendations are implemented, foundation settlement due to consolidation and structural loads is anticipated to be less than 2 inches. Differential static settlement may be taken as half of the total settlement (i.e., 1-inch over a horizontal span of 40 feet due to structural loads).

Seismically induced settlement is discussed in Section 2.6.1.

Resistance to lateral loads can be provided by friction acting at the base of foundations and by passive earth pressure. For concrete/soil frictional resistance, an allowable coefficient of friction of 0.25 may be assumed with dead-load forces. For slabs constructed over a moisture retarder, the allowable friction coefficient should be provided by the manufacturer. An allowable passive lateral earth pressure of 200 psf per foot of depth (or pcf) to a maximum of 2,000 psf may be used for the sides of footings poured against properly compacted fill. Allowable passive pressure may be increased to 270 pcf (maximum of 2,700 psf) for short duration seismic loading. This passive pressure is applicable for level (ground slope equal to or flatter than 5H:1V) conditions.

Frictional resistance and passive pressure may be used in combination without reduction. We recommend that the upper foot of passive resistance be neglected if finished grade will not be covered with concrete or asphalt. The provided allowable passive pressures are based on a factor of safety of 1.5 and 1.1 for static and seismic loading conditions, respectively.

4.4 Lateral Earth Pressures for Retaining Walls
The following may be used for design of site retaining walls. Lateral earth pressures are provided as equivalent fluid unit weights, in psf per foot of depth (or pcf). These values do not contain an appreciable factor of safety, so the retaining wall designer should apply the applicable factors of safety and/or load factors during design. A soil unit weight of 120 pcf may be assumed for calculating the actual weight of soil over the wall footing.

The following lateral earth pressures are presented in Table 5 for approved imported granular soils with a maximum of 35 percent fines (passing the No. 200 sieve per ASTM D-421/422) and a “Very Low” expansion potential (EI of 20 or less per ASTM D4829). The onsite soils are not suitable for retaining wall backfill due to their fines content and expansion potential. Therefore, import of sandy soils meeting the criteria outlined above will be required by the contractor for obtaining suitable retaining wall backfill soil.

Project No. 21198‐01 Page 23 December 21, 2021
The wall designer should clearly indicate on the retaining wall plans the required select sandy soil backfill criteria. These preliminary findings should be confirmed during grading.

TABLE 5
Lateral Earth Pressures – Imported Sandy Soils
Conditions
Equivalent Fluid Unit Weight
(pcf)
Equivalent Fluid Unit Weight
(pcf)
Level Backfill 2:1 Sloped Backfill
Approved Sandy Soils (Import) Approved Sandy Soils (Import) Active 35 55
At-Rest 55 70
If the wall can yield enough to mobilize the full shear strength of the soil, it can be designed for “active” pressure. If the wall cannot yield under the applied load, the earth pressure will be higher. This would include 90-degree corners of retaining walls. Such walls should be designed for “at-rest.” The equivalent fluid pressure values assume free-draining conditions. If conditions other than those assumed above are anticipated, the equivalent fluid pressure values should be provided on an individual-case basis by the geotechnical engineer.

Retaining wall structures should be provided with appropriate drainage and appropriately waterproofed. To reduce, but not eliminate, saturation of near-surface (upper approximate 1- foot) soils in front of the retaining walls, the perforated subdrain pipe should be located as low as possible behind the retaining wall. The outlet pipe should be sloped to drain to a suitable outlet. In general, we do not recommend retaining wall outlet pipes be connected to area drains. If subdrains are connected to area drains, special care and information should be provided to homeowners to maintain these drains. Typical retaining wall drainage is illustrated in Figure 3. It should be noted that the recommended subdrain does not provide protection against seepage through the face of the wall and/or efflorescence. Efflorescence is generally a white crystalline powder (discoloration) that results when water containing soluble salts migrates over a period of time through the face of a retaining wall and evaporates. If such seepage or efflorescence is undesirable, retaining walls should be waterproofed to reduce this potential. Waterproofing and outlet systems are not the purview of the geotechnical consultant.

Surcharge loading effects from any adjacent structures should be evaluated by the retaining wall designer. In general, structural loads within a 1:1 (horizontal: vertical) upward projection from the bottom of the proposed retaining wall footing will surcharge the proposed retaining wall. In addition to the recommended earth pressure, retaining walls adjacent to streets should be designed to resist a uniform lateral pressure of 85 pounds per square foot (psf) due to normal street vehicle traffic, if applicable. Uniform lateral surcharges may be estimated using the applicable coefficient of lateral earth pressure using a rectangular distribution. A factor of

0.45 and 0.3 may be used for at-rest and active conditions, respectively. The retaining wall designer should contact the geotechnical consultant for any required geotechnical input in

Project No. 21198‐01 Page 24 December 21, 2021
estimating surcharge loads.

If a retaining wall greater than 6 feet in height is proposed, the retaining wall designer should contact the geotechnical engineer for specific seismic lateral earth pressure increments based on the configuration of the planned retaining wall structures.

Soil bearing and lateral resistance (friction coefficient and passive resistance) are provided in Section 4.3. Earthwork considerations (temporary backcuts, backfill, compaction, etc.) for retaining walls are provided in Section 4.1 (Site Earthwork) and the subsequent earthwork related sub-sections.

4.5 Soil Corrosivity
Although not corrosion engineers (LGC Geotechnical is not a corrosion consultant), several governing agencies in Southern California require the geotechnical consultant to determine the corrosion potential of soils to buried concrete and metal facilities. We therefore present the results of our testing with regard to corrosion for the use of the client and other consultants, as they determine necessary.

Corrosion testing of a near-surface bulk sample indicated a soluble sulfate content ranging from approximately 0.032 to 0.254 percent, a chloride content ranging from 140 to 600 parts per million (ppm), pH of 8.92, and a minimum resistivity of 210 ohm-centimeters. Based on Caltrans Corrosion Guidelines (Caltrans, 2021), soils are considered corrosive to structural elements if the pH is 5.5 or less, or the chloride concentration is 500 ppm or greater, or the sulfate concentration is 2,000 ppm (0.2 percent) or greater. Based on the preliminary test results, soils are considered corrosive using Caltrans criteria.

Based on preliminary laboratory sulfate test results, the near surface soils are designated to a class “S2” per ACI 318, Table 19.3.1.1 with respect to sulfates. Concrete in direct contact with the onsite soils can be designed according to ACI 318, Table 19.3.2.1 using the “S2” sulfate classification.

Laboratory testing may need to be performed at the completion of grading by the project corrosion engineer to further evaluate the as-graded soil corrosivity characteristics.

Accordingly, revision of the corrosion potential may be needed, should future test results differ substantially from the conditions reported herein. The client and/or other members of the development team should consider this during the design and planning phase of the project and formulate an appropriate course of action.

4.6 Control of Surface Water and Drainage Control
From a geotechnical perspective, we recommend that compacted finished grade soils adjacent to proposed residences be sloped away from the proposed residence and towards an approved drainage device or unobstructed swale. Drainage swales, wherever feasible, should not be constructed within 5 feet of buildings. Where lot and building geometry necessitates that the side yard drainage swales be routed closer than 5 feet to structural foundations, we recommend the use of area drains together with drainage swales. Drainage swales used in

Project No. 21198‐01 Page 25 December 21, 2021
conjunction with area drains should be designed by the project civil engineer so that a properly constructed and maintained system will prevent ponding within 5 feet of the foundation. Code compliance of grades is not the purview of the geotechnical consultant.

Planters with open bottoms adjacent to buildings should be avoided. Planters should not be designed adjacent to buildings unless provisions for drainage, such as catch basins, liners, and/or area drains, are made. Overwatering must be avoided.

4.7 Subsurface Water Infiltration
Recent regulatory changes in some jurisdictions have recommended that low flow runoff be infiltrated rather than discharged via conventional storm drainage systems. Typically, a combination of methods is implemented to reduce surface water runoff and increase infiltration including; permeable pavements/pavers for roadways and walkways and directing surface water runoff to grass-lined swales, retention areas, and/or drywells. It should be noted that intentionally infiltrating storm water conflicts with the geotechnical engineering objective of directing surface water away from structures and improvements. The geotechnical stability and integrity of the project site is reliant upon appropriately handling all surface water. In general, the vast majority of geotechnical distress issues are directly related to improper drainage. In general, distress in the form of movement of improvements could occur as a result of soil saturation and loss of soil support, expansion, internal soil erosion, collapse and/or settlement.

Infiltrated water may enter underground utility pipe zones and migrate along the pipe backfill, potentially impacting other improvements located far away from the point of infiltration.

Geotechnical stability and integrity of the project site is reliant upon appropriate handling of surface water. Due to the extremely low measured infiltration rate, low permeability fine-grained soils at depth, shallow groundwater and site liquefaction potential, we strongly recommend against the intentional infiltration of storm water into subsurface soils.

4.8 Preliminary Asphalt Concrete Pavement Sections
The following provisional minimum asphalt concrete (AC) street sections are provided in Table 6 for Traffic Indices (TI) of 5.0, 5.5 and 6.0. These sections are based on an assumed R-value of 10.

These recommendations must be confirmed with R-value testing of representative near-surface soils at the completion of grading and after underground utilities have been installed and backfilled. Final pavement sections should be confirmed by the project civil engineer based upon the final design Traffic Index. If requested, LGC Geotechnical will provide sections for alternate TI values. Should the City of Los Alamitos have more stringent requirements, updated pavement recommendation can be provided.

Project No. 21198‐01 Page 26 December 21, 2021
TABLE 6
Preliminary Pavement Section Options
Assumed Traffic Index 5.0 5.5 6.0
R ‐Value Subgrade 10 10 10
AC Thickness 4.0 inches 4.0 inches 5.0 inches
Aggregate Base Thickness 7.0 inches 9.0 inches 9.0 inches The pavement section thicknesses provided above are considered minimum thicknesses.

Increasing the thickness of any or all of the above layers will reduce the likelihood of the pavement experiencing distress during its service life. The above recommendations are based on the assumption that proper maintenance and irrigation of the areas adjacent to the roadway will occur throughout the design life of the pavement. Failure to maintain a proper maintenance and/or irrigation program may jeopardize the integrity of the pavement.

Earthwork recommendations regarding aggregate base and subgrade are provided in the previous Section 4.1 (Site Earthwork) and the related sub-sections of this report.

4.9 Nonstructural Concrete Flatwork
Nonstructural concrete flatwork (such as walkways, private drives, patio slabs, etc.) has a potential for cracking due to changes in soil volume related to soil-moisture fluctuations. To reduce the potential for excessive cracking and lifting, concrete may be designed in accordance with the minimum guidelines outlined in Table 7 on the following page. These guidelines will reduce the potential for irregular cracking and promote cracking along construction joints but will not eliminate all cracking or lifting. Thickening the concrete and/or adding additional reinforcement will further reduce cosmetic distress.

