HomeMy WebLinkAboutCT 08-06; HIGHLAND JAMES SUBDIVISION; STORM WATER QUALITY MANAGEMENT PLAN; CDP 15-47, CDP 15-48, CDP 15-49, DWG 483-6B, SWMP 16-28; 2017-02-07CITY OF CARLSBAD
PRIORITY DEVELOPMENT PROJECT (PDP)
STORM WATER QUALITY MANAGEMENT PLAN (SWQMP)
FOR
3980 HIGHLAND AVENUE
PROJECT ID (CT/MS/SOP/CDP/PD) CDP 15-47, 15-48 & 15-49, CT-08-06
PARCEL Nos. 207-130-75-00, 207-130-76-00, 207-130-77-00 & 207-130-78-00
DRAWING No. (DWG 483-68 & 483-6C)
SWQMP No. 16-28
;_:::;;fASON EVANS PE, MS, ToR, QSP/QSD
CALIFORNIA PROFESSIONAL ENGINEER LICENSE#: 74792
PREPARED FOR:
VECK INVESTMENT PROPERTIES, INC.
33276 HIGHLAND DRIVE
CARLSBAD, CA 92008
(619) 204-4903
PREPARED BY:
TERRAMAR ENGINEERING
2888 LOKER AVENUE EAST, SUITE 303
CARLSBAD, CA 92010
(760) 603-1907
DATE:
February th, 2017
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 1 a: OMA Exhibit
Attachment 1 b: Tabular Summary of DMAs and Design Capture Volume Calculations
Attachment 1 c: Harvest and Use Feasibility Screening (when applicable)
Attachment 1 d: Categorization of Infiltration Feasibility Condition (when applicable)
Attachment 1 e: Pollutant Control BMP Design Worksheets I Calculations
Attachment 2: Backup for PDP Hydromodification Control Measures
Attachment 2a: Hydromodification Management Exhibit
Attachment 2b: Management of Critical Coarse Sediment Yield Areas
Attachment 3: Single Sheet BMP (SSBMP) Exhibit
CERTIFICATION PAGE
Project Name: Highland-James Subdivision
Project ID: CDPs 15-47, 15-48 & 15-49, CT-08-06
Parcel Numbers: 207-130-75-00, 207-130-76-00, 207-130-77-00 & 207-130-78-00
I hereby declare that l 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.
EngJneer of Work's Signature, PE Number & Expiration Date ,,, ..
JJ-/3/111
Jason Evans
Print Name
Terramar Engineering
Company
02/07/2017
Date
PROJECT VICINITY MAP
Project Name: Highland-James Subdivision
Project ID: CDPs 15-47, 15-48 & 15-49, CT-08-06
Parcel Numbers: 207-130-75-00, 207-130-76-00, 207-130-77-00 & 207-130-78-00
Source: Google Earth
i': l._ City of
Carlsbad
I INSTRUCTIONS:
STORM WATER
STANDARDS
QUESTIONNAIRE
E-34
Development Services
Land Development Engineering
1635 Faraday Avenue
760-602-2750
www.carlsbadca.gov
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 (BMP's) 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' (PDP) 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
ti concurren 1y.
PROJECT INFORMATION
PROJECTNAME: Highland-James Subdivision
PROJECT ID: CDP 15-47, 15-48 & 15-49
The project is (check one): D New Development QQ Redevelopment
The total proposed disturbed area is: 4 9 / 653 ft2 ( 1.14 ) acres
The total proposed newly created and/or replaced impervious area is: 22,146ft2( 0.51 ) acres
If your project is covered by an approved SWQMP as part of a larger development project, provide the project ID and the
SWQMP # of the larger development project:
Project ID: N/A SWQMP#: N/A
Then, go to Step 1 and follow the instructions. When completed, sign the form at the end and submit this with your
aoolication to the City.
E-34 Page 1 of 4 REV 02/16
,;;~j~Siii;'sTEPA'f ,'tl::J~/,}~:r~i~r':
COMPLETECJtt"oRALL 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)? X
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):
If you answered "no" to the above question, the project is a 'development project', go to Step 2.
'*''"0,.;. STEP 2 • ·.· l':i:; . . ..
TO BE COMPCETED FO~,Al..L DEVELOPMENT PROJECTS
To determine if your project is exempt from PDP requirements pursuant to MS4 Permit Provision E.3.b.(3), please answer
the following questions:
Is your project LIMITED to one or more of the following:
YES NO
1. Constructing new or retrofitting paved sidewalks, bicycle lanes or trails that meet the following criteria:
a) Designed and constructed to direct storm water runoff to adjacent vegetated areas, or other non-
erodible permeable areas;
b) 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?
If you answered "yes" to one or more of the above questions, provide discussion/justification below, then Go to step 5,
mark the second box stating "my project is EXEMPT from PDP ... "and complete applicant information.
X
X
X
Discussion to justify exemption ( e.g. the project redeveloping existing road designed and constructed in accordance with
the USEPA Green Street guidance):
If you answered "no" to the above questions, your project is not exempt from PDP, go to Step 3.
E-34 Page 2 of 4 REV. 02/16
' STEP 3 1
TO BE COMij,~ED FORALL NEW O,~ ~EDEVELOP..,§~f.PROJECTS .
To determine if your project is a PDP, please answer the following questions
(MS4 Permit Provision E.3.b.(1 )):
YES NO
1. 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, X
and public development projects on public or private land.
2. 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 X
more of impervious surface? This includes commercial, industrial, residential, mixed-use, and public
development projects on public or private land.
3. 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 X
and refreshment stands selling prepared foods and drinks for immediate consumption (Standard
Industrial Classification (SIC) code 5812).
4. 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 X
development project includes development on anv natural slope that is twenty-five percent or qreater.
5. 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 X
is a land area or facility for the temporary parking or storage of motor vehicles used personally for
business or for commerce.
6. 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 X 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.
7. 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 X Sensitive Area (ESA)? "Discharging Directly to" includes flow that is conveyed overland a distance
of 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 comminqled with flows from adiacent lands).*
8. 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 X
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.
