HomeMy WebLinkAboutSDP 16-13; CARLSBAD VETERANS HOUSING; STORM WATER MANATEMENT PLAN; 2020-06-05CITY OF CARLSBAD
PRIORITY DEVELOPMENT PROJECT (POP)
STORM WATER QUALITY MANAGEMENT PLAN (SWQMP)
FOR
OAK VETERANS HOUSING
(965 AND 967 OAK AVENUE)
PROJECT ID: SDP 16-13
GR 2020-0008, Drawing No. 523-5A
ENGINEER OF WORK:
((ffNo. 46548
Exp. 6/30/21
j
Wayne W. Chang, MS, fE 46548, Expir021
'
30~/
PREPARED FOR:
AFFIRMED HOUSING GROUP
13520 EVENING CREEK DRIVE NORTH, SUITE 160
SAN DIEGO, CA 92128
(858) 679-2828
PREPARED BY:
ChInVammm
Civil Engineering o Hydrology a Hydraulics o Sedimentation
P.O. Box 9496
Rancho Santa Fe, CA 92067
(858) 692-0760
DATE:
JUNE 5, 2020
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 Classification Map
Attachment Ib: Tabular Summary of DMAs and Design Capture Volume Calculations
Attachment 1c: Harvest and Use Feasibility Screening (when applicable)
Attachment id: Categorization of Infiltration Feasibility Condition (when applicable)
Attachment le: Pollutant Control BMP Design and DCV Worksheets / 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: Oak Veterans Housing
Project ID: SDP 16-13
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.
46548, Expires 6/30/2021
Work's Signre, PE Number & Expiration Date
Wayne W. Chang
Print Name
Chang Consultants
Company
June 5, 2020
Date
ç.O5ESSI
ff No. 46548 oVI
CF
IOTA
rrov
AN MARCOS
CITY OF 9NCINITAS
PROJECT VICINITY MAP
( STORM WATER STANDARDS Development Services city of
Carlsbad QUESTIONNAIRE Land Development Engineering
1635 Faraday Avenue
E-34 (760) 602-2750
www.carlsbadca.gov
,... . ................. .,,,:,. .. ........... . .. ......1
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: Oak Veterans Housing PROJECT ID: SDP 16-13
ADDRESS: 965 and 967 Oak Avenue, Carlsbad, CA 92008 APN: 204-111-02
The project is (check one): 0 New Development 0 Redevelopment
The total proposed disturbed area is: 18,944 ft2 (0.435 acres
The total proposed newly created and/or replaced impervious area is: 14,299 2 ( 0.328 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 Swamp #: 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 02/16
1 ... :.,. ,. .... • . TOBE COM
STEP
PLETEDJQk,1LL 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
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.
TER A11.
TO B9,COMPLEYEPQR
To determine if your project is exempt from POP 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;
C) 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
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 discussionljustification below, then go to Step 5, mark
the second box stating 'my project is EXEMPT from POP . .." 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 02116
S!1EP3
To determine if your project is a POP, 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, 0 111
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 0 121
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 0 121
development on_ any that is twenty-five greater. _project _includes _development _natural _slope _percent _or
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 0 El 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
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? 0 121
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 3of4 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) = 3,992 sq. ft. 0 0
Total proposed newly created or replaced impervious area (B) =_14,299 sq. ft.
Percent impervious area created or replaced (B/A)'lOO = 358
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 POP ...' 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 POP ...' and complete applicant Information.
STEP 5
CHECK THE APPROPRIATE BOX AND COMPLETE APPLICANT INFORMATION
IZ) My project Is a POP and must comply with POP 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 POP 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 close to meeting the POP threshold, staff may require detailed impervious area calculations
and exhibits to verify If 'STANDARD PROJECT stormwater requirements apply.
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: 1'V"\tft.LJ2 Date:
uvIrI.uIuwIItIIy Quifillivu fvw=ul'.1w. IJUl ow iuui ,uullou w dii '..uowi VYdWE pzg ecuan Impairea water Dodies; areas designated as Area of Spidàt Biological Significance by the SW. Water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1994) 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); area designated as preselves 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 wltith have been identified by the City.
ThiR any frir1M, I )am lint,,
CIty Concurrence:
YES NO
[ o o
By:
Date:
Project ID:
E-34 Page 4cf4 REV021I6
SITE INFORMATION CHECKLIST
ProjectSümmaryIiiformatibn
Project Name Oak Veterans Housing
Project ID SDP 16-13
Project Address 965 and 967 Oak Avenue
Carlsbad, CA 92008
Assessor's Parcel Number(s) (APN(s)) 204111-02
Project Watershed (Hydrologic Unit) Carlsbad 904
Parcel Area 0.434 Acres (18,894 Square Feet)
Existing Impervious Area
(subset of Parcel Area) 0.092 Acres (3,992 Square Feet)
Area to be disturbed by the project
(Project Area) 0.435 Acres (18,944 Square Feet)
Project Proposed Impervious Area
(subset of Project Area) 0.328 Acres (14,299 Square Feet)
Project Proposed Pervious Area
(subset of Project Area) 0.107 Acres (4,645 Square Feet)
Note: Proposed Impervious Area + Proposed Pervious Area = Area to be Disturbed by the
Project.