Project No. 21198‐01 Page 27 December 21, 2021
TABLE 7
Nonstructural Concrete Flatwork for Low Expansion Potential Homeowner
Sidewalks Private Drives Patios/
Entryways
City Sidewalk
Curb and
Gutters
Minimum
Thickness (in.) 4 (nominal) 4 (full) 4 (full) City/Agency Standard
Presoaking Wet down prior
to placing
Wet down prior to
placing
Wet down prior to
placing
City/Agency
Standard
Reinforcement  No. 3 at 24 inches
on centers
No. 3 at 24
inches on
centers
City/Agency
Standard
Thickened
Edge (in.)  8 x 8  City/Agency
Standard
Crack Control
Joints
Saw cut or deep
open tool joint
to a minimum of
1/3 the concrete
thickness
Saw cut or deep
open tool joint to a
minimum
of 1/3 the concrete
thickness
Saw cut or deep
open tool joint
to a minimum
of 1/3 the
concrete
thickness
City/Agency
Standard
Maximum
Joint Spacing 5 feet
10 feet or quarter
cut whichever is
closer
6 feet City/Agency
Standard
Aggregate
Base
Thickness (in.)
   City/Agency
Standard
To reduce the potential for driveways to separate from the garage slab, the builder may elect to install dowels to tie these two elements together. Similarly, future homeowners should consider the use of dowels to connect flatwork to the foundation.

4.10 Geotechnical Plan Review
When available, grading, retaining wall and foundation plans should be reviewed by LGC Geotechnical in order to verify our geotechnical recommendations are implemented. Updated recommendations and/or additional field work may be necessary.

4.11 Geotechnical Observation and Testing During Construction The recommendations provided in this report are based on limited subsurface observations and geotechnical analysis. The interpolated subsurface conditions should be checked in the field during construction by a representative of LGC Geotechnical. Geotechnical observation and testing is required per Section 1705 of the 2019 California Building Code (CBC).

Project No. 21198‐01 Page 28 December 21, 2021
Geotechnical observation and/or testing should be performed by LGC Geotechnical at the following stages:
 During grading (removal bottoms, fill placement, etc);  During retaining wall backfill and compaction;
 During utility trench backfill and compaction;
 After presoaking building pads and other concrete-flatwork subgrades, and prior to placement of aggregate base or concrete;
 Preparation of pavement subgrade and placement of aggregate base;  After building and wall footing excavation and prior to placing steel reinforcement and/or concrete; and
 When any unusual soil conditions are encountered during any construction operation subsequent to issuance of this report.

Project No. 21198‐01 Page 29 December 21, 2021

5.0 LIMITATIONS
Our services were performed using the degree of care and skill ordinarily exercised, under similar circumstances, by reputable soils engineers and geologists practicing in this or similar localities. No other warranty, expressed or implied, is made as to the conclusions and professional advice included in this report.

This report is based on data obtained from limited observations of the site, which have been extrapolated to characterize the site. While the scope of services performed is considered suitable to adequately characterize the site geotechnical conditions relative to the proposed development, no practical evaluation can completely eliminate uncertainty regarding the anticipated geotechnical conditions in connection with a subject site. Variations may exist and conditions not observed or described in this report may be encountered during grading and construction.

This report is issued with the understanding that it is the responsibility of the owner, or of his/her representative, to ensure that the information and recommendations contained herein are brought to the attention of the other consultants (at a minimum the civil engineer, structural engineer, landscape architect) and incorporated into their plans. The contractor should properly implement the recommendations during construction and notify the owner if they consider any of the recommendations presented herein to be unsafe, or unsuitable.

The findings of this report are valid as of the present date. However, changes in the conditions of a site can and do occur with the passage of time, whether they be due to natural processes or the works of man on this or adjacent properties. The findings, conclusions, and recommendations presented in this report can be relied upon only if LGC Geotechnical has the opportunity to observe the subsurface conditions during grading and construction of the project, in order to confirm that our preliminary findings are representative for the site. This report is intended exclusively for use by the client, any use of or reliance on this report by a third party shall be at such party’s sole risk.

In addition, changes in applicable or appropriate standards may occur, whether they result from legislation or the broadening of knowledge. Accordingly, the findings of this report may be invalidated wholly or partially by changes outside our control. Therefore, this report is subject to review and modification.

Approximate Location of Hollow Stem Auger Boring by
LGC Geotechnical, With Total Depth in Feet
LEGEND
Approximate Location of Hollow Stem Auger Infiltration
Boring by LGC Geotechnical, With Total Depth in Feet
Approximate Location of Hand Auger Boring by
LGC Geotechnical, With Total Depth in Feet
I-2
T.D. = 5'
HS-3
T.D. = 21.5'
Approximate Site Limits
I-1
T.D. = 5'
I-2
T.D. = 5'
HS-1
T.D. = 21.5'
HS-2
T.D. = 46.5'
HS-3
T.D. = 21.5'
HA-1
T.D. = 5'
HA-2
T.D. = 5'
HA-2
T.D. = 5'
FIGURE 2
Boring Location Map ENG. / GEOL.

PROJECT NO.

PROJECT NAME
SCALE
DATE
1" = 100'
December 2021
MWIG - Los Alamitos
RLD
21198-01 LGC Geotechnical, Inc.
131 Calle Iglesia, Ste. 200
San Clemente, CA 92672
TEL (949) 369-6141 FAX (949) 369-6142

4 INCH DIAMETER, SCHEDULE 40 PERFORATED

PVC PIPE TO FLOW TO DRAINAGE DEVICE

SAND BACKFILL
(Percent Passing #200 Sieve 35% or Less)
and (EI 20 or Less)

NATIVE BACKFILL COMPACTED
TO MINIMUM 90% RELATIVE
COMPACTION PER ASTM1557-D
MINIMUM 1 CUBIC FOOT PER LINEAR FOOT

BURRITO TYPE SUBDRAIN, CONSISTING OF
3/4 INCH CRUSHED ROCK WRAPPED IN
MIRAFI 140N OR APPROVED EQUIVALENT

FOOTING/WALL PER DESIGN ENGINEER

WATER PROOFING PER DESIGN ENGINEER
12" MINIMUM
18" MAXIMUM

BACKCUT PER OSHA

EXTENT OF FREE DRAINING SAND BACKFILL, MINIMUM
HEEL WIDTH OR H/2 WHICH EVER IS GREATER WALL HEIGHT, H
NOTE:

PLACEMENT OF SUBDRAIN

AT BASE OF WALL WILL NOT

PREVENT SATURATION OF SOILS

BELOW AND / OR IN FRONT OF WALL
FIGURE 3
Retaining Wall
Backfill Detail
DATE December 2021
ENG. / GEOL.

PROJECT NO.

PROJECT NAME
SCALE
RLD
Not to Scale
MWIG - Los Alamitos
21198-01

Appendix A
References

Project No. 21198‐01 A‐1 December 21, 2021

APPENDIX A
References
American Concrete Institute, 2014, Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary (ACI 318R-14).

American Society of Civil Engineers (ASCE), 2017, Minimum Design Loads for Buildings and Other Structures, ASCE/SEI 7-16, Third Printing, 2017.
_________, 2018, Standard 7-16, Minimum Design Loads for Buildings and Associated Criteria for Buildings and Other Structures, Supplement 1, effective: December 12, 2018.

American Society for Testing and Materials (ASTM), Volume 04.08 Soil and Rock (I): D420 – D5876.

Bray, J.D., and Sancio, R. B., 2006, Assessment of Liquefaction Susceptibility of Fine-Grained Soils, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, pp. 1165-1177, dated September 2006.

California Building Standards Commission, 2019, California Building Code, California Code of Regulations Title 24, Volumes 1 and 2, dated July 2019.

California Department of Transportation (Caltrans), 2021, Corrosion Guidelines, Version 3.2, dated May 2021.

California Division of Mines and Geology (CDMG), 1998, Seismic Hazard Evaluation of the Los Alamitos

7.5-Minute Quadrangle, Los Angeles and Orange Counties, California, Open-File Report 98-10. _________, 1999, Seismic Hazard Zones, Los Alamitos Quadrangle, California, dated March 25, 1999.

California Geological Survey [CGS], 2008, California Geological Society Special Publication 117A:

Guidelines for Evaluating and Mitigating Seismic Hazards in California. _________, 2018, Earthquake Fault Zones, Special Publication 42; A Guide for Government Agencies, Property Owners/Developers, and Geoscience Practitioners for Assessing Fault Rupture Hazards in California, Revised 2018.

County of Orange, 2013, Technical Guidance Document for the Preparation of Conceptual/Preliminary and/or Project Water Quality Management Plans (WQMPs), Exhibit 7.III, December 20, 2013.

Historic Aerials, 2021, viewed December 2, 2021, Aerials viewed from: 1952 through 2018, https://www.historicaerials.com/.

KTGY Architecture and Planning, 2021, Conceptual Density Study, Lampson – Los Alamitos, dated August 24, 2021.

NCEER, 1997, “Proceeding of the NCEER Workshop on Evaluation of Liquefaction Resistance of Soils”, T.L. Youd and I. M. Idriss Editors, Technical Report NCEER-97-0022, NCEER, Buffalo, NY.

Project No. 21198‐01 A‐2 December 21, 2021
Post-Tensioning Institute (PTI), 2012, Standard Requirements for Design and Analysis of Shallow PostTensioned Concrete Foundations on Expansive Soils, PTI DC10.5-12.

Southern California Earthquake Center (SCEC), 1999, “Recommended Procedure for Implementation of DMG Special Publication 117, Guidelines for Analyzing and Mitigation Liquefaction Hazards in California”, Edited by Martin, G.R., and Lew, M., dated March 1999.

Tokimatsu, K., and Seed, H. B., 1987, “Evaluation of Settlements in Sands Due to Earthquake Shaking”, Journal of Geotechnical Engineering, ASCE, Vol. 113, No. 8, pp. 861-878.

Structural Engineers Association of California (SEAOC), 2021, OSHPD Seismic Design Maps, Retrieved December 1, 2021, from: https://seismicmaps.org/.

United States Geological Survey (USGS), 2014, Unified Hazard Tool, Dynamic: Conterminous U.S. 2014 (v4.2.0), Retrieved December 1, 2021, from: https://earthquake.usgs.gov/hazards/interactive/. _________, 2016, Geologic Map of the Long Beach 30’ X 60’ Quadrangle, California, Compiled by George J.

Saucedo and others, Version 2.0, 2016.

Appendix B
Boring Logs

THIS SUMMARY APPLIES ONLY AT THE LOCATION OF THIS BORING AND AT THE TIME OF DRILLING. SUBSURFACE CONDITIONS MAY DIFFER AT OTHER LOCATIONS AND MAY CHANGE AT THIS LOCATION WITH THE PASSAGE OF TIME. THE DATA PRESENTED IS A SIMPLIFICATION OF THE ACTUAL CONDITIONS ENCOUNTERED. THE DESCRIPTIONS

PROVIDED ARE QUALITATIVE FIELD DESCRIPTIONS

AND ARE NOT BASED ON QUANTITATIVE
ENGINEERING ANALYSIS. CN CONSOLIDATION

CR CORROSION

AL ATTERBERG LIMITS CO COLLAPSE/SWELL RV R-VALUE
-#200 % PASSING # 200 SIEVE

DIRECT SHEAR MAXIMUM DENSITY

SIEVE ANALYSIS

SIEVE AND HYDROMETER

EXPANSION INDEX
TEST TYPES: DSMD
SA
S&H
EI
SAMPLE TYPES: B BULK SAMPLE R RING SAMPLE (CA Modified Sampler) G GRAB SAMPLE

SPT STANDARD PENETRATION

TEST SAMPLE GROUNDWATER TABLE
30 25
20 15
10 5
0 Elevation (ft) Depth (ft) Graphic Log Sample Number Blow Count Dry Density (pcf) Moisture (%) USCS Symbol DESCRIPTION Type of Test Hole Diameter:

Hole Location: See Geotechnical Map
Drop:

Type of Rig:

Project Number:

Elevation of Top of Hole: Drive Weight:

Drilling Company:

Project Name:

Date:
20 15
10 5
0 -5
Geotechnical Boring Log Borehole HS-1
11/11/2021
~24' MSL
6"
Track Mounted
30"
140 pounds
Cal Pac Drilling
MWIG - Los Alamitos
21198-01
Logged By BPP
Sampled By BPP
Checked By RLD

@0' to T.D. - Quaternary Young Alluvium (Qya):
@0'- 1' of Topsoil; Sandy SILT: brown/gray, slightly
moist
R-1 10
7 9

92.9 8.6 CL-ML @2.5'- Silty CLAY with Sand: grayish brown, slightly moist, stiff
R-2 4
6 8

94.5 24.6 @5'- Silty CLAY: olive brown, very moist, stiff R-3 3
3 4

94.0 27.9 SM/CL @7.5'- Top: Silty SAND: brown, wet, loose; Bottom: CLAY: brown, wet, medium stiff
R-4 3
4 5

99.0 26.3 CL-ML @10'- Silty CLAY: olive brown, wet, medium stiff SPT-1 2
3 4

27.8 @15'- Silty CLAY: olive brown, wet, stiff
R-5 7
9 12
106.1 20.9 SM @20'- Silty SAND: grayish brown, wet, medium dense Total Depth = 21.5'
Groundwater Encountered at Approximately 13'
Backfilled with Cuttings on 11/11/2021 B-1 Last Edited: 12/16/2021

THIS SUMMARY APPLIES ONLY AT THE LOCATION OF THIS BORING AND AT THE TIME OF DRILLING. SUBSURFACE CONDITIONS MAY DIFFER AT OTHER LOCATIONS AND MAY CHANGE AT THIS LOCATION WITH THE PASSAGE OF TIME. THE DATA PRESENTED IS A SIMPLIFICATION OF THE ACTUAL CONDITIONS ENCOUNTERED. THE DESCRIPTIONS

PROVIDED ARE QUALITATIVE FIELD DESCRIPTIONS

AND ARE NOT BASED ON QUANTITATIVE
ENGINEERING ANALYSIS. CN CONSOLIDATION

CR CORROSION

AL ATTERBERG LIMITS CO COLLAPSE/SWELL RV R-VALUE
-#200 % PASSING # 200 SIEVE

DIRECT SHEAR MAXIMUM DENSITY

SIEVE ANALYSIS

SIEVE AND HYDROMETER

EXPANSION INDEX
TEST TYPES: DSMD
SA
S&H
EI
SAMPLE TYPES: B BULK SAMPLE R RING SAMPLE (CA Modified Sampler) G GRAB SAMPLE

SPT STANDARD PENETRATION

TEST SAMPLE GROUNDWATER TABLE
30 25
20 15
10 5
0 Elevation (ft) Depth (ft) Graphic Log Sample Number Blow Count Dry Density (pcf) Moisture (%) USCS Symbol DESCRIPTION Type of Test Hole Diameter:

Hole Location: See Geotechnical Map
Drop:

Type of Rig:

Project Number:

Elevation of Top of Hole: Drive Weight:

Drilling Company:

Project Name:

Date:
20 15
10 5
0 Geotechnical Boring Log Borehole HS-2
11/11/2021
~25' MSL
6"
Track Mounted
30"
140 pounds
Cal Pac Drilling
MWIG - Los Alamitos
21198-01
Logged By BPP
Sampled By BPP
Checked By RLD

@0 to T.D. - Quaternary Young Alluvium (Qya):
@0'- 1' of Topsoil; Sandy SILT: gray/brown, slightly
moist
R-1 13
7 11

94.9 25.1 CL-ML @2.5'- Silty CLAY: olive brown, wet, stiff R-2 3
6 9

96.3 28.1 @5'- Silty CLAY: olive brown, wet, stiff
R-3 5
5 4

89.3 33.2 CL @7.5'- CLAY: olive brown, wet, medium stiff AL CN
R-4 2
3 4

97.8 27.8 @10'- CLAY: brown, wet, medium stiff
R-5 5
5 8
101.2 26.2 @15'- CLAY: brown, wet, stiff AL
SPT-1 4
6 8

22.9 ML @20'- Sandy SILT: grayish brown, wet, medium dense R-6 6
6 5

99.1 30.4 CL @25'- CLAY: dark gray, wet, stiff Last Edited: 12/16/2021

60 TEST TYPES: DSMD
SA
S&H

EI DIRECT SHEAR MAXIMUM DENSITY

SIEVE ANALYSIS

SIEVE AND HYDROMETER

EXPANSION INDEX
55 50
45 40
35 Elevation (ft) Depth (ft) Graphic Log Sample Number Blow Count Dry Density (pcf) Moisture (%) USCS Symbol DESCRIPTION Type of Test Date:

Project Name:

Project Number:

Elevation of Top of Hole:

Hole Location: See Geotechnical Map
Drilling Company:

Type of Rig:

Drop:

Drive Weight:

Hole Diameter:
30 CN CONSOLIDATION

CR CORROSION

AL ATTERBERG LIMITS CO COLLAPSE/SWELL RV R-VALUE
-#200 % PASSING # 200 SIEVE
THIS SUMMARY APPLIES ONLY AT THE LOCATION OF THIS BORING AND AT THE TIME OF DRILLING. SUBSURFACE CONDITIONS MAY DIFFER AT OTHER LOCATIONS AND MAY CHANGE AT THIS LOCATION WITH THE PASSAGE OF TIME. THE DATA PRESENTED IS A SIMPLIFICATION OF THE ACTUAL CONDITIONS ENCOUNTERED. THE DESCRIPTIONS

PROVIDED ARE QUALITATIVE FIELD DESCRIPTIONS

AND ARE NOT BASED ON QUANTITATIVE
ENGINEERING ANALYSIS.

SAMPLE TYPES: B BULK SAMPLE R RING SAMPLE (CA Modified Sampler) G GRAB SAMPLE

SPT STANDARD PENETRATION

TEST SAMPLE GROUNDWATER TABLE
-5
-10
-15
-20
-25
Geotechnical Boring Log Borehole HS-2
11/11/2021
~25' MSL
6"
Track Mounted
30"
140 pounds
Cal Pac Drilling
MWIG - Los Alamitos
21198-01
Logged By BPP
Sampled By BPP
Checked By RLD

SPT-2 3
5 7

32.3 @30'- CLAY: olive gray, wet, very stiff AL
R-7 6
21 33
110.9 17.4 SM @35'- Silty SAND: gray, wet, dense
SPT-3 5
7 15

28.1 @40'- Silty SAND: dark gray, wet, medium dense -#200 R-8 7
9 11

99.2 26.6 @45'- Silty SAND: dark gray, wet, medium dense -#200 Total Depth = 46.5'
Groundwater Encountered at Approximately 11.5'
Backfilled with Cuttings on 11/11/2021
CL

THIS SUMMARY APPLIES ONLY AT THE LOCATION OF THIS BORING AND AT THE TIME OF DRILLING. SUBSURFACE CONDITIONS MAY DIFFER AT OTHER LOCATIONS AND MAY CHANGE AT THIS LOCATION WITH THE PASSAGE OF TIME. THE DATA PRESENTED IS A SIMPLIFICATION OF THE ACTUAL CONDITIONS ENCOUNTERED. THE DESCRIPTIONS

PROVIDED ARE QUALITATIVE FIELD DESCRIPTIONS

AND ARE NOT BASED ON QUANTITATIVE
ENGINEERING ANALYSIS. CN CONSOLIDATION

CR CORROSION

AL ATTERBERG LIMITS CO COLLAPSE/SWELL RV R-VALUE
-#200 % PASSING # 200 SIEVE

DIRECT SHEAR MAXIMUM DENSITY

SIEVE ANALYSIS

SIEVE AND HYDROMETER

EXPANSION INDEX
TEST TYPES: DSMD
SA
S&H
EI
SAMPLE TYPES: B BULK SAMPLE R RING SAMPLE (CA Modified Sampler) G GRAB SAMPLE

SPT STANDARD PENETRATION

TEST SAMPLE GROUNDWATER TABLE
30 25
20 15
10 5
0 Elevation (ft) Depth (ft) Graphic Log Sample Number Blow Count Dry Density (pcf) Moisture (%) USCS Symbol DESCRIPTION Type of Test Hole Diameter:

Hole Location: See Geotechnical Map
Drop:

Type of Rig:

Project Number:

Elevation of Top of Hole: Drive Weight:

Drilling Company:

Project Name:

Date:
20 15
10 5
0 -5
Geotechnical Boring Log Borehole HS-3
11/11/2021
~24' MSL
6"
Track Mounted
30"
140 pounds
Cal Pac Drilling
MWIG - Los Alamitos
21198-01
Logged By BPP
Sampled By BPP
Checked By RLD

@0' to T.D. - Quaternary Young Alluvium (Qya):
@0'- Topsoil; Sandy SILT: brown/gray, slightly moist
MD
DS
EI
R-1 CR 5
7 14
110.5 15.2 CL-ML @2.5'- Silty CLAY: olive brown, moist, very stiff R-2 7
8 13
101.6 22.0 CL @5'- CLAY: olive brown, very moist, very stiff R-3 5
2 3

87.4 35.4 @7.5'- CLAY: olive brown, wet, soft AL
CN
R-4 1
3 4

98.7 26.9 @10'- CLAY: olive brown, wet, medium stiff
SPT-1 2
3 3

24.7 @15'- CLAY: olive brown, wet, medium stiff
R-5 3
5 6
107.9 20.7 @20'- CLAY: olive brown, wet, stiff
Total Depth = 21.5'
Groundwater Encountered at Approximately 11'
Backfilled with Cuttings on 11/11/2021 B-1 Last Edited: 12/16/2021

THIS SUMMARY APPLIES ONLY AT THE LOCATION OF THIS BORING AND AT THE TIME OF DRILLING. SUBSURFACE CONDITIONS MAY DIFFER AT OTHER LOCATIONS AND MAY CHANGE AT THIS LOCATION WITH THE PASSAGE OF TIME. THE DATA PRESENTED IS A SIMPLIFICATION OF THE ACTUAL CONDITIONS ENCOUNTERED. THE DESCRIPTIONS

PROVIDED ARE QUALITATIVE FIELD DESCRIPTIONS

AND ARE NOT BASED ON QUANTITATIVE
ENGINEERING ANALYSIS. CN CONSOLIDATION

CR CORROSION

AL ATTERBERG LIMITS CO COLLAPSE/SWELL RV R-VALUE
-#200 % PASSING # 200 SIEVE

DIRECT SHEAR MAXIMUM DENSITY

SIEVE ANALYSIS

SIEVE AND HYDROMETER

EXPANSION INDEX
TEST TYPES: DSMD
SA
S&H
EI
SAMPLE TYPES: B BULK SAMPLE R RING SAMPLE (CA Modified Sampler) G GRAB SAMPLE

SPT STANDARD PENETRATION

TEST SAMPLE GROUNDWATER TABLE
30 25
20 15
10 5
0 Elevation (ft) Depth (ft) Graphic Log Sample Number Blow Count Dry Density (pcf) Moisture (%) USCS Symbol DESCRIPTION Type of Test Hole Diameter:

Hole Location: See Geotechnical Map
Drop:

Type of Rig:

Project Number:

Elevation of Top of Hole: Drive Weight:

Drilling Company:

Project Name:

Date:
20 15
10 5
0 -5
Geotechnical Boring Log Borehole I-1
11/11/2021
~23' MSL
8"
Track Mounted
30"
140 pounds
Cal Pac Drilling
MWIG - Los Alamitos
21198-01
Logged By BPP
Sampled By BPP
Checked By RLD