9. 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 X
includes RGO's that meet the following criteria: (a) 5,000 square feet or more or (b) a project Average
Dailv Traffic (ADT) of 100 or more vehicles per dav.
10. Is your project a new or redevelopment project that results in the disturbance of one or more acres of X land and are expected to generate pollutants post construction?
11. Is your project located within 200 feet of the Pacific Ocean and (1) creates 2,500 square feet or more X of impervious surface or (2) increases impervious surface on the property by more than 10%? (CMC
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 statinq "Mv project is a 'STANDARD PROJECT' ... " and complete applicant information.
E-34 Page 3 of 4 REV. 02/16
.. STEP4
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) = 4,340 sq. ft. X
Total proposed newly created or replaced impervious area (B) = 22,146 sq. ft.
Percent impervious area created or replaced (B/ A)*100 = 499 %
If you answered "yes", the structural BM P's required for PDP apply only to the creation or replacement of impervious
surface and not the entire development. Go to step 5, check the first box stating "My project is a PDP ... " and complete
applicant information.
If you answered "no," the structural BM P's required for PDP apply to the entire development. Go to step 5, check the
check the first box stating "My project is a PDP ... " and complete applicant information.
STEPS
CHECK THE APPROPRIATE BOX AND COMPLETE APPLICANT INFORMATION
IBl My project is a PDP and must comply with PDP stormwater requirements of the BMP Manual. I understand I must
prepare a Storm Water Quality Management Plan (SWQMP) for submittal at time of application.
D My project is a 'STANDARD PROJECT' OR EXEMPT from PDP and must only comply with 'STANDARD PROJECT'
stormwater requirements of the BMP Manual. As part of these requirements, I will submit a "Standard Project
Requirement Checklist Form E-36" and incorporate low impact development strategies throughout my project.
Note: For projects that are close to meeting the PDP threshold, staff may require detailed impervious area calculations and
exhibits to verify if 'STANDARD PROJECT' stormwater requirements apply.
D My Project is NOT a 'development project' and is not subject to the requirements of the BMP Manual.
Applicant Information and Signature Box
Assessor's Parcel Number(s):
207-130-75-00 THROUGH 207-130-78-00
A~plicant Name: E izabeth Temple, Veck Investment
Applicant Title:
Properties Principal
Applicant Signatu~ Date: 10/25/2016 ~.lbm~
* Environmentally Sensitive Areas include but are not limited to all Clean Water Act Section 303(d) impaired water bodies; areas designated as Areas of
Special Biological Significance by the State 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); areas designated as preserves or their equivalent under the Multi Species Conservation Program within the Cities
and County of San Diego; Habitat Management Plan; and any other equivalent environmentally sensitive areas which have been identified by the City.
Th" B fi C"t U O I /S ox or l'V se nlV
City Concurrence: I YES I NO
I I
By:
Date:
Project ID:
E-34 Page 4 of 4 REV. 02/16
SITE INFORMATION CHECKLIST
Project Summary Information
Project Name HiQhland-James Subdivision
Project ID CPD 15-47, 48 & 49, CT-08-06
Project Address 3980 Highland Drive
Carlsbad, CA 92008
Assessor's Parcel Number(s) (APN(s)) 207-130-75-00, -76-00, -77-00 and -78-00
Project Watershed (Hydrologic Unit) Carlsbad 904
Parcel Area 1.06 Acres (46,349 sq-ft)
Existing Impervious Area 0.10 Acres (4,340 sq-ft) (subset of Parcel Area)
Area to be disturbed by the project 1.14 Acres (49,653 sq-ft) (Project Area)
Project Proposed Impervious Area 0.51 Acres (22,146 sq-ft) (subset of Project Area)
Project Proposed Pervious Area 0.63 Acres (27,507 sq-ft) (subset of Project Area)
Note: Proposed Impervious Area+ Proposed Pervious Area= Area to be Disturbed by the Project.
This may be less than the Parcel Area
Please note that in this case the Area to be Disturbed by the Project is greater than the Parcel Area
because there is some work (0.08 acres) associated with the project's utility connections and
driveway aprons outside of the property lines (a.k.a. offsite work).
This SWQMP has been prepared for CDPs 15-47, 15-48 and 15-49 for Lots 1, 2 and 3, associated with
APNs 207-130-75, -76 and -77, respectively. This project anticipates the ultimate development of APN
207-130-78 including its subdivision into proposed Lots 4 and 5. It is important to note that Lots 4 and 5
are not a part of CDPs 15-47, 15-48 or 15-49 and will be subject to a separate CDP, but are included as
part of the total project site area per CT08-06 for cross lot drainage purposes, and in anticipation of their
final development. The following table breaks down the total areas within each Lot in terms of proposed
impervious and pervious areas and provides the associated CDPs and APNs for clarity.
LOT CDP APN Parcel Parcel Proposed Proposed Proposed Proposed
Area Area Imp.Area Imp. Area Perv. Area Perv. Area
# # # sq-ft ac sq-ft ac sf ac
1 15-47 207-130-75 7505 0.17 3937 0.09 3568 0.08
2 15-48 207-130-76 7505 0.17 4107 0.09 3398 0.08
3 15-49 207-130-77 7505 0.17 3984 0.09 3521 0.08
Remainder Parcel N/A 207-130-78 23833 0.55 9405 0.22 14428 0.33
This SWQMP anticipates the Remainder Parcel will be subdivided into Lots 4 & 5 with the following characteristics:
4 TBD TBD 11917 0.27 4860 0.11 7057 0.16
5 TBD TBD 11917 0.27 4545 0.10 7372 0.17
There are 2 additional DMAs (Nla and N2a) in the Highland Ave. right-of-way that drain to Lots 4 and 5, as follows:
OMA Total Total Proposed Proposed Proposed Proposed
Area Area Imp. Area Imp. Area Perv. Area Perv. Area
# sq-ft ac sq-ft ac sf ac
Nla 1635 0.04 352 0.00 1283 0.03
N2a 1669 0.04 361 0.00 1308 0.03
If the future development of Lots 4 and 5 exceed the proposed impervious area of 4,860 sq-ft and
4,545 sq-ft respectively additional analysis of the structural BMPs will be required to determine
whether it is in compliance with current MS4 regulations (i.e. another SWQMP will be prepared).
