HomeMy WebLinkAboutSDP 16-12; CARLSBAD VETERANS HOUSING; PRIORITY DEVELOPMENT PROJECT (PDP) STORM WATER MANAGEMENT PLAN (SWQMP);CITY OF CARLSBAD
PRIORITY DEVELOPMENT PROJECT (PDP)
STORM WATER QUALITY MANAGEMENT PLAN (SWQMP)
FOR
HARDING VETERANS HOUSING
(3606, 3618, AND 3630 HARDING STREET)
PROJECT ID: SDP 16-12
GR 2020-0007, Drawing No. 523-4A
ENGINEER OF WORK:
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Wayne W. Chang, MS, PE 46548, Expires 6/30/2021
PREPARED FOR:
AFFIRMED HOUSING GROUP
13520 EVENING CREEK DRIVE NORTH, SUITE 160
SAN DIEGO, CA 92128
(858) 679-2828
PREPARED BY:
0h811(ftMM[[Nn
Civil Engineering Hydrology Hydraulics Sedimentation
P.O. Box 9496
Rancho Santa Fe, CA 92067
(858) 692-0760
DATE:
JULY 14, 2020
CO JUL 20 2020
LAND DEVELOPMENT
ENGINEERING
TABLE OF CONTENTS
Certification Page
Project Vicinity Map
FORM E-34 Storm Water Standard Questionnaire
Site Information
FORM E-36 Standard Project Requirement Checklist
Summary of PDP Structural BMPs
Attachment 1: Backup for PDP Pollutant Control BMPs
Attachment Ia: DMA Exhibit and Soil Classifications Map
Attachment 1 b: Tabular Summary of DMAs and Design Capture Volume Calculations
Attachment ic: Harvest and Use Feasibility Screening (when applicable)
Attachment ld: Categorization of Infiltration Feasibility Condition (when applicable)
Attachment le: Pollutant Control BMP Design and DCV Worksheets I Calculations
Attachment 2: Backup for POP Hydromodification Control Measures - N/A. Project is Exempt
Attachment 3: Structural BMP Maintenance Thresholds and Actions
Attachment 4: Single Sheet BMP (SSBMP) Exhibit
CERTIFICATION PAGE
Project Name: Harding Veterans Housing
Project ID: 16-12
I hereby declare that I am the Engineer in Responsible Charge of design of storm water BMPs for
this project, and that I have exercised responsible charge over the design of the project as defined
in Section 6703 of the Business and Professions Code, and that the design is consistent with the
requirements of the BMP Design Manual, which is based on the requirements of SDRWQCB
Order No. R9-2013-0001 (MS4 Permit) or the current Order.
I have read and understand that the City Engineer has adopted minimum requirements for
managing urban runoff, including storm water, from land development activities, as described in
the BMP Design Manual. I certify that this SWQMP has been completed to the best of my ability
and accurately reflects the project being proposed and the applicable source control and site
design BMPs proposed to minimize the potentially negative impacts of this project's land
development activities on water quality. I understand and acknowledge that the plan check review
of this SWQMP by the City Engineer is confined to a review and does not relieve me, as the
Engineer in Responsible Charge of design of storm water BMPs for this project, of my
responsibilities for project design.
PE 46548, Expires 6/30/2021 OESS Io,
Engineer of s Signature, PE Number & Expiration Date
Wayne W. Chang
Print Name
Chang Consultants
Company
July 14, 2020
Date
CITY OF ENCiNITAB
PROJECT VICINITY MAP
rA
(OY
I MARCOS
CCity of STORM WATER STANDARDS Development Services
Carlsbad QUESTIONNAIRE Land Development Engineering
1635 Faraday Avenue E-34 (760) 602-2750
www.carlsbadca.gov
INSTRUCTIONS:
To address post-development pollutants that may be generated from development projects, the city requires that new
development and significant redevelopment priority projects incorporate Permanent Storm Water Best Management
Practices (BMPs) into the project design per Carlsbad BMP Design Manual (BMP Manual). To view the BMP Manual,
refer to the Engineering Standards (Volume 5).
This questionnaire must be completed by the applicant in advance of submitting for a development application
(subdivision, discretionary permits and/or construction permits). The results of the questionnaire determine the level of
storm water standards that must be applied to a proposed development or redevelopment project. Depending on the
outcome, your project will either be subject to 'STANDARD PROJECT' requirements or be subject to 'PRIORITY
DEVELOPMENT PROJECT' (POP) requirements.
Your responses to the questionnaire represent an initial assessment of the proposed project conditions and impacts. City
staff has responsibility for making the final assessment after submission of the development application. If staff
determines that the questionnaire was incorrectly filled out and is subject to more stringent storm water standards than
initially assessed by you, this will result in the return of the development application as incomplete. In this case, please
make the changes to the questionnaire and resubmit to the city.
If you are unsure about the meaning of a question or need help in determining how to respond to one or more of the
questions, please seek assistance from Land Development Engineering staff.
A completed and signed questionnaire must be submitted with each development project application. Only one
completed and signed questionnaire is required when multiple development applications for the same project are
submitted concurrently.
PROJECT INFORMATION
PROJECT NAME: Harding Veterans Housing PROJECT ID: SDP 16-12
ADDRESS: 3606, 3618, and 3630 Harding Street, Carlsbad, CA 92008 APN: 204-192-05,204-192-06
The project is (check one): 0 New Development IZI Redevelopment
The total proposed disturbed area is: 28,248 ft2 (0.649 ) acres
The total proposed newly created and/or replaced impervious area is: 16,925 ft2 (0.389 ) acres
If your project is covered by an approved SWQMP as part of a larger development project, provide the project ID and the
SWQMP # of the larger development project:
Project ID N/A SWQMP #: N/A
Then, go to Step I and follow the instructions. When completed, sign the form at the end and submit this with your
application to the city.
E-34 Page 1 of 4 REV 02116
STEP I
TO BE COMPLETED FOR ALL PROJECTS
To determine if your project is a "development project", please answer the following question:
YES NO
Is your project LIMITED TO routine maintenance activity and/or repair/improvements to an existing building o izi or structure that do not alter the size (See Section 1.3 of the BMP Design Manual for guidance)?
If you answered "yes" to the above question, provide justification below then go to Step 5, mark the third box stating "my
project is not a 'development project' and not subject to the requirements of the BMP manual" and complete applicant
information.
Justification/discussion: (e.g. the project includes only interior remodels within an existing building):
N/A
If you answered "no" to the above question, the project is a 'development project', go to Step 2.
STEP 2
TO BE COMPLETED FOR ALL DEVELOPMENT PROJECTS
To determine if your project is exempt from PDP requirements pursuant to MS4 Permit Provision E.3.b.(3), please answer
the following questions:
Is your project LIMITED to one or more of the following:
YES NO
1. Constructing new or retrofitting paved sidewalks, bicycle lanes or trails that meet the following criteria:
Designed and constructed to direct storm water runoff to adjacent vegetated areas, or other non-
erodible permeable areas;
Designed and constructed to be hydraulically disconnected from paved streets or roads;
Designed and constructed with permeable pavements or surfaces in accordance with USEPA
Green Streets guidance?
2. Retrofitting or redeveloping existing paved alleys, streets, or roads that are designed and constructed in o zi accordance with the USEPA Green Streets guidance?
3. Ground Mounted Solar Array that meets the criteria provided in section 1.4.2 of the BMP manual? 0 121
If you answered "yes" to one or more of the above questions, provide discussion/justification below, then go to Step 5, mark
the second box stating "my project is EXEMPT from PDP .....and complete applicant information.
Discussion to justify exemption (e.g. the project redeveloping existing road designed and constructed in accordance with
the USEPA Green Street guidance):
N/A
If you answered "no" to the above questions, your project is not exempt from PDP, go to Step 3.
E-34 Page 2of4 REV 02/16
STEP 3
TO BE COMPLETED FOR ALL NEW OR REDEVELOPMENT PROJECTS
To determine if your project is a PDP, please answer the following questions (MS4 Permit Provision E.3.b.(1)):
YES NO
Is your project a new development that creates 10,000 square feet or more of impervious surfaces
collectively over the entire project site? This includes commercial, industrial, residential, mixed-use, 0 121
and public development projects on public or private land.
Is your project a redevelopment project creating and/or replacing 5,000 square feet or more of
impervious surface collectively over the entire project site on an existing site of 10,000 square feet or
more of impervious surface? This includes commercial, industrial, residential, mixed-use, and public
development projects on public or private land.
Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more
of impervious surface collectively over the entire project site and supports a restaurant? A restaurant is
a facility that sells prepared foods and drinks for consumption, including stationary lunch counters and 0
refreshment stands selling prepared foods and drinks for immediate consumption (Standard Industrial
Classification (SIC) code 5812).
Is your project a new or redevelopment project that creates 5,000 square feet or more of impervious
surface collectively over the entire project site and supports a hillside development project? A hillside U
development project includes development on any natural slope that is twenty-five percent or greater.
Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more
of impervious surface collectively over the entire project site and supports a parking lot? A parking lot is
a land area or facility for the temporary parking or storage of motor vehicles used personally for
business or for commerce.
Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more
of impervious surface collectively over the entire project site and supports a street, road, highway
freeway or driveway? A street, road, highway, freeway or driveway is any paved impervious surface
used for the transportation of automobiles, trucks, motorcycles, and other vehicles.
Is your project a new or redevelopment project that creates and/or replaces 2,500 square feet or more
of impervious surface collectively over the entire site, and discharges directly to an Environmentally
Sensitive Area (ESA)? "Discharging Directly to" includes flow that is conveyed overland a distance of 0 121
200 feet or less from the project to the ESA, or conveyed in a pipe or open channel any distance as an
isolated flow from the project to the ESA (i.e. not commingled with flows from adjacent lands).*
Is your project a new development or redevelopment project that creates and/or replaces 5,000 square
feet or more of impervious surface that supports an automotive repair shop? An automotive repair
shop is a facility that is categorized in any one of the following Standard Industrial Classification (SIC)
codes: 5013, 5014, 5541, 7532-7534, or 7536-7539.
Is your project a new development or redevelopment project that creates and/or replaces 5,000 square
feet or more of impervious area that supports a retail gasoline outlet (RGO)? This category includes El 0 RGO's that meet the following criteria: (a) 5,000 square feet or more or (b) a project Average Daily
Traffic (AD T) of 100 or more vehicles per day.
Is your project a new or redevelopment project that results in the disturbance of one or more acres of land
and are expected to generate pollutants post construction?
Is your project located within 200 feet of the Pacific Ocean and (1) creates 2,500 square feet or more of
impervious surface or (2) increases impervious surface on the property by more than 10%? (CMC 0 121
21.203.040)
If you answered "yes" to one or more of the above questions, your project is a PDP. If your project is a redevelopment
project, go to step 4. If your project is a new project, go to step 5, check the first box stating "My project is a PDP ..."
and complete applicant information.
