APPENDIX 8.5 Hydrology/Drainage Study - City of Milpitas...City of Milpitas - SCVURPPP C.3. Data Form Page 3 of 4 12/2013 6. Selection of Specific Stormwater Control Measures: Site

APPENDIX 8.5 Hydrology/Drainage Study

City of Milpitas - SCVURPPP C.3. Data Form Page 1 of 4 12/2013

City of Milpitas – Stormwater Requirements C.3 Data Form Santa Clara Valley Urban Run-Off Pollution Prevention Program

1. Project Information

Project Name: ____________________________________APN #

Project Address:

Cross Streets:

Applicant/Developer Name:

Project Phase(s): ______of______ Engineer:

Project Type (Check all that apply): New Development Redevelopment

Residential Commercial Industrial Mixed Use Public Institutional

Restaurant Uncovered Parking Retail Gas Outlet Auto Service (SIC code) _______

Other ________________________________________

Project Description: _______________________________________________________________

Project Watershed/Receiving Water (creek, river, or bay):_______________________________

Which Projects Must Comply with Stormwater Requirements?

All projects that create and/or replace 10,000 sq. ft. or more of impervious surface on the project site must

fill out this worksheet and submit it with the development project application.

All restaurants, auto service facilities, retail gasoline outlets, and uncovered parking lot projects (stand-alone or part of another development project, including the top uncovered portion of parking

structures) that create and/or replace 5,000 sq. ft. or more of impervious surface on the project site must also

fill out this worksheet.

Interior remodeling projects, routine maintenance or repair projects such as re-roofing and re-paving, and

single family homes that are not part of a larger plan of development are NOT required to complete this

worksheet.

What is an Impervious Surface?

An impervious surface is a surface covering or pavement that prevents the land’s natural ability to absorb and

infiltrate rainfall/stormwater. Impervious surfaces include, but are not limited to rooftops, walkways, paved

patios, driveways, parking lots, storage areas, impervious concrete and asphalt, and any other continuous

watertight pavement or covering. Pervious pavement, underlain with pervious soil or pervious storage

material (e.g., drain rock), that infiltrates rainfall at a rate equal to or greater than surrounding unpaved areas

OR that stores and infiltrates the water quality design volume specified in Provision C.3.d of the Municipal

Regional Stormwater Permit (MRP) is not considered an impervious surface.

For More Information

For more information regarding selection of Best Management Practices for stormwater pollution prevention

or stormwater treatment in Santa Clara County: http://www.scvurppp-w2k.com/c3_handbook_2012.shtml

(5013-5014, 5541, 7532-7534, 7536-7539)

✔

✔


2. Project Size

a. Total Site Area:

____________________acre b. Total Site Area Disturbed: __________________ acre (including clearing, grading, or excavating)

Existing Area (ft2) Proposed Area (ft2) Total Post-Project

Area (ft2) Replaced New

Impervious Area

Roof

Parking

Sidewalks and Streets

c. Total Impervious Area

d. Total new and replaced impervious area

Pervious Area

Landscaping

Pervious Paving

Other (e.g. Green Roof)

e. Total Pervious Area

f. Percent Replacement of Impervious Area in Redevelopment Projects (Replaced Total Impervious Area ÷

Existing Total Impervious Area) x 100% = _______________________%

3. State Construction General Permit Applicability:

a. Is #2.b. equal to one acre or more?

Yes, applicant must obtain coverage under the State Construction General Permit (i.e.,

file a Notice of Intent and prepare a Stormwater Pollution Prevention Plan) (see

www.swrcb.ca.gov/water_issues/programs/stormwater/construction.shtml for details).

No, applicant does not need coverage under the State Construction General Permit.

4. MRP Provision C.3 Applicability:

a. Is #2.d. equal to 10,000 sq. ft. or more, or 5,000 sq. ft. or more for restaurants, auto service

facilities, retail gas outlets, and uncovered parking?

Yes, C.3. source control, site design, and treatment requirements apply.

No, C.3. source control and site design requirements may apply – check with local agency

b. Is #2.f. equal to 50% or more?

Yes, C.3. requirements (site design, source control, as appropriate, and stormwater

treatment) apply to entire site.

No, C.3. requirements only apply to impervious area created and/or replaced.

5. Hydromodification Management (HM) Applicability:

a. Does project create and/or replace one acre or more of impervious surface AND is the total post-project impervious area greater than the pre-project (existing) impervious area?

Yes (continue) No – exempt from HM, go to page 3

b. Is the project located in an area of HM applicability (green area) on the HM Applicability Map? ( www.scvurppp-w2k.com/hmp_maps.htm )

Yes, project must implement HM requirements

No, project is exempt from HM requirements

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6. Selection of Specific Stormwater Control Measures:

Site Design Measures

Minimize land disturbed

Minimize impervious surfaces

Minimum-impact street or parking lot design

Cluster structures/ pavement

Disconnected downspouts

Pervious pavement

Green roof

Microdetention in landscape

Other self-treating area

Self-retaining area

Rainwater harvesting and use (e.g., rain barrel, cistern

connected to roof drains) 1

Preserved open space: _______ ac. or sq. ft .(circle one)

Protected riparian and wetland areas/buffers (Setback from top of bank:

_______ft.)

Other _______________

Source Control Measures

Alternative building materials

Wash area/racks, drain to sanitary sewer2

Covered dumpster area, drain to sanitary sewer2

Sanitary sewer connection or accessible

cleanout for swimming

pool/spa/fountain2

Beneficial landscaping (minimize irrigation, runoff,

pesticides and fertilizers;

promotes treatment)

Outdoor material storage protection

Covers, drains for loading docks, maintenance bays,

fueling areas

Maintenance (pavement sweeping, catch basin

cleaning, good housekeeping)

Storm drain labeling

Other _______________

Treatment Systems

None (all impervious surface drains to self-retaining areas)

LID Treatment

Rainwater harvest and use (e.g., cistern or rain barrel sized for C.3.d treatment)

Infiltration basin

Infiltration trench

Exfiltration trench

Underground detention and infiltration system (e.g. pervious pavement drain

rock, large diameter conduit)

Biotreatment 3

Bioretention area

Flow-through planter

Tree box with bioretention soils

Other _______________

Other Treatment Methods

Proprietary tree box filter4

Media filter (sand, compost, or proprietary media)

4

Vegetated filter strip5

Dry detention basin5

Other _______________

Flow Duration Controls for Hydromodification Management (HM)

Detention basin Underground

tank or vault

Bioretention with outlet

control

Other

_______________

1 Optional site design measure; does not have to be sized to comply with Provision C.3.d treatment requirements. 2 Subject to sanitary sewer authority requirements. 3 Biotreatment measures are allowed only with completed feasibility analysis showing that infiltration and rainwater

harvest and use are infeasible. 4 These treatment measures are only allowed if the project qualifies as a “Special Project”. 5 These treatment measures are only allowed as part of a multi-step treatment process.

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7. Treatment System Sizing for Projects with Treatment Requirements

Indicate the hydraulic sizing criteria used and provide the calculated design flow or volume:

Treatment System Component Hydraulic Sizing

Criteria Used3

Design Flow or

Volume

(cfs or cu.ft.)