Similarly if the future development of DMAs R1 and R2 exceed the proposed contributing
impervious area of 352 sq-ft and 361 sq-ft to Lots 4 and 5 respectively, then additional analysis of
the structural BMPs may be required to determine whether the modifications are in compliance
with current MS4 regulations (i.e. another SWQMP may be required).
Description of Existing Site Condition and Drainage Patterns
Current Status of the Site (select all that apply)
~ Existing development
~ Previously graded but not built out
D Agricultural or other non-impervious use
~ Vacant, undeveloped/natural
Description I Additional Information
The existing site contains one free standing home with a detached garage on APN 207-130-78.
Existing Land Cover Includes (select all that apply)
~ Vegetative Cover D Non-Vegetated Pervious Areas
~ Impervious Areas
Description I Additional Information
Impervious features --house, garage and driveway. Established vegetative cover on remainder.
Underlying Soil belongs to Hydrologic Soil Group (select all that apply):
0 NRCS Type A
~ NRCS Type B
0 NRCS Type C
0 NRCS Type D
According to a site-specific Soils Report generated on USDA NRCS WSS the site is Type B.
Approximate Depth to Groundwater: D Groundwater Depth< 5 feet
D 5 feet < Groundwater Depth < 10 feet
~ 10 feet < Groundwater Depth < 20 feet
~ Groundwater Depth > 20 feet
The actual depth to groundwater is not known. A Soils Report generated on the USDA NRCS
WSS indicates that the depth to water table is greater than 200 mm. A Site Inspection (09/02/05)
performed by Soil Testers, Inc., had borings up to 15-ft without encountering groundwater.
Existing Natural Hydrologic Features (select all that apply)
D Watercourses D Seeps D Springs D Wetlands
~ None
Description I Additional Information None identified
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 subject site is a residential parcel located on the easterly side of Highland Drive. The property
is located at the top of a rise with the east side of the site fronting James Drive approximately 15 to
20 feet lower than the west side. A 10-foot, approximately 2: 1 cut slope extends midway through
the site from the south to north. A 2-to-3 feet fill slope is located at the top of the cut on the north
end. The property is presently occupied by a one-story single-family residence with a detached
garage and driveway. There is a four-foot retaining wall behind the garage and a 3-foot rock
retaining wall behind the house.
There is a 12-inch public storm drain (with a 5-ft easement) that conveys runoff from Highland
Drive eastward through the site along its northern perimeter down to James Drive; however the
property does not contain any storm drain infrastructure for stormwater generated onsite. Existing
topography dictates that stormwater runoff sheet flows along the ground surface of the property
from west to east and discharge offsite and onto James Drive at the sites eastern edge. In
pre-development conditions the entire site may be considered as a single drainage management
area with one point of discharge (at its eastern perimeter).
Once the runoff discharges onto James Drive it is collected by a curb inlet on the west side of the
street which is part of the municipal separate storm sewer system (MS4) owned and operated by
the City of Carlsbad. The City MS4 conveys the runoff further downstream to the Agua Hedionda
Lagoon with ultimate discharge into the Pacific Ocean along Carlsbad State Beach (at Tamarack
jetties and at the discharge for the Encina Power Station).
Description of Proposed Site Development and Drainage Patterns
Project Description I Proposed Land Use and/or Activities:
This SWQMP has been prepared for CDPs 15-47, 15-48 and 15-49 for Lots 1, 2 and 3, associated
with APNs 207-130-75, -76 and -77, respectively. This SQWMP also anticipates the ultimate
development of APN 207-130-78 including its subdivision into proposed Lots 4 and 5. It is
important to note that Lots 4 and 5 are not a part of CDPs 15-4 7, 15-48 or 15-49 and will be
subject to a separate CDP, but are included as part of the total project site area per Carlsbad Tract
CT-08-06-01 (Map # 16021) for cross lot drainage purposes, and in anticipation of their final
development. In summary this SWQMP is intended for the final development of Lots 1, 2, 3 and
the Remainder Parcel on Map 16021 for Carlsbad Tract CT-08-06-01.
The proposed development will demolish the existing home/detached garage, and ultimately
construct 5 new free standing single family homes with driveways. Post-development activities at
the site will be consistent with typical residential activities currently conducted throuQhout the City.
List/describe proposed impervious features of the project (e.g., buildings, roadways, parking lots,
courtyards, athletic courts, other impervious features):
Proposed impervious features include 5 free standing single family homes and their associated
driveways. In total the project proposes 22,146 sq-ft (0.51 acres) of new impervious surfaces
List/describe proposed pervious features of the project (e.g., landscape areas):
Proposed pervious features include the front, back and side yards of the 5 free standing homes
including the slope separating the two benches. Efforts will be made to preserve some of the
existing vegetation, although grading activities are planned on almost the entire site. All of the
permeable areas will be vegetated/landscaped.
Does the project include grading and changes to site topography?
[:8J Yes
D No
Description I Additional Information:
The proposed grading will more or less maintain the same pattern, with the uphill portion tying into
Highland Avenue and the downhill connecting to James Drive. The two existing benches at the
top and bottom of the slope will be extended in order to construct the proposed building pads for
the homes. Swales will be incorporated to convey flows around the lower bench and along the
perimeters and in between Lots 1, 2 and 3.
Does the project include changes to site drainage (e.g., installation of new storm water
conveyance systems)?
C8l Yes
D No
Description I Additional Information:
A combination of swales and inlets/storm drain will be incorporated near the toe of the slope and
in between Lots 1, 2 and 3. Runoff will still discharge along the sites eastern edge but will be
collected by an onsite storm drain system and piped into the existing curb inlet on James Drive
(this is the projects sole point of discharge). The swales convey drainage throughout the site and
facilitate cross lot drainage in accordance with the existing drainage easements detailed on Map
16021 for Carlsbad Tract CT-08-06-01. The proposed grading/swales/inlets effectively subdivide
the site into 12 Drainage Management Areas (DMAs) which all combine and discharge into the
City MS4 (at the James Drive inlet), and have the following characteristics:
• OMA N1a is 0.038-acres (22% impervious) and an area within the public right-of-way along
Highland Avenue that flows onto OMA N1 b. OMA N1a consists of landscaping and the driveway for
Lot 4 that ties into Highland Avenue.