If you answered "no" to all of the above questions, your project is a 'STANDARD PROJECT.' Go to step 5, check the
second box stating "My project is a 'STANDARD PROJECT ...... and complete applicant information.
E-34 Page 3 of 4 REV 02/16
STEP 4
TO BE COMPLETED FOR REDEVELOPMENT PROJECTS THAT ARE PRIORITY DEVELOPMENT PROJECTS (PDP)
ONLY
Complete the questions below regarding your redevelopment project (MS4 Permit Provision E.3.b.(2)):
YES NO
Does the redevelopment project result in the creation or replacement of impervious surface In an amount
of less than 50% of the surface area of the previously existing development? Complete the percent
impervious calculation below.
Existing impervious area (A) = 9,342 sq. ft. 0
Total proposed newly created or replaced impervious area (B) = 16,925 sq. ft.
Percent impervious area created or replaced (B/A)100 = 181
If you answered "yes", the structural BMPs required for POP apply only to the creation or replacement of Impervious
surface and not the entire development. Go to step 5, check the first box stating "My project is a PDP ..? and complete
applicant information.
If you answered "no," the structural BMP's required for POP apply to the entire development. Go to step 5, check the
check the first box stating "My project is a PDP ..." and complete applicant information.
- STEP
CHECK THE APPROPRIATE BOX AND COMPLETE APPLICANT INFORMATION
IZi My project Is a PDP and must comply with PDP stormwater requirements of the BMP Manual. I understand I must
prepare a Storm Water Quality Management Plan (SWQMP) for submittal at time of application.
0 My project Is a 'STANDARD PROJECT' OR EXEMPT from PDP and must only comply with 'STANDARD PROJECT'
stormwater requirements of the BMP Manual. As part of these requirements, I Will submit a "Standard Project
Requirement Checklist Form E-36" and incorporate low impact development strategies throughout my project.
Note: For projects that are dose to meeting the PDP threshold, staff may require detailed impervious area calculations
and exhibits to verify if 'STANDARD PROJECT' stormwater requirements apply.
E] My Project is NOT a 'development project' and is not subject to the requirements of the BMP Manual.
Applicant Information and Signature Box
Applicant Name: Marie Allen Applicant Title: Project Manager
Applicant Signature: -. Date:
,. 'fl21At ,,,r hrvflc d,,cinn,tM as Amns of SoArthI Environmentally Sensitive Areas IflCIUOO oul UFO r1u ILJlIIU u, G' ,,'- ........................
.......... Biological Significance by the State Water Resources Control Board (Water Quality Control Plan tar the San Diego Basin (1954) and amendments); water bodies
designated with the RARE beneficial use by the State Water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1994) and
amendments): areas designated as preserves or their equivalent under the Multi Species Conservation Program within the Cities and County of San Diego; Habitat
Management Plan: and any other equivalent environmentally sensitive areas which have been identified by the City.
This fox for ON Use OnW
YES NO
City Concurrence: o o
By:
Date:
Project ID:
E.34 Page 4of4 REV 02116
SITE INFORMATION CHECKLIST
Project Summary Information
Project Name Harding Veterans Housing
Project ID SDP 16-12
Project Address 3606, 3618, and 3630 Harding Street
Carlsbad, CA 92008
Assessor's Parcel Number(s) (APN(s)) 204-192-05, 204-192-06
Project Watershed (Hydrologic Unit) Carlsbad 904
Parcel Area 0.543 Acres (23,653 Square Feet)
Existing ',mpervious Area
(subset of Parcel Area)
0.215 Acres (9,342 Square Feet)
Area to be disturbed by the project
(Project Area) 0.649 Acres (28,248 Square Feet)
Project Proposed Impervious Area
(subset of Project Area)
0.389 Acres (16,925 Square Feet)
Project Proposed Pervious Area
(subset of Project Area)
0.260 Acres (11,323 Square Feet)
Note: Proposed Impervious Area + Proposed Pervious Area = Area to be Disturbed by the
Project.
This may be less than the Parcel Area.
Description of Existing Site Condition and Drainage Patterns
Current Status of the Site (select all that apply):
X Existing development
o Previously graded but not built out
0 Agricultural or other non-impervious use
U Vacant, undeveloped/natural
Description /Additional Information:
The site historically contained two separate single-family residences and a detached garage
between the two residences on APN 204-192-05, and a single-family residence with attached
garage on adjacent APN 204-192-06. These structures will be demolished prior to development.
Existing Land Cover Includes (select all that apply):
X Vegetative Cover
X Non-Vegetated Pervious Areas
X Impervious Areas
Description /Additional Information:
The impervious surfaces include the residences, driveways, and hardscape. The vegetative
cover is landscaping, which is primarily adjacent to the residences. The pervious surfaces are
primarily the rear yards, which are dirt with scattered grasses, weeds, bushes, and trees.
Underlyng Soil belongs to Hydrologic Soil Group (select all that apply):
0 NRCS Type A
X NRCS Type B
U NRCS Type C
U NRCS Type D
Approximate Depth to Groundwater (GW):
U GW Depth < 5 feet
U 5 feet < GW Depth < 10 feet
X 10 feet < GW Depth <20 feet (11 feet per soils report)
U GW Depth > 20 feet
Existing Natural Hydrologic Features (select all that apply):
U Watercourses
U Seeps
U Springs
O Wetlands
X None
Descrrption /Additional Information:
The project is an infill development with existing single-family residences. There are no
watercourses, seeps, springs, or wetlands.
Description of Existing Site Topography and Drainage [How is storm water runoff conveyed from
the site? At a minimum, this description should answer (1) whether existing drainage
conveyance is natural or urban; (2) describe existing constructed storm water conveyance
systems, if applicable; and (3) is runoff from offsite conveyed through the site? if so, describe]:
The existing site contains single-family development on two gently sloping lots. The lots slope
southwesterly towards the frontage along Harding Street. The drainage conveyance is urban
and typical of single-family residential development. Storm runoff sheet flows across portions of
the yards into either a private yard drainage system or directly onto Harding Street. One inlet
was observed on-site and ths most likely discharges through a nearby curb core observed on
Harding Street.
Interstate 5 is located behind the rear yards. There is an approximately 15-foot high slope
behind the rear yard that rises up to Interstate 5. Off-site storm runoff on the slope is conveyed
onto the site, and then to Harding Street.
Description of Proposed Site Development and Drainage Patterns
Project Description / Proposed Land Use and/or Activities:
The project will provide for veterans housing. There will be three floors containing 26 units
varying from studios to three bedrooms and 24 parking stalls (2 outdoor and 22 indoor). A
parking garage, office, lobby, utility rooms, laundry room, trash storage, property manager's
unit, and residential units will be on the ground level. An office/amenity room, laundry room,
trash storage, and residential units will be on the second and third levels.
List/desc-ibe proposed impervious features of the project (e.g., buildings, roadways, parking
lots, courtyards, athletic courts, other impervious features):
The impervious features include the residential building, a driveway, parking, courtyards, and
walkways. In addition, new curb, gutter, and sidewalk along the Harding Street frontage will
replace the existing curb, gutter and sidewalk.
List/describe proposed pervious features of the project (e.g., landscape areas):
The pervious features include landscaping and biofiltration basins.
Does the project include grading and changes to site topography?
X Yes
E No
Description /Additional Information:
The site is currently gently sloping. Minor grading will need to be performed based on the
grading design.
Does the project include changes to site drainage (e.g., installation of new storm water
conveyance systems)?
X Yes
11 No
Description /Additional Information:
A private on-site drainage system will be installed to direct the project runoff (and minor off-site
run-on) to the proposed biofiltration basins. Once treated, the runoff will be conveyed towards
Harding Street. A portion of the runoff will flow directly onto Harding Street, while a portion will
be conveyed to the existing public storm drain along the project frontage within Harding Street.
Identify whether any of the following features, activities, and/or pollutant source areas will be
present (select all that apply):
X On-site storm drain inlets
X Interior floor drains and elevator shaft sump pumps
X Interior parking garages
X Need for future indoor & structural pest control
X Landscape/Outdoor Pesticide Use
U Pools, spas, ponds, decorative fountains, and other water features
U Food service
X Refuse areas
U Industrial processes
U Outdoor storage of equipment or materials
U Vehicle and Equipment Cleaning
O Vehicle/Equipment Repair and Maintenance
O Fuel Dispensing Areas
U Loading Docks
X Fire Sprinkler Test Water
X Miscellaneous Drain or Wash Water
X Plazas, sidewalks, and parking lots
Identification of Receiving Water Pollutants of Concern
Describe path of storm water from the project site to the Pacific Ocean (or bay, lagoon, lake or
reservoir, as applicable):
Site runoff is captured by a public storm drain in Harding Street. The storm drain continues north
to Chestnut Avenue, turns west and continues on Chestnut Avenue to the railroad tracks. The
storm drain then parallels the railroad tracks to the south and discharges into the Agua
Hedionda Lagoon.
List any 303(d) impaired water bodies within the path of storm water from the project site to the
Pacific Ocean (or bay, lagoon, lake or reservoir, as applicable), identify the
pollutant(s)/stressor(s) causing impairment, and identify any TMDLs for the impaired water
bodies:
303(d) Impaired Water Body Pollutant(s)/Stressor(s) TMDLs
N/A. Agua Hedionda Lagoon
is not 303(d) impaired.
Identification of Project Site Pollutants
Identify pollutants anticipated from the project site based on all proposed use(s) of the site (see
BMP Design Manual A pendix B.6):
Pollutant
Not Applicable to
the Project Site
Anticipated from the
Project Site
Also a Receiving
Water Pollutant of
Concern
Sediment A
Nutrients A
Heavy Metals A
Organic Compounds A
Trash & Debris A
Oxygen Demanding
Substances P
OU & Grease A
Bacteria & Viruses P
Pesticides A
A - Anticipated
P - Potential
Hydromodification Management Requirements
Do hydromodification management requirements apply (see Section 1.6 of the BMP Design
Manual)?
U Yes, hydromodification management flow control structural BMPs required.
X No, the project will discharge runoff directly to existing underground storm drains discharging
directly to water storage reservoirs, lakes, enclosed embayments, or the Pacific Ocean.
U No, the project will discharge runoff directly to conveyance channels whose bed and bank are
concrete-lined all the way from the point of discharge to water storage reservoirs, lakes,
enclosed embayments, or the Pacific Ocean.
U No, the project will discharge runoff directly to an area identified as appropriate for an
exemption by the WMAA for the watershed in which the project resides.