3Key: 1a: Volume – WEF Method

1b: Volume – CASQA BMP Handbook Method

2a: Flow – Factored Flood Flow Method

2b: Flow – CASQA BMP Handbook Method

2c: Flow – Uniform Intensity Method

3: Combination Flow and Volume Design Basis

8. Alternative Certification: Was the treatment system sizing and design reviewed by a qualified third-

party professional that is not a member of the project team or agency staff?

Yes No Name of Reviewer: ___________________________________________

9. Operation & Maintenance Information A. Property Owner’s Name: _________________________________________ B. Responsible Party for Stormwater Treatment/Hydromodification Control O&M:

a. Name: _________________________________________ b. Address: _________________________________________ c. Phone/E-mail: _________________________________________

This section to be completed by City of Milpitas staff.

O&M Responsibility Mechanism Indicate how responsibility for O&M is assured. Check all that apply:

O&M Agreement

Other mechanism that assigns responsibility (describe below): ________________________________________________________________________________________

________________________________________________________________________________________

Reviewed:

Planning Department Public Works Department

Planning Division: ________ Land Development: ________

Other (Specify): ________ Other (Specify): ________

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✔

Storm Water Management Plan 985 Montague Expressway

KIER & WRIGHT CIVIL ENGINEERS & SURVEYORS, INC.

3350 Scott Boulevard, Bldg. 22 Santa Clara, California 95054 408-727-6665 408-727-5641 - 1 -

TABLE OF CONTENTS

1.0 PROJECT DESCRIPTION ................................................................................................... 2

2.0 HMP APPLICABILITY DETERMINATION ........................................................................... 2

3.0 SITE CONSTRAINT AND BMP MEASURES ........................................................................ 2

4.0 POST CONSTRUCTION BMP MAINTENANCE AND SOURCE CONTROL .............................. 3

Appendices

C.3 Data Form Appendix A Infiltration/Harvesting Infeasibility Worksheet Appendix B Special Project Worksheet [Not Applicable] Appendix C Soil Properties Appendix D MRP Calculations Appendix E BMP Sizing Calculations Appendix F Site Plan Appendix G Treatment Measure Details Appendix H Operations and Maintenance Plan Appendix I Third Party Certification Appendix J




1.0 PROJECT DESCRIPTION A. PROJECT LOCATION AND DESCRIPTION The project site is located at 985 Montague Expressway at the northeast corner of the intersection of South Milpitas Boulevard and Montague Expressway, Milpitas CA. The site consists of approximately 4.5± acres of land. This self-storage development consists of multiple buildings and onsite parking. The site will be treated by biotreatment ponds. The project currently drains to a municipal stormdrain system that outfalls to the Berryessa Creek, and ultimately to the South San Francisco Bay.

B. ASSESSOR’S PARCEL NUMBER

The project consists of one parcel: APN 086-32-020. C. PROJECT ZONING AND USE The project is zoned as a heavy industrial district (M2). D. POLLUTANTS OF CONCERN

The anticipated pollutants of concern are listed as follows: a. Petroleum Hydrocarbons b. Oil & Grease c. Sediments d. Pesticides e. Trash

2.0 HMP APPLICABILITY DETERMINATION

A review of the HMP Applicability Map for the City of Milpitas indicates that the project site’s “subwatersheds and catchments are greater than or equal to 65% impervious” thus is not subject to HMP requirements, though HM controls

3.0 SITE CONSTRAINT AND BMP MEASURES

Based on the calculations shown in Appendix A for the existing and proposed impervious/pervious areas, the project site is replacing more than 50% of the pre-existing impervious surface. Therefore, the entire site will be subject to numerical sizing for storm water BMPs.




As part of the storm water treatment measures, the project was designed to utilize the same pre-development watershed areas for storm water runoff; this will prevent to need to upsize downstream storm systems. The BMP summary table in Appendix F identifies the areas associated with each BMP measure based on their flow requirements and weighted runoff coefficients.

A. BIOTREATMENT POND The project will be treated by biotreatment ponds. The storm runoff from the site will be directed to the on-site storm drainage system before runoff is discharged to the pond. Refer to Appendix F for actual location of treatment ponds. The treatment pond is a depressed landscaping area that allows the collection of stormwater runoff to percolate through a sandy loam soil into an under-drain, thereby promoting pollutant removal. B. LABELING OF STORMWATER INLETS

Storm water inlets shall have metal badges installed with the logo “No Dumping -Flows to Bay”. This educational measure is intended to prevent unlawful dumping of waste materials such as motor oil or trash into the inlets.

C. INTEGRATED PEST MANAGEMENT

Alternative methods for pest reduction methods will be employed to limit the usage of pesticides. Method includes the incorporation of planting materials. Owner and maintenance staff shall review and adhere to the Landscape Maintenance Techniques for Pest Reduction in Appendix I.

4.0 POST CONSTRUCTION BMP MAINTENANCE AND SOURCE CONTROL A. SPILL RESPONSE PROCEDURES

Due to the nature of the proposed uses at the site, spill responses are not anticipated.

B. PREVENTIVE MAINTENANCE OF STRUCTURAL BMPs

The property owner will enter into a perpetual maintenance contract for the maintenance of the biotreatment pond and flow-through planters. Regular maintenance, sweeping, and trash pick-up from the parking and landscaping areas will be employed to decrease the incidence of solids and pollutants entering into the on-site storm drainage system. See Appendix I. C. MATERIALS HANDLING AND STORAGE




No outside storage of materials is anticipated or allowed. Materials handling will only be allowed for normal business operations for office use. No car washing will be allowed within the project site. No vehicle storage will be anticipated on-site.




D. POST-CONSTRUCTION BMP MAINTENANCE AND/OR SOURCE CONTROL ACTIVITIES Name of Party or Agency/Company responsible for BMP Maintenance: Branagh Development, Inc. If different from above, identify each of the parties responsible for Source Control Activities and attach to this report. (e.g., sweeping, litter pick up, landscape maintenance, if a part of the BMP) Address: 100 School Street Danville, CA 94526 Phone: (925) 743-9500

E-mail: (Cristian Streeter) [email protected]

Structural BMP / Source Control Measure Descriptions

Date When BMP Began Operation

Proposed Maintenance Schedule (daily, weekly, quarterly, etc.) and

description of maintenance activities

Biotreatment Pond

At start of position

Once in the dry season: Inspect unit and remove sediments or replace cartridges as needed.

Once in the rainy season: Inspect unit and remove sediments or replace cartridges as needed.

Once after every major storm: Remove sediments and replace cartridges as needed.

Sweeping/Litter Removal At start of position Monthly: Inspect and sweep parking lots.




E. SELF-INSPECTION PROGRAM DESCRIPTION

Name of Party or Agency/Company responsible for Self-Inspections: Branagh Development, Inc. If different from above, identify the party responsible for Inspections and attach to this report. Address: 100 School Street Danville, CA 94526 Phone: (925) 743-9500


Description of Items for Self Inspection (e.g. BMP, non-storm water discharges, BMP maintenance actions, soil erosion, and others as applicable to site)

Self-Inspection Schedule

Biotreatment Ponds

Remove obstructions, debris and trash from bioretention area and dispose of properly.

Monthly, or as needed after storm events.

Inspect bioretention area for ponded water. If ponded water does not drain within 2-3 days, till and replace the surface soil and replant.


Inspect inlets for channels, soil exposure or other evidence of erosion. Clear obstructions and remove sediment.


Remove and replace all dead and diseased vegetation. Twice a year.