@0' to 2.5' - Older Artificial Fill (afo):

22.0 SC @0'- 3" of Asphalt over 5" of Base
@1'- Clayey SAND: gray/brown, very moist
@2.5' to T.D. - Quaternary Young Alluvium (Qya):
@2.5'- Clayey SAND: gray/brown, very moist
Total Depth = 5'
Groundwater Not Encountered
3" Perforated Pipe With Filter Sock Installed,
Surrounded by Gravel, and Presoaked on 11/11/2021
Pipe Removed and Boring Backfilled With Cuttings on
11/12/2021 B-1 Last Edited: 12/16/2021

THIS SUMMARY APPLIES ONLY AT THE LOCATION OF THIS BORING AND AT THE TIME OF DRILLING. SUBSURFACE CONDITIONS MAY DIFFER AT OTHER LOCATIONS AND MAY CHANGE AT THIS LOCATION WITH THE PASSAGE OF TIME. THE DATA PRESENTED IS A SIMPLIFICATION OF THE ACTUAL CONDITIONS ENCOUNTERED. THE DESCRIPTIONS

PROVIDED ARE QUALITATIVE FIELD DESCRIPTIONS

AND ARE NOT BASED ON QUANTITATIVE
ENGINEERING ANALYSIS. CN CONSOLIDATION

CR CORROSION

AL ATTERBERG LIMITS CO COLLAPSE/SWELL RV R-VALUE
-#200 % PASSING # 200 SIEVE

DIRECT SHEAR MAXIMUM DENSITY

SIEVE ANALYSIS

SIEVE AND HYDROMETER

EXPANSION INDEX
TEST TYPES: DSMD
SA
S&H
EI
SAMPLE TYPES: B BULK SAMPLE R RING SAMPLE (CA Modified Sampler) G GRAB SAMPLE

SPT STANDARD PENETRATION

TEST SAMPLE GROUNDWATER TABLE
30 25
20 15
10 5
0 Elevation (ft) Depth (ft) Graphic Log Sample Number Blow Count Dry Density (pcf) Moisture (%) USCS Symbol DESCRIPTION Type of Test Hole Diameter:

Hole Location: See Geotechnical Map
Drop:

Type of Rig:

Project Number:

Elevation of Top of Hole: Drive Weight:

Drilling Company:

Project Name:

Date:
20 15
10 5
0 -5
Geotechnical Boring Log Borehole I-2
11/11/2021
~23' MSL
8"
Track Mounted
30"
140 pounds
Cal Pac Drilling
MWIG - Los Alamitos
21198-01
Logged By BPP
Sampled By BPP
Checked By RLD

@0' to 2.5'- Older Artificial Fill (afo):

16.9 SM @0'- 3" of Asphalt over 5" of Base
@1'- Silty SAND: dark gray, very moist
@2.5' to T.D. - Quaternary Young Alluvium (Qya):
@2.5'- Silty SAND: dark gray, very moist
Total Depth = 5'
Groundwater Not Encountered
3" Perforated Pipe With Filter Sock Installed,
Surrounded by Gravel, and Presoaked on 7/23/2021
Pipe Removed and Boring Backfilled With Cuttings on
11/12/2021 B-1 Last Edited: 12/16/2021

THIS SUMMARY APPLIES ONLY AT THE LOCATION OF THIS BORING AND AT THE TIME OF DRILLING. SUBSURFACE CONDITIONS MAY DIFFER AT OTHER LOCATIONS AND MAY CHANGE AT THIS LOCATION WITH THE PASSAGE OF TIME. THE DATA PRESENTED IS A SIMPLIFICATION OF THE ACTUAL CONDITIONS ENCOUNTERED. THE DESCRIPTIONS

PROVIDED ARE QUALITATIVE FIELD DESCRIPTIONS

AND ARE NOT BASED ON QUANTITATIVE
ENGINEERING ANALYSIS. CN CONSOLIDATION

CR CORROSION

AL ATTERBERG LIMITS CO COLLAPSE/SWELL RV R-VALUE
-#200 % PASSING # 200 SIEVE

DIRECT SHEAR MAXIMUM DENSITY

SIEVE ANALYSIS

SIEVE AND HYDROMETER

EXPANSION INDEX
TEST TYPES: DSMD
SA
S&H
EI
SAMPLE TYPES: B BULK SAMPLE R RING SAMPLE (CA Modified Sampler) G GRAB SAMPLE

SPT STANDARD PENETRATION

TEST SAMPLE GROUNDWATER TABLE
30 25
20 15
10 5
0 Elevation (ft) Depth (ft) Graphic Log Sample Number Blow Count Dry Density (pcf) Moisture (%) USCS Symbol DESCRIPTION Type of Test Hole Diameter:

Hole Location: See Geotechnical Map
Drop:

Type of Rig:

Project Number:

Elevation of Top of Hole: Drive Weight:

Drilling Company:

Project Name:

Date:
20 15
10 5
0 -5
Geotechnical Boring Log Borehole HA-1
11/11/2021
~24' MSL
3"
Track Mounted
30"
140 pounds
Cal Pac Drilling
MWIG - Los Alamitos
21198-01
Logged By BPP
Sampled By BPP
Checked By RLD

@0' to T.D. - Quaternary Young Alluvium (Qya):

12.8 ML @0'- 1' of Topsoil
@1'- Sandy SILT: brown, slightly moist

12.8 CL @3'- Silty CLAY: brown, moist
Total Depth = 5'
Groundwater Not Encountered
Backfilled with Cuttings on 11/11/2021 B-1 Last Edited: 12/16/2021

THIS SUMMARY APPLIES ONLY AT THE LOCATION OF THIS BORING AND AT THE TIME OF DRILLING. SUBSURFACE CONDITIONS MAY DIFFER AT OTHER LOCATIONS AND MAY CHANGE AT THIS LOCATION WITH THE PASSAGE OF TIME. THE DATA PRESENTED IS A SIMPLIFICATION OF THE ACTUAL CONDITIONS ENCOUNTERED. THE DESCRIPTIONS

PROVIDED ARE QUALITATIVE FIELD DESCRIPTIONS

AND ARE NOT BASED ON QUANTITATIVE
ENGINEERING ANALYSIS. CN CONSOLIDATION

CR CORROSION

AL ATTERBERG LIMITS CO COLLAPSE/SWELL RV R-VALUE
-#200 % PASSING # 200 SIEVE

DIRECT SHEAR MAXIMUM DENSITY

SIEVE ANALYSIS

SIEVE AND HYDROMETER

EXPANSION INDEX
TEST TYPES: DSMD
SA
S&H
EI
SAMPLE TYPES: B BULK SAMPLE R RING SAMPLE (CA Modified Sampler) G GRAB SAMPLE

SPT STANDARD PENETRATION

TEST SAMPLE GROUNDWATER TABLE
30 25
20 15
10 5
0 Elevation (ft) Depth (ft) Graphic Log Sample Number Blow Count Dry Density (pcf) Moisture (%) USCS Symbol DESCRIPTION Type of Test Hole Diameter:

Hole Location: See Geotechnical Map
Drop:

Type of Rig:

Project Number:

Elevation of Top of Hole: Drive Weight:

Drilling Company:

Project Name:

Date:
20 15
10 5
0 -5
Geotechnical Boring Log Borehole HA-2
11/12/2021
~24' MSL
3"
Track Mounted
30"
140 pounds
Cal Pac Drilling
MWIG - Los Alamitos
21198-01
Logged By BPP
Sampled By BPP
Checked By RLD

@0' to 2.5'- Undocumented Artificial Fill (afu):
@0'- Silty SAND: grayish brown, dry
EI
CR
SC
@2.5' to T.D. - Quaternary Young Alluvium (Qya):
@2.5'- Clayey SAND: grayish brown, very moist
Total Depth = 5'
Groundwater Not Encountered
Backfilled with Cuttings on 11/12/2021 B-1 Last Edited: 12/16/2021 SM

Appendix C
Laboratory Test Results

Project No. 21198‐01 C‐1 December 2021

APPENDIX C
Laboratory Testing Procedures and Test Results
The laboratory testing program was formulated towards providing data relating to the relevant engineering properties of the soils with respect to residential construction. Samples considered representative of site conditions were tested in general accordance with American Society for Testing and Materials (ASTM) procedure and/or California Test Methods (CTM), where applicable.

The following summary is a brief outline of the test type and a table summarizing the test results.

Moisture and Density Determination Tests: Moisture content (ASTM D2216) and dry density determinations (ASTM D2937) were performed on relatively undisturbed samples obtained from the test borings and/or trenches. The results of these tests are presented in the boring logs. Where applicable, only moisture content was determined from undisturbed or disturbed samples.

Expansion Index: The expansion potential of selected samples was evaluated by the Expansion Index Test, Standard ASTM D4829. Specimens are molded under a given compactive energy to approximately the optimum moisture content and approximately 50 percent saturation or approximately 90 percent relative compaction. The prepared 1-inch-thick by 4-inch-diameter specimens are loaded to an equivalent 144 psf surcharge and are inundated with tap water until volumetric equilibrium is reached. The results of these tests are presented in the table below.

Sample
Location
Expansion
Index
Expansion
Potential*
HS-3 @ 1-5 feet 32 Low
HA-2 @ 1-5 feet 30 Low
* ASTM D4829
Grain Size Distibution/Fines Content: Representative samples were dried, weighed and soaked in water until individual soil particles were separated (per ASTM D421) and then washed on a No. 200 sieve (ASTM D1140). Where applicable, the portion retained on the No. 200 sieve and dried and then sieved on a U.S. Standard brass sieve set in accordance with ASTM D6913 (sieve).

Sample
Location
Description % Passing #
200 Sieve
HS-2 @ 40 feet Silty Sand 16.5
HS-2 @ 45 feet Silty Sand 15

APPENDIX C (Cont’d)
Laboratory Testing Procedures and Test Results
Project No. 21198‐01 C‐2 December 2021
Atterberg Limits: The liquid and plastic limits (“Atterberg Limits”) were determined per ASTM D4318 for engineering classification of fine-grained material and presented in the table below. The USCS soil classification indicated in the table below is based on the portion of sample passing the No. 40 sieve and may not necessarily be representative of the entire sample. The plot is provided in this Appendix.

Sample Location Liquid Limit
(%)
Plastic Limit
(%)
Plasticity
Index (%)
USCS
Soil
Classification
HS-2 @ 7.5 feet 31 19 12 CL
HS-2 @ 15 feet 34 17 17 CL
HS-2 @ 30 feet 35 16 19 CL
HS-3 @ 7.5 feet 48 24 24 CL
Consolidation: Two consolidation tests were performed per ASTM D2435. A sample (2.4 inches in diameter and 1 inch in height) was placed in a consolidometer and increasing loads were applied.

The sample was allowed to consolidate under “double drainage” and total deformation for each loading step was recorded. The percent consolidation for each load step was recorded as the ratio of the amount of vertical compression to the original sample height. The consolidation pressure curve is provided in this Appendix.

Direct Shear: One direct shear test was performed on remolded samples, which was soaked for a minimum of 24 hours prior to testing. The samples were tested under various normal loads using a motor-driven, strain-controlled, direct-shear testing apparatus (ASTM D3080). The plot is provided in this Appendix.