Description / Additional Information (to be provided if a 'No' answer has been selected above):
Site runoff is captured by a public storm drain in Harding Street adjacent to the site. The storm
drain continues north to Chestnut Avenue, turns west and continues on Chestnut Avenue to the
railroad tracks. The storm drain then parallels the railroad tracks to the south and discharges
into Agua Hedionda Lagoon. This storm drain system was designed per Carlsbad as-built
drawing 360-5. The storm drain profile on the as-built shows that the 100-year hydraulic grade
line is below the ground surface. In addition, the plan shows proper energy dissipation at the
outlet into the lagoon and that the riprap dissipater extends below the low tide level. See Chang
Consultants September 17, 2015, Hydromodification Exemption Analyses for Select Carlsbad
Watersheds, for details on the hydromodification exemption
Critical Coarse Sediment Yield Areas*
*This Section only required if hydromodification management requirements apply
Based on the maps provided within the WMAA, do potential critical coarse sediment yield areas
exist within the project drainage boundaries?
El Yes
X No, No critical coarse sediment yield areas to be protected based on WMAA maps
If yes, have any of the optional analyses presented in Section 6.2 of the BMP Design Manual
been performed?
U 6.2.1 Verification of Geomorphic Landscape Units (GLUs) Onsite
U 6.2.2 Downstream Systems Sensitivity to Coarse Sediment
U 6.2.3 Optional Additional Analysis of Potential Critical Coarse Sediment Yield Areas Onsite
U No optional analyses performed, the project will avoid critical coarse sediment yield areas
identified based on WMAA maps
If optional analyses were performed, what is the final result?
U No critical coarse sediment yield areas to be protected based on verification of GLUs onsite
U Critical coarse sediment yield areas exist but additional analysis has determined that
protection is not required. Documentation attached in Attachment 8 of the SWQMP.
U Critical coarse sediment yield areas exist and require protection. The project will implement
management measures described in Sections 6.2.4 and 6.2.5 as applicable, and the areas
are identified on the SWQMP Exhibit.
Discussion /Additional Information:
The Carlsbad WMAA's Potential Critical Coarse Sediment Yield Areas exhibit does not show
CCSYA's at the site.
Flow Control for Post-Project Runoff*
*This Section only required if hydromodification management requirements apply
List and describe point(s) of compliance (POCs) for flow control for hydromodification
management (see Section 6.3.1). For each P00, provide a POC identification name or number
correlating to the project's HMP Exhibit and a receiving channel identification name or number
correlating to the project's HMP Exhibit.
N/A. The project is not subject to hydromodification as discussed on the prior page.
Has a geomorphic assessment been performed for the receiving channel(s)?
No, the low flow threshold is 0.1Q2 (default low flow threshold)
ii Yes, the result is the low flow threshold is 0.1Q2
E Yes, the result is the low flow threshold is 0.3Q2
E Yes, the result is the low flow threshold is 0.5Q2
If a geomorphic assessment has been performed, provide title, date, and preparer:
N/A. The project is not subject to hydromodification.
Discussion /Additional Information: (optional)
N/A
Other Site Requirements and Constraints
When applicable, list other site requirements or constraints that will influence storm water
management design, such as zoning requirements including setbacks and open space, or City
codes governing minimum street width, sidewalk construction, allowable pavement types, and
drainage requirements.
The project's geotechnical engineer, NOVA Services, has determined that full and partial
infiltration are not feasible at the site."
Furthermore, their finding of groundwater 11 feet below existing grade indicates that
groundwater depths below the bottom of an infiltration basin will be less than the required
separation of 10 feet.
Optional Additional Information or Continuation of Previous Sections As Needed
This space provided for additional information or continuation of information from previous
sections as needed.
N/A.
k City of
Carlsbad
STANDARD PROJECT
REQUIREMENT
CHECKLIST
E-36
Development Services
Land Development Engineering
1635 Faraday Avenue
(760) 602-2750
www.carlsbadca.gov
Project Information
Project Name: Harding Veterans Housing
Project ID: SDP 16-12
DWG No. or Building Permit No.: Drawing No. 5234A
Source Control BMPs
All development projects must implement source control BMPs SC-1 through SC-6 where applicable and feasible. See
Chapter 4 and Appendix E.1 of the BMP Design Manual for information to implement source control BMPs shown in this.
checklist.
Answer each category below pursuant to the following.
"Yes" means the project will implement the source control BMP as described in Chapter 4 and/or Appendix E.1 of the
Model BMP Design Manual. Discussion/justification is not required.
"No" means the BMP is applicable to the project but it is not feasible to implement. Discussion/justification must be
provided. Please add attachments if more space is needed.
"N/A" means the BMP is not applicable at the project site because the project does not include the feature that is
addressed by the BMP (e.g., the project has no outdoor materials storage areas). Discussion/justification may be
provided.
Source Control Requirement Applied?
SC-I Prevention of Illicit Discharges into the MS4 0 Yes 0 No I 0 N/A
Discussion/justification if SC-I not implemented:
N/A
SC-2 Storm Drain Stenciling or Signage 0 Yes 0 No 0 N/A
Discussion/justification if SC-2 not implemented:
N/A
SC-3 Protect Outdoor Materials Storage Areas from Rainfall, Run-On, Runoff, and Wind o Yes 0 No IZI N/A Dispersal
Discussion/justi'ication if SC-3 not implemented:
N/A
E-36 Page 1 of 4 Revised 03/16
Source Control Requirement (continued) Applied?
SC-4 Protect Materials Stored in Outdoor Work Areas from Rainfall Run-On Runoff, and
Wind Dispersal DYes 0 N 0NIA
Discussion/justification if SC-4 not implemented:
N/A
SC-5 Protect Trash Storage Areas from Rainfall, Run-On, Runoff, and Wind Dispersal l Yes 0 No 0 N/A
Discussion/justification if SC-5 not implemented:
N/A
SC-6 Additional BMPs based on Potential Sources of Runoff Pollutants must answer for each source listed below and
identify additional BMPs. (See Table in Appendix E.1 of BMP Manual for guidance).
J On-site storm drain inlets 0 Yes 0 No 0 N/A
LZI Interior foor drains and elevator shaft sump pumps 0 Yes 0 No 0 N/A
J Interior parking garages 0 Yes 0 No 0 N/A
J Need for future indoor & structural pest control 0 Yes 0 No 0 N/A
J Landscape/Outdoor Pesticide Use 0 Yes 0 No 0 N/A
Pools, spas, ponds, decorative fountains, and other water features 0 Yes 0 No 0 N/A
Food service 0 Yes 0 No 0 N/A
J Refuse areas 0 Yes 0 No 0 N/A
Industrial processes 0 Yes 0 No 0 N/A
Outdoor equipment or materials _storage _of 0 Yes 0 No 0 N/A
Vehicle and Equipment Cleaning 0 Yes 0 No 0 N/A
Vehicle/Equipment Repair and Maintenance 0 Yes 0 No 0 N/A
Fuel Dispensing Areas 0 Yes 0 No 0 N/A
Loading Docks 0 Yes 0 No 0 N/A
I Fire Sprinkler Test Water 0 Yes 0 No 0 N/A
I Miscellaneous Drain or Wash Water 0 Yes 0 No 0 N/A
j Plazas, sidewalks, and parking lots 0 Yes 0 No 0 N/A
For "Yes' answers, identify the additional BMP per Appendix E.1. Provide justification for "No' answers.
The on-site storm drain inlets will be labeled. Interior floor drains and elevator shaft sump pumps as well as parking garage
floor drains will be plumbed to sanitary sewer. These shall be inspected and maintained to prevent blockages and overflow.
Maintain landscaping using minimum or no pesticides. Interior refuse areas are designated on the plans. Fire spinkler test
water will drain to the sanitary sewer or a BMP. Miscellaneous drain water will drain to the sanitary sewer where required by
code, or will drain to a BMP. Plazas, sidewalks, and parking lots shall be swept regularly to prevent the accumulation of
litter and debris.
E-36 Page 2 of 4 Revised 03/16
Site Design BMPs
All development projects must implement site design BMPs SD-1 through SD-8 where applicable and feasible. See
Chapter 4 and Appendix E.2 thru E.6 of the BMP Design Manual for information to implement site design BMPs shown in
this checklist.
Answer each category below pursuant to the following.
'Yes" means the project will implement the site design BMPs as described in Chapter 4 and/or Appendix E.2 thru E.6 of
the Model BMP Design Manual. Discussion /justification is not required.
"No" means the BMPs is applicable to the project but it is not feasible to implement. Discussion/justification must be
provided. Please add attachments if more space is needed.
"N/A" means the BMPs is not applicable at the project site because the project does not include the feature that is
addressed by the BMPs (e.g., the project site has no existing natural areas to conserve). Discussion/justification may be
provided.
Source Control Requirement Applied?
SD-1 Maintain Natural Drainage Pathways and Hydrologic Features 0 Yes I 0 No I N/A
Discussion/justification if SD-1 not implemented:
N/A. The current site is developed.
SD-2 Conserve Natural Areas, Soils, and Vegetation I 0 Yes I 0 No I J N/A
Discussion/justification if SD-2 not implemented:
N/A. The current site is developed.
SD-3 Minimize Impervious Area I Zi Yes I 0 No I 0 N/A
Discussion/justification if SD-3 not implemented:
N/A
SD-4 Minimize Soil Compaction I i Yes I 0 No I 0 N/A
Discussion/justification if SD4 not implemented:
N/A
SD-5 Impervious Area Dispersion I i Yes I 0 No I 0 N/A
Discussion/justification if SD-5 not implemented:
N/A
E-36 Page 3 of 4 Revised 03/16
Source Control Requirement (continued) Applied?
SD-6 Runoff Collection 0 Yes 0 No TEI N/A
Discussion/justification if SD-6 not implemented:
N/A
SD-7 Landscaping with Native or Drought Tolerant Species I i Yes I 0 No 1 0 N/A
Discussion/justification if SD-7 not implemented:
N/A
SD-8 Harvesting and Using Precipitation I 0 Yes I 0 No 1 0 N/A
Discussion/justification if SD-8 not implemented:
N/A
E-36 Page 4 of 4 Revised 03/16
SUMMARY OF PDP STRUCTURAL BMPS
PDP Structural BMPs
All PDPs must implement structural BMPs for storm water pollutant control (see Chapter 5 of
the BMP Design Manual). Selection of PDP structural BMPs for storm water pollutant control
must be based on the selection process described in Chapter 5. PDPs subject to
hydromodification management requirements must also implement structural BMPs for flow
control for hydromodification management (see Chapter 6 of the BMP Design Manual). Both
storm water pollutant control and flow control for hydromodification management can be
achieved within the same structural BMP(s).
PDP structural BMPs must be verified by the City at the completion of construction. This may
include requiring the project owner or project owner's representative to certify construction of
the structural BMPs (see Section 1.12 of the BMP Design Manual). PDP structural BMPs must
be maintained into perpetuity, and the City must confirm the maintenance (see Section 7 of the
BMP Design Manual).