Maintain vegetation and irrigation system. Prune and weed to keep bioretention area neat and orderly in appearance. Remove and or replace any dead plants.

Twice a year.

Check that mulch is at appropriate depth (2 inches per soil specifications) and replenish as necessary before wet season begins.

Monthly




F. EMPLOYEE TRAINING PROGRAM

Name of Party or Agency/Company responsible for training: Branagh Development, Inc. If different from above, identify party responsible for training and attach to this report. Address: 100 School Street Danville, CA 94526 Phone: (925) 743-9500


Description of Items for Training (e.g. maintenance, inspection, pesticide use,

others as applicable to site) Training Schedule

Employees To Be Trained (Job Category or Title)

Building maintenance staff will be trained to comply with the storm water inlet labels painted with the logo “No Dumping/Flows to Bay”. This educational measure is intended to prevent unlawful dumping of waste materials, such as motor oil, into the storm drains.


Building Maintenance Staff.

Maintenance staff will be trained to in the maintenance of the plants and use pesticides as a last resort. When pesticides must be used, maintenance staff will be trained to do so with the least impact.


Building Maintenance Staff




G. RECORD KEEPING

The owner shall be responsible for record keeping of all inspection and maintenance reports. The types of records kept shall be:

1. Biotreatment Pond: a. Inspection Report (Appendix I)

H. RESPONSIBLE PARTY The party responsible for maintenance, inspections, and record keeping of the storm water measures contained within this report shall be the property owner-of-record: Contact: Cristian Streeter Branagh Development, Inc. 100 School Street Danville, CA 94526 (925) 743-9500 [email protected]

APPENDIX A

C.3 DATA FORM


City of Milpitas – Stormwater Requirements C.3 Data Form Santa Clara Valley Urban Run-Off Pollution Prevention Program

1. Project Information

Project Name: ____________________________________APN #

Project Address:

Cross Streets:

Applicant/Developer Name:

Project Phase(s): ______of______ Engineer:

Project Type (Check all that apply): New Development Redevelopment

Residential Commercial Industrial Mixed Use Public Institutional

Restaurant Uncovered Parking Retail Gas Outlet Auto Service (SIC code) _______

Other ________________________________________

Project Description: _______________________________________________________________

Project Watershed/Receiving Water (creek, river, or bay):_______________________________

Which Projects Must Comply with Stormwater Requirements? All projects that create and/or replace 10,000 sq. ft. or more of impervious surface on the project site must fill out this worksheet and submit it with the development project application.

All restaurants, auto service facilities, retail gasoline outlets, and uncovered parking lot projects (stand-alone or part of another development project, including the top uncovered portion of parking structures) that create and/or replace 5,000 sq. ft. or more of impervious surface on the project site must also fill out this worksheet.

Interior remodeling projects, routine maintenance or repair projects such as re-roofing and re-paving, and single family homes that are not part of a larger plan of development are NOT required to complete this worksheet.

What is an Impervious Surface? An impervious surface is a surface covering or pavement that prevents the land’s natural ability to absorb and infiltrate rainfall/stormwater. Impervious surfaces include, but are not limited to rooftops, walkways, paved patios, driveways, parking lots, storage areas, impervious concrete and asphalt, and any other continuous watertight pavement or covering. Pervious pavement, underlain with pervious soil or pervious storage material (e.g., drain rock), that infiltrates rainfall at a rate equal to or greater than surrounding unpaved areas OR that stores and infiltrates the water quality design volume specified in Provision C.3.d of the Municipal Regional Stormwater Permit (MRP) is not considered an impervious surface.

For More Information For more information regarding selection of Best Management Practices for stormwater pollution prevention or stormwater treatment in Santa Clara County: http://www.scvurppp-w2k.com/c3_handbook_2012.shtml

(5013-5014, 5541, 7532-7534, 7536-7539)

New Self-Storage Facility 086-32-020985 Monatgue ExpresswayWatson Court and South Milpitas Boulevard

Branagh Development, Inc.1 1 Nektarios Matheou, PE

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New self storage facility.

Berryessa Creek


2. Project Size

a. Total Site Area: ____________________acre

b. Total Site Area Disturbed: __________________ acre (including clearing, grading, or excavating)

Existing Area (ft2) Proposed Area (ft2) Total Post-Project

Area (ft2) Replaced New Impervious Area Roof

Parking

Sidewalks and Streets

c. Total Impervious Area

d. Total new and replaced impervious area

Pervious Area Landscaping

Pervious Paving

Other (e.g. Green Roof)

e. Total Pervious Area

f. Percent Replacement of Impervious Area in Redevelopment Projects (Replaced Total Impervious Area ÷ Existing Total Impervious Area) x 100% = _______________________%

3. State Construction General Permit Applicability: a. Is #2.b. equal to one acre or more?

Yes, applicant must obtain coverage under the State Construction General Permit (i.e., file a Notice of Intent and prepare a Stormwater Pollution Prevention Plan) (see www.swrcb.ca.gov/water_issues/programs/stormwater/construction.shtml for details).

No, applicant does not need coverage under the State Construction General Permit.

4. MRP Provision C.3 Applicability: a. Is #2.d. equal to 10,000 sq. ft. or more, or 5,000 sq. ft. or more for restaurants, auto service facilities, retail gas outlets, and uncovered parking?

Yes, C.3. source control, site design, and treatment requirements apply.

No, C.3. source control and site design requirements may apply – check with local agency

b. Is #2.f. equal to 50% or more?

Yes, C.3. requirements (site design, source control, as appropriate, and stormwater treatment) apply to entire site.

No, C.3. requirements only apply to impervious area created and/or replaced.

5. Hydromodification Management (HM) Applicability: a. Does project create and/or replace one acre or more of impervious surface AND is the total

post-project impervious area greater than the pre-project (existing) impervious area?

Yes (continue) No – exempt from HM, go to page 3

b. Is the project located in an area of HM applicability (green area) on the HM Applicability Map? ( www.scvurppp-w2k.com/hmp_maps.htm )

Yes, project must implement HM requirements

No, project is exempt from HM requirements

4.54.5

14,905

91,264

76,35914,90576,359

0 091,264

71,01503,00874,023

85,92076,3593,008165,287

165,287

104,854 30,747 0 30,74700104,854

0030,747

000

0030,747

100

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6. Selection of Specific Stormwater Control Measures:

Site Design Measures

Minimize land disturbed

Minimize impervious surfaces

Minimum-impact street or parking lot design

Cluster structures/ pavement

Disconnected downspouts

Pervious pavement

Green roof

Microdetention in landscape

Other self-treating area

Self-retaining area

Rainwater harvesting and use (e.g., rain barrel, cistern connected to roof drains) 1

Preserved open space: _______ ac. or sq. ft .(circle one)

Protected riparian and wetland areas/buffers (Setback from top of bank: _______ft.)