Maximum Density Tests: The maximum dry density and optimum moisture content of typical materials were determined in accordance with ASTM D1557. The results of these tests are presented in the table below:

Sample
Location Sample Description
Maximum
Dry Density
(pcf)
Optimum
Moisture
Content (%)
HS-3 @ 1-5 feet Dark Olive Brown Clayey Sand 116.0 13.0

APPENDIX C (Cont’d)
Laboratory Testing Procedures and Test Results
Project No. 21198‐01 C‐3 December 2021
Chloride Content: Chloride content was tested in accordance with Caltrans Test Method (CTM) 422. The results are presented below.

Sample Location Chloride Content, ppm
HS-3 @ 1-5 feet 600
HA-2 @ 1-5 feet 140
Soluble Sulfates: The soluble sulfate contents of selected samples were determined by standard geochemical methods (CTM 417). The soluble sulfate content is used to determine the appropriate cement type and maximum water-cement ratios. The test results are presented in the table below.

Sample
Location
Sulfate Content
(ppm)
Sulfate Exposure
Class *
HS-3 @ 1-5 feet 2535 S2
HA-2 @ 1-5 feet 317 S0
*Based on ACI 318R-14, Table 19.3.1.1
Minimum Resistivity and pH Tests: Minimum resistivity and pH tests were performed in general accordance with CTM 643 and standard geochemical methods. The results are presented in the table below.

Sample
Location pH Minimum Resistivity(ohms‐cm)
HS-3 @ 1-5 feet 8.92 210

Project Name: Los Alamitos Tested By: S. Felter Date: 12/03/21 Project No. : Input By: J. Ward Date: 12/14/21
Boring No.: Checked By: J. Ward
Sample No.: Depth (ft.) 7.5
Soil Identification:
121234
34 27 17

10.70 10.61 21.36 20.43 20.11

9.13 9.08 16.65 15.91 15.53

1.08 1.12 1.11 1.06 1.04

19.50 19.22 30.31 30.44 31.61
31 19
12 CL
PI at "A" - Line = 0.73(LL-20) 8.03
One - Point Liquid Limit Calculation
LL =Wn(N/25)

PROCEDURES USED
Wet Preparation
Multipoint - Wet
X Dry Preparation
Multipoint - Dry
X Procedure A
Multipoint Test
Procedure B
One-point Test
Light olive brown lean clay (CL)

ATTERBERG LIMITS
ASTM D 4318
21198-01
HS-2
R-3
Dry Wt. of Soil + Cont. (g)
Wt. of Container (g)
Moisture Content (%) [Wn]
TEST
NO.

Liquid Limit
Plastic Limit
Plasticity Index
Classification
Number of Blows [N]
Wet Wt. of Soil + Cont. (g)

PLASTIC LIMIT LIQUID LIMIT
0 10
20 30
40 50
60 0 10 20 30 40 50 60 70 80 90 100
Plasticity Index (PI)
Liquid Limit (LL)

0.121
CL or OL
ML or OL
MH or OH
For classification of finegrained soils and finegrained fraction of coarsegrained soils "A" Line
7 4
CH or OH
CL- ML
29 30
31 32
33 10 100
Moisture Content (%)
Number of Blows
20 25 30 40 50 60 70 80 90

Project Name: Los Alamitos Tested By: S. Felter Date: 12/03/21 Project No. : Input By: J. Ward Date: 12/14/21
Boring No.: Checked By: J. Ward
Sample No.: Depth (ft.) 15.0
Soil Identification:
121234
34 25 15

10.21 10.20 20.36 20.23 21.00

8.90 8.89 15.65 15.33 15.77

1.08 1.06 1.10 1.09 1.12

16.75 16.73 32.37 34.41 35.70
34 17
17 CL
PI at "A" - Line = 0.73(LL-20) 10.22
One - Point Liquid Limit Calculation
LL =Wn(N/25)

PROCEDURES USED
Wet Preparation
Multipoint - Wet
X Dry Preparation
Multipoint - Dry
X Procedure A
Multipoint Test
Procedure B
One-point Test
Brown lean clay (CL)

ATTERBERG LIMITS
ASTM D 4318
21198-01
HS-2
R-5
Dry Wt. of Soil + Cont. (g)
Wt. of Container (g)
Moisture Content (%) [Wn]
TEST
NO.

Liquid Limit
Plastic Limit
Plasticity Index
Classification
Number of Blows [N]
Wet Wt. of Soil + Cont. (g)

PLASTIC LIMIT LIQUID LIMIT
0 10
20 30
40 50
60 0 10 20 30 40 50 60 70 80 90 100
Plasticity Index (PI)
Liquid Limit (LL)

0.121
CL or OL
ML or OL
MH or OH
For classification of finegrained soils and finegrained fraction of coarsegrained soils "A" Line
7 4
CH or OH
CL- ML
31 32
33 34
35 36
37 10 100
Moisture Content (%)
Number of Blows
20 25 30 40 50 60 70 80 90

Project Name: Los Alamitos Tested By: S. Felter Date: 12/03/21 Project No. : Input By: J. Ward Date: 12/14/21
Boring No.: Checked By: J. Ward
Sample No.: Depth (ft.) 30.0
Soil Identification:
121234
35 25 18

10.49 10.83 20.53 20.10 21.13

9.24 9.48 15.72 15.13 15.74

1.08 1.06 1.12 1.07 1.08

15.32 16.03 32.95 35.35 36.77
35 16
19 CL
PI at "A" - Line = 0.73(LL-20) 10.95
One - Point Liquid Limit Calculation
LL =Wn(N/25)

PROCEDURES USED
Wet Preparation
Multipoint - Wet
X Dry Preparation
Multipoint - Dry
X Procedure A
Multipoint Test
Procedure B
One-point Test
Olive gray lean clay (CL)

ATTERBERG LIMITS
ASTM D 4318
21198-01
HS-2
SPT-2
Dry Wt. of Soil + Cont. (g)
Wt. of Container (g)
Moisture Content (%) [Wn]
TEST
NO.

Liquid Limit
Plastic Limit
Plasticity Index
Classification
Number of Blows [N]
Wet Wt. of Soil + Cont. (g)

PLASTIC LIMIT LIQUID LIMIT
0 10
20 30
40 50
60 0 10 20 30 40 50 60 70 80 90 100
Plasticity Index (PI)
Liquid Limit (LL)

0.121
CL or OL
ML or OL
MH or OH
For classification of finegrained soils and finegrained fraction of coarsegrained soils "A" Line
7 4
CH or OH
CL- ML
32 33
34 35
36 37
38 10 100
Moisture Content (%)
Number of Blows
20 25 30 40 50 60 70 80 90

Project Name: Los Alamitos Tested By: S. Felter Date: 12/03/21 Project No. : Input By: J. Ward Date: 12/14/21
Boring No.: Checked By: J. Ward
Sample No.: Depth (ft.) 7.5
Soil Identification:
121234
34 28 21

10.09 10.02 20.94 20.13 20.15

8.36 8.30 14.72 14.05 13.85

1.04 1.14 1.05 1.03 1.01

23.63 24.02 45.50 46.70 49.07
48 24
24 CL
PI at "A" - Line = 0.73(LL-20) 20.44
One - Point Liquid Limit Calculation
LL =Wn(N/25)

PROCEDURES USED
Wet Preparation
Multipoint - Wet
X Dry Preparation
Multipoint - Dry
X Procedure A
Multipoint Test
Procedure B
One-point Test
Olive brown lean clay (CL)

ATTERBERG LIMITS
ASTM D 4318
21198-01
HS-3
R-3
Dry Wt. of Soil + Cont. (g)
Wt. of Container (g)
Moisture Content (%) [Wn]
TEST
NO.

Liquid Limit
Plastic Limit
Plasticity Index
Classification
Number of Blows [N]
Wet Wt. of Soil + Cont. (g)

PLASTIC LIMIT LIQUID LIMIT
0 10
20 30
40 50
60 0 10 20 30 40 50 60 70 80 90 100
Plasticity Index (PI)
Liquid Limit (LL)

0.121
CL or OL
ML or OL
MH or OH
For classification of finegrained soils and finegrained fraction of coarsegrained soils "A" Line
7 4
CH or OH
CL- ML
44 45
46 47
48 49
50 10 100
Moisture Content (%)
Number of Blows
20 25 30 40 50 60 70 80 90

Project Name: Los Alamitos Tested By:G. Bathala Date: 11/30/21 Project No.: Checked By: J. Ward Date: 12/16/21
Boring No.: Depth (ft.): 7.5
Sample No.: Sample Type: Ring
Soil Identification: Light olive brown lean clay (CL)

2.415

1.000
191.82

45.88 0.9595
270.84
216.12

51.16 33.2

91.1 100

0.3176
246.12
216.12

59.16 27.01

96.3 92

0.2743

2.82 62.43

0.10 0.3176 1.0000 0.00 0.00 0.932 0.00

0.25 0.3166 0.9990 0.05 0.10 0.931 0.05

0.50 0.3146 0.9970 0.10 0.31 0.928 0.21

1.00 0.3100 0.9924 0.18 0.76 0.920 0.58

1.00 0.3099 0.9923 0.18 0.77 0.920 0.59

2.00 0.3028 0.9852 0.27 1.48 0.908 1.21

4.00 0.2924 0.9748 0.40 2.53 0.891 2.13

8.00 0.2795 0.9619 0.56 3.81 0.869 3.25

16.00 0.2624 0.9448 0.77 5.53 0.840 4.76

8.00 0.2643 0.9467 0.65 5.33 0.841 4.68

4.00 0.2666 0.9490 0.54 5.10 0.844 4.56

1.00 0.2719 0.9543 0.36 4.57 0.850 4.21

0.50 0.2743 0.9567 0.28 4.33 0.853 4.05

ONE-DIMENSIONAL CONSOLIDATION
PROPERTIES of SOILS
ASTM D 2435
R-3
21198-01
HS-2
Weight of Container (g)
Final Moisture Content (%)
Water Density (pcf)
Final Dry Density (pcf)
Final Saturation (%)
Final Vertical Reading (in.)
Specific Gravity (assumed)
Initial Moisture Content (%)
Initial Dry Density (pcf)
Initial Saturation (%)
Initial Vertical Reading (in.)
Wt.of Wet Sample+Cont. (g)
Wt. of Dry Sample+Cont. (g)
Sample Diameter (in.)
Sample Thickness (in.)
Wt. of Sample + Ring (g)
Weight of Ring (g)
After Test
Height after consol. (in.)
Wt.Wet Sample+Cont. (g)
Wt.of Dry Sample+Cont. (g)
Weight of Container (g)
Before Test
Corrected
Deformation (%)
Time Readings
Date Time Elapsed
Time (min)
Square Root
of Time
Dial Rdgs.
(in.)
Pressure
(p)
(ksf)
Final
Reading
(in.)
Apparent
Thickness
(in.)
Load
Compliance
(%)
Deformation
% of
Sample
Thickness
Void
Ratio

0.820

0.840

0.860

0.880

0.900

0.920

0.940

0.10 1.00 10.00 100.

Void Ratio
Pressure, p (ksf)
Inundate with
Tap water

Initial Final Initial Final Initial Final Initial Final Boring
No.

Sample
No.

Depth
(ft.)
Moisture
Content (%)

ONE-DIMENSIONAL CONSOLIDATION
PROPERTIES of SOILS
ASTM D 2435
HS-2 R-3 33.2 27.0 96.3
Soil Identification: Light olive brown lean clay (CL)
Project No.:

Los Alamitos
12-21
21198-01
Time Readings

91.1 0.853 100 92
Degree of
Saturation (%) Dry Density (pcf)

0.932
Void Ratio

7.5 0.0000

0.2000

0.4000

0.6000

0.8000

1.0000

1.2000

0.1 1.0
Deformation Dial Reading (in.)
Log of Time (min.)