This may be less than the Parcel Area.
Z M..DësriPtion6f ExiStirigSitèCÔflditiöh
Current Status of the Site (select all that apply):
X Existing development
Previously graded but not built out
LI Agricultural or other non-impervious use
O Vacant, undeveloped/natural
Description /Additional Information:
The site historically contained two separate single-family residences and a detached garage
behind the two residences. 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.
Underlying Soil belongs to Hydrologic Soil Group (select all that apply):
0 NRCS Type A
XNRCS Type B
DNRCS Type C
LINRCS Type D
Approximate Depth to Groundwater (GM:
O GW Depth < 5 feet
Li 5 feet < GW Depth < 10 feet
X 10 feet < GW. Depth <20 feet (13 to 14 feet per soils report)
0 GW Depth > 20 feet
Existing Natural Hydrologic Features (select all that apply):
Watercourses
O Seeps
Springs
O Wetlands
X None
Description /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 the gently sloping lot. The lot slopes
towards the westerly property line, then northerly along a wall on the westerly property line to
Oak Avenue. The drainage conveyance is urban and typical of single-family residential
development. Storm runoff sheet flows across the site and ultimately to the adjacent public
street, Oak Avenue.
Another single-family lot is adjacent to the east side of the project site and Interstate 5 is just
east of the adjacent lot. There is an approximately 13-foot high slope along the adjacent lot that
rises up to Interstate 5. Off-site storm runoff from the slope is conveyed onto the adjacent lot,
combines with flow on the adjacent lot, and is then directed onto the project site approximately
midway along the project site's easterly boundary. The on- and off-site runoff then flows across
the existing project site as described in the preceding paragraph and onto Oak Avenue.
3Décriptión ofPoosedSitëDévèlbptheflt
Project Description I Proposed Land Use and/or Activities:
The project will provide for veterans housing. There will be three floors containing 24 units
varying from studios to two bedrooms and 23 parking stalls (2 outdoor and 21 indoor). A parking
garage, office, lobby, and trash storage will be on the ground level. An office, laundry room,
trash storage, and residential units will be on the second level. A laundry room, trash storage,
and residential units will be on the third level.
List/describe 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, hardscape, and
walkways. In addition, new curb, gutter, and sidewalk along the Oak Avenue 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
U No
Description I 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
U No
Description /Additional Information:
A private on-site drainage system will be installed to direct the project runoff to the proposed
biofiltration basins. Once treated, the runoff will be conveyed towards Oak Avenue. A portion of
the runoff will flow directly onto Oak Avenue, while a portion will be conveyed to the existing
public storm drain along the project frontage within Oak Avenue. The off-site run-on will be
captured by a separate storm drain system to avoid commingling with the on-site runoff. The
separate storm drain will convey the off-site runoff to Oak Avenue.
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
Li Pools, spas, ponds, decorative fountains, and other water features
U Food service
X Refuse areas
LI Industrial processes
U Outdoor storage of equipment or materials
Vehicle and Equipment Cleaning
Vehicle/Equipment Repair and Maintenance
Fuel Dispensing Areas
Loading Docks
X Fire Sprinkler Test Water
X Miscellaneous Drain or Wash Water
X Plazas, sidewalks, and parking lots
.: çldentificatión ofReeiingWateiPolIutihtsbf CôWceth:
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 Oak Avenue. 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
Oil& Grease A
Bacteria & Viruses P
Pesticides A
:
Do hydromodification management requirements apply (see Section 1.6 of the BMP Design
Manual)?
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.
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.
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 I Additional Information (to be provided if a 'No' answer has been selected above):
Site runoff is captured by a public storm drain in Oak Avenue adjacent to the site. The storm
drain continues west to Harding Street, extends south down Harding Street, turns west onto
Chestnut Avenue, 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
Critióal Coarse Sediment Yield Areas*
*This Section only required if hydromodification managementrequirements apply.
Based on the maps provided within the WMAA, do potential critical coarse sediment yield areas
exist within the project drainage boundaries?
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?
El 6.2.1 Verification of Geomorphic Landscape Units (GLUs) Onsite
El 6.2.2 Downstream Systems Sensitivity to Coarse Sediment
6.2.3 Optional Additional Analysis of Potential Critical Coarse Sediment Yield Areas Onsite
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?
No critical coarse sediment yield areas to be protected based on verification of GLUs onsite
El Critical coarse sediment yield areas exist but additional analysis has determined that
protection is not required. Documentation attached in Attachment 8 of the SWQMP.