• OMA N 1 b is 0.27 4-acres ( 41 % impervious) and contains proposed Lot 4. OMA N 1 b accepts run-on
from OMA N1a. Runoff discharges into a Bioretention BMP for pollutant control. Flows leaving the
BMP are managed by infiltration and an overflow weir. The overflow weir conveys flows to OMA
N1c.
• OMA N1c is 0.014-acres (0% impervious) and contains the western edge of Lot 3 and southern half
of the western edge of Lot 2 (i.e. the 6-ft strip of landscaping with drainage swale above the
retaining wall). This OMA conveys runoff from DMAs N 1 a and N 1 b into the private storm drain
system via the proposed riprap drainage swale which terminates at a catch basin.
• OMA N2a is 0.038-acres (22% impervious) and an area within the public right-of-way along
Highland Avenue that flows onto OMA N2b. OMA N2a consists of landscaping and the driveway for
Lot 5 that ties into Highland Avenue.
• OMA N2b is 0.274-acres (38% impervious) and contains proposed Lot 5. OMA N2b accepts run-on
from OMA N2a. Runoff discharges into a Bioretention BMP for pollutant control. Flows leaving the
BMP are managed by infiltration and an overflow weir. The overflow weir conveys flows OMA N2c.
• OMA N2c is 0.011-acres (0% impervious) and contains the western edge of Lot 1 and northern half
of the western edge of Lot 2 (i.e. the 6-ft strip of landscaping with drainage swale above the
retaining wall). This OMA conveys runoff from DMAs N2a and N2b into the private storm drain
system via the proposed riprap drainage swale which terminates at a catch basin.
• OMA N3 is 0.082-acres (62% impervious) contains the southern half of Lot 3, and the drainage
easement and storm drain infrastructure that coveys flows from Lot 4 and the southern half of Lot 3
along its southern perimeter prior to bending north into OMA N4 and discharging the City MS4.
• OMA N4 is 0.082-acres (50% impervious) contains the northern half of Lot 3, and a swale and storm
drain that coveys runoff along its northern edge prior to bending south and discharging into the City
MS4. There is also a drainage easement along the eastern perimeter of OMA N4 that accepts flows
from Lots 1, 2 and 5. OMA N4 contains the projects sole point of discharge as flows from the entire
site (Lots 1-5) will combine within the onsite storm drain system and will be piped into the back of
the curb inlet on James Drive (which is part of the City MS4).
• OMA N5 is 0.082-acres (65% impervious) contains the southern half of Lot 2, and a swale and
storm drain that coveys flows eastward along the southern edge of Lot 2 to the drainage easement
along the eastern edge of Lot 3.
• OMA N6 is 0.082-acres (50% impervious) contains the northern half of Lot 2 and a swale and storm
drain that coveys flows eastward along the northern edge of Lot 2 to the drainage easement along
the eastern edge of Lot 3.
• OMA N7 is 0.082-acres (61 % impervious) contains the southern half of Lot 1, and the drainage
easement and storm drain infrastructure that coveys flows eastward from Lot 5 and the southern
half of Lot 1 along its southern perimeter prior to bending south and discharging into the drainage
easement along the eastern edge of Lots 2 and 3.
• OMA N8 is 0.082-acres (49% impervious) and contains the northern half of Lot 1 and a swale and
storm drain that conveys runoff eastward along the northern edge of Lot 1 to bending south and
discharging into the drainage easement along the eastern edge of Lots 2 and 3. OMA N8 also
contains a 12-inch public storm drain with a 5-ft easement along its northern perimeter that conveys
flows from Highland eastward through the site and into storm drain under James Drive (please note
that the proiect does not contribute runoff to this pipeline).
Identify whether any of the following features, activities, and/or pollutant source areas will be
present (select all that apply)
1:8] Onsite storm drain inlets
D Interior floor drains and elevator shaft sump pumps
1:8] Interior parking garages
1:8] Need for future indoor & structural pest control
1:8] Landscape/outdoor pesticide use
D Pools, spas, ponds, decorative fountains, and other water features
D Food service
1:8] Refuse areas D Industrial processes
D Outdoor storage of equipment or materials
1:8] Vehicle and equipment cleaning D Vehicle/equipment repair and maintenance D Fuel dispensing areas D Loading docks
D Fire sprinkler test water
1:8] Miscellaneous drain or wash water
1:8] Plazas, sidewalks, and parking lots
Identification of Receiving Water Pollutants of Concern
Describe path of storm water from the project site to the Pacific Ocean (or bay, lagoon, lake or
reservoir, as applicable):
In existing conditions the site does not contain any storm drain infrastructure for stormwater
generated onsite, and topography dictates that runoff sheet flows along the ground surface
from west to east and discharges offsite and onto James Drive along the sites eastern edge.
The proposed storm will replace sheet flow with a combination of sheet, channel and pipe flows;
however the point of discharge along the sites eastern edge will remain the same.
Once the runoff discharges onto James Drive it is collected by a curb inlet on which is part of the
municipal separate storm sewer system (MS4) owned and operated by the City of Carlsbad.
The City MS4 conveys the runoff further downstream to the Agua Hedionda Lagoon with
ultimate discharge into the Pacific Ocean along Carlsbad State Beach (at Tamarack jetties and
at the discharge for the Encina Power Station).
Although there are not any 303(d) impaired water bodies within the path of stormwater from the
site to the Pacific Ocean, the following pollutant(s)/stressor(s) and associated TMDLs, are listed
for the Agua Hedionda Creek which also discharges to the Agua Hedionda Lagoon.