0.00 0.50

1.00 1.50

2.00 2.50

3.00 3.50

4.00 4.50

5.00 0.10 1.00 10.00 100.00
Deformation (%)
Pressure, p (ksf)

0.0000

0.2000

0.4000

0.6000

0.8000

1.0000

1.2000

0.0 10.0
Square Root of Time (min.1/2)
Inundate with
Tap water

Project Name: Los Alamitos Tested By:G. Bathala Date: 11/30/21 Project No.: Checked By: J. Ward Date: 12/16/21
Boring No.: Depth (ft.): 7.5
Sample No.: Sample Type: Ring
Soil Identification: Olive brown lean clay (CL)

2.415

1.000
190.90

45.41 0.8542
264.56
210.43

57.44 35.4

89.4 100

0.3339
234.04
209.24

53.68 22.51
107.2
95 0.1866

2.89 62.43

0.10 0.3273 0.9934 0.00 0.66 1.005 0.66

0.25 0.3174 0.9835 0.02 1.65 0.986 1.63

0.50 0.3080 0.9741 0.04 2.59 0.967 2.55

1.00 0.2941 0.9602 0.07 3.98 0.940 3.91

1.00 0.2940 0.9601 0.07 3.99 0.939 3.92

2.00 0.2711 0.9372 0.11 6.28 0.894 6.17

4.00 0.2374 0.9035 0.18 9.65 0.827 9.47

8.00 0.2031 0.8692 0.28 13.08 0.760 12.80

16.00 0.1646 0.8307 0.41 16.93 0.685 16.52

8.00 0.1668 0.8329 0.36 16.71 0.689 16.35

4.00 0.1710 0.8371 0.30 16.29 0.696 15.99

1.00 0.1819 0.8480 0.19 15.20 0.716 15.01

0.50 0.1866 0.8527 0.15 14.73 0.724 14.58

ONE-DIMENSIONAL CONSOLIDATION
PROPERTIES of SOILS
ASTM D 2435
R-3
21198-01
HS-3
Weight of Container (g)
Final Moisture Content (%)
Water Density (pcf)
Final Dry Density (pcf)
Final Saturation (%)
Final Vertical Reading (in.)
Specific Gravity (assumed)
Initial Moisture Content (%)
Initial Dry Density (pcf)
Initial Saturation (%)
Initial Vertical Reading (in.)
Wt.of Wet Sample+Cont. (g)
Wt. of Dry Sample+Cont. (g)
Sample Diameter (in.)
Sample Thickness (in.)
Wt. of Sample + Ring (g)
Weight of Ring (g)
After Test
Height after consol. (in.)
Wt.Wet Sample+Cont. (g)
Wt.of Dry Sample+Cont. (g)
Weight of Container (g)
Before Test
Corrected
Deformation (%)
Time Readings
Date Time Elapsed
Time (min)
Square Root
of Time
Dial Rdgs.
(in.)
Pressure
(p)
(ksf)
Final
Reading
(in.)
Apparent
Thickness
(in.)
Load
Compliance
(%)
Deformation
% of
Sample
Thickness
Void
Ratio

0.650

0.700

0.750

0.800

0.850

0.900

0.950

1.000

1.050

0.10 1.00 10.00 100.

Void Ratio
Pressure, p (ksf)
Inundate with
Tap water

Initial Final Initial Final Initial Final Initial Final Boring
No.

Sample
No.

Depth
(ft.)
Moisture
Content (%)

ONE-DIMENSIONAL CONSOLIDATION
PROPERTIES of SOILS
ASTM D 2435
HS-3 R-3 35.4 22.5 107.2
Soil Identification: Olive brown lean clay (CL)
Project No.:

Los Alamitos
12-21
21198-01
Time Readings

89.4 0.724 100 95
Degree of
Saturation (%) Dry Density (pcf)

1.019
Void Ratio

7.5 0.0000

0.2000

0.4000

0.6000

0.8000

1.0000

1.2000

0.1 1.0
Deformation Dial Reading (in.)
Log of Time (min.)

0.00 2.00

4.00 6.00

8.00 10.00

12.00 14.00

16.00 18.00

0.10 1.00 10.00 100.00
Deformation (%)
Pressure, p (ksf)

0.0000

0.2000

0.4000

0.6000

0.8000

1.0000

1.2000

0.0 10.0
Square Root of Time (min.1/2)
Inundate with
Tap water

Project Name: Los Alamitos Tested By: G. Bathala Date: 12/07/21 Project No.: 21198-01 Checked By: J. Ward Date: 12/14/21 Boring No.: Sample Type: Ring
Sample No.: Depth (ft.): 1-5
Soil Identification:

2.415 2.415 2.415

1.000 1.000 1.000
187.01 186.85 187.84

45.35 44.87 45.57
Before Shearing
163.89 163.89 163.89
151.63 151.63 151.63

57.48 57.48 57.48

0.2546 0.2461 0.0000

0.2615 0.2585 -0.0239
After Shearing
213.85 185.81 215.32
188.00 160.70 191.32

64.02 36.53 68.15

2.70 2.70 2.70

62.43 62.43 62.43

DIRECT SHEAR TEST
Consolidated Drained - ASTM D 3080
Water Density(pcf):

Specific Gravity (Assumed):

Weight of Container(gm):

Weight of Dry Sample+Cont.(gm):

Weight of Ring(gm):

Weight of Container(gm):

Weight of Dry Sample+Cont.(gm):

Weight of Wet Sample+Cont.(gm):

HS-3
Dark olive brown clayey sand (SC)
Sample Diameter(in):

Weight of Wet Sample+Cont.(gm):

Vertical Rdg.(in): Final
Vertical Rdg.(in): Initial
Sample Thickness(in.):

Weight of Sample + ring(gm):

B-1
DS HS-3, B-1 @ 1-5 Page 2261 of 3005
Normal Stress (kip/ft²)
Peak Shear Stress (kip/ft²)
Shear Stress @ End of Test (ksf)
Deformation Rate (in./min.)
Initial Sample Height (in.)
Diameter (in.)
Initial Moisture Content (%)
Dry Density (pcf)
Saturation (%)
Soil Height Before Shearing (in.)
Final Moisture Content (%)
104.7

1.000

2.415

13.02 Boring No.

Sample No.

Depth (ft)
HS-3
B-1
1-5

57.3 0.9876

20.2 Soil Identification: 13.02
104.5

13.02 104.2

1.339

0.0017

4.000

2.408

2.408

0.0017

1.000

0.729

0.657

0.0017

1.000

2.415

1.000

2.415

2.000

1.412

57.0 0.9931

20.9 Los Alamitos DIRECT SHEAR TEST RESULTS
Consolidated Drained - ASTM D 3080

57.6 0.9761

19.5 12-21
Project No.: 21198-01
Sample Type:

Ring
Dark olive brown clayey sand
(SC)

0.00 0.50

1.00 1.50

2.00 2.50

3.00 0 0.1 0.2 0.3
Shear Stress (ksf)
Horizontal Deformation (in.)

0.00 0.50

1.00 1.50

2.00 2.50

3.00 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 6.00 Shear Stress (ksf)
Normal Stress (ksf)
DS HS-3, B-1 @ 1-5 Page 2262 of 3005
Appendix D
Infiltration Test Data

Boring Number:

Test hole dimensions (if circular)
5 8
3 Pre‐Test (Sandy Soil Criteria)*
1 8:47 9:12 25.0 2.52 2.54 0.02
2 9:12 9:37 25.0 2.54 2.56 0.02
Main Test Data
1 9:37 10:07 30.0 2.56 2.57 0.01 0.02
2 10:07 10:37 30.0 2.57 2.58 0.01 0.02
3 10:37 11:07 30.0 2.58 2.59 0.01 0.02
4 11:07 11:37 30.0 2.59 2.60 0.01 0.02
5 11:37 12:07 30.0 2.60 2.61 0.01 0.02
6 12:07 12:37 30.0 2.61 2.62 0.01 0.02
7 12:37 13:07 30.0 2.62 2.63 0.01 0.02
8 13:07 13:37 30.0 2.63 2.64 0.01 0.02
9 13:37 14:07 30.0 2.64 2.66 0.02 0.03
10 14:07 14:37 30.0 2.66 2.67 0.01 0.02
11 14:37 15:07 30.0 2.67 2.68 0.01 0.02
12 15:07 15:37 30.0 2.68 2.70 0.02 0.03
Factor of Safety
Sketch: Notes:

Infiltration Test Data Sheet
21198‐01
Boring Diameter (inches):

I‐1
LGC Geotechnical, Inc
131 Calle Iglesia Suite 200, San Clemente, CA 92672     tel. (949) 369‐6141 Project Name:

Boring Depth (feet)*: Pit Depth (feet):

Project Number:

Test pit dimensions (if rectangular)
Date: 11/12/2021
MWIG ‐ Los Alamitos
Pipe Diameter (inches): Pit Breadth (feet):

Spreadsheet Revised on: 10/26/2016
Calculated
Infiltration
Rate(in/hr)
*If two consecutive measurements show that six inches of water seeps away in less than 25 minutes, the test shall be run for an additional hour with measurements taken every 10 minutes. Otherwise, pre‐soak (fill) overnight, and then obtain at least twelve measurements per hole over at least six hours (approximately 30 minute intervals) with a precision of at least 0.25 inches Start Time
(24:HR)
Greater Than or
Equal to

0.5 feet (yes/no)
Stop Time
(24:HR)
No
Initial Depth to
Water  (feet)
Final Depth
to Water
(feet)
Trial No.

Based on Guidelines from: Orange County 12/20/2013
Pit Length (feet):

Initial Depth to
Water, Do (feet)
Final Depth
to Water, Df
(feet)
Calculated Infiltration Rate (With Factor of Safety)
Trial No. Time Interval, t
(min)
Start Time
(24:HR)
Stop Time
(24:HR)
No
Total Change
in Water Level
(feet)
Calculated Infiltration Rate (No factors of safety) 0.03 Change in
Water Level,
D (feet)
Time Interval
(min)

Boring Number:

Test hole dimensions (if circular)
5 8
3 Pre‐Test (Sandy Soil Criteria)*
1 8:54 9:19 25.0 2.72 2.74 0.02
2 9:19 9:44 25.0 2.74 2.75 0.01
Main Test Data
1 9:44 10:14 30.0 2.75 2.76 0.01 0.02
2 10:14 10:44 30.0 2.76 2.77 0.01 0.02
3 10:44 11:14 30.0 2.77 2.78 0.01 0.02
4 11:14 11:44 30.0 2.78 2.80 0.02 0.03
5 11:44 12:14 30.0 2.80 2.81 0.01 0.02
6 12:14 12:44 30.0 2.81 2.82 0.01 0.02
7 12:44 13:14 30.0 2.82 2.83 0.01 0.02
8 13:14 13:44 30.0 2.83 2.85 0.02 0.03
9 13:44 14:14 30.0 2.85 2.87 0.02 0.03
10 14:14 14:44 30.0 2.87 2.88 0.01 0.02
11 14:44 15:14 30.0 2.88 2.89 0.01 0.02
12 15:14 15:44 30.0 2.89 2.91 0.02 0.04
Factor of Safety
Sketch: Notes:

Infiltration Test Data Sheet
LGC Geotechnical, Inc
131 Calle Iglesia Suite 200, San Clemente, CA 92672     tel. (949) 369‐6141 Project Name: MWIG ‐ Los Alamitos
Project Number: 21198‐01
Date: 11/12/2021
I‐2
Test pit dimensions (if rectangular)
Boring Depth (feet)*: Pit Depth (feet):

Boring Diameter (inches): Pit Length (feet):

Pipe Diameter (inches): Pit Breadth (feet):

Trial No.