El 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
CCSYksat the site.
-
.1.: • W:
IQ& 1hIstSectuon only:reguired.require
List and describe point(s) of compliance (POCs) for flow control for hydromodification
management (see Section 6.3.1). For each POC, 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)
Yes, the result is the low flow threshold is 0.1 Q2
Yes, the result is the low flow threshold is 0.3Q2
0 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..Re ons ran
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 13 to 14 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.
Ccity of
Carlsbad
STANDARD PROJECT
REQUIREMENT
CHECKLIST
E-36
Development Services
Land Development Engineering
1635 Faraday Avenue
(760) 602-2750
www.carlsbadca.gov
Projectlnfo?nation -
Project Name: Oak Veterans Housing
Project ID: SDP 16-13
DWG No. or Building Permit No.: Drawing No. 523-5A
Source Cóntçol BMPs.
All development projects must implement source control BMPs SC-I 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. Discussionljustification 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). Discussionljustification may be
provided.
Source Control Requirement Applied?
SC-1 Prevention of Illicit Discharges into the MS4 0 Yes 0 No 0 N/A
Discussionljustification 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
Dispersal 0 Yes 0 No 0N/A
Discussion/justification 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 r-i yes U r N0 N/A
Discussion/justification if SC-4 not implemented:
N/A
SC-5 Protect Trash Storage Areas from Rainfall, Run-On, Runoff, and Wind Dispersal 0 Yes 1 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
121 Interior floor drains and elevator shaft sump pumps Iii Yes 0 No 0 N/A
J Interior parking garages 121 Yes 0 No 0 N/A
121 Need for future indoor & structural pest control 121 Yes 0 No 0 N/A
J Landscape/Outdoor.Pesticide Use 121 Yes 0 No 0 N/A
Pools, spas, ponds, decorative fountains, and other water features 0 Yes 0 No 121 N/A
Food service 0 Yes 0 No 121 N/A
121 Refuse areas 121 Yes 0 No 0 N/A
Industrial processes 0 Yes 0 No 121 N/A
Outdoor storage of equipmentor materials 0 Yes 0 No 121 N/A
Vehicle and Equipment Cleaning 0 Yes 0 No 121 N/A
Vehicle/Equipment Repair and Maintenance 0 Yes 0 No 0 N/A
Fuel Dispensing Areas 0 Yes 0 No 121 N/A
Loading Docks 0 Yes 0 No 121 N/A
121 Fire Sprinkler Test Water 121 Yes 0 No 0 N/A
I Miscellaneous Drain or Wash Water 121 Yes 0 No 0 N/A
121 Plazas, sidewalks, and parking lots 121 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-I 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. Discussionljustification 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 l N/A
Discussion/justification if SD-I not implemented:
N/A. The current site is developed.
SD-2 Conserve Natural Areas, Soils, and Vegetation I 0 Yes I 0 No I 121 N/A
Discussion/justification if SD-2 not implemented:
N/A. The current site is developed.
SD-3 Minimize Impervious Area I IZI Yes I 0 No I 0 N/A
Discussion/justification if SD-3 not implemented:
N/A
SD-4 Minimize Soil Compaction I Yes I 0 No I 0 N/A
Discussion/justification if SD-4 not implemented:
N/A
SD-5 Impervious Area Dispersion 121 Yes I 0 No I 0 N/A
Discussionljustification if SD-5 not implemented:
N/A
E-36 Page 3 of 4 Revised 03116
SourceControlReqUirernEnt(contifluëd) * Applied'
SD-6 Runoff Collection 21 Yes 0 No 0 N/A
Discussion/justification if SD-6 not implemented:
N/A
SD-7 Landscaping with Native or Drought Tolerant Species I 21 Yes I 0 No I 0 N/A
Discussion/justification if SD-7 not implemented:
N/A
SD-8 Harvesting and Using Precipitation I 0 Yes 0 No I 21 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
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 0.583
inches (see Attachment IC). The DCV based on this value is calculated on attached Worksheet
B.2-1 and is 648 cubic feet. Form 1-7 from the manual indicates that the 36 hour demand must
be greater than 0.25DCV (0.25 x 648 cf = 162 cf or 1,212 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 87 residents (1,212 - 14
= 87) for harvest and use to be feasible. The project will merely create 24 units (including 14
studios), which will support less than 87 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 ID). Furthermore, the groundwater is 13
to 14 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-
I from the Manual (see Attachment I E). The biofiltration basins will be adjacent to buildings, so
impervious liners are anticipated. Sizing has been performed for the each of the six 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.
•:• StrucraI •BMP Sun "ärylnf&ñiätiàii •:.•.:•1 a Mg FrNww : wlCdpy' AA' this page ?