Use this form to provide narrative description of the general strategy for structural BMP
implementation at the project site in the box below. Then complete the PDP structural BMP
summary information sheet for each structural BMP within the project (copy the BMP summary
information page as many times as needed to provide summary information for each individual
structural BMP).
Describe the general strategy for structural BMP implementation at the site. This information
must describe how the steps for selecting and designing storm water pollutant control BMPs
presented in Section 5.1 of the BMP Design Manual were followed, and the results (type of
BMPs selected). For projects requiring hydromodification flow control BMPs, indicate whether
pollutant control and flow control BMPs are integrated together or separate.
The procedures in the 2016 Carlsbad BMP Design Manual (Manual) were followed in selecting
and then sizing the appropriate BMPs for the project. The Manual requires that harvest and use,
then infiltration be considered before biofiltration.
Harvest and use is assessed by comparing the design capture volume with the on-site water
use. The design capture volume (DCV) is the 24-hour, 85th percentile storm volume at the site.
Figure B.1-1 from the Manual shows that the 24-hour, 85th percentile precipitation is 0.582
inches (see Attachment IC). The DCV based on this value is calculated on attached Worksheet
B.2-1 and is 794 cubic feet. Form 1-7 from the manual indicates that the 36 hour demand must
be greater than 0.25DCV (0.25 x 794 cf = 198.5 cf or 1,485 gallons) for harvest and use to be
feasible. The demand from attached Table B.3-1 is 9.3 gallons per resident per day (24 hours)
or 14 gallons per 36 hours. Based on this, the site would need to have 106 residents (1,485 +
14 = 106) for harvest and use to be feasible. The project will merely create 26 units, which will
support less than 106 residents. Therefore, harvest and use is not feasible.
The project's geotechnical engineer, NOVA Services, has determined that partial and full
infiltration are not feasible at the site (see Attachment 10). Furthermore, the groundwater is 11
feet below existing grade, so groundwater depths below the bottom of an infiltration basin will be
less than the required separation of 10 feet. Therefore, infiltration is not feasible.
The next BMP in the hierarchy is biofiltration. Biofiltration basins are sized using Worksheet B.5-
1 from the Manual (see Attachment 1 E). The biofiltration basins will be adjacent to buildings, so
impervious liners are anticipated. Sizing has been performed for the each of the seven
proposed biofiltration basins (see the DMA Exhibit for locations) based on the worksheet. The
attached spreadsheet output provides the sizing for each basin. The spreadsheet determines
the DCV tributary to each biofiltration basin first followed by the basin sizing.
Structural BMP Summary Information
[Copy this page as needed to provide information for each individual proposed
structural BMP]
Structural BMP ID No. Biofiltration Basin 1 through 7
DWG: Grading Plan Sheet No. 3
Type of structural BMP:
Retention by harvest and use (HU-1)
Retention by infiltration basin (lNF-1)
El Retention by bioretention (INF-2)
0 Retention by permeable pavement (INF-3)
O Partial retention by biofiltration with partial retention (PR-1)
X Biofiltration (BF-1)
Li Flow-thru treatment control included as pre-treatment/forebay for an onsite retention or
biofiltration BMP (provide BMP type/description and indicate which onsite retention or
biofiltration BMP it serves in discussion section below)
0 Detention pond or vault for hydromodification management
E) Other (describe in discussion section below)
Purpose:
X Pollutant control only
LI Hydromodification control only
Combined pollutant control and hydromodification control
El Pre-treatment/forebay for another structural BMP
El Other (describe in discussion section below)
Discussion (as needed):
The project proposes seven biofiltration basins spread throughout the site. The biofiltration
basins are being sized to treat their individual tributary areas.
There is a landscape area along the southerly edge of the site that does not contain impervious
surfaces. The runoff from this landscape area will flow directly onto Harding Street. Therefore,
this area is considered to be self-mitigating and a structural BMP is not required.
The portion of the proposed driveway to the site within the public right-of-way is considered a de
minimis area.
ATTACHMENT I
BACKUP FOR PDP POLLUTANT CONTROL BMPS
This is the cover sheet for Attachment 1.
Check which Items are Included behind this cover sheet:
Attachment Contents Checklist
Sequence
Attachment 1 DMA Exhibit (Required) X Included
See DMA Exhibit Checklist on the
back of this Attachment cover sheet.
(24"x36" Exhibit typically required)
Attachment lb Tabular Summary of DMAs Showing El Included on DMA Exhibit in
DMA ID matching DMA Exhibit, DMA Attachment la
Area, and DMA Type (Required)* X Included as Attachment ib,
separate from DMA Exhibit *Provide table in this Attachment OR
on DMA Exhibit in Attachment la
Attachment ic Form 1-7, Harvest and Use Feasibility X Included
Screening Checklist (Required unless E Not included because the entire
the entire project will use infiltration project will use infiltration BMPs
BMPs)
Refer to Appendix 13.3-1 of the BMP
Design Manual to complete Form 1-7.
Attachment id Form 1-8, Categorization of Infiltration X Included
Feasibility Condition (Required E Not included because the entire
unless the project will use harvest and project will use harvest and use
use BMPs) BMPs
Refer to Appendices C and D of the
BMP Design Manual to complete
Form 1-8.
Attachment le Pollutant Control BMP Design X Included
Worksheets I Calculations (Required)
Refer to Appendices B and E of the
BMP Design Manual for structural
pollutant control BMP design
guidelines
LEGEND:
DRAINAGE BASIN BOUNDARY TRIBUTARY
TO PROPOSED BIOFILTRATION BASIN
EXISTING IMPERVIOUS AREAS
PROPOSED DRAINAGE FACILITY
51 I PROPOSED BIOFILTRATION BASIN
PROPOSED IMPERVIOUS SURFACES
(ROOFS. DRIVEWAY. HARDSCAPE)
PROPOSED PERVIOUS SURFACES
(LANDSCAPING)
PROPOSED SELF-MITIGATING AREA
PROPOSED DE MINIMIS AREA
NOTES:
THE HYDROLOGIC SOIL GROUP AT THE SITE IS
ENTIRELY B.
THE APPROXIMATE DEPTH TO GROUNDWATER IS 11
FEET.
THERE ARE NO NATURAL HYDROLOGIC FEATURES
OR CRITICAL COURSE SEDIMENT YIELD AREAS AT
THE SITE.
SEE ATTACHMENT lB FOR TABULATION OF DMAS.
BIOFILTRATION BASIN SHOWN HEREON REPRESENTS
BASIN FLOOR AREA REQUIRED PER CALCULATIONS.
ATTACHMENT 1A - DRAINAGE MANAGEMENT AREAS (DMA) EXHIBIT
468460 458490
S
468520
330 023"N
Hydrologic Soil Group—San Diego County Area, California
468250 468280 465310 468340 4E'7) 468400 468430
339 N \i\ \
0;,; m #
H
468430
3J'9'1N -
468250 468850 466310 468340 468370 468400
S
MapScale: 1:1,380ifprintedonAlandsc8pe(11"x8.5")9heet
Meters N 0 20 40 80 120
d ea ,\\ 0 50 100 200 3(8)
Map projection: Web Mercator Corner coordinates: WGS84 Edge ti UTM Zone uN WGSE4
JSF)A Natural Resources Web Soil Survey
Conservation Service National Cooperative Soil Survey
'\ 33 0 10 N
468460 468490 468520
S
8.
5/4/2016
Page 1 of 4
Hydrologic Soil Group—San Diego County Area, California
MAP LEGEND MAP INFORMATION
Area of Interest (AOl) C The soil surveys that comprise your AOl were mapped at 1:24,000.
Area of Interest (AOl) CID Warning: Soil Map may not be valid at this scale. Soils
Soil Rating Polygons
D Enlargement of maps beyond the scale of mapping can cause
A o Not rated or not available misunderstanding of the detail of mapping and accuracy of soil line
placement. The maps do not show the small areas of contrasting
AID Water Features soils that could have been shown at a more detailed scale.
Streams and Canals
Transportation Please rely on the bar scale on each map sheet for map
• BID +44 Rails measurements.
C Interstate Highways Source of Map: Natural Resources Conservation Service
OlD Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov
US Routes Coordinate System: Web Mercator (EPSG:3857)
LJ D Major Roads Maps from the Web Soil Survey are based on the Web Mercator
Not rated or not available Local Roads projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the Soil Rating Lines Background Albers equal-area conic projection, should be used if more accurate
A Aerial Photography calculations of distance or area are required.
AID This product is generated from the USDA-NRCS certified data as of
B the version date(s) listed below.
B/D Soil Survey Area: San Diego County Area, California
Survey Area Data: Version 9, Sep 17, 2015
ø- C
Soil map units are labeled (as space allows) for map scales 1:50,000
0/0 or larger.
... D Date(s) aerial images were photographed: Nov 3, 2014—Nov 22,
0 Not rated or not available 2014
Soil Rating Points The orthophoto or other base map on which the soil lines were
• A compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor shifting
• ND of map unit boundaries may be evident.
• B
• B/D
USDA Natural Resources Web Soil Survey 5/4/2016
200 Conservation Service National Cooperative Soil Survey Page 2 of 4
Hydrologic Soil Group—San Diego County Area, California
Hydrologic Soil Group
Hydrologic Soil Group— Summary by Map Unit - San Diego County Area, California (CA638)
Map unit symbol Map unit name Rating Acres in AOl Percent of AOl
99 Marina loamy coarse
sand, 2 to 9 percent
slopes
7.6 100.0%
Totals for Area of Interest 7.6 100.0%
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive precipitation
from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (AID, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly
wet. These consist mainly of deep, well drained to excessively drained sands or
gravelly sands. These soils have a high rate of water transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well drained
soils that have moderately fine texture to moderately coarse texture. These soils
have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of water
transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These consist chiefly of clays that have a high shrink-swell
potential, soils that have a high water table, soils that have a claypan or clay layer
at or near the surface, and soils that are shallow over nearly impervious material.
These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, BID, or CID), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in their
natural condition are in group D are assigned to dual classes.
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
USDA Natural Resources Web Soil Survey 5/4/2016
Conservation Service National Cooperative Soil Survey Page 3 of 4
ATTACHMENT lB
TABULAR SUMMARY OF DMAS
DMA/BMP Impervious Area, sf Pervious Area, sf Total Area, sf
1 3,874 738 4,612
2 2,859 1,560 4,419
3 3,343 5,584 8,927
4 2,500 1,085 3,585
5 1 1,110 468 1,578
6 2,721 633 3,354
7 518 443 961
See DMA Exhibit for DMNBMP locations. The impervious area includes proposed
roofs, the driveway, and hardscape. The pervious area includes proposed landscaping.
Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods
Worksheet B.2-1. DCV
him 13,
i 85 percentile 24-hr storm depth from Figure BA -I d= 0.582 inches
2 Area tributary to BMP (s) A= 0.65 acres
Area weighted runoff factor (estimate using Appendix 0.58
3 B.1.1 and B.2.1) C= unitless
0 4 Tree wells volume reduction TCV= cubic-feet
5 Rain barrels volume reduction RCV= 0 cubic-feet
Calculate DCV =
794
6 (3630 x C x d x A) - TCV - RCV DCV= cubic-feet
For the overall drainage area under proposed conditions, the pervious area
covers 11,323 sf, the impervious area covers 16,925 sf, and the total area is
28,248 sf (0.65 acres).
Based on this, the area weighted runoff factor from the equation in B.1.1 on next
sheet is:
[(11,323 x 0.1) + (16,925 x 0.9)] /28,248 = 0.58
See DCV calculations for each DMA in Attachment I E.
B-10 February 2016
Appendix I: Forms and Checklists
ATTACHMENT IC
Is there a demand for harvested water (check all that apply) at the project site that is reliably present during
the wet season?
El Toilet and urinal flushing
O Landscape irrigation
F1 Other:________________
If there is a demand; estimate the anticipated average wet season demand over a period of 36 hours. Guidance
for planning level demand calculations for toilet/urinal flushing and landscape irrigation is provided in Section
B.3.2.
[Provide a summary of calculations here]
Per "Summary of PDP Structural BMPs" section in SWQMP, there is not enough
demand for harvest and use to be feasible.
Calculate the DCV using worksheet B.2-1.
DCV = __ (cubic feet)
3a. Is the 36 hour demand greater 3b. Is the 36 hour demand greater than 3c. Is the 36 hour demand
than or equal to the DCV? 0.25DCV but less than the full DCV? less than 0.25DCV?
E Yes / 0 No => 0 Yes / 0 No IN Yes
Harvest and use appears to be Harvest and use may be feasible.
feasible. Conduct more detailed Conduct more detailed evaluation and
evaluation and sizing calculations sizing calculations to determine
to confirm that DCV can be used feasibility. Harvest and use may only be
at an adequate rate to meet able to be used for a portion of the site,
drawdown criteria, or (optionally) the storage may need to be
upsized to meet long term capture targets
while draining in longer than 36 hours.
Is harvest and use feasible based on further evaluation?
O Yes, refer to Appendix E to select and size harvest and use BMPs.
O No, select alternate BMPs.
See attached sheets for runoff factor and demand data.
See Attachment 1 B for DCV.
1-2 February 2016
0582" —
AT SITE
San Diego County
85 th Percentile lsopluvials
24-HOUR, 85TH-PERCENTILE
PRECIPITATION FROM FIGURE
B.1-1 IN CARLSBAD BMP DESIGN
MANUAL
Legend
85th PERCENTILE ISOPLUVIAL
Li INCORPORATED CITY
ENC IN1A
Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods
B.1 DCV
DCV is defined as the volume of storm water runoff resulting from the 85' percentile, 24-hr storm
event. The following hydrologic method shall be used to calculate the DCV:
DCV = C x d x A x 43,560 sf/ac x 1/12 ft/in
DCV= 3,630xCxdxA
Where:
DCV = Design Capture Volume in cubic feet
C = Runoff factor (unitless); refer to section B.1.1
d = 85th percentile, 24-hr storm event rainfall depth (inches), refer to section B.1.3
A = Tributary area (acres) which includes the total area draining to the BMP, including any
offsite or onsite areas that comingles with project runoff and drains to the BMP. Refer
to Section 3.3.3 for additional guidance. Street redevelopment projects consult Section
1.4.2.
B.1.1, Runoff Factor
Estimate the area weighted runoff factor for the tributary area to the BMP using runoff factor (from
Table B.1-1) and area of each surface type in the tributary area and the following equation:
\rA j7f -&CXX)
Axi '=)
Where:
C = Runoff factor for area X
Ax = Tributary area X (acres)
These runoff factors apply to areas receiving direct rainfall only. For conditions in which runoff is
routed onto a surface from an adjacent surface, see Section B.2 for determining composite runoff
factors for these areas.
Table B.1-1: Runoff factors for surfaces draining to BMPs - Pollutant Control BMPs
Roofs", 0.90
(Concrete orAspha1t) (0.90)
Unit Payers (grouted)1 0.90
Decomposed Granite 0.30
Cobbles or Crushed Aggregate 0.30
(01{0)
Compacted Soil (e.g., unpaved parking) 0.30
1. Surface is considered impervious and could benefit from use of Site Design BMPs and
adjustment of the runoff factor per Section B.2.1.
B-2 February 2016
Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods
Table B.3-1. Toilet and Urinal Water Usage per Resident or Employee
18.5 NA NA 0.5 9.3 Rdcntial Resident csi
Employee Office 9.0 2.27 1.1 0.5 (non-visitor) 7
(avg) Employee Retail 9.0 2.11 1.4 0.5 (non-visitor)
Schools Employee 6.7 3.5 6.4 0.5 33 (non-student)
Various Industrial
Employee Uses (excludes 9.0 2 1 0.5 (non-visitor)
process water)
1-Based on American Waterworks Association Research Foundation,1999. Residential End Uses of Water. Denver, CO: AWWARF
2 - Based on use of 3.45 gallons per flush and average number of per employee flushes per subsector, Table D-1 for MWD (Pacific
Institute, 2003)
3 - Based on use of 1.6 gallons per flush, Table D-4 and average number of per employee flushes per subsector, Appendix D (Pacific
Institute, 2003)
4 - Multiplied by the demand for toilet and urinal flushing for the project to account for visitors. Based on proportion of annual use
allocated to visitors and others (includes students for schools; about 5 students per employee) for each subsector in Table D-1 and D-
4 (Pacific Institute, 2003)
5 -Accounts for requirements to use ultra low flush toilets in new development projects; assumed that requiremeats will reduce toilet
and urinal flushing demand by half on average compared to literature estimates. Ultra low flush toilets are required in all new
construction in California as of January 1, 1992. Ultra low flush toilets must use no more than 1.6 gallons per flush and Ultra low
flush urinals must use no more than 1 gallon per flush. Note: If zero flush urinals are being used, adjust accordingly.
13.3.2.2 General Requirements for Irrigation Demand Calculations
The following guidelines should be followed for computing harvested water demand from landscape
irrigation:
If reclaimed water is planned for use for landscape irrigation, then the demand for harvested
storm water should be reduced by the amount of reclaimed water that is available during the
wet season.
Irrigation rates should be based on the irrigation demand exerted by the types of landscaping
that are proposed for the project, with consideration for water conservation requirements.
Irrigation rates should be estimated to reflect the average wet season rates (defined as
November through April) accounting for the effect of storm events in offsetting harvested
water demand. In the absence of a detailed demand study, it should be assumed that irrigation
demand is not present during days with greater than 0.1 inches of rain and the subsequent 3-
day period. This irrigation shutdown period is consistent with standard practice in land
application of wastewater and is applicable to storm water to prevent irrigation from resulting
B-13 February 2016
GEOTECHNICAL
MATERIALS ATTACHMENT I D
NOVA I SPECIAL INSPECTION
SBE • DVBE
Affirmed Housing Group
C/O Marie Allen
13520 North Evening Creek Drive
San Diego, CA 92128
Attention: Ms. Allen
March 12, 2020
NOVA Project No. 3019097
(via email; mariecaffirmedhousinq.com)
Subject: Update Geotechnical Engineering Report
Project: Proposed Three-Story Apartment Building
3606-3618 & 3630 Harding Street, Carlsbad, California
References:
CWE 2016a. Report of Preliminary Geotechnical Investigation, Affirmed Housing, 3606-3618 & 3630
Harding Street, Carlsbad, California, Christian Wheeler Engineering, June 2, 2016.
CWE 2016b. Report of Preliminary Recommendations, Affirmed Housing, 3606-3618 & 3630 Harding
Street, Carlsbad, California, Christian Wheeler Engineering, April 20, 2016.
KL 2020. Rough Grading Plan (Sheet 3 of 8), Harding Veterans Housing, Kettler Leweck Engineering,
March 11, 2020.
Dear Mrs. Allen,
The intent of this Update Geotechnical Engineering Report is to provide updated
recommendations to address changes in design and to update previously prepared seismic
design parameters for the project. NOVA Services, Inc. (NOVA) has been retained by Affirmed
Housing as Geotechnical Engineer-of-Record (GEOR) for the subject project.
NOVA has reviewed the referenced geotechnical reports and plans for the subject development.
With specific consideration of its roll as GEOR, NOVA has reviewed and agrees with the data,
recommendations, and conclusions contained in the referenced project geotechnical reports
(CWE 2016a and CWE 2016b) except as updated and revised herein.
OBSERVATIONS AND BACKGROUND
A NOVA Services representative recently visited the subject property to observe existing
conditions at the site. Observations made during the visit revealed no apparent significant
changes since the referenced reports were issued. The following Figure 1, presents an image
of the site taken during NOVA's recent site visit.
4373 Viewridge Avenue, Suite B www.usa-nova.com 24632 San Juan Avenue, Suite 100
San Diego, CA 92123 Dana Point, CA 92629
P: 858.292.7575 P: 949.388.7710
A Update Geotechnical Engineering Report
3606-3618 & 3630 Harding Street, CrIsbad, CA
Project Nc.: 3019397
NOVA March 12, 2020
Figure 1. Existing Si-.e Conditions as of December 20, 2019.
Figure 2 (following page) depicts the subsurface exploration locations based on existing site
conditions. Plates IA and I B, provided immediately following the text of this report, present
these locations in larger scale on the existing site condition and on a planned improvements
plar, respectively.
2
A
Ski
NOVA
Update Geotechnical Engineering Report
3606-3618 & 3630 Harding Street, Carlsbad, CA
Project No.: 3019097
March 12, 2020
1-igure Z.Approximate Location OT bunsurtace txpiorations
(source: adapted r0m Christian Wheeler, 2016)
Seismic Design Criteria
This site is subject to strong ground shaking due to potential fault movements along the
Newport Inglewood Fault (off-shore). Engineered design and earthquake-resistant co--is-ruction
increase safety and allow development of seismic areas.
In accordance with the project requirements, Seismic Design Parameters are updatec herein in
after the 2016 edition of the California Building Code (CBC) and ASCE 7-10. Mapped seismic
coefficients are orovided in the following Table 1.
The intent of the CBC lateral force requirerents is to provide a structural design that will resist
collapse to provide reasonable life safety from a major earthquake, but may experience some
structural and nonstructural damage. A fundamental tenet of seismic design is that inelastic
yielding is allowed to adapt to the seismic demand on the structure. In other words, damage is
allowed. The CBC lateral force requiremen:s should be considered a minimum design. The
owner and the Designer may evaluate the level of risk and performance that is acceptable.