Other _______________

Source Control Measures

Alternative building materials

Wash area/racks, drain to sanitary sewer2

Covered dumpster area, drain to sanitary sewer2

Sanitary sewer connection or accessible cleanout for swimming pool/spa/fountain2

Beneficial landscaping (minimize irrigation, runoff, pesticides and fertilizers; promotes treatment)

Outdoor material storage protection

Covers, drains for loading docks, maintenance bays, fueling areas

Maintenance (pavement sweeping, catch basin cleaning, good housekeeping)

Storm drain labeling

Other _______________

Treatment Systems

None (all impervious surface drains to self-retaining areas)

LID Treatment

Rainwater harvest and use (e.g., cistern or rain barrel sized for C.3.d treatment)

Infiltration basin

Infiltration trench

Exfiltration trench

Underground detention and infiltration system (e.g. pervious pavement drain rock, large diameter conduit)

Biotreatment 3

Bioretention area

Flow-through planter

Tree box with bioretention soils

Other _______________

Other Treatment Methods

Proprietary tree box filter4

Media filter (sand, compost, or proprietary media)4

Vegetated filter strip5

Dry detention basin5

Other _______________

Flow Duration Controls for Hydromodification Management (HM)

Detention basin Underground tank or vault

Bioretention with outlet control

Other _______________

1 Optional site design measure; does not have to be sized to comply with Provision C.3.d treatment requirements. 2 Subject to sanitary sewer authority requirements. 3 Biotreatment measures are allowed only with completed feasibility analysis showing that infiltration and rainwater

harvest and use are infeasible. 4 These treatment measures are only allowed if the project qualifies as a “Special Project”. 5 These treatment measures are only allowed as part of a multi-step treatment process.

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7. Treatment System Sizing for Projects with Treatment Requirements Indicate the hydraulic sizing criteria used and provide the calculated design flow or volume:

Treatment System Component Hydraulic Sizing Criteria Used3

Design Flow or Volume

(cfs or cu.ft.)

3Key: 1a: Volume – WEF Method 1b: Volume – CASQA BMP Handbook Method 2a: Flow – Factored Flood Flow Method 2b: Flow – CASQA BMP Handbook Method 2c: Flow – Uniform Intensity Method 3: Combination Flow and Volume Design Basis

8. Alternative Certification: Was the treatment system sizing and design reviewed by a qualified third-

party professional that is not a member of the project team or agency staff?

Yes No Name of Reviewer: ___________________________________________ 9. Operation & Maintenance Information

A. Property Owner’s Name: _________________________________________ B. Responsible Party for Stormwater Treatment/Hydromodification Control O&M:

a. Name: _________________________________________ b. Address: _________________________________________ c. Phone/E-mail: _________________________________________

This section to be completed by City of Milpitas staff.

O&M Responsibility Mechanism Indicate how responsibility for O&M is assured. Check all that apply:

O&M Agreement Other mechanism that assigns responsibility (describe below):

________________________________________________________________________________________

________________________________________________________________________________________

Reviewed:

Planning Department Public Works Department

Planning Division: ________ Land Development: ________

Other (Specify): ________ Other (Specify): ________

Biotreatment Pond 3 0.729 cfs

✔ Caitlin Gilmore, PE

Branagh Development, Inc.

TBD

TBDTBD

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APPENDIX B

INFILTRATION/HARVESTING INFEASIBILITY WORKSHEET

* For definitions, see Glossary (Attachment 1).

Page 1 of 3 FINAL November 2011

Santa Clara Valley Urban RunoffPollution Prevention Program

Infiltration/Harvesting and Use Feasibility Screening Worksheet Apply these screening criteria for C.3 Regulated Projects* required to implement Provision C.3 stormwater treatment requirements. See the Glossary (Attachment 1) for definitions of terms marked with an asterisk (*). Contact municipal staff to determine whether the project meets Special Project* criteria. If the project meets Special Project criteria, it may receive LID treatment reduction credits.

1. Applicant Info Site Address: , CA APN:

Applicant Name: Phone No.:

Mailing Address:

2. Feasibility Screening for Infiltration

Do site soils either (a) have a saturated hydraulic conductivity* (Ksat) that will NOT allow infiltration of 80% of the annual runoff (that is, the Ksat is LESS than 1.6 inches/hour), or, if the Ksat rate is not available, (b) consist of Type C or D soils?1

Yes (continue) No – complete the Infiltration Feasibility Worksheet. If infiltration of the C.3.d amount of runoff is found to be feasible, there is no need to complete the rest of this screening worksheet.

3. Recycled Water Use

Check the box if the project is installing and using a recycled water plumbing system for non-potable water use. The project is installing a recycled water plumbing system, and installation of a second non-potable water system

for harvested rainwater is impractical, and considered infeasible due to cost considerations. Skip to Section 6.

4. Calculate the Potential Rainwater Capture Area* for Screening of Harvesting and Use Complete this section for the entire project area. If rainwater harvesting and use is infeasible for the entire site, and the project includes one or more buildings that each have an individual roof area of 10,000 sq. ft. or more, then complete Sections 4 and 5 of this form for each of these buildings.

4.1 Table 1 for (check one): The whole project Area of 1 building roof (10,000 sq.ft. min.)

Table 1: Calculation of the Potential Rainwater Capture Area*The Potential Rainwater Capture Area may consist of either the entire project area or one building with a roof area of 10,000 sq. ft. or more.

1 2 3 4

Pre-Project Impervious surface2

(sq.ft.), if applicable

Proposed Impervious Surface2 (IS), in sq. ft.

Post-project landscaping

(sq.ft.), if applicableReplaced

3 IS Created4 IS

a. Enter the totals for the area to be evaluated:

b. Sum of replaced and created impervious surface: N/A N/A

c. Area of existing impervious surface that will NOT be replaced by the project. N/A N/A

1 Base this response on the site-specific soil report, if available. If this is not available, consult soil hydraulic conductivity maps in Attachment 3. 2, Enter the total of all impervious surfaces, including the building footprint, driveway(s), patio(s), impervious deck(s), unroofed porch(es), uncovered parking lot (including top deck of parking structure), impervious trails, miscellaneous paving or structures, and off-lot impervious surface (new, contiguous impervious surface created from road projects, including sidewalks and/or bike lanes built as part of new street). Impervious surfaces do NOT include vegetated roofs or pervious pavement that stores and infiltrates rainfall at a rate equal to immediately surrounding, unpaved landscaped areas, or that stores and infiltrates the C.3.d amount of runoff*.3 “Replaced” means that the project will install impervious surface where existing impervious surface is removed. 4 “Created” means the project will install new impervious surface where there is currently no impervious surface.

985 Montague Expressway 086-32-020

Branagh Development, Inc.

x

x

x

91,264 91,264 74,023

165,287

30,747

100 School Street, Danville, CA 94526

925.743.9500

Infiltration/Harvesting and Use Feasibility Screening Worksheet



4.2 Answer this question ONLY if you are completing this section for the entire project area. If existing impervious surface will be replaced by the project, does the area to be replaced equal 50% or more of the existing area of impervious surface? (Refer to Table 1, Row “a”. Is the area in Column 2 > 50% of Column 1?)

Yes, C.3. stormwater treatment requirements apply to areas of impervious surface that will remain in place as well as the area created and/or replaced. This is known as the 50% rule.

No, C.3. requirements apply only to the impervious area created and/or replaced.

4.3 Enter the square footage of the Potential Rainwater Capture Area*. If you are evaluating only the roof area of a building, or you answered “no” to Question 4.2, this amount is from Row “b” in Table 1. If you answered “yes” to Question 4.2, this amount is the sum of Rows “b” and “c” in Table 1.:

square feet.

4.4 Convert the measurement of the Potential Rainwater Capture Area* from square feet to acres (divide the amount in Item 4.3 by 43,560):

acres.