Structural BMP ID No. Biofiltration Basin I through 6
DWG: Grading Plan Sheet No. 3
Type of structural BMP:
Li Retention by harvest and use (HU-1)
Li Retention by infiltration basin (lNF-1)
Li Retention by bioretention (INF-2)
U Retention by permeable pavement (INF-3)
o Partial retention by biofiltration with partial retention (PRA)
X Biofiltration (BF-1)
U 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)
Li Detention pond or vault for hydromodification management
Li Other (describe in discussion section below)
Purpose:
X Pollutant control only
Li Hydromodification control only
Li Combined pollutant control and hydromodification control
Li Pre-treatment/forebay for another structural BMP
Li Other (describe in discussion section below)
Discussion (as needed):.
The project proposes six biofiltration basins spread throughout the site. The biofiltration basins
are being sized to treat their individual tributary areas.
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 0 Included on DMA Exhibit in
DMA ID matching DMA Exhibit, DMA Attachment 1
Area, and DMA Type (Required)* X Included as Attachment 1b,
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 0 Not included because the entire
the entire project will use infiltration project will use infiltration BMPs
BMPs)
Refer to Appendix B.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 unless 0 Not included because the entire
the project will use harvest and use project will use harvest and 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
J i7
r/
I
DMA
\
1" = 20'
0 20
/
/
DMA
/
DMA4
/
/
III
LEGEND:
DRAINAGE BASIN BOUNDARY TRIBUTARY
TO PROPOSED BIOFILTRA11ON BASIN NOTES:
EXISTING IMPERVIOUS AREAS THE HYDROLOGIC SOIL GROUP AT THE SITE IS
ENTIRELY B.
PROPOSED DRAINAGE FACILITY
THE APPROXIMATE DEPTH TO GROUNDWATER IS 13
51 ]PROPOSED BIOFILTRA11ON BASIN TO 14 FEET.
PROPOSED IMPERVIOUS SURFACES THERE ARE NO NATURAL HYDROLOGIC FEATURES
(ROOFS, DRIVEWAY, HARDSCAPE) OR CRITICAL COURSE SEDIMENT YIELD AREAS AT
THE SITE.
PROPOSED PERVIOUS SURFACES
(LANDSCAPING) SEE ATTACHMENT lB FOR TABULATION OF DMAS.
BIOFILTRA11ON BASIN SHOWN HEREON REPRESENTS
PROPOSED DE MINIMIS AREA BASIN FLOOR AREA REQUIRED PER CALCULATIONS.
N
IN
ATTACHMENT 1A - DRAINAGE MANAGEM ENT AREAS (DMA) EXHIBIT
8
9-
33 9'44'N
Hydrologic Soil Group—San Diego County Area, California PR
467930 467970 418010 468050 468090 1'
33944N
Ne
' wilp
70 tv jt
IT \ \ \
Vel
Vt
\\
? r \\
. /' \, V
¶. "
21
Nr 994 \\\
\'4 J \
411 \\ It
467930 467970 41 468210
Map Scale: 1:1,720 if printed onAlandscape (11"x8.5') sheet.
9- Meters N 25 50 100 150
Feet ,\\ 0 50 100 200 300
Map projection: Web Mercator Corner coordinates: WGS84 Edge ties: UTM Zone uN WGS84
USDA Natural Resources Web Soil Survey 5/4/2016
Conservation Service National Cooperative Soil survey Page 1 of 4
Hydrologic Soil Group—San Diego County Area, California
MAP LEGEND MAP INFORMATION
Area of Interest (AOl) El C The soil surveys that comprise your AOl were mapped at 1:24,000.
El Area of Interest (AOl) CID Warning: Soil Map may not be valid at this scale. Soils D Soil Rating Polygons Enlargement of maps beyond the scale of mapping can cause
El A Not rated or not available misunderstanding of the detail of mapping and accuracy of soil line I placement The maps do not show the small areas of contrasting I
AID Water Features soils that could have been shown at a more detailed scale.
,.-. Streams and Canals B
Transportation Please rely on the bar scale on each map sheet for map
BID F44 Rails measurements.
El C Interstate Highways Source of Map: Natural Resources Conservation Service
1 J CID Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov
US Routes Coordinate System: Web Mercator (EPSG:3857)
El D Major Roads Maps from the Web Soil Survey are based on the Web Mercator
El Not rated or not available
___ Local Roads projection, which preserves direction and shape but distorts
Soil Rating Lines distance and area. A projection that preserves area, such as the
Background Albers equal-area conic projection, should be used if more accurate A Aerial Photography calculations of distance or area are required.
— AID
— B
— BID
— C
— C/D
This product is generated from the USDA-NRCS certified data as of
the version date(s) listed below.
Soil Survey Area: San Diego County Area, California
Survey Area Data: Version 9, Sep 17, 2015
Soil map units are labeled (as space allows) for map scales 1:50,000
or larger.
D Date(s) aerial images were photographed: Nov 3, 2014—Nov 22,
• 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
• AID of map unit boundaries may be evident.