Performance based criteria could be set in The design. The Design Engiieer should exercise
special care so that all components of the design are fully met with attention to providing a
continuous load path. An adequate quality assurance and control program is urged during
3
Update Geotechnical Engineering Report
3606-3618 & 3630 Harding Street, Carlsbad, CA
4 Project No.: 3019097 '111
NOVA March 12, 2020
project construction to verify that the design plans and good construction practices are followed.
This is especially important for sites lying close to the major seismic sources.
Table 1. Seismic Design Parameters, 2016 CBC and ASCE 7-10
Parameter Value
Site Soil Class C
Site Latitude (decimal degrees) 33.15536°N
Site Longitude (decimal degrees) - 117.33908°W
Site Coefficient, Fa 1.0
Site Coefficient, Fv 1.361
Mapped Short Period Spectral Acceleration, Ss 1.143 g
Mapped One-Second Period Spectral Acceleration, Si 0.439 g
Short Period Spectral Acceleration Adjusted for Site Class, SMS 1.143 g
One-Second Period Spectral Acceleration Adjusted for Site Class, Sm, 0.597 g
Design Short Period Spectral Acceleration, Sos 0.762 g
Design One-Second Period Spectral Acceleration, 5D1 0.398 g
Modified Peak Ground Acceleration, PGAM 10.452 g
Source: OSHPD Seismic Design Maps, found at: https://seismicmaps.orgJ
Review of Geotechnical Feasibility Criteria
It is common that seven factors be considered by the project geotechnical professional while
assessing the feasibility of infiltration related to geotechnical conditions. These factors are:
C2.1) Soil and Geologic Conditions
C2.2) Settlement and Volume Change
C2.3) Slope Stability
C2.4) Utility Considerations
C2.5) Groundwater Mounding
C2.6) Retaining Walls and Foundations
C2.7) Other Factors
The above geotechnical feasibility criteria are reviewed in the following subsections.
Soil and Conditions
The soil borings completed for this assessment disclose the sequence of soil units described
below.
Unit 1, Fill. (Qaf) Fill material was encountered generally in the upper 2 to 4 feet of
the subsurface is predominantly silty sand and placement is undocumented.
4
Update Geotechnical Engineering Report
3606-3618 & 3630 Harding Street, Carlsbad, CA
4 Project No.: 3019097
NOVA March 12, 2020
Unit 2, Old Paralic Deposits (Qop). Quaternary-age old paralic deposits were
previously encountered at depths of 2 to 4 feet below existing grade. Old paralic
deposits were found to consist of very fine to medium grained silty sand and poorly-
graded sand with silt.
Unit 3, Santiago Formation (isa). Tertiary-age sediment deposits of the Santiago
Formation were encountered at depths of about 11 feet below existing grade. When
disturbed by drilling tools, the formational material consisted of silty sand and clayey
sand.
Settlement and Volume Change
The Unit 1 and Unit 2 soils have very low expansion potential. These soils will not be prone to
swelling upon wetting. The existing fill soils may be prone to hydro consolidation upon wetting.
Slope Stability
BMPs should not be located near slopes. There are no structural slopes at the site.
Utilities
Infiltration can potentially damage subsurface and underground utilities. BMPs should be sited a
minimum of 10 feet away from underground utilities.
Groundwater Mounding
Stormwater infiltration can result in groundwater mounding during wet periods, affecting utilities,
pavements, flat work, and foundations.
Retaining Walls and Foundations
BMPs should not be located near foundations. BMPs should be sited a minimum of 25 feet
away from any foundations or retaining walls.
Other Factors
Historic ground water was found to be at depths of about 26 (+50 feet msl) feet below ground
surface 1500 feet south of the site within monitoring well no. 6 at the address of 970 Tamarack
Road. CWE reporting encountered seeping water at depths of 11 feet bgs during site
subsurface exploration.
Suitability of the Site for Stormwater Infiltration
It is NOVA's judgment that the site is not suitable for development of stormwater infiltration
BMPs. This judgment is based upon consideration of the variety of factors detailed above, most
significantly the location of planned stormwater BMPs and (i) proximity to planned foundations,
and (ii) proximity to existing utility lines and the City Right of Way (ROW).
Appendix A provides completed forms related to stormwater infiltration feasibility.
5
A
I 116.
NOVA
Update Geotechnical Engineering Report
3606-3618 & 3630 Harding Street, Carlsbad, CA
Project No.: 3019097
March 12, 2020
CLOSURE
NOVA considers that the recommendations contained in the referenced geotechnical report are
adequate and NOVA does not have additional recommendations based on the plans provided
other than those specified herein.
NOVA appreciates the opportunity to provide its services on this project. Should you have any
questions regarding this letter or other matters, please do not hesitate to contact the
undersigned at (949) 388-7710.
Sincerely,
NOVA Services, Inc.
9- V-K
— J.e"CE 84335 SViohr Engineer
r C84335
0 CM-
Attachments:
Plate IA. Subsurface Investigation Map on Existing Conditions
Plate 1 B. Subsurface Investigation Map on Proposed Development
Appendix A. Infiltration Feasibility Worksheets
6
Al GEOTECHNICAL \ \ xeia MATERIALS
SPECIAL INSPEC11ON
NOVA SEE • DVBE
24032 San Juan Avenue. Suite 100
Dana Point, CA 92629
P: 010.3887710
4373 Viewridge Avenue. Suite B
Sari Diego, CA 02123
P: 858.292.7575
-
x eo.e www.usa-nova.com
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DATE MARCH 2020 Qaf FILL 29 X6t2 X82.2 DRAWN BY DIW
*2 Qop OLD PARALIC DEPOSITS w TIM
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B-3 GEOTECHNICAL BORING (CHRISTIAN .
0 30' 60'
0 WHEELER, 2016) SUBSURFACE
x624 INVESTIGATION MAP
GEOLOGIC CONTACT, QUERIED EXISTING CONDITIONS
WHERE INFERRED
PLATE NO. 1A
Update Geotechnical Engineering Report
3606-3618 & 3630 Harding Street, Carlsbad, CA
Project No.: 3019097
NOVA I March 12, 2020
APPENDIX A
Infiltration Feasibility Worksheets
Appendix I: Forms and Checklists
Part 1 - Full Infiltration Feasibility Screening Criteria
Would infiltration of the full design volume be feasible from a physical perspective without any undesirable
consequences that cannot be reasonably mitigated?
Criteria Screening Question Yes No
Is the estimated reliable infiltration rate below proposed
facility locations greater than 0.5 inches per hour? The response
1 to this Screening Question shall be based on a comprehensive
evaluation of the factors presented in Appendix C.2 and Appendix
D.
Provide basis:
Infiltration rate of on-site soils have not been measured.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
Can infiltration greater than 0.5 inches per hour be allowed
without increasing risk of geotechnical hazards (slope stability,
2 groundwater mounding, utilities, or other factors) that cannot X be mitigated to an acceptable level? The response to this
Screening Question shall be based on a comprehensive evaluation of
the factors presented in Appendix C.2.
Provide basis:
C2.2: Settlement and Volume Change: The existing fills are subject to hydro consolidation as a result of
increased moisture content.
C2.4: Utility Considerations: The site area is relatively small and proposed and existing utility trenches and the
adjacent utility trenches within the City Right of Way are susceptible to saturation and lateral migration of
infiltrated storm water.
C2.6: Foundations: The site area is relatively small, and any proposed infiltration facilities would place infiltration
storm water in close proximity to planned foundations.
1-3 February 2016
Appendix I: Forms and Checklists
Criteri Screening Question Yes No a
Can infiltration greater than 0.5 inches per hour be allowed
without increasing risk of groundwater contamination (shallow
water table, storm water pollutants or other factors) that cannot
be mitigated to an acceptable level? The response to this
Screening Question shall be based on a comprehensive evaluation of
the factors presented in Appendix C.3.
Provide basis:
Risk of groundwater contamination has not been evaluated. However, groundwater was encountered at a
depth of 11 feet below ground surface which woulld generally be considered shallow. Depths to
groundwater from the bottom of basin would be < 10 feet.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
Can infiltration greater than 0.5 inches per hour be allowed
without causing potential water balance issues such as change
of seasonality of ephemeral streams or increased discharge of
contaminated groundwater to surface waters? The response to
this Screening Question shall be based on a comprehensive
evaluation of the factors presented in Appendix C.3.
Provide basis:
The risk of causing potential water balance issues have not been evaluated at this time.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
If all answers to rows 1 - 4 are "Yes" a full infiltration design is potentially feasible.
Part 1 The feasibility screening category is Full Infiltration
Result
* If any answer from row 1-4 is "No", infiltration may be possible to some extent but
would not generally be feasible or desirable to achieve a "full infiltration" design.
Proceed to Part 2
*To be completed using gathered site information and best professional judgment considering the definition of MEP in
the MS4 Permit. Additional testing and/or studies may be required by the City to substantiate findings.
1-4 February 2016
Appendix I: Forms and Checklists
Part 2— Partial Infiltration vs. No Infiltration Feasibility Screening Criteria
Would infiltration of water in any appreciable amount be physically feasible without any negative
consequences that cannot be reasonably mitigated?
Criteria Screening Question Yes No
Do soil and geologic conditions allow for infiltration in any
5 appreciable rate or volume? The response to this Screening X
Question shall be based on a comprehensive evaluation of the
factors presented in Appendix C.2 and Appendix D.
Provide basis:
C2.2: Settlement and Volume Chance: The existing fills are subject to hydro consolidation as a result of
increased moisture content.
C2.4: Utility Considerations: The site area is relatively small and proposed and existing utility trenches and the
adjacent utility trenches within the City Right of Way are susceptible to saturation and lateral migration of
infiltrated storm water.
C2.6: Foundations: The site area is relatively small, and any proposed infiltration facilities would place infiltration
storm water in close proximity to planned foundations.
Can Infiltration in any appreciable quantity be allowed
without increasing risk of geotechnical hazards (slope
6 stability, groundwater mounding, utilities, or other factors) X
that cannot be mitigated to an acceptable level? The response
to this Screening Question shall be based on a comprehensive
evaluation of the factors presented in Appendix C.2.
Provide basis:
C2.2: Settlement and Volume Change: The existing fills are subject to hydro consolidation as a result of
increased moisture content.
C2.4: Utility Considerations: The site area is relatively small and proposed and existing utility trenches
and the adjacent utility trenches within the City Right of Way are susceptible to saturation and lateral
migration of infiltrated storm water.
C2.6: Foundations: The site area is relatively small, and any proposed infiltration facilities would place
infiltration storm water in close proximity to planned foundations.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates.