Start Time
(24:HR)
Stop Time
(24:HR)
Time Interval
(min)
Initial Depth to
Water  (feet)
Final Depth
to Water
(feet)
Total Change
in Water Level
(feet)
Greater Than or
Equal to

0.5 feet (yes/no)
No
No
*If two consecutive measurements show that six inches of water seeps away in less than 25 minutes, the test shall be run for an additional hour with measurements taken every 10 minutes. Otherwise, pre‐soak (fill) overnight, and then obtain at least twelve measurements per hole over at least six hours (approximately 30 minute intervals) with a precision of at least 0.25 inches Trial No.

Start Time
(24:HR)
Stop Time
(24:HR)
Time Interval, t
(min)
Initial Depth to
Water, Do (feet)
Calculated Infiltration Rate (With Factor of Safety)
Based on Guidelines from: Orange County 12/20/2013
Spreadsheet Revised on: 10/26/2016
Final Depth
to Water, Df
(feet)
Change in
Water Level,
D (feet)
Calculated
Infiltration
Rate(in/hr)
Calculated Infiltration Rate (No factors of safety) 0.04

Appendix E
General Earthwork and Grading Specifications for
Rough Grading

General Earthwork and Grading Specifications for Rough Grading

1.0 General

1.1 Intent
These General Earthwork and Grading Specifications are for the grading and earthwork shown on the approved grading plan(s) and/or indicated in the geotechnical report(s). These Specifications are a part of the recommendations contained in the geotechnical report(s). In case of conflict, the specific recommendations in the geotechnical report shall supersede these more general Specifications. Observations of the earthwork by the project Geotechnical Consultant during the course of grading may result in new or revised recommendations that could supersede these specifications or the recommendations in the geotechnical report(s).

1.2 The Geotechnical Consultant of Record
Prior to commencement of work, the owner shall employ a qualified Geotechnical Consultant of Record (Geotechnical Consultant). The Geotechnical Consultant shall be responsible for reviewing the approved geotechnical report(s) and accepting the adequacy of the preliminary geotechnical findings, conclusions, and recommendations prior to the commencement of the grading.

Prior to commencement of grading, the Geotechnical Consultant shall review the "work plan" prepared by the Earthwork Contractor (Contractor) and schedule sufficient personnel to perform the appropriate level of observation, mapping, and compaction testing.

During the grading and earthwork operations, the Geotechnical Consultant shall observe, map, and document the subsurface exposures to verify the geotechnical design assumptions. If the observed conditions are found to be significantly different than the interpreted assumptions during the design phase, the Geotechnical Consultant shall inform the owner, recommend appropriate changes in design to accommodate the observed conditions, and notify the review agency where required.

The Geotechnical Consultant shall observe the moisture-conditioning and processing of the subgrade and fill materials and perform relative compaction testing of fill to confirm that the attained level of compaction is being accomplished as specified. The Geotechnical Consultant shall provide the test results to the owner and the Contractor on a routine and frequent basis.

1.3 The Earthwork Contractor
The Earthwork Contractor (Contractor) shall be qualified, experienced, and knowledgeable in earthwork logistics, preparation and processing of ground to receive fill, moistureconditioning and processing of fill, and compacting fill. The Contractor shall review and accept the plans, geotechnical report(s), and these Specifications prior to commencement of grading. The Contractor shall be solely responsible for performing the grading in accordance with the project plans and specifications. The Contractor shall prepare and submit to the owner and the Geotechnical Consultant a work plan that indicates the sequence of earthwork grading, the number of “equipment” of work and the estimated quantities of daily earthwork General Earthwork and Grading Specifications for Rough Grading Page 1

contemplated for the site prior to commencement of grading. The Contractor shall inform the owner and the
Geotechnical Consultant of changes in work schedules and updates to the work plan at least 24 hours in advance of such changes so that appropriate personnel will be available for observation and testing. The Contractor shall not assume that the Geotechnical Consultant is aware of all grading operations.

The Contractor shall have the sole responsibility to provide adequate equipment and methods to accomplish the earthwork in accordance with the applicable grading codes and agency ordinances, these Specifications, and the recommendations in the approved geotechnical report(s) and grading plan(s). If, in the opinion of the Geotechnical Consultant, unsatisfactory conditions, such as unsuitable soil, improper moisture condition, inadequate compaction, insufficient buttress key size, adverse weather, etc., are resulting in a quality of work less than required in these specifications, the Geotechnical Consultant shall reject the work and may recommend to the owner that construction be stopped until the conditions are rectified. It is the contractor’s sole responsibility to provide proper fill compaction.

2.0 Preparation of Areas to be Filled

2.1 Clearing and Grubbing
Vegetation, such as brush, grass, roots, and other deleterious material shall be sufficiently removed and properly disposed of in a method acceptable to the owner, governing agencies, and the Geotechnical Consultant.

The Geotechnical Consultant shall evaluate the extent of these removals depending on specific site conditions. Earth fill material shall not contain more than 1 percent of organic materials (by volume). Nesting of the organic materials shall not be allowed.

If potentially hazardous materials are encountered, the Contractor shall stop work in the affected area, and a hazardous material specialist shall be informed immediately for proper evaluation and handling of these materials prior to continuing to work in that area.

As presently defined by the State of California, most refined petroleum products (gasoline, diesel fuel, motor oil, grease, coolant, etc.) have chemical constituents that are considered to be hazardous waste. As such, the indiscriminate dumping or spillage of these fluids onto the ground may constitute a misdemeanor, punishable by fines and/or imprisonment, and shall not be allowed. The contractor is responsible for all hazardous waste relating to his work. The Geotechnical Consultant does not have expertise in this area. If hazardous waste is a concern, then the Client should acquire the services of a qualified environmental assessor.

2.2 Processing
Existing ground that has been declared satisfactory for support of fill by the Geotechnical Consultant shall be scarified to a minimum depth of 6 inches. Existing ground that is not satisfactory shall be over-excavated as specified in the following section. Scarification shall continue until soils are broken down and free of oversize material and the working surface is reasonably uniform, flat, and free of uneven features that would inhibit uniform compaction.

General Earthwork and Grading Specifications for Rough Grading Page 2

2.3 Over-excavation
In addition to removals and over-excavations recommended in the approved geotechnical report(s) and the grading plan, soft, loose, dry, saturated, spongy, organic-rich, highly fractured or otherwise unsuitable ground shall be over-excavated to competent ground as evaluated by the Geotechnical Consultant during grading.

2.4 Benching
Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to vertical units), the ground shall be stepped or benched. Please see the Standard Details for a graphic illustration. The lowest bench or key shall be a minimum of 15 feet wide and at least 2 feet deep, into competent material as evaluated by the Geotechnical Consultant. Other benches shall be excavated a minimum height of 4 feet into competent material or as otherwise recommended by the Geotechnical Consultant. Fill placed on ground sloping flatter than 5:1 shall also be benched or otherwise over-excavated to provide a flat subgrade for the fill.

2.5 Evaluation/Acceptance of Fill Areas
All areas to receive fill, including removal and processed areas, key bottoms, and benches, shall be observed, mapped, elevations recorded, and/or tested prior to being accepted by the Geotechnical Consultant as suitable to receive fill. The Contractor shall obtain a written acceptance from the Geotechnical Consultant prior to fill placement. A licensed surveyor shall provide the survey control for determining elevations of processed areas, keys, and benches.

3.0 Fill Material

3.1 General
Material to be used as fill shall be essentially free of organic matter and other deleterious substances evaluated and accepted by the Geotechnical Consultant prior to placement. Soils of poor quality, such as those with unacceptable gradation, high expansion potential, or low strength shall be placed in areas acceptable to the Geotechnical Consultant or mixed with other soils to achieve satisfactory fill material.

3.2 Oversize
Oversize material defined as rock, or other irreducible material with a maximum dimension greater than 8 inches, shall not be buried or placed in fill unless location, materials, and placement methods are specifically accepted by the Geotechnical Consultant. Placement operations shall be such that nesting of oversized material does not occur and such that oversize material is completely surrounded by compacted or densified fill. Oversize material shall not be placed within 10 vertical feet of finish grade or within 2 feet of future utilities or underground construction.

General Earthwork and Grading Specifications for Rough Grading Page 3

3.3 Import
If importing of fill material is required for grading, proposed import material shall meet the requirements of the geotechnical consultant. The potential import source shall be given to the Geotechnical Consultant at least 48 hours (2 working days) before importing begins so that its suitability can be determined and appropriate tests performed.

4.0 Fill Placement and Compaction

4.1 Fill Layers
Approved fill material shall be placed in areas prepared to receive fill (per Section 3.0) in near-horizontal layers not exceeding 8 inches in loose thickness. The Geotechnical Consultant may accept thicker layers if testing indicates the grading procedures can adequately compact the thicker layers. Each layer shall be spread evenly and mixed thoroughly to attain relative uniformity of material and moisture throughout.

4.2 Fill Moisture Conditioning
Fill soils shall be watered, dried back, blended, and/or mixed, as necessary to attain a relatively uniform moisture content at or slightly over optimum. Maximum density and optimum soil moisture content tests shall be performed in accordance with the American Society of Testing and Materials (ASTM Test Method D1557).

4.3 Compaction of Fill
After each layer has been moisture-conditioned, mixed, and evenly spread, it shall be uniformly compacted to not less than 90 percent of maximum dry density (ASTM Test Method D1557). Compaction equipment shall be adequately sized and be either specifically designed for soil compaction or of proven reliability to efficiently achieve the specified level of compaction with uniformity.

4.4 Compaction of Fill Slopes
In addition to normal compaction procedures specified above, compaction of slopes shall be accomplished by backrolling of slopes with sheepsfoot rollers at increments of 3 to 4 feet in fill elevation, or by other methods producing satisfactory results acceptable to the Geotechnical Consultant. Upon completion of grading, relative compaction of the fill, out to the slope face, shall be at least 90 percent of maximum density per ASTM Test Method D1557.

4.5 Compaction Testing
Field tests for moisture content and relative compaction of the fill soils shall be performed by the Geotechnical Consultant. Location and frequency of tests shall be at the Consultant's discretion based on field conditions encountered. Compaction test locations will not necessarily be selected on a random basis. Test locations shall be selected to verify adequacy of compaction levels in areas that are judged to be prone to inadequate compaction (such as close to slope faces and at the fill/bedrock benches).

General Earthwork and Grading Specifications for Rough Grading Page 4

4.6 Frequency of Compaction Testing
Tests shall be taken at intervals not exceeding 2 feet in vertical rise and/or 1,000 cubic yards of compacted fill soils embankment. In addition, as a guideline, at least one test shall be taken on slope faces for each 5,000 square feet of slope face and/or each 10 feet of vertical height of slope. The Contractor shall assure that fill construction is such that the testing schedule can be accomplished by the Geotechnical Consultant. The Contractor shall stop or slow down the earthwork construction if these minimum standards are not met.

4.7 Compaction Test Locations
The Geotechnical Consultant shall document the approximate elevation and horizontal coordinates of each test location. The Contractor shall coordinate with the project surveyor to assure that sufficient grade stakes are established so that the Geotechnical Consultant can determine the test locations with sufficient accuracy. At a minimum, two grade stakes within a horizontal distance of 100 feet and vertically less than 5 feet apart from potential test locations shall be provided.