• B
• B/D
USDA Natural Resources Web Soil Survey 5/4/2016
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
Ml Manna loamy coarse 11.1 100.0%
sand, 2 to 9 percent
slopes
Totals for Area of Interest 11.1 100.0%
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 (A/D, BID, 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 do), 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
us Natural Resources Web Soil Survey 5/4/2016
Conservation Service National Cooperative Soil Survey Page 3 of 4
Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods
Worksheet B.2-1. DCV
Design Capture Volume Worksheet B-2.1
1 85 h percentile 24-hr storm depth from Figure B.1-1 d= 0.583 inches
2 Area tributary to BMP (s) . A= 0.43 acres
Area weighted runoff factor (estimate using Appendix 0.70
3 1 B.1.1 and B.2.1) C= unitless
4 Tree wells volume reduction TCV= 0 cubic-feet
5 Rain barrels volume reduction RCV= 0 cubic-feet
Calculate DCV =
648 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 4,645 sf, the impervious area covers 14,299 sf, and the total area is
18,944 sf (0.44 acres).
Based on this, the area weighted runoff factor from the equation in B.1 .1 on next
sheet is:
[(4,645 x 0.1) + (14,299 x 0.9)]/ 18,944 = 0.70
See DCV calculations for each DMA in Attachment I E.
B-10 February 2016
ATTACHMENT lB
TABULAR SUMMARY OF DMAS
DMA/BMP Impervious Area, sf Pervious Area, sf Total Area, sf
1 3,618 843 4,461
2 1,108 566 1,674
3 2,121 1,215 3,336
4 3,975 624 4,599
5 1,640 478 2,118
6 1,837 919 2,756
See DMA Exhibit for DMA/BMP locations. The impervious area includes proposed
roofs, the driveway, and hardscape. The pervious area includes proposed landscaping.
Appendix I: Forms and Checklists
ATTACHMENT IC
Hairvestiiand tUse LrnIrNY Checklist ii
IL
1. Is there a demand for harvested water (check all that apply) at the project site that is reliably present during
the wet season?
Toilet and urinal flushing
Landscape irrigation
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?
U Yes / U No LI Yes / U No Yes
Harvest and use appears to be Harvest and use may be feasible. Harvest and use
feasible. Conduct more detailed Conduct more detailed evaluation and (considered to be infeasible.
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?
Yes, refer to Appendix E to select and size harvest and use BMPs.
LI No, select alternate BMPs.
See attached sheets for runoff factor and demand data.
See Attachment I B for DCV.
1-2 February 2016
½
\.sit.,.1•
AT SITE
San Diego County4$j
15 th Percentfle Isopluvials
U &". )
24
I 85TH-PERCENTILE
OM FIGU PRECIPITATION
£ • I - st Bml-1 IN
ESIGN
MANUAL
Legend
85th PERCENTILE ISOPLUVIAL -
INCORPORATED CITY a
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 = 85' 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:
/iA' j
Where:
C = Runoff factor for area X
A. = 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
Surface
____
Runoff Factor
I
Concrete or"Asphalt1 O.90
Unit Payers (grouted)1 0.90
Decomposed Granite 0.30
Cobbles or. Crushed Aggregate 0.30
'Amended, Mulched Soils or Landscape 0.10
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
Land Use Type Toilet User 'iilTI!l
Per Capita
Unit
Use per Total Use
Resident
Ridigj Resident 185 NA NA 05
Office Employee 9.0 2.27 1.1 0.5 (non-visitor) 7
(avg) Retail Employee 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 5.5
process water)
(non-visitor)
Based on American Waterworks Association Research Foundation.1999. Residential End Uses of Water. Denver. CO: AWWARF
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 requirements 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 ofJanuary 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
A GEOTECHNICAL
MATERIALS ATTACHMENT ID
NOVA SPECIAL INSPECTION
SBE.DVBE
Affirmed Housing Group
CIO Marie Allen
13520 North Evening Creek Drive
San Diego, CA 92128
Attention: Ms. Allen
March 11, 2020
NOVA Project No. 3019096
(via email; marieaffirmedhousing.com)
Subject: Update Geotechnical Engineering Report
Project: Proposed Three-Story Apartment Building
965-967 Oak Avenue, Carlsbad, California
References:
CWE 2016a. Report of Preliminary Geotechnical Investigation, Affirmed Housing, 965-967 Oak Avenue,
Carlsbad, California, Christian Wheeler Engineering, June 3, 2016.
CWE 2016b. Report of Preliminary Recommendations, Affirmed Housing, 965-967 Oak Avenue, Carlsbad,
California, Christian Wheeler Engineering, April 20, 2016.
KL 2020. Rough Grading Plan (Sheet 3 of 8), Oak Veterans Housing, Kettler Leweck Engineering, March
11, 2020.