1-5 February 2016
Appendix I: Forms and Checklists
&M
Criteria Screening Question Yes No
Can Infiltration in any appreciable quantity be allowed
without posing significant risk for groundwater related
concerns (shallow water table, storm water pollutants or other
factors)? The response to this Screening Question shall be based
on a comprehensive evaluation of the factors presented in
Appendix CA
Provide basis:
Risk of groundwater contamination has not been evaluated at this time.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates.
Can infiltration be allowed without violating downstream
8 water rights? The response to this Screening Question shall be
based on a comprehensive evaluation of the factors presented in
Appendix C.3.
Provide basis:
Risk of potential water balance issues has not been evaluated at this time.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates.
If all answers from row 5-8 are yes then partial infiltration design is potentially feasible.
P 2The Part feasibility screening category is Partial Infiltration.
No Result* If any answer from row 5-8 is no, then infiltration of any volume is considered to be i ci +• Infiltration
infeasible within the drainage area. The feasibility screening category is No Infiltration.
'To be completed using gathered site information and best professional judgment considering the definition of MEP in
the MS4 Permit Additional testing and/or studies may be required by the City to substantiate findings.
1-6 February 2016
w
CHRISTIAN WHEELER-
EN G IN E E P,- ING
The groundwater excerpt from the preliminary
report is included for reference.
REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION
AFFIRMED HARDING STREET
3606-3618 AND 3630 HARDING STREET
CARLSBAD, CALIFORNIA
PREPARED FOR:
AFFIRMED HOUSING GROUP
13520 EVENING CREEK DRIVE N, SUITE 160
SAN DIEGO, CALIFORNIA 92128
PREPARED BY:
CHRISTIAN WHEELER ENGINEERING
3980 HOME AVENUE
SAN DIEGO, CALIFORNIA 92105
3980 Home Avenue + San Diego, CA 92105 + 619-550-1700 + FAX 619-550-1701
I"
CHRISTIAN WHEELER
ENGINEERING
August 4, 2016
Affirmed Housing Group CWE 2160237.02R
13520 Evening Creek Drive N, Suite 160
San Diego, California 92128
Attention: Sydney Cordova
Subject: Report of Preliminary Geotechnical Investigation
Affirmed Harding Street, 3606-3618 and 3630 Harding Street, Carlsbad,
California
Ladies and Gentlemen:
In accordance with your request and our proposal dated April 20, 2016, we have completed a
geotechnical investigation for the subject project. We are presenting herewith a report of our findings
and recommendations.
It is our professional opinion and judgment that no geotechnical conditions exist on the subject
property that would preclude the construction of the proposed apartment project provided the
recommendations presented herein are followed.
If you have questions after reviewing this report, please do not hesitate to contact our office. This
opportunity to be of professional service is sincerely appreciated.
Respectfully submitted,
CHRISTIAN WHEELER ENGINEERING
WDaniel., 4RCE 0 6037
DBA:tsw
Sydney@affirmedhousing.com
NAL
jj No. 2551
0.. CERTIFIED —4
ENGINEERING
* GEOLOGIST *
Expires i-al-li
9f.-'J L
OF
CA
Troy S. Wilson, C.E.G. #2551
3980 Home Avenue + San Diego, CA 92105 + 619-550-1700 + FAX 619-550-1701
CWE 2160237.02R August 4, 2016 Page No. 4
may exist in areas of the site not investigated. These materials generally consisted of brown and
dark brown, dry to moist, loose, silty sand (SM). The topsoil/artificial fill was judged to have a
very low expansion potential (El < 20). The soil was judged to be in Hydrologic Soil Group B
and considered susceptible to hydro-collapse.
OLD PARALIC DEPOSITS (Qop): Quaternary-age old paralic (terrace) deposits were
encountered underlying the undifferentiated topsoil/artificial fill. The old paralic deposits
extended to a depth of about ii feet below existing grade. The old paralic deposits generally
consisted of light brown, light orangish-brown, and light gray, moist to very moist, medium
dense and dense, poorly graded sand with silt (SP-SM), with some interbedded layers of silty sand
(SM). The upper 1112 feet was weathered within boring B-i. The old paralic deposits were judged
to have a very low Expansion Index (El <20). The soil was judged to be in Hydrologic Soil Group
C and considered susceptible to hydro-collapse.
SANTIAGO FORMATION (Tsa): Tertiary-age sedimentary deposits of the Santiago
Formation were encountered underlying the old paralic deposits at a depth of about 11 feet
below existing grade. The formational soils generally consisted of light gray and olive gray, very
moist and moist, silty sand (SM) and clayey sand (SC). The sandy Santiago Formation was judged
to have a very low Expansion Index (El < 20) whereas the clayey formational soils were judged to
have a lcw to medium Expansion Index (El between 21 and 90). Based on the soil conditions
observec and the perched water, the soil was judged to be in Hydrologic Soil Group D.
GROUNDWATER: Perched groundwater was encountered in all the borings at the contact between
the old paralic deposits and the Santiago Formation(pgeneral, groundwater was encountered at a dep)
(f about 11 feet blow existing gWe do not expect any significant groundwater related conditions
during or after the proposed construction. However, it should be recognized that minor groundwater
seepage problems might occur after construction and landscaping are completed, even at a site where
none were present before construction. These are usually minor phenomena and are often the result of
an alteration in drainage patterns and/or an increase in irrigation water. Based on the anticipated
construction and the permeability of the on-site soils, it is our opinion that any seepage problems that
may occur will be minor in extent. It is further our opinion that these problems can be most
effectively corrected on an individual basis if and when they occur.
ATTACHMENT I
Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods
Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs
w
1 1 Remaining DCV after implementing retention BMPs 1 cubic-feet
Partial Retention
2 Infiltration rate from Form 1-9 if partial infiltration is feasible in/hr.
3 Allowable drawdown time for aggregate storage below the underdrain 36 hours
4 Depth of runoff that can be infiltrated [Line 2 x Line 3] inches
5 Aggregate pore space 0.40 in/in
6 1 Required depth of gravel below the underdrain [Line 4/ Line 51 inches
7 Assumed surface area of the biofiltration BMP sq-ft
8 Media retained pore storage 0.1 in/in
9 Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 cubic-feet
10 DCV that requires biofiltration [Line 1 - Line 9] cubic-feet
BMP Parameters
11 Surface Ponding [6 inch minimum, 12 inch maximum] inches
12 Media Thickness [18 inches minimum], also add mulch layer thickness to
this line for sizing calculations inches
13 Aggregate Storage above underdrain invert (12 inches typical) - use 0
inches for sizing if the aggregate is not over the entire bottom surface area inches
14 Media available pore space 0.2 in/in
15
-
Media filtration rate to be used for sizing (5 in/hr. with no outlet control;
. i if the filtration s controlled by the outlet, use the outlet controlled rate)
5 in/hr..
Baseline Calculations
16 Allowable Routing Time for sizing 6 hours
17 Depth filtered during storm [Line 15 x Line 16] 30 inches
18 Depth of Detention Storage
. . . [Lin e_11+_(Line_12 x Line (Line x Line 5)] _14)_+_ _13 inches
19 Total Depth Treated [Line 17 + Line 18] inches
9ption_1 - Biofilter_1.5_ times _the _DCV
20 Required biofiltered volume [1.5 x Line 10] cubic-feet
21 Required Footprint [Line 20/ Line 19] x 12 sq-ft
Option 2 - Store 0.75 of remaining DCV in pores and ponding
22 Required Storage (surface + pores) Volume [0.75 x Line 10] cubic-feet
23 Required Footprint [Line 22/ Line 18] x 12 sq-ft
Footprint of the BMP
24 Area draining to the BMP sq-ft
25 Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and B.2)
26 Minimum BMP Footprint [Line 24 x Line 25 x 0.03] sq-ft
27 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 26) sq-ft
Note: Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until
its equivalent to the required biofiltration footprint (either Line 21 or Line 23)
See attached spreadsheet for individual bioretention basin sizing calculations based on this worksheet.
B-26 February 2016
BIOFILTRATION BASIN SIZING FOR TREATMENT CONTROL
Design Capture Volume (Worksheet B.2-1. DCV, cf)
Biofiltration Basin 1 Biofiltration Basin 2 Biofiltration Basin 3
85th %, in 0.582 85th %, in 0.582 85th %, in 0.582
Area, ac 0.11 Area, ac 0.10 Area, ac 0.20
C 0.77 C 0.62 C 0.40
DCV, cf 173 DCV, cf 132 DCV, cf 173
Pervious, sf 738 Pervious, sf 1,560 Pervious, sf 5,584
Impervious, sf 3,874 Impervious, sf 2,859 Impervious, sf 3,343
Total 4,612 Total 4,419 Total 8,927
Note: C is determined from the following equation using above values:
C = [(Impervious x 0.9) + (Pervious x 0.1)]! Total
Basin Sizing (Worksheet B.5-1)
Biofiltration Basin 1
Row Number on
Worksheet B.5-1 Value
1 173
2 0
3 36
4 0
5 0.4
6 0
7 0
8 0.1
9 0
10 173
11 6
12 21
13 12
14 0.2
15 5
16 6
17 30
18 15
19 45
20 259
21 69
22 130
23 104
24 4,612
25 0.77
26 107
27 [ 107
Biofiltration Basin 2
Worksheet B.5-1 B.5•
1 Value
1 132
2 0
3 36
4 0
5 0.4
6 0
7 0
8 0.1
9 0
10 132
11 6
12 21
13 12
14 0.2
15 5
16 6
17 30
18 15
19 45
20 199
21 53
22 99
23 79
24 4,419
25 0.62
26 82
27 [ 82]
Biofiltration Basin 3
Row Number on
Worksheet B5-1 Value
1 173
2 0
3 36
4 0
5 0.4
6 0
7 0
8 0.1
9 0
10 173
11 6
12 21
13 12
14 0.2
15 5
16 6
17 30
18 15
19 45
20 260
21 69
22 130
23 104
24 8,927
25 0.40
26 107
27
Biofiltration Basin 4 Biofiltration Basin 5 Biofiltration Basin 6
85th %, in 0.582 85th %, in 0.582 85th %, in 0.582
Area, ac 0.08 Area, ac 0.04 Area, ac 0.08
C 0.66 C 0.66 C 0.75
DCV, cf 114 DCV, cf 51 DCV, cf 122
Pervious, sf 1,085 Pervious, sf 468 Pervious, sf 633
Impervious, sf 2,500 Impervious, sf 1,110 Impervious, sf 2,721
Total 3,585 Total 1,578 Total 3,354
Note: C is determined from the following equation using above values:
C = [(Impervious x 0.9) + (Pervious x 0.1)] / Total
Biofiltration Basin 4 Biofiltration Basin 5 Biofiltration Basin 6
Row Number on Row Number on Row Number on
Worksheet B.5-1 Value Worksheet B.5-1 Value Worksheet B.5-1 Value
1 114 1 51 1 122
2 0 2 0 2 0
3 36 3 36 3 36
4 0 4 0 4 0
5 0.4 5 0.4 5 0.4
6 0 6 0 6 0
7 0 7 0 7 0
8 0.1 8 0.1 8 0.1
9 0 9 0 9 0
10 114 10 51 10 122
11 6 11 6 11 6
12 21 12 21 12 21
13 12 13 12 13 12
14 0.2 14 0.2 14 0.2
15 5 15 5 15 5
16 6 16 6 16 6
17 30 17 30 17 30
18 15 18 15 18 15
19 45 19 45 19 45
20 172 20 76 20 183
21 46 21 20 21 49
22 86 22 38 22 91
23 69 23 30 23 73
24 3,585 24 1,578 24 3,354
25 0.66 25 0.66 25 0.75
26 71 26 31 26 75
27 [71 1 27 31 1 27 [
Biofiltration Basin 7
85th %, in 0.582
Area, ac 0.02
C 0.53
DCV, cf 25
Pervious, Sf 443
Impervious, sf 518
Total 961
Note: C is determined from the following equation using above values:
C = [(Impervious x 0.9) + (Pervious x 0.1)1/Total
Biofiltration Basin 7
Row Number on
Worksheet B.5-1 Value
1 25
2 0
3 36
4 0
5 0.4
6 0
7 0
8 0.1
9 0
10 25
11 6
12 21
13 12
14 0.2
15 5
16 6
17 30
18 15
19 45
20 37
21 10
22 19
23 15
24 961
25 0.53
26 15
27 15
pq
I
ATTACHMENT 2
BACKUP FOR PDP HYDROMODIFICATION CONTROL MEASURES
[This is the cover sheet for Attachment 2.1
Indicate which Items are Included behind this cover sheet:
Attachment Contents Checklist
Sequence
Attachment 2a Hydromodification Management E Included N/A, project is exempt
Exhibit (Required) from hydromodification.