303(d) Impaired Water Body Pollutant(s)/Stressor(s) TMDLs
Agua Hedionda Creek Enterococcus 2019
Agua Hedionda Creek Fecal Coliform 2019
Agua Hedionda Creek Manganese 2019
Agua Hedionda Creek Phosphorus 2019
Agua Hedionda Creek Selenium 2019
Agua Hedionda Creek Total Dissolved Solids 2019
Agua Hedionda Creek Total Nitrogen as N 2019
Agua Hedionda Creek Toxicity 2019
Identification of Project Site Pollutants
Identify pollutants expected from the project site based on all proposed use(s) of the site (see
manual Appendix 8.6):
Pollutant Not Applicable to Expected from the Also a Receiving
the Project Site Water
Project Site Pollutant of Concern
Sediment X X
Nutrients X X
Heavy Metals X X
Organic X X Compounds
Trash & Debris X
Oxygen Demanding X Substances
Oil & Grease X
Bacteria & Viruses X X
Pesticides X
Toxicity X X
Hydromodification. Management Requirements
Do hydromodification management requirements apply (see Section 1.6 of the BMP Design
Manual)? D Yes, hydromodification management flow control structural BMPs required.
D 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.
D 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.
IZI 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):
According to the Hydromodification Exemption Analyses prepared by Chang Consultants
(September, 2015), the site is located within the hydromodification exempt area. Furthermore,
maps included under Carlsbad Watershed Management Area Analysis (WMAA) Attachment B.2
indicate that the receiving public storm drain is also an exempt conveyance system. For further
details, please refer to Attachment 2a of the SWQMP.
Critical Coarse Sediment Yield Areas*
*This Section only required if hydromodification management requirements aooly
Based on the maps provided within the WMAA, do potential critical coarse sediment yield areas
exist within the project drainage boundaries?
D Yes IZI 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?
D 6.2.1 Verification of Geomorphic Landscape Units (GLUs) Onsite
D 6.2.2 Downstream Systems Sensitivity to Coarse Sediment
D 6.2.3 Optional Additional Analysis of Potential Critical Coarse Sediment Yield Areas Onsite D 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?
D No critical coarse sediment yield areas to be protected based on verification of GLUs onsite
D Critical coarse sediment yield areas exist but additional analysis has determined that
protection is not required. Documentation attached in Attachment 8 of the SWQMP. D 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 I Additional Information:
According to the Potential Critical Coarse Sediment Yield Areas Exhibit (Attachment A.4 of the
Carlsbad WMAA) the site is not located within an area known as a potentially critical source of
coarse sediment yield. For further details, please refer to SWQMP Attachment 2b.
Flow Control for Post-Project Runoff*
*This Section only required if hydromodification management requirements apply
List and describe point(s) of compliance (POCs) for flow control for hydromodification
management (see Section 6.3.1 ). For each 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 -according to the Hydromodification Exemption Analyses for select Carlsbad Watersheds
prepared by Chang Consultants (September, 2015), the site is located in a hydromodification
exempt area and is therefore exempt from the City's hydromodification requirements.
Nevertheless, in post-development conditions the site will be subdivided into 8 Drainage
Management Areas (DMAs) with one (1) points where stormwater exits the site at its only point of
discharge into the curb inlet on James Drive (which is part of the City MS4) located along the
eastern edge of the subject property. Please refer to the Description of Proposed Site
Development and Drainage Patterns Section of this SWQMP (above) for further information
regarding the 8 proposed DMAs.
Has a geomorphic assessment been performed for the receiving channel(s)? D No, the low flow threshold is 0.1 Q2 ( default low flow threshold)
D Yes, the result is the low flow threshold is 0.1 Q2
D Yes, the result is the low flow threshold is 0.3Q2
D Yes, the result is the low flow threshold is 0.5Q2
C8J N/A, the site is exempt from the City's hydromodification requirements.
If a geomorphic assessment has been performed, provide title, date, and preparer:
Discussion I Additional Information: (optional)
N/A -according to the Hydromodification Exemption Analyses for select Carlsbad Watersheds
prepared by Chang Consultants (September, 2015), the site is located in a hydromodification
exempt area and is therefore exempt from the City's hydromodification requirements. For further
details, please refer to Hydromodification Management Exhibit and the Hydromodification
Management Exemption Map included under Attachment 2a of the SWQMP.
Other Site Requirements and Constraints
When applicable, list other site requirements or constraints that will influence storm water
management design, such as zoning requirements including setbacks and open space, or City
codes governing minimum street width, sidewalk construction, allowable pavement types, and
drainage requirements.
Site constraints include the surrounding topography, multiple private drainage easements
throughout the site, existing 12-inch public storm drain (and easement) along the site's northern
perimeter, the proposed property lines associated with the lot split, and changes in elevation from
east-to-west across the site.
Optional Additional lnf8ftttation or Continuation ,of Previous Sections As Needed
This space provided for additional information or continuation of information from previous
sections as needed.
Although the site is challenged with the aforementioned constraints, it has fairly well draining soils
and the drainage easements may be more of a benefit then a constraint allowing for cross
property drainage. The site has been designed to maximize the use of site design BMPs, such
that 6 of the 8 proposed DMAs may be considered Self-Retaining DMAs via Qualifying Site
Design BMPs. Structural BMPs (i.e. two bioretention basins) have been designed for the 2 DMAs
that could not be treated solely with site design BMPs. The specific BMPs for the subject
development are Tree Wells (BMP SD-1), Impervious Area Dispersion (BMP SD-5), and
Biofiltration with partial retention (BMP PR-1) and they have been engineered in accordance with
the City of Carlsbad BMP Design Manual (02/16/16).
Project Name: Highland-James
Project ID: CDP 15-47, 15-48
DWG No. or Building Permit No.:
STANDARD PROJECT
REQUIREMENT
CHECKLIST
E-36
Project Information
Subdivision
& 15-49
483-68 & 483-6C
Source Control BMPs
Development Services
Land Development Engineering
1635 Faraday Avenue
760-602-2750
www.carlsbadca.gov
All development projects must implement source control BMPs SC-1 through SC-6 where applicable and feasible.
See Chapter 4 and Appendix E.1 of the BMP Design Manual for information to implement source control BMPs
shown in this checklist.
Answer each category below pursuant to the following.
• "Yes" means the project will implement the source control BMP as described in Chapter 4 and/or Appendix E.1
of the Model BMP Design Manual. Discussion/justification is not required.