Dear Ms. 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
da
NOVA
Update Geotechnical Engineering Report
965-967 Oak Avenue, Carlsbad, CA
Project No.: 3019096
March 11, 2020
Figure 1. Existing Site Conditions as of December 20, 2019.
Figure 2 (following page) depicts the subsurface exploration locations based on existing site
conditions. Plates IA and IB, provided immediately following the text of this report, present
these locations in larger scale on the existing site condition and on a planned improvements
plan, respectively.
2
Update Geotechnical Engineering Report
965-967 Oak Avenue, Carlsbad, CA
Project No.: 3019096
NOVA March 11, 2020
- -,. - INTERSTATE 5
,- -.---------------
- - .- - - ----- - - ----.---- - --- -
C I:
C - C
4 . -. •. . . - . ....
I C
..:. .- ...... .-......' ,..-.... . ........-
.• .... .7 . - ..' ... ....
?.%r —'.•.--B-2 -'.....'• •.:
-
131
-. - '--.- ..-- . - •... ...:........
.. •.%_.. . •
B-3
7.
rn
9
••••••••••-..-•
KEY TO SYMBOLS ..
0 GEOTECHNICAL BORING (CHRISTIAN WHEELER. 2016)
Figure 2. Approximate Location of Subsurface Explorations
(source: adapted from Christian Wheeler Engineering, 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 construction
increase safety and allow development of seismic areas.
In accordance with the project requirements, Seismic Design Parameters are updated herein in
after the 2016 edition of the California Building Code (CBC) and ASCE 7-10. Mapped seismic
coefficients are provided in the following Table 1.
The intent of the CBC lateral force requirements 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 component 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 requirements 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 Engineer 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
3
Z I Update Geotechnical Engineering Report
965-967 Oak Avenue, Carlsbad, CA
Project No.: 3019096
NOVA I March 11, 2020
during 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) 33.16143°N
Site Longitude (decimal degrees) - 117.34225°W
Site Coefficient, Fa 1.0
Site Coefficient, Fv 1.362
Mapped Short Period Spectral Acceleration, Ss 1.143 g
Mapped One-Second Period Spectral Acceleration, S1 0.438 g
Short Period Spectral Acceleration Adjusted for Site Class, SMS 1.143 g
One-Second Period Spectral Acceleration Adjusted for Site Class, SM1 0.597 g
Design Short Period Spectral Acceleration, SDS 0.762 g
Design One-Second Period Spectral Acceleration, SDI 0.398 g
Modified Peak Ground Acceleration, PGAM 0.452 g
Source: OSHPD Seismic Design Maps, found at: https:llseismicmaps.orq/
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.
4
Update Geotechnical Engineering Report
965-967 Oak Avenue, Carlsbad, CA
Project No.: 3019096
NOVA March 11, 2020
Unit 1. Fill. (Qaf) Fill material was encountered generally in the upper 2 feet of the
subsurface is predominantly silty sand and placement is undocumented.
Unit 2, Old Paralic Deposits Pop). Quaternary-age old paralic deposits were
previously encountered at depths of 2 feet below existing grade. Old paralic deposits
were found to consist of fine to medium grained silty sand and poorly-graded sand
with silt.
Unit 3, Santiago Formation (Tsa). Tertiary-age sediment deposits of the Santiago
Formation were encountered at depths of 13 feet below existing grade. When
disturbed by drilling tools, the formational material consisted of poorly-graded sand
with silt.
Settlement and Volume Change
The Unit I 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 10.5 (61.5 feet msl) to 14 (+58.0 feet
msl) feet below ground surface 330 feet north of the site within monitoring well no. 8. In addition,
CWE reporting encountered seeping water at depths of 13 and 14 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). In addition, historic
groundwater was found to be relatively shallow.
5
A
ilk
NOVA
Update Geotechnical Engineering Report
965-967 Oak Avenue, Carlsbad, CA
Project No.: 3019096
March 11, 2020
Appendix A provides completed forms related to stormwater infiltration feasibility.
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.
F;4 1, ~' J W, s6w WiA WW illml
Attachments: Plate IA. Subsurface Investigation Map on Existing Conditions
Plate I B. Subsurface Investigation Map on Proposed Development
Appendix A. Infiltration Feasibility Worksheets
6
NOVAI
GEOTECHNICAL
SPECIAL INSPECTiON
SEE ODVBE
24632 San Juan Avenue, Suite 100
Dana Point, CA 92629
P: 949.388.7710
4373 Viewiidge Avenue, Suite B
San Diego, CA 92123
P: 858.292.7575
www.usa-nova.com
KEY TO SYMBOLS
Qop OLD PARALIC DEPOSITS
Tsa SANTIAGO FORMATION
B-3
GEOTECHNICAL BORING (CHRISTIAN WHEELER, 2016)
0 40' 80'
PROJECT NO.: 3019096
DATE: MARCH 2020
DRAWN BY: 01W
REVIEWED BY: JDB
SCALE: 1=40'
DRAWING TITLE:
SUBSURFACE
INVESTIGATION MAP -
EXISTING CONDITIONS
PLATE NO. IA
01 \.