5.0 Subdrain Installation
Subdrain systems shall be installed in accordance with the approved geotechnical report(s), the grading plan, and the Standard Details. The Geotechnical Consultant may recommend additional subdrains and/or changes in subdrain extent, location, grade, or material depending on conditions encountered during grading. All subdrains shall be surveyed by a land surveyor/civil engineer for line and grade after installation and prior to burial. Sufficient time should be allowed by the Contractor for these surveys.

6.0 Excavation
Excavations, as well as over-excavation for remedial purposes, shall be evaluated by the Geotechnical Consultant during grading. Remedial removal depths shown on geotechnical plans are estimates only.

The actual extent of removal shall be determined by the Geotechnical Consultant based on the field evaluation of exposed conditions during grading. Where fill-over-cut slopes are to be graded, the cut portion of the slope shall be made, evaluated, and accepted by the Geotechnical Consultant prior to placement of materials for construction of the fill portion of the slope, unless otherwise recommended by the Geotechnical Consultant.

7.0 Trench Backfills

7.1 The Contractor shall follow all OHSA and Cal/OSHA requirements for safety of trench excavations.

7.2 All bedding and backfill of utility trenches shall be done in accordance with the applicable provisions of Standard Specifications of Public Works Construction. Bedding material shall have a Sand Equivalent greater than 30 (SE>30). The bedding shall be placed to 1 foot over General Earthwork and Grading Specifications for Rough Grading Page 5

General Earthwork and Grading Specifications for Rough Grading Page 6 the top of the conduit and densified by jetting. Backfill shall be placed and densified to a minimum of 90 percent of maximum from 1 foot above the top of the conduit to the surface.

7.3 The jetting of the bedding around the conduits shall be observed by the Geotechnical Consultant.

7.4 The Geotechnical Consultant shall test the trench backfill for relative compaction. At least one test should be made for every 300 feet of trench and 2 feet of fill.

7.5 Lift thickness of trench backfill shall not exceed those allowed in the Standard Specifications of Public Works Construction unless the Contractor can demonstrate to the Geotechnical Consultant that the fill lift can be compacted to the minimum relative compaction by his alternative equipment and method.

Attachment G
Notice of Responsibility of Transfer Form

Water Quality Management Plan
Notice of Transfer of Responsibility
Submission of this Notice of Transfer of Responsibility constitutes notice to the City of Los Alamitos that responsibility for the Water Quality Management Plan (“WQMP”) for the subject property identified below, and implementation of that plan, is being transferred from the Previous Owner (and his/ her agent) of the site (or a portion thereof) to the New Owner, as further described below.

I. Previous Owner/ Previous Responsibility Party Information Company/ Individual Name Contact Person
Street Address Title
City State Zip Phone
II. Information about Site Transferred
Name of Project
Title of WQMP Applicable to Site:

Street Address of Site
Tract Number(s) for Site Lot Numbers
Date WQMP Prepared (or Revised)
III. New Owner/ New Responsible Party Information
Company/ Individual Name Contact Person
Street Address Title
City State Zip Phone
IV. Ownership Transfer Information
General Description of Site Transferred
to New Owner
General Description of Portion of Project/ Parcel
Subject to WQMP Retained by Owner (if any)
Lot/ Tract Number(s) of Site Transferred to New Owner
Remaining Lot/ Tract Number(s) to WQMP still held by Owner (if any) Date of Ownership Transfer
Note: When the Previous Owner is transferring a Site that is a portion of a larger project/ parcel addressed by the WQMP, as opposed to the entire project/ parcel addressed by the WQMP, the General Description of the Site transferred and the remainder of the project/ parcel no transferred shall be set forth as maps attached to this notice.   These maps shall show those portions of the project/ parcel addressed by the WQMP that are transferred to the New Owner (the Transferred Site), those portions retained by the Previous Owner, and those portions previously transferred by the Previous Owner.   Those portions retained by the Previous Owner shall be labeled “Previous Owner,” and those portions previously transferred by the Previous Owner shall be labeled as “Previously Transferred.”

V. Purpose of Notice of Transfer
The purposes of this Notice of Transfer of Responsibility are: 1) to track transfer of responsibility for implementation and amendment of the WQMP when property to which the WQMP is transferred from the Previous Owner to the New Owner, and 2) to facilitate notification to a transferee of property subject to a WQMP that such New Owner is now the Responsible Party of record for the WQMP for this portions of the site that it owns.

VI. Certifications
A. Previous Owner
I certify under penalty of law that I am no longer the owner of the Transferred Site as described in Section II above.   I have provided the New Owner with a copy of the WQMP applicable to the Transferred Site that the New Owner is acquiring from the New Owner.

Print Name of Previous Owner
Representative
Title
Signature of Previous Owner Representative Date
B. New Owner
I certify under penalty of law that I am the owner of the Transferred Site, as described in Section II above, that I have been provided a copy of the WQMP, and that I have informed myself and understand the New Owner’s responsibilities related to the WQMP, its implementation, and Best Management Practices associated with it.  I understand that by signing this notice, the New Owner is accepting all ongoing responsibilities for implementation and amendment of the WQMP for the Transferred Site, which the New Owner has acquired from the Previous Owner.

Print Name of New Owner
Representative
Title
Signature of New Owner Representative Date

PRELIMINARY HYDROLOGY STUDY
4665 Lampson Avenue

LOS ALAMITOS, CA
TTM No. 19263
Project Address:
4665 Lampson Avenue
Los Alamitos, California 90720
Prepared For:

MJW Investments, LLC
27702 Crown Valley Parkway,
Suite D-4-197
Ladera Ranch, CA 92694
Prepared By:

C&V Consulting Inc.
9830 Irvine Center Drive
Irvine, CA 92618
Contact: Dane McDougall, P.E.
(949) 916-3800
Prepared: October 2022
Revised: August 2024

TABLE OF CONTENTS

SECTION PAGE

1.0 SITE DESCRIPTION 2

2.0 PURPOSE OF STUDY 2

3.0 EXISTING CONDITIONS 2

4.0 PROPOSED CONDITIONS 3

5.0 METHODOLOGY 6

6.0 RESULTS 6

7.0 CONCLUSION 8

8.0 DESIGN PARAMETERS 9

9.0 REFERENCES 9
APPENDIX A: Hydrology Maps
A.1 Existing Conditions Hydrology Map
A.2 Proposed Conditions Preliminary Hydrology Map
A.3 Offsite Existing Conditions Hydrology Map
APPENDIX B: Hydrology Calculations
B.1 Existing Conditions Hydrology Calculations (10, 25, 100-year Storm Event) B.2 Offsite Existing Conditions Hydrology Calculations (2, 25, 100-year Storm Event) B.3 Proposed Conditions Hydrology Calculations (10, 25, 100-year Storm Event) APPENDIX C: Hydraulic Calculations
C.1 Catch Basin Sizing
C.2 WSPG Calculations
C.3 Detention Calculations
C.4 Outlet Pipe Orifice Calculation
C.5 Lampson Avenue Street Capacity Calculations
APPENDIX D: Reference Materials
D.1 Orange County Drainage Facilities Maps
D.2 City of Seal Beach Master Plan of Drainage Update: Figure 1-3 D.3 Infeasible Drainage System Outlets 1 and 2 Exhibits APPENDIX E: Soils Map

Preliminary Hydrology Study
For
TTM 19263
4665 Lampson Avenue, Los Alamitos
This Preliminary Hydrology Study was prepared by C&V Consulting, Inc. under the supervision of Dane McDougall, P.E.

Dane McDougall, R.C.E. 80705 Date
Principal, C&V Consulting, Inc.
1 8/23/24 Page 2287 of 3005

1.0 SITE DESCRIPTION:

The proposed development encompasses one parcel consisting of approximately 12.37 acres (APN:
130-012-35). The project is bounded by Lampson Avenue to the south, a golf course to the east, the Los Alamitos Joint Forces Training Base (JFTB) to the west, and Arbor Park to the north. There are two (2) existing driveways that provide access to the site from Lampson Avenue. Majority of the site consists of an existing paved parking lot and 2-story office building with walkways and various landscaping. The remaining portion of the site consists a large, vacant brush filled open space area. Per the City of Los Alamitos General Plan, the site is located within the Limited Multiple Family Residential designation. According to the city of Los Alamitos Zoning Map the site is located within the Multi-Family Residential (R-3) zone.

2.0 PURPOSE OF STUDY:

The purpose of this report is to provide quantitative information to verify the design of the storm drain infrastructure and hydrologic methodology of the project site. This report demonstrates that the subject site is designed and planned in accordance with the Orange County Hydrology Manual, the City of Los Alamitos and City of Seal Beach drainage requirements.

3.0 EXISTING CONDITIONS:

Per the existing topography, the site elevations range from approximately 21 to 26’ above mean sea level. The existing site generally flows in an east to westerly direction, however directs stormwater in the southerly direction to an existing westerly flowing concrete-lined channel along the site’s southerly property line. The existing concrete channel outlets to an 18” corrugated metal pipe (CMP) storm drain with headwall that flows under the existing offsite private roadway and discharges into an offsite earthen channel within the Los Alamitos Joint Forces Training Base (JFTB) property. Stormwater runoff flows within this earthen channel converge with runoff flows from portions of Arbor Park and JFTB and are then collected by an existing 24” CMP that continues to flow westerly, ultimately draining to the Old Ranch Country Club, located southwest from the site. Stormwater runoff is then ultimately conveyed downstream into the San Gabriel River/ San Pedro-Los Alamitos Bay.

Per field observations conducted by C&V Consulting, Inc., the existing concrete channel along the site’s southerly property line currently ponds up and overflows onto Lampson Avenue near the southwest corner of the site. Overflowing occurs on to Lampson Avenue due to the existing topography of the area. The westerly adjacent private roadway for Arbor Park access drains in the southerly direction directly onto Lampson Avenue. Refer to the Existing Conditions Hydrology Map in Appendix A.1 for additional information. Per conversations with City of Seal Beach staff, historical stormwater flows in Lampson Avenue exceed the top of curb elevation during large storm events. Based on the existing topography of the site, in the event the outlet pipe were to become clogged, the existing overflows from the property would flow onto Lampson Avenue at the low point at the southwest corner of the site.

Refer to the following photographic images of existing ponding during a March 2023 rain event:

Existing JFTB Earthen Channel (looking North)
Existing Onsite Channel/ Existing 18” CMP Outlet
(near southwest corner of site, looking East)

Existing Onsite Channel (looking West)
Per Orange County Flood Protection Goals: Figure 3-1 enclosed in Appendix A:

1. Flooding is allowed over the curb and to the right of way for the 100-year flood level as long as a minimum 1’ freeboard from the building pad to the water surface elevation is provided and

2. Flooding is allowed to the top of the curb for 25-year flood level street flows as long as a 12’ wide travel lane is provided for emergency vehicles. As shown in the existing street flow calculations enclosed in Appendix C.3, the 25-year water surface level street flows in Lampson Avenue along the project frontage are contained below the top of curb with a 12’ wide travel lane provided for emergency vehicles in accordance with Orange County Flood Protection requirements.

In addition, the low point of Lampson Avenue occurs approximately 2,100 feet west of the site near the Old Ranch Country Club. Ponding is anticipated at this location based on the street design and ultimately low point. However, per the existing street flow calculations enclosed within Appendix C.3, the 100-year water surface elevation at this location is approximately 6” which is being held within the curb. Based on the existing topography of Lampson Avenue, flooding is not anticipated along the frontage of the site due to the flow-by nature of the existing Refer to the Existing Conditions Hydrology Map located within Appendix A.1 of this report for additional information.