• "No" means the BMP is applicable to the project but it is not feasible to implement. Discussion/justification must
be provided.
• "N/A" means the BMP is not applicable at the project site because the project does not include the feature that is
addressed by the BMP (e.g., the project has no outdoor materials storage areas). Discussion/justification may be
provided.
Source Control Requirement I Applied?
SC-1 Prevention of Illicit Discharges into the MS4 I !l<i Yes I D No I D N/A
Discussion/justification if SC-1 not implemented:
SC-2 Storm Drain Stenciling or Signage I~ Yes I D No I D N/A
Discussion/justification if SC-2 not implemented:
SC-3 Protect Outdoor Materials Storage Areas from Rainfall, Run-On, I D Yes I D No I lxl N/A Runoff, and Wind Dispersal
Discussion/justification if SC-3 not implemented:
There are not any proposed outdoor material storage areas associated with the subject
redevelopment
SC-4 Protect Materials Stored in Outdoor Work Areas from Rainfall, Run-On, I D Yes
Runoff, and Wind Dispersal I D No I ~N/A
Discussion/justification if SC-4 not implemented:
There are not any proposed outdoor work areas associated with the subject redevelopment
SC-5 Protect Trash Storage Areas from Rainfall, Run-On, Runoff, and Wind I ~Yes I D No I D N/A
Dispersal
Discussion/justification if SC-5 not implemented:
Trash will be stored within sealed containers issued by Waste Management, Inc. as is standard
throughout the City, with separate containers for trash, recyclables and green waste. Trash will
be stored such that it cannot come into direct contact with rainfall or stormwater flows.
E-36 Page 1 of 3 REV 02/16
/{ . , .. Source Co'l'.ftrol Requirement . "'" : '
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).
l&I On-site storm drain inlets
D Interior floor drains and elevator shaft sump pumps
e3 Interior parking garages
~ Need for future indoor & structural pest control
il1 Landscape/Outdoor Pesticide Use
D Pools, spas, ponds, decorative fountains, and other water features
D Food service
0 Refuse areas
D Industrial processes
D Outdoor storage of equipment or materials
D Vehicle and Equipment Cleaning
D Vehicle/Equipment Repair and Maintenance
D Fuel Dispensing Areas
D Loading Docks
D Fire Sprinkler Test Water
D Miscellaneous Drain or Wash Water
~ Plazas, sidewalks, and parking lots
»a Yes
D Yes
~Yes
~Yes
~Yes
D Yes
o Yes
~Yes
D Yes
DYes
o Yes
D Yes
D Yes
D Yes
D Yes
o Yes
l&I Yes
. ,,,, ...... Applied?
D No ~N/A
D No ~ N/A
D No D N/A
D No D N/A
D No D N/A
D No ~ N/A
D No 18:1 N/A
D No D N/A
D No ~ N/A
D No ~ N/A
J)(I No D N/A
lxl No D N/A
D No ~N/A
D No 0N/A
D No ~N/A
~ No D N/A
D No D N/A
For "Yes" answers, identify the additional BMP per Appendix E.1. Provide justification for "No" answers.
The potential sources checked N/A above are considered not applicable because the
project does not include the feature or corresponding BMP. Onsite inlets will be
stenciled or stamped to discourage dumping and inform people that they drain to the
Ocean. Trash and refuse containers shall be sealed and water tight and it is
recommended that they be stored in such a manner that the refuse cannot come into
direct contact with rainfall or stormwater run-on/runoff. Potential sources checked No
are not applicable to small residential development (i.e. residents in Carlsbad are
allowed to clean and repair there vehicles on their property without installing a
commercial car wash or an auto repair shop, residents may encounter miscellaneous drain
or wash water at times, and the public sidewalk constructed as part of the project will
be built per City standards and will more than likely be dedicated to the City upon
completion). Furthermore, the grading/drainage has been designed such that any non-
stormwater generated onsite not addressed by the aforementioned Source Control BMPs
will drain to the proposed site design and/or structural LID BMPs to improve water
aualitv orior to offsite discharae.
E-36 Page 2 of 3 REV. 02/16
.• , ; •;'>
':, .,, '" '/< Site;:l)~sign BMPs . ·• ·, . ;y,.;\»:;,,; :f .. ,;:;
•'
All development projects must implement site design BMPs SD-1 through SD-8 where applicable and feasible. See
Chapter 4 and Appendix E.2 thru E.6 of the BMP Design Manual for information to implement site design BMPs
shown in this checklist.
Answer each category below pursuant to the following.
• "Yes" means the project will implement the site design BMPs as described in Chapter 4 and/or Appendix E.2
thru E.6 of the Model BMP Design Manual. Discussion I justification is not required.
• "No" means the BMPs is applicable to the project but it is not feasible to implement. Discussion/justification must
be provided.
• "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.
Site Design RequirenieijJ,, I Applied?
SD-1 Maintain Natural Drainage Pathways and Hydrologic Features I 5a Yes I D No I D N/A
Discussion/justification if SD-1 not implemented:
Although grading will alter the topogrpahy, the site will still be characterized by surface flow
in a west-to-east direction and the single discharge point located at the sites southeast corner
will remain unchanqed.
SD-2 Conserve Natural Areas, Soils, and Vegetation I ~Yes I D No I D N/A
Discussion/justification if SD-2 not implemented:
The proposed site plan requires grading throughout the site, still efforts have been made to
conserve some vegetation, and the infiltration capabilities of the soils onsite.
SD-3 Minimize Impervious Area I~ Yes I D No I D N/A
Discussion/justification if SD-3 not implemented:
Impervious areas have been minimized as much as practical for the subject development.
Furthermore the site has been designed to drain impervious surfaces to permeable areas to promote
onsite infiltration of stormwater runoff.
SD-4 Minimize Soil Compaction I lxl Yes I D No I D N/A
Discussion/justification if SD-4 not implemented:
Soil compaction will be minimized except where necessary (i.e. building pads for the homes,
trenches for utilities,construction of driveways, sidewalks, patios, etc.)