7' \\
V Qop
> '!i Tsa
\
\ \
'
\ B-2' \
\ . Qop \\ '
\ Tsa \\ \\
WUP
7 \\\\
OLD PARALIC DEPOSITS \ .
\•
\
Tsa SANTIAGO FORMATION \ u
Qop B-3
GEOTECHNICAL BORING (CHRISTIAN WHEELER, 2016) \ -' Tsa 00
APPROXIMATE LIMITS OF ANTICIPATED REMEDIAL GRADING
100,
,
7
KEY TO SYMBOLS
~~ A
li
GEOTECHNICAL
MATERIALS
SPECIAL INSPECTION
NOVAI SBE
24632 San Juan Avenue, Suite 100
Dana Point, CA 92629
P: 949.388.7710
4373 Viewrtdge Avenue, Suite B
San Diego, CA 92123
P: 858.292.7575
www.usa-nova.com
ISEMEN MEMEMEMEM L
SITE PLAN
1LIUI•I• — SHEET
AO.2
PROJECT NO.: 3019096
DATE: MARCH 2020
DRAWN BY: DTW
REVIEWED BY: JDB
SCALE: 1=30'
DRAWING TITLE:
SUBSURFACE
INVESTIGATION MAP -
PROPOSED DEVELOPMENT
PLATE NO. lB
Update Geotechnical Engineering Report
965-967 Oak Avenue, Carlsbad, CA
Project No.: 3019096
NOVA I March 11, 2020
APPENDIX A
Infiltration Feasibility Worksheets
Appendix I: Forms and Checklists
Categorization of Infiltration Feasibility Form 1-8
I1T!mc.i.
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.
C2.7: Other Factors: Historic groundwater was encountered to be relatively shallow (+10 below existing ground
surface).
1-3 February 2016
Appendix I: Forms and Checklists
k.i.u. :iPage.t1t
I 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 about 13 to 14 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
Form 1-8 Page 3 of 4
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
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 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.
C2.7: Other Factors: Historic groundwater was encountered to be relatively shallow (+10 below existing ground
surface).
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.
C2.7: Other Factors: Historic groundwater was encountered to be relatively shallow (+10 below existing
ground surface).
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
....1-8 Page 4 of 4
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 C.3.
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.
Part 2 The feasibility screening category is Partial Infiltration.
N Result* If any answer from row 5-8 is no, then infiltration of any volume is considered to be
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
N
CHRISTIAN WHEELER
ENGINEERING
The goundwater excerpt from the preliminary
report is included for reference.
REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION
AFFIRMED OAK AVENUE
965-967 OAK AVENUE
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
w
CHRISTIAN WHEELER
ENGINEERING
August 4, 2016
Affirmed Housing Group
13520 Evening Creek Drive N, Suite 160
San Diego, California 92128
Attention: Sydney Cordova
CWE 2160236.02R
Subject: Report of Preliminary Geotechnical Investigation
Affirmed Oak Avenue, 965-967 Oak Avenue, 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
1"Jao'. 477
Daniel B. Adler, RCE # 36037
DBA:tsw
ec: Sydney@affirmedhousing.com
0L. G4\
61.
No. 2551
DI CERTIFIED i-4 I ENGINEERING I
GEOLOGIST I *
Explresl.3117
OFcAi
Troy S. Wilson, C.E.G. #2551
3980 Home Avenue + San Diego, CA 92105 + 619-550-1700 + FAX 619-550-1701
CWE 2160236.02R August 4, 2016 Page No. 4
loose, silty sand (SM). The topsoil 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 topsoil. The old paralic deposits extended to a depth of about 13 feet
below existing grade. The old paralic deposits generally consisted of orangish-brown, damp to
moist, medium dense to dense, poorly graded sand with silt (SP-SM), with some interbedded
layers of silty sand (SM), and sand (SP). The upper approximately 2 feet was loose to medium
dense and moderately to highly weathered. 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 13 feet
below existing grade. The formational soils generally consisted of light gray, very moist and
moist, silty poorly graded sand with silt (SP-SM). Approximately the upper ½ feet to 3 feet of
the formational soils were medium dense. Below said depth the formational soils are very dense.