5. Feasibility Screening for Rainwater Harvesting and Use

5.1 Use of harvested rainwater for landscape irrigation: Is the onsite landscaping LESS than 2.5 times the size of the Potential Rainwater Capture Area* (Item 4.3)?

(Note that the landscape area(s) would have to be contiguous and within the same Drainage Management Area to use harvested rainwater for irrigation via gravity flow.)

Yes (continue) No – Direct runoff from impervious areas to self-retaining areas* OR refer to Table 11 and the curves in Appendix F of the LID Feasibility Report to evaluate feasibility of harvesting and using the C.3.d amount of runoff for irrigation.

5.2 Use of harvested rainwater for toilet flushing or non-potable industrial use:

a. Residential Projects: Proposed number of dwelling units: ______________________________ Calculate the dwelling units per impervious acre by dividing the number of dwelling units by the acres of the Potential Rainwater Capture Area* in Item 4.4. Enter the result here:

)Is the number of dwelling units per impervious acre LESS than 100 (assuming 2.7 occupants/unit)?

Yes (continue) No – complete the Harvest/Use Feasibility Worksheet.

b. Commercial/Industrial Projects: Proposed interior floor area: __________________________ (sq. ft.)

Calculate the proposed interior floor area (sq.ft.) per acre of impervious surface by dividing the interior floor area (sq.ft.) by the acres of the Potential Rainwater Capture Area* in Item 4.4. Enter the result here:

Is the square footage of the interior floor space per impervious acre LESS than 70,000 sq. ft.? Yes (continue) No – complete the Harvest/Use Feasibility Worksheet

c. School Projects: Proposed interior floor area: _______________________________________ (sq. ft.)

Calculate the proposed interior floor area per acre of impervious surface by dividing the interior floor area (sq.ft.) by the acres of the Potential Rainwater Capture Area* in Item 4.4 . Enter the result here: .Is the square footage of the interior floor space per impervious acre LESS than 21,000 sq. ft.?

Yes (continue) No – complete the Harvest/Use Feasibility Worksheet

x

165,287

3.794

x

173,908

45,838

x

Infiltration/Harvesting and Use Feasibility Screening Worksheet



d. Mixed Commercial and Residential Use Projects

Evaluate the residential toilet flushing demand based on the dwelling units per impervious acre for the residential portion of the project, following the instructions in Item 5.2.a, except you will use a prorated acreage of impervious surface, based on the percentage of the project dedicated to residential use. Evaluate the commercial toilet flushing demand per impervious acre for the commercial portion of the project, following the instructions in Item 5.2.a, except you will use a prorated acreage of impervious surface, based on the percentage of the project dedicated to commercial use.

e. Industrial Projects: Estimated non-potable water demand (gal/day): ___________________________

Is the non-potable demand LESS than 2,400 gal/day per acre of the Potential Rainwater Capture Area?

Yes (continue) No – refer to the curves in Appendix F of the LID Feasibility Report to evaluate feasibility of harvesting and using the C.3.d amount of runoff for industrial use.

6. Use of Biotreatment If only the “Yes” boxes were checked for all questions in Sections 2 and 5, or the project will have a recycled water system for non-potable use (Section 3), then the applicant may use appropriately designed bioretention facilities for compliance with C.3 treatment requirements. The applicant is encouraged to maximize infiltration of stormwater if site conditions allow.

7. Results of Screening Analysis

Based on this screening analysis, the following steps will be taken for the project (check all that apply):

Implement biotreatment measures (such as an appropriately designed bioretention area). Conduct further analysis of infiltration feasibility by completing the Infiltration Feasibility Worksheet. Conduct further analysis of rainwater harvesting and use (check one):

Complete the Rainwater Harvesting and Use Feasibility Worksheet for: The entire project Individual building(s), if applicable, describe:__________________________________

Evaluate the feasibility of harvesting and using the C.3.d amount of runoff for irrigation, based on Table 11 and the curves in Appendix F of the LID Feasibility Report Evaluate the feasibility of harvesting and using the C.3.d amount of runoff for non-potable industrial use, based on the curves in Appendix F of the LID Feasibility Report.

x

APPENDIX C

SPECIAL PROJECTS WORKSHEET (NOT APPLICABLE)

APPENDIX D

SOIL PROPERTIES

(GEOTECHNICAL REPORT)

January 29, 2015Project 1741-13

BRANAGH DEVELOPMENT100 School StreetDanville, CA 94526

Attention: Mr Cristian Streeter

Gentlemen:Report UpdateProposed Commercial Development985 Montague ExpresswayMilpitas, California

Introduction

As requested, we have completed a geotechnical investigation at the site for the plannedcommercial development. The property is located at 985 Montague Expressway in Milpitas,California. This report summarizes our findings, conclusions and recommendations. This reportis submitted to update a previous geotechnical investigation report dated September 2004. The2004 geotechnical investigation report was prepared for WPI. The general location of theproperty is shown on the Vicinity Map, Figure 1.

Proposed Development

The site is to be developed into a self-storage facility. The facility will consist of six buildingsfive of which will be single story in height and the other one will be two stories high. One of thesingle story buildings will be designed such that another story can be added on in future. Theproposed facility will be accessed from Montague Expressway. The storage buildings will beaccessed by interior driveways that will be required to withstand vehicular loading from firetrucks and occasional moving trucks.


Information Provided

We were provided with electronic photographic copies of the proposed of the proposeddevelopment. We were also provided with a pdf copy of the site plan showing the outline of theproposed construction in relation to the existing surroundings. A copy of the layout plan wasused to prepare our site plan, Figure 2. Figure 2 also shows the approximate location of theexploratory holes that were made as part of the investigation for this report update.

Scope Of Work

Our scope of work was to evaluate the conditions at the property, particularly the subsurfacesoils and the fill soils from a geotechnical engineering viewpoint and provide information for thedevelop of the project. To this end, we performed the following scope of work

1 Reviewed our files for the work we have previously done at the property.

2 Made site reconnaissance visits to check the existing conditions and comparethem with those that existed at the time when we performed our fieldinvestigation in 2000. This was completed on Wednesday, October 2, 2014.

3 Complemented the subsurface data currently in our files by means of four smalldiameter exploratory holes to obtain samples for laboratory testing. The holeswere logged by a certified engineering geologist who supervised the fieldexploration and obtained samples for laboratory testing.

4 Performed laboratory testing on selected samples obtained from the fieldexploration to evaluate their index and mechanical properties.

5 Collated the field and laboratory data obtained to develop information for sitepreparation, grading and compaction including the demolition of existingstructures and the removal of their foundation system; provided information forthe design and construction of the proposed building foundations, concrete slabs-on-grade, retaining walls, utility trench backfilling and site drainage.

6 Provided minimum pavement section for site driveways and parking area basedon the site soils and projected traffic indices.

7 Summarized our findings, conclusions and recommendations in this writtenreport.

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Findings

Surface Conditions

In addition to the conditions described in our December 4, 2000 report, a stockpile of soil hadbeen brought on to the northern end of the property in addition to the existing structures. Thconcrete pads encountered during our 2000 investigation were still in existence at the time of ourrecent soil exploration. There were a few electrical components that had been placed in thesouthern area of the property and appeared to be being assembled together by some workers atthe time of our site visits. Ground elevation at the property is about 85 feet above Mean SeaLevel.