SD-5 Impervious Area Dispersion I fil Yes I D No I D N/A
Discussion/justification if SD-5 not implemented:
The site has been designed such that impervious surfaces drain to permeable areas to promote onsit e
infiltration of stormwater prior to offsite discharge.
SD-6 Runoff Collection I IKIYes I D No I D N/A
Discussion/justification if SD-6 not implemented:
Runoff will be collected in bioretention basins and permeable vegetated swales to convey the
flows and promote onsite infiltration of stormwater.
SD-7 Landscaping with Native or Drought Tolerant Species I ~Yes I D No I D N/A
Discussion/justification if SD-7 not implemented:
The proposed landscaping will utilize native and/or drought tolerant species in accordance with
City standards.
SD-8 Harvesting and Using Precipitation I D Yes I ~No I D N/A
Discussion/justification if SD-8 not implemented:
Water quality requirements are met with Bioretention Basins and Self-Retaining DMAs via
Qualifying Site Design BMPs. Precipitation Harvest/Re-Use is not included as part of project,
but future home Owners could install catchments/cisterns on their own properties as they see fit.
E-36 Page 3 of 3 REV. 02/16
SUMMARY OF PDP STRUCTURAL BMPS
PDP Structural BMPs
All PDPs must implement structural BMPs for storm water pollutant control (see Chapter 5 of the BMP Design
Manual). Selection of PDP structural BMPs for storm water pollutant control must be based on the selection
process described in Chapter 5. PDPs subject to hydromodification management requirements must also
implement structural BMPs for flow control for hydromodification management (see Chapter 6 of the BMP
Design Manual). Both storm water pollutant control and flow control for hydromodification management can
be achieved within the same structural BMP(s).
PDP structural BMPs must be verified by the City at the completion of construction. This may include requiring
the project owner or project owner's representative to certify construction of the structural BMPs (see Section
1.12 of the BMP Design Manual). PDP structural BMPs must be maintained into perpetuity and the City must
confirm the maintenance (see Section 7 of the BMP Design Manual).
Use this form to provide narrative description of the general strategy for structural BMP implementation at the
project site in the box below. Then complete the PDP structural BMP summary information sheet for each
structural BMP within the project (copy the BMP summary information page as many times as needed to
provide summary information for each 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.
Since the site is exempt from the City's hydromodification requirements, this evaluation was performed to
address pollutant control BMPs only. First the site was evaluated at OMA scale to determine if portions of the
project could be considered "self-mitigating", "de minimis" or "self-retaining". The site was subdivided into 12
DMAs to convey runoff through the property with the intent that each OMA could be a Self-Retaining OMA via
Qualifying Site Design BMPs. The grading and drainage of each OMA was designed to disperse runoff from
impervious areas to permeable areas to promote infiltration onsite (i.e. BMP SD-5: Impervious Area
Dispersion). Review of the site-specific Soils Report generated on the USDA NRCS Web Soil Survey the
entire site is underlain with Hydrologic Soil Group B. The impervious:pervious ratio required for compliance
with BMP SD-5 is less than or equal to one (1) in these types of soils.
Calculations (included under SWQMP Attachment 1 e) determined the impervious:pervious ratios for each of
the DMAs. The ratios for DMAs N1 a, N1 b, N1 c, N2a, N2b, N2c, N4 and N8 are less than or equal to one so it
appears that these DMAs may be considered Self-Retaining DMAs via qualifying Site Design BMPs, and
compliant with City requirements. It is however important to note that the majority of the receiving permeable
area for DMAs N 1 a, N 1 b, N2a, and N2b is sloped steeper than 5% and therefore is not eligible for impervious
area dispersion (BMP SD-5). Therefore additional stormwater measures (i.e. Biofiltration with partial retention
Basins-PR-1) have been included in the design to treat the runoff from DMAs N1a, N1b, N2a, and N2b.
At this point in the analysis DMAs N1 c, N2c, N4 and N8 are the only DMAs that may be considered as
Self-Retaining DMAs via qualifying Site Design BMPs via SD-5. Additional BMPs are needed for DMAs N1 a,
N1 b, N2a, N2b, N3, NS, N6 and N7, so for these DMAs the required Design Capture Volume must be
calculated as the product of the C-value 851h percentile storm depth and the contributing drainage area. The
table below summarizes the calculations used to determine the DCV for each OMA and if each OMA could be
treated by Impervious dispersion (BMP SD-5) alone:
DMA A A A,imp A,imp A,per A,per imp:perv C DCV WQ Compliant
sq-ft ac sq-ft ac sf ac Ratio cu-ft ai/ap < 1?
Nla 1635 0.038 352 0.01 1283 0.03 0.274 0.27 22 No*
Nlb 11917 0.274 4860 0.11 7057 0.16 0.689 0.43 250 No*
Nla + Nlb 13552 0.311 5212 0.12 8340 0.19 0.625 0.41 272 No*
Nlc 605 0.014 0 0.00 605 0.01 0.000 0.10 3 Yes
N2a 1669 0.038 361 0.01 1308 0.03 0.276 0.27 22 No*
N2b 11917 0.274 4545 0.10 7372 0.17 0.617 0.41 237 No*
N2a +N2b 13586 0.312 4906 0.11 8680 0.20 0.565 0.39 260 No*
N2c 484 0.011 0 0.00 484 0.01 0.000 0.10 2 Yes
N3 3571 0.082 2202 0.05 1369 0.03 1.608 0.59 104 No
N4 3571 0.082 1782 0.04 1789 0.04 0.996 0.50 88 Yes
NS 3571 0.082 2309 0.05 1262 0.03 1.830 0.62 108 No
N6 3571 0.082 1798 0.04 1773 0.04 1.014 0.50 88 No
N7 3571 0.082 2172 0.05 1399 0.03 1.553 0.59 103 No
NB 3571 0.082 1765 0.04 1806 0.04 0.977 0.50 87 Yes
TOTAL 49653 1.14 22146 0.51 27507 0.63 0.805 0.46 1115
* = DMAs Nla, Nlb, N2a and N2b meet the BMP SD-5 water quality requirement in terms of imp:perv ratio,
however the DCV reduction associated with BMP SD-5 has not been counted because a significant portion of the
receiving permeable area is sloped greater than 5%.