The Santiago Formation was judged to have a very low Expansion Index OR <20). Based on the
soil conditions observed 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 betwee)
(he old paralic deposits and the Santiago Formation. In general, groundwater was encountered at a dep)
(of 13 feet to 14 feet to below existing gra4J We 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 Bioffitration BMPs
Simple Sizing Method for Biofiltration BMPs Worksheet B.5-1
1 Remaining DCV after implementing retention BMPs I 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 5] 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)1/12] x Line 7 cubic-feet
10 DCV that requires biofiltration [Line I - 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;
if the filtration is controlled by the outlet, use the outlet controlled rate)
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
[Linell+ (Line 12x Line 14)+ (Line 13x Line 5)] inc es h
19 Total Depth Treated [Line 17 + Line 18] inches
Option 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 theBMP
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
Design Capture Volume (Worksheet B.2-1. DCV, cf)
Biofiltration Basin 1 Biofiltration Basin 2
85th %, in 0.582 85th %, in 0.583
Area, ac 0.10 Area, ac 0.04
C 0.75 C 0.63
DCV, cf 162 DCV, cf 51
Pervious, sf 843 Pervious, sf 566
Impervious, sf 3,618 Impervious, sf 1,108
Total 4,461 Total 1,674
Note: C is determined from the following equation using above values:
C = [(Impervious x 0.9) + (Pervious x 0.1)] /Total
Biofiltration Basin 3
85th %, in 0.583
Area, ac 0.08
C 0.61
DCV, cf 99
Pervious, sf 1,215
Impervious, sf 2,121
Total 3,336
Biofiltration Basin 3
Row Number on
Worksheet B.5-1 Value
1 99
2 0
3 36
4 0
5 0.4
6 0
7 0
8 0.1
9 0
10 99
11 6
12 21
13 12
14 0.2
15 5
16 6
17 30
18 15
19 45
20 148
21 39
22 74
23 59
24 3,336
25 0.61
26 61
27 61
Value
51
0
36
0
0.4
0
0
0.1
0
51
6
21
12
0.2
5
6
30
15
45
77
20
38
31
1,674
0.63
32 r 32
BIOFILTRATION BASIN SIZING FOR TREATMENT CONTROL
Basin Sizing (Worksheet B.5-1)
Biofiltration Basin 1 Biofiltration Basin 2
Row Number on Row Number on
Worksheet B.5-1 Value Worksheet B.5-1
1 162 1
2 0 2
3 36 3
4 0 4
5 0.4 5
6 0 6
7 0 7
8 0.1 8
9 0 9
10 162 10
11 6 11
12 21 12
13 12 13
14 0.2 14
15 5 15
16 6 16
17 30 17
18 15 18
19 45 19
20 243 20
21 65 21
22 122 22
23 97 23
24 4,461 24
25 0.75 25
26 100 26
27 100 27
Note: The row 25 value is C value above (both shaded blue)
Biofiltration Basin 4 Biofiltration Basin 5 Bioflltration Basin 6
85th %, in 0.583 85th %, in 0.583 85th %, in 0.583
Area, ac 0.11 Area, ac 0.05 Area, ac 0.06
C 0.79 C 0.72 C 0.63
DCV, cf 177 DCV, cf 74 DCV, cf 85
Pervious, sf 624 Pervious, sf 478 Pervious, sf 919
Impervious, sf 3,975 Impervious, sf 1,640 Impervious, sf 1,837
Total 4,599 Total 2,118 Total 2,756
Note: C is determined from the following equation using above values:
C = [(Impervious x 0.9) + (Pervious x 0.1)1/Total
Biofiltration Basin 4 Bioflltration 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
1 177 1 74 1 85
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
10 177 10 74 10 85
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
20 265 20 111 20 127
21 71 21 30 21 34
22 133 22 56 22 64
23 106 23 44 23 51
24 4,599 24 2,118 24 2,756
25 0.79 25 0.72 25 0.63
26 109 26 46 26 52
27 L log 27 46 27 52
Note: The row 25 value is C value above (both shaded blue)
r pp~
ATTACHMENT 2
BACKUP FOR PDP HYDROMODIFICATION CONTROL MEASURES
[This is the cover sheet for Attachment 2.]
Indicate which Items are Included behind this cover sheet:
Attachment Contents Checklist
Sequence
Attachment 2a Hydromodification Management 0 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 D 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
O 6.2.1 Verification of Geomorphic
Landscape Units Onsite
06.2.2 Downstream Systems
Sensitivity to Coarse Sediment
o 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) 0 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
15-1
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!PlanninglCEQA level submittal:
Attachment 3 must identify:
D 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
U 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)
U Manufacturer and part number for proprietary parts of structural BMP(s) when
applicable
U 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
U 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
Bioltration 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.
7.7Mäintenancë•lfldcatois and Actions fOr
Structural BMPS
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:
(Vegetated Infiltration or filfratiónBMP
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 of 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.I1), BF-1 (biofiltration in Appendix E.12) or FT-1 (vegetated
7-7 February 2016
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.
TABLE 7-2. Maintenance Indicators and Actions for Vegetated BMPs)
Typical Maintenance
Indicator(s) for Vegetated BMPs Maintenance Actions
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 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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4
ATTACHMENT 4
City standard Single Sheet BMP (SSBMP) Exhibit
[Use the City's standard Single Sheet BMP Plan.]