Subsurface Conditions

The descriptions given below pertain only to the subsurface conditions found at the site at thetime of our field exploration on January 8, 2015. Subsurface conditions, particularly,groundwater levels and the consistency of the near-surface soils will vary with time and theseasons.

Subsurface soils at the site were explored by means of six small diameter exploratory holes usinga truck-mounted drill rig with an auger attachment (Mobil B24 with solid stem augers). Sampleswere obtained by driving down a sampler 18 inches using a 140 pound hammer over a cat head. The hammer was dropped freely a distance of 30 inches to drive the sampler18 inches into“undisturbed” soil. The number of blows required (unless otherwise stated) to drive the samplerthe last 12 inches into the soil is shown on the attached boring logs.

The drill holes encountered fill, clay, silt, sand and gravel. Fill was encountered in all fourexploratory holes. One of the holes encountered concrete at a depth of four feet and had to berelocated six feet to the north of the original location. Concrete was encountered at the samedepth and the hole had to be abandoned.

The fill encountered consists of brown and black mottled sandy clay with some gravel. The clayis moist and firm to stiff. The fill thickness at the borings ranged between three and seven feet.The fill is underlain by brown clayey sand with gravel that grades to dark sandy clay with graveto the maximum depth of exploration. The clayey sand is moist and medium dense. Theunderlying sandy clay is moist and firm to stiff. The holes were backfilled with cement grout.No free groundwater was encountered in any of the exploratory holes. Depth to groundwater isexpected to vary with time and the seasons.

Detailed descriptions of the materials encountered in the borings are given on the appended

-3-


boring logs.

Seismic Considerations

This project site is located within the seismically active San Francisco Bay region but outside ofany mapped as the Alquist-Priolo Earthquake Fault Zones.

Type A and Type B faults close to the site are listed in the following table.

TABLE 1 - TYPES A AND B FAULTS CLOSE TO THE SITE*

Fault TypeMaximum Moment

MagnitudeSlip Rate(mm/yr)

Distance(miles/km)

San Andreas (1906 Segment) A 7.9 24 16/26

Hayward (Total Length) A 7.1 9 5/8

Calaveras (So of CalaverasReservoir)

B 6.2 15 5/8

Calaveras (North of CalaverasReservoir)

B 6.8 6 5 /8

Hayward (SE Extension) B 6.4 3 12/19

*California Division Of Mines And Geology

Seismic hazards can be divided into two general categories, hazards due to ground rupture andhazards due to ground shaking. Since no active faults are known to cross this property, the riskof earthquake-induced ground rupture occurring across the project site appears to be remote.

Should a major earthquake occur with an epicentral location close to the site, ground shaking atthe site will undoubtedly be severe, as it will for other property in the general area. Even underthe influence of severe ground shaking, the soils that underlie the area proposed for the planneddevelopment are unlikely to liquefy. Even in the unlikely event of liquefaction of the clayeysand, the most likely result will be differential settlement across the property.

The following general site seismic parameters may be used for design in accordance with the2013 California Building Code:

Site Class: DSite Coordinates Latitude = 37.41 degrees Longitude = -121.89 degreesFa = 1.0; Fv =1.5

-4-


Spectral Response Accelerations SMs and SM1SMs = FaSs and SM1 = FvS1; For Site Class D with Fa = 1.0, and Fv = 1.5

Period Sa (sec) (g) 0.2 1.648 (SMs, Site Class D) 1.0 0.972 (SM1, Site Class D)

SDs = 2/3 x SMs and SD1 = 2/3 x SM1; For Site Class D with Fa = 1.0, and Fv = 1.5

Period Sa (sec) (g) 0.2 1.099 (SDs, Site Class D) 1.0 0.648 (SD1, Site Class D)

Discussion

As discussed in our December 2000 report, the principal geotechnical item that will impact theproposed development is the presence of undocumented fill soil. Since no records are availableas to the manner in which the fill was placed, we recommend that the fill be removed andreplaced as properly compacted structural fill. The fill excavation should extend a minimum of24 inches below the bottom of proposed building foundations and 12 inches below proposedpavement subgrades.

The near-surface native soils are moderately expansive. Expansive soils contract when dry butincrease in volume when they gain water. The degree of expansion depends on the antecedentsoil water content prior to gaining water. The cycle of contraction and expansion in the soil tendto have detrimental effects on foundation elements, particularly, on concrete elements. Thisshould be considered during foundation construction. The proposed buildings may be supported on conventional, shallow footing-type foundations. Details are provided below.

Recommendations

The following recommendations, which are presented as guidelines to be used by projectplanners and designers, have been prepared assuming FRIAR ASSOCIATES,INCORPORATED will be commissioned to review the grading and foundation plans prior toconstruction, and to observe and test during site grading and foundation construction. This

-5-


additional opportunity to inspect the project site will allow us to compare subsurface conditionsexposed during construction with those that were observed during this investigation.

Site Preparation, Grading and Compaction

Existing buildings, pavements and other structures designated for removal on the Project Plansshould be demolished and their foundations and associated substructures should be excavated outand hauled off-site. Utility lines, sanitary sewers and storm drain designated for abandonment onthe Project Plans, should either be excavated out or filed with concrete

Any or all of the existing monitoring wells designated for abandonment on the Project Plansshould be sealed and capped I accordance with the requirements of the Santa Clara CountyValley District.

Areas to be built on or paved should be stripped to remove surface vegetation and organic ladentopsoil. Soil containing more than two percent by weight of organic matter should be consideredorganic. Striping depths should be determined in the field by a member from our office at thetime of stripping. For planning purposes, an average depth of three inches may be assumed. Strippings should be wasted off-site or, if so required by the Project Landscape Architect,stockpiled for subsequent use in landscape areas.

Loose fill or soil and any debris within the area proposed for construction should be excavatedout to expose firm native ground. The depth and horizontal limits of these excavations should bedetermined in the field by the soil engineer at the time of excavation. For planning purposes, itmay be assumed that these excavations will extend to an average depth of about 24 inches belowproposed building foundations and 12 inches below proposed pavement subgrade. Theseexcavations should extent at least five feet horizontally beyond proposed building lines and threefeet horizontally beyond pavement edges. Soil from these excavations may be stockpiled forsubsequent use as structural fill, if needed.. If not, the excavated soil should be wasted off-site.

Soil surfaces exposed by excavations of loose fills should be scarified to a depth of at least eightinches, conditioned with water (or allowed to dry, as necessary) to produce a soil water contentof at least three percent above the optimum water content and then compacted to about 90percent of the maximum dry density as determined by ASTM Test Method D1557-09.

Structural fill may then be placed up to design grades in the proposed building and pavementareas. Structural fill using on-site inorganic soil, or approved import, should be placed in layers,each not exceeding eight inches thick (before compaction), conditioned with water (or allowed todry, as necessary) to produce a soil water content of at three percent above the optimum value,and then compacted to 90 percent relative compaction based of ASTM Test D1557-09.On-site soils proposed for use as structural fill should be inorganic, free from deleterious

-6-


materials, and should contain no more than 15% by weight of rocks larger than three inches(largest dimension) and no rocks larger than six inches. The suitability of existing fill soil forreuse as a structural fill should be determined by a member of our staff at the time of grading. Ifimport soil is required for use as structural fill, it should be inorganic, should preferably have alow expansion potential and should be free from clods or rocks larger than four inches in largestdimension. Prior to delivery to the site, proposed import should be tested in our laboratory toverify its suitability for use as structural fill and, if found to be suitable, further tested to estimatethe water content and density at which it should be placed.