See Hydromodification Management
Exhibit Checklist on the back of this
Attachment cover sheet.
Attachment 2b Management of Critical Coarse 0 Exhibit showing project drainage
Sediment Yield Areas (WMAA Exhibit boundaries marked on WMAA is required, additional analyses are Critical Coarse Sediment Yield
optional) Area Map (Required) N/A
See Section 6.2 of the BMP Design Optional analyses for Critical Coarse Manual. Sediment Yield Area Determination
06.2.1 Verification of Geomorphic
Landscape Units Onsite
06.2.2 Downstream Systems
Sensitivity to Coarse Sediment
0 6.2.3 Optional Additional Analysis
of Potential Critical Coarse
Sediment Yield Areas Onsite
Attachment 2c Geomorphic Assessment of Receiving X Not performed
Channels (Optional) o Included
See Section 6.3.4 of the BMP Design
Manual.
Attachment 2d Flow Control Facility Design and 0 Included N/A. project is exempt
Structural BMP Drawdown from hydromodification.
Calculations (Required)
See Chapter 6 and Appendix G of the
BMP Design Manual
3
I
I®
ATTACHMENT 3
Structural BMP Maintenance Information
Use this checklist to ensure the required information has been included in the Structural
BMP Maintenance Information Attachment:
Preliminary Design/Planning/CEQA level submittal:
Attachment 3 must identify:
LI Typical maintenance indicators and actions for proposed structural BMP(s) based
on Section 7.7 of the BMP Design Manual
Final Design level submittal:
Attachment 3 must identify:
X Specific maintenance indicators and actions for proposed structural BMP(s). This
shall be based on Section 7.7 of the BMP Design Manual and enhanced to reflect
actual proposed components of the structural BMP(s)
X How to access the structural BMP(s) to inspect and perform maintenance
LI Features that are provided to facilitate inspection (e.g., observation ports,
cleanouts, silt posts, or other features that allow the inspector to view necessary
components of the structural BMP and compare to maintenance thresholds)
o Manufacturer and part number for proprietary parts of structural BMP(s) when
applicable
LI Maintenance thresholds for BMPs subject to siltation or heavy trash(e.g., silt level
posts or other markings shall be included in all BMP components that will trap and
store sediment, trash, and/or debris, so that the inspector may determine how full
the BMP is, and the maintenance personnel may determine where the bottom of
the BMP is . If required, posts or other markings shall be indicated and described
on structural BMP plans.)
X Recommended equipment to perform maintenance
LI When applicable, necessary special training or certification requirements for
inspection and maintenance personnel such as confined space entry or
hazardous waste management
STRUCTURAL BMP MAINTENANCE
The project proposes seven biofiltration basins for its structural pollutant control BMPs. The
biofiltration basins will contain overflow catch basins set approximately 6" above each basin floor
(or other approved outlet) to convey the flow rates in excess of the water quality flows.
Biofiltration basins are shallow, vegetated basins underlain by an engineered soil media and gravel.
Healthy plant and biological activity in the root zone maintain and renew the macro-pore space in
the soil and maximize plant uptake of pollutants and runoff. This keeps the BMP from becoming
clogged and allows more of the soil column to function as both a sponge (retaining water) and a
highly effective and self-maintaining biofilter.
The landscape maintenance staff shall inspect each basin during routine weekly landscaping
maintenance visits. Access will be from adjacent walkways, landscape areas, or paved areas. The
vegetation shall be replanted, trimmed, pruned, and removed manually, as needed, to maintain
proper coverage and growth. The irrigation system shall be maintained, as needed. The drainage
overflow from the basins and interconnecting pipes shall be inspected monthly and after large
storm events. Debris, sediment, and other obstructions shall be removed immediately from each
basin, its outlet, and the interconnecting pipes. The infiltration rate shall be reviewed during storm
events and the underlying soil/gravel shall be replaced as needed to maintain the required
drawdown time. The removal can be performed with manual tools or a small bobcat type
excavator.
Signs identifying the biofiltration basins and the need for preservation shall be installed in each
basin. The grading plans identify the required signage.
Chapter 7: Long Term Operation and Maintenance
Vegetation requirements including plant type, coverage, and minimum height when applicable
shall be provided on the structural BMP and/or landscaping plans as appropriate or as required
by the City Engineer and/or City Planner.
Signage indicating the location and boundary of the structural BMPs such as Retention and/or
Biofiltration Basin is required.
When designing a structural BMP, the engineer should review the typical structural BMP maintenance
actions listed in Section 7.7 to determine the potential maintenance equipment and access needs.
When selecting permanent structural BMPs for a project, the engineer-of-work and project owner
should consider the long term cost of maintenance and what type of maintenance contracts a future
property owner, homeowners association or property owners association will need to manage. The
types of materials used (e.g. proprietary vs. non-proprietary parts), equipment used (e.g. landscape
equipment vs. vactor truck), actions/labor expected in the maintenance process and required
qualifications of maintenance personnel (e.g. confined space entry) affect the cost of long term O&M
of the structural BMPs presented in this manual.
7.7
StructuraFBM'P
This Section presents typical maintenance indicators and expected maintenance actions
(routine and corrective) for typical structural BMPs.
There are many different variations of structural BMPs, and structural BMPs may include multiple
components. For the purpose of maintenance, the structural BMPs have been grouped into four
categories based on common maintenance requirements:
or fiiB)
Non-vegetated infiltration BMPs
Non-vegetated filtration BMPs
Detention BMPs
The project civil engineer is responsible for determining which categories are applicable based on the
components cf the structural BMP, and identifying the applicable maintenance indicators from within
the category. Maintenance indicators and actions shall be included in the project-specific O&M section
of the SWQMP.
During inspection, the inspector checks the maintenance indicators. If one or more thresholds are
met or exceeded, maintenance must be performed to ensure the structural BMP will function as
designed during the next storm event.
7.7.1 Maintenance of Vegetated Infiltration or Filtration BMPs
"Vegetated infiltration or filtration BMPs" are BMPs that include vegetation as a component of the
BMP. Applicable Fact Sheets may include INF-2 (bioretention in Appendix E.9), PR-1 (biofiltration
with partial retention in Appendix E.li), BF-1 (biofiltration in Appendix E.12) or FT-1 (vegetated
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Chapter 7: Long Term Operation and Maintenance
swale in Appendix E.15)*. The vegetated BMP may or may not include amended soils, subsurface
gravel layer, underdrain, and/or impermeable liner. The project civil engineer is responsible for
determining which maintenance indicators and actions shown below are applicable based on the
components of the structural BMP.
TABLE7:2:Mifjtenance IifdiEtors
Accumulation of sediment, litter,, or Remove and properly dispose of accumulated materials, without
debris damage to the vegetation.
Poor vegetation establishment Re-seed, re-plant, or re-establish vegetation per original plans.
Overgrown vegetation Mow or trim as appropriate, but not less than the design height of
the vegetation per original plans when applicable (e.g. a vegetated
swale may require a minimum vegetation height).
Erosion due to concentrated irrigation Repair/re-seed/re-plant eroded areas and adjust the irrigation
flow system.
Erosion due to concentrated storm Repair/re-seed/re-plant eroded areas, and make appropriate
water runoff flow corrective measures such as adding erosion control blankets,
adding stone at flow entry points, or minor re-grading to restore
proper drainage according to the original plan. If the issue is not
corrected by restoring the BMP to the original plan and grade, the
City Engineer shall be contacted prior to any additional repairs or
reconstruction.
Standing water in vegetated swales used Make appropriate corrective measures such as adjusting irrigation
for pretreatment and/or site design system, removing obstructions of debris or invasive vegetation,
BMPs i loosening or replacing top soil to allow for better infiltration, or
minor re-grading for proper drainage. If the issue is not corrected
by restoring the BMP to the original plan and grade, the City
Engineer shall be contacted prior to any additional repairs or
reconstruction.
Standing water in bioretention, Make appropriate corrective measures such as
biofiltration with partial retention, or inspecting/unclogging orifice opening, adjusting irrigation system,
biofiltration areas, or flow-through removing obstructions of debris or invasive vegetation, clearing
planter boxes* for longer than 96 hours underdrains (where applicable), or repairing/replacing clogged or
following a storm event** compacted soils.
Obstructed inlet or outlet structure Clear obstructions.
Damage to structural components such Repair or replace as applicable.
as weirs, inlet or outlet structures
**These BMPs typically include a surface ponding layer as part of their function which may take 96 hours to
drain following a storm event.
'Vegetated swales and flow-through planter boxes in regards to flow-thru treatment control BMPs are not options as
structural BMPs. Carlsbad has not adopted an Alternative Compliance Program.
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E
ATTACHMENT 4
City standard Single Sheet BMP (SSBMP) Exhibit
[Use the City's standard Single Sheet BMP Plan.],