Building Foundations

Shallow Footing-Type Foundations

The proposed building may be supported on conventional, shallow foundations bearing on thenative competent “undisturbed” soil or properly compacted fill as recommended above under“Site Preparation, Grading and Compaction,” provided a level building pad is created duringgrading.

Continuous, reinforced concrete foundations may be designed to impose pressures on foundationsoils up to 3000 pounds per square foot (psf) from dead plus normal live loading. Continuousfoundations should be least 15 inches wide and should be embedded at least 24 inches belowrough pad grade or adjacent finished grade, whichever is lower.

Interior isolated foundations, such as may support column loads, may be designed to imposepressures on foundation soils up to3500 pounds per square foot from dead plus normal liveloading. Interior foundations should be embedded at least 18 inches below rough pad grade andshould be at least 18 inches in smallest dimension.

For the purposes of calculating bending moments, shear and deflection in the continuousfoundations, a modulus of subgrade reaction (Kv1) of 250 pounds per cubic inch may be assumedfor the foundation soils.

Lateral forces on the proposed buildings may be resisted by passive pressure acting against thesides of the footings and by friction between the soil and the bottom of slabs and footings. Anequivalent fluid pressure of 350 pounds per square foot per foot of depth may be used tocalculate the ultimate passive resistance to lateral loads. Unless the ground adjacent to thefoundation is paved, the top nine inches of embedment should be neglected when calculatinghorizontal passive resistance of the soil against the foundation. A coefficient of friction of 0.35may be assumed to calculate resistance to lateral loads at the base of concrete slabs andfoundations. If both passive resistance and friction are used to resist lateral loads, the lowervalue of the two should be reduced by 50 percent.

-7-


The allowable foundation pressures given previously may be increased by one-third whenconsidering additional short-term wind or seismic loading.

During foundation construction, care should be taken to minimize evaporation of water fromfoundation and floor subgrades. Scheduling the construction sequence to minimize the timeinterval between foundation excavation and concrete placement is important. Concrete shouldbe placed only in foundation excavations that have been kept moist, are free from drying cracksand contain no loose or soft soil or debris.

Based on our experience with similar building constructed on similar soils, we anticipate thattotal and differential settlements of building foundations designed and constructed asrecommended above will be nominal (about 0.75 inch for long-term static settlement anddifferential settlement to be between 0.5 and 0.75 of the long-term total settlement).

Concrete Slabs-On-Grade

Concrete floor slabs should be constructed on compacted soil subgrades prepared as described inthe section under “Site Preparation, Grading and Compaction”. The soil water content at slabs-on-grade prior to the placement of the concrete will be critical at expansive soil subgrade areas.

Interior slabs should be underlain by a section of capillary break material at least five inchesthick and covered with a membrane vapor barrier be placed between the floor slab and thecompacted soil subgrade. The capillary break should be a free-draining material, such as 3/8"pea gravel or a permeable aggregate complying with CALTRANS Standard Specifications,Section 68, Class 1, Type A or Type B. The membrane vapor barrier should be a high qualitymembrane. A protective cushion of sand or capillary break material at least two inches thickshould be placed between the membrane vapor barrier and the floor slab. It is important thatclayey subgrades at slab-on-grade areas be maintained at the s-graded soil water content tominimize post-construction movement of slabs due to expansion/contraction of the subgradesoils.

If floor dampness is not objectionable, concrete slabs may be constructed directly on a minimumof six-inch-thick compacted aggregate base material over the water-conditioned and compactedsoil subgrade and the non-expansive soil cap. The aggregate base should be compacted to aminimum of 92 percent relative compaction as determined by ASTM Test Method D1557-09.

Cement Type

In general, soils in the San Francisco Bay area contain negligible amounts of water solublesulfates and water soluble chlorides. Type II Portland cement may be used in concrete for allstructures with soil contact unless chemical analysis of the fill soils prove otherwise. It will be

-8-


prudent to test the soils for water soluble sulfates and chlorides after grading and prior toconcrete placement to confirm the proper type of cement needed to be used for structures indirect contact with the site soils.

Driveway Pavement

Based on our experience with soils with identical properties, the near-surface soil at the site willhave low support when used for pavement support; therefore, an R-value of 5 was used inpavement design calculations shown below. This is based on the R-value test we conducted on asample of the site soils from our 2000 geotechnical investigation. We recommend that R-valuetest of the pavement subgrade soil be performed when roadway subgrades are established todetermine the actual pavement sections required based on the projected Traffic Indices listed inthe table below. Therefore, the design sections shown in the table below are preliminary.

TABLE 2 - RECOMMENDED MINIMUM ASPHALT CONCRETE PAVEMENTSECTIONS

Traffic Index (T.I.)Asphalt Concrete

(inches)Class 2 Aggregate

Base (inches)Total Thickness

(inches)

4.5 3.0 8.0 11.0

5.0 3.0 9.0 12.0

5.5 3.5 10.0 13.5

6.0 4.0 11.0 15.0

Pavement subgrades should be compacted as described above in the section under “SitePreparation Grading and Compaction”.

Curbs and gutters should be constructed directly on the soil subgrade rather than on a layer ofaggregate base. This will minimize the amount of surface water that seeps below the curb andinto the pavement subgrade. The seepage of water into subgrade soils beneath vehiclepavements, can result in subgrade softening and premature pavement distress.

Pavement construction should comply with the requirements of the CALTRANS StandardSpecifications, latest editions, except that compaction requirements for pavement soil subgradesand aggregate base should be based on ASTM Test D1557-09, as described in the part of thisreport dealing with "Site Preparation, Grading and Compaction."

-9-


Utility Trenches

The attention of contractors, particularly the underground contractor, should be drawn to therequirements of California Code of Regulations, Title 8, Construction Code Section 1540regarding Safety Orders for "Excavations, Trenches, Earthwork". All trenches and excavationsfour feet and deeper should be supported. A lateral active pressure of 45 pcf equivalent fluidpressure may be used for the design of shoring for temporary excavation.

For purposes of this section of the report, bedding is defined as material placed in a trench up toone foot above a utility pipe and backfill is all material placed in the trench above the bedding.

Unless concrete bedding is required around utility pipes, free-draining sand should be used asbedding. Sand proposed for use in bedding should be tested in our laboratory to verify itssuitability and to measure its compaction characteristics. Sand bedding should be compacted bymechanical means to achieve at least 90 percent compaction density based on ASTM TestsD1557-09.

Approved, on-site, inorganic soil, or imported material may be used as utility trench backfill. Proper compaction of trench backfill will be necessary under and adjacent to structural fill,building foundations, concrete slabs and vehicle pavements. In these areas, backfill should beconditioned with water (or allowed to dry) to produce a soil-water content of about three percentabove the optimum value and placed in horizontal layers not exceeding six inches in thickness(before compaction). Each layer should be compacted to 85-90 percent relative compactionbased of ASTM Test D1557-09. The upper eight inches of pavement subgrades should becompacted to about 90 percent relative compaction based on ASTM Test D1557-09.

Where any trench crosses the perimeter foundation line of any building, the trench should becompletely plugged and sealed with compacted clay soil for a horizontal distance of at least twofeet on either side of the foundation.

Surface Drainage

Surface drain gradients should be planned to prevent ponding and to promote drainage of surfacewater away from building foundations, slabs, edges of pavements and sidewalks, and towardssuitable collection and discharge facilities.

Water seepage or the spread of extensive root systems into the soil subgrades of foundations,slabs, or pavements, could cause differential movements and consequent distress in thesestructural elements. This potential risk should be given due consideration in the design andconstruction of landscaping.

-10-


Follow-up Geotechnical Services

Our recommendations are based on the assumption that FRIAR ASSOCIATES,INCORPORATED will be commissioned to perform the following services.

1. Review final grading and foundation plans prior to construction.

2. Observe, test and advise during site preparation, grading and excavations.

3. Observe, test and advise during foundation excavations for the proposed buildings.

4. Observe, test and advise during utility trench backfilling.

5. Observe, test and advise during pavement construction.

6. Observe and advise during site drainage provisions.

Limitations

The recommendations contained in this report are based on certain plans, information and datathat have been provided to us. Any change in those plans, information and data will render ourrecommendations invalid unless we are commissioned to review the change and to make anynecessary modifications and/or additions to our recommendations.

Subsurface exploration of any site is necessarily confined to selected locations. Conditions may,and often do, vary between and around such locations. Should conditions different from thoseencountered in our explorations come to light during project development, additionalexploration, testing and analysis may be necessary; changes in project design and constructionmay also be necessary.

Our recommendations have been made in accordance with the principles and practices generallyemployed by the geotechnical engineering profession. This is in lieu of all other warranties,express or implied.

-11-


All earthwork and associated construction should be observed by our field representative, andtested where necessary, to compare the generalized site conditions assumed in this report withthose found at the site at the time of construction, and to verify that construction complies withthe intent of our recommendations.

Sincerely,

FRIAR ASSOCIATES, INCORPORATED

John H. FriarCE 52281

-12-

APPENDIX E

MRP CALCULATIONS

139

,574

5,59

433

,980

1,35

91,03

6NO

559

34,539

995

YES

238

,293

3,33

234

,961

1,39

81,05

9NO

333

35,294

1,01

6YES

338

,012

5,97

532

,037

1,28

197

9NO

598

32,635

940

YES

424

,242

7,94

816

,294

652

513

NO

795

17,089

492

YES

534

,597

3,53

831

,059

1,24

299

0NO

354

31,413

905

YES

612

,095

3,41

78,67

834

726

0NO

342

9,02

026

0YES

79,22

194

38,27

833

125

1NO

948,37

224

1YES

STORA

GE STORM

WAT

ER CAL

CULA

TIONS

DMA

TOTA

LPE

RVIM

PERV

BIO (R

EQ'D)

BIO

(PRO

V'D)

4% RULE

EQ. IMPE

RVTO

TAL IM

PRCO

MBO

CAL

C BIO

(REQ

'D)

Y/N

APPENDIX F

BMP SIZING CALCULATIONS

STEP 1 Contributing drainage area to the treatment measure: 39,574

STEP 2 Determine the equivalent impervious area draining to the treatment measure:Impervious area draining to the treatment measure: 33,980 sq. ft.Pervious area draining to the treatment measure: 5,594 sq. ft.

For grass, landscapeing or pervious paving, multiply the pervious area bya runoff coefficient of 0.10 to compute the equivalent impervious area.

Equivalent impervious area = pervious area x 0.10 = 559 sq. ft.

Total equivalent impervious area: 34,539 sq. ft.

STEP 3 Determine the required treatment volume using Adapted CASQA Stormwater BMPHandbook Approach

Volume Calculation:Mean Annual Precipitation(Site) Mapsite= 15.0 inchesMean Annual Precipitation(Gage) Mapgage= 13.9 inches

Correction Factor 1.08Soil Type Type D Sandy ClayAverage Slope of Site s= 1.0%Unit Basin Storage UBS1%= 0.58 inchesUnit Basin Storage UBS15%= 0.60 inchesAdjusted Unit BasinStorage (UBS) Volume: UBSsite= 0.5800 inches

Water Quality Design (WQD) Volume: 1,802 cu. ft.

STEP 4 Determine the design rainfall intensity (Section III.B, Step 7, or Section III.C, Step 3):

Design Rainfall Intensity: 0.2 in/hr

STEP 5 Assume that the rain event that generates the Unit Basin Storage Volume of runoff occursat the design rainfall intensity for the entire length of the storm. Calculate the duration ofthe storm by dividing the adjusted Unit Basin Storage Volume by the design rainfall intensity.In other words, determine the amount of time required for the Unit Basin Storage Volume to

Duration = UBS Volume (inches) / Rainfall Intensity (inches/hour)Duration = (Step 3) / (Step 4) = 3.13

STEP 6 Make a preliminary estimate of the surface area of the bioretention facility by multiplyingthe area of impervious surface to be treated by a sizing factor of 0.03.

Estimated Surface Area = 34,539 sq. ft. x 0.03 = 1,036 sq. ft.

Assume the modified surface area is 100%of the preliminary estimate above, or 1,036 sq. ft.

STEP 7 Calculate the volume of runoff that filters through the biotreatment soil at a rate of5 inches per hour (the design surface loadig rate for the bioretention facilities), for

Volume of Treated Runoff = Estimated Surface Area x 5 in/hr x (1ft/12in) x Duration

Volume of Treated Runoff = 1,351 cu. ft.

STEP 8 Calculate the portion of the water quality design (WQD) volume remaining after treatmentis accomplished by filtering through the biotreatment soil. The result is the amount that Step 6.

Volume in ponding area = WQD Volume - Volume of Treated Runoff

Volume in ponding area = 450 cu. ft.

STEP 9 Calculate the depth of the volume in the ponding area by dividing this volume by the estimated surface area in Step 6.

Depth of ponding = Volume in Ponding Area / Estimated Survey Area

Depth of ponding = 0.43 ftor 5.2 inches

Ponding shall be between 0.5' and 1.0'

SCVURPPP METHODSIZING FOR FLOW & VOLUME-BASED TREATMENT MEASURES

985 MONTAGUE EXPRESSWAY (DMA 01)















Estimated Surface Area = 35,294 sq. ft. x 0.03 = 1,059 sq. ft.

Assume the modified surface area is 100%of the preliminary estimate above, or 1,059 sq. ft.



























Estimated Surface Area = 32,635 sq. ft. x 0.03 = 979 sq. ft.

Assume the modified surface area is 100%of the preliminary estimate above, or 979 sq. ft.





















Water Quality Design (WQD) Volume: 891 cu. ft.










Volume of Treated Runoff = 668 cu. ft.


















Water Quality Design (WQD) Volume: 470 cu. ft.










Volume of Treated Runoff = 339 cu. ft.











STEP 2 Determine the equivalent impervious area draining to the treatment measure:Impervious area draining to the treatment measure: 8,278 sq. ft.Pervious area draining to the treatment measure: 943 sq. ft.

For grass, landscapeing or pervious paving, multiply the pervious area bya runoff coefficient of 0.10 to compute the equivalent

APPENDIX 8.5 Hydrology/Drainage Study - City of Milpitas...City of Milpitas - SCVURPPP C.3. Data Form Page 3 of 4 12/2013 6. Selection of Specific Stormwater Control Measures: Site

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