As noted in the table above the impervious:pervious ratios for DMAs N3, N5, N6 and N7 are larger than one
(1 ), and the receiving pervious area for DMAs N1 a, N1 b, N2a and N2b is steeper than 5%, so therefore these
DMAs require additional BMPs for compliance. For these DMAs, the Runoff Factor (C) was calculated and
then adjusted by accounting for the effects of BMP SD-5 in accordance with City BMP Design Manual Section
5.3 and Appendix 8.2. Next the Design Capture Volume (DCV) was re-calculated using the adjusted C factor.
The adjusted C-values and DCVs for the DMAs requiring additional BMPs are provided in the table, below:
Il\4\ C-Value ocv Adjustrrent Adjusted Adjusted
Factor C-Value ocv
# unitless cu-ft unitless unitless cu-ft
Nla + Nlb 0.41 272 N/A 272
Nlc 0.10 3 N/A 3
N2a + N2b 0.39 260 N/A 260
N2c 0.10 2 N/A 2
N3 0.59 104 0.16 0.13 23
N4 0.50 88 N/A 88
NS 0.62 108 0.22 0.17 29
N6 0.50 88 0.00 0.05 9
N7 0.59 103 0.15 0.12 21
N8 0.50 87 N/A 87
TOTAL DCV = 1115 TOTAL ADJUSTED DCV = 793
The City of Carlsbad allows up to 25% of total DCV to be treated by Tree Wells (BMP SD-1 ), and Tree Credit
Volumes may be issued at 10 cu-ft and 40 cu-ft for trees with canopies reaching 5-ft and 10-ft, respectively at
maturity. Tree Wells have been strategically located into the site landscaping and drainage plans to receive
runoff from impervious surfaces, and treat the remainder DCV from DMAs N3, and N5-N8 as follows:
OM<\ Adjusted Trees TCV Trees TCV Total Adj.OCV \\Q Struct. BM> ocv (d=5ft) (d=5ft) (d=lOft) (d= 10 ft) TCV (via SD-6) ComnJiant? needed?
# cu-ft # cu-ft/tree # cu-ft/tree cu-ft cu-ft Yes/No
Nla+Nlb 272 Yes
Nlc 3 NJ
N2a+N2b 260 Yes
N2c 2 NJ
N3 23 1 40 40 -17 Yes NJ
N:1-88 NJ
N5 29 1 40 40 -11 Yes NJ
:N(j 9 1 10 10 -1 Yes NJ
N7 21 1 40 40 -19 Yes NJ
N8 87 NJ
Total TCV= 130
The City of Carlsbad BMP Design Manual allows for a Tree Credit Volume (TCV) up to up to 25% of the DCV
for the project, and as noted in the table above the project has a TCV equal to 130 cu-ft. It is not clear whether
the TCV is to be applied to the original DCV or the Adjusted DCV, so the project has been designed in
compliance with both as follows:
Compliance Check for Project TCV (equal to 130 cu-ft):
TCV must be less than 25% of DCV 7 0.25*DCV = 0.25 * 1, 115 cu-ft = 279 cu-ft 7
TCV = 130 cu-ft < 0.25*DCV = 279 cu-ft 7 OK
TCV must be less than 25% of Adjusted DCV 7 0.25*Adjusted DCV = (0.25) * 793 cu-ft= 198 cu-ft 7
TCV = 130 cu-ft< 0.25*Adjusted DCV = 198 cu-ft 7 OK
As noted in the table above structural BMPs are still required for DMAs N1 a, N1 b, N2a and N2b. Also noted in
the summary table at the top of this section the DCV reduction associated with BMP SD-5 has not been
counted for DMAs N 1 a, N 1 b, N2a and N2b. because a significant portion of the receiving permeable area is
sloped greater than 5%. So, two (2) Biofiltration with Partial Retention Basins (BMP PR-1) have been
incorporated into the grading and drainage design to treat the runoff from N 1 a, N 1 b, and from N2a and N2b,
respectively. Soils onsite are classified as Hydrologic Soil Type Band percolation testing indicates that they
infiltrate at 0.125 in/hr. Given these conditions, the 2 proposed Biofiltration with Partial Retention Basins have
been designed in accordance with the requirements for Biofiltration with Partial Retention Basins (BMP PR-1)
as detailed in the Structural BMP Summary Information Section of this SWQMP (below) and the calculations
included under SWQMP Attachment 1 e.
In summary, 2 Biofiltration with Partial Retention Basins (BMP PR-1a and PR-2b) have been designed to treat
runoff from the remaining DMAs (N1a/N1b and N2a/N2b) that could not be treated via qualifying Site Design
BMPs. Impervious Area Dispersion (BMP SD-5) alone is sufficient for treating DMAs N1c, N2c, N4 & N8 and
a combination of Impervious Area Dispersion (BMP SD-5) and Tree Wells (BMP SD-1) was used to treat
DMAs N3, NS, N6 and N7. So, in total 8 out of the 12 proposed DMAs (DMAs N 1 c, N2c, & N3 -NS) may be
considered Self-Retaining DMAs via Qualifying Site Design BMPs, while the other4 DMAs (DMAs N1a, N1b,
N2a and N2b) are treated with structural BMPs (i.e. 2 Biofiltration with Partial Retention Basins, 1 for DMAs
N 1 a & N1 band the other for N2a & N2b). This proposed combination of site design and structural BMPs has
been engineered to adequately address post-development stormwater runoff from all 12 proposed DMAs in
compliance with the City of Carlsbad water quality requirements as detailed in the BMP summary information
below and in the LID BMP calculations included under SWQMP Attachment 1 e.
Structural BMP Summary Information
Structural BMP ID No. PR-1a (for OMA N1a and N1b)
DWG 483-6C Sheet No. 2 -=----
Type of structural BMP:
D Retention by harvest and use (HU-1) D Retention by infiltration basin (INF-1)
D Retention by bioretention (INF-2) D Retention by permeable pavement (INF-3)
~ Partial retention by biofiltration with partial retention (PR-1)
D Biofiltration (BF-1)
D 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)
D Detention pond or vault for hydromodification management D Other (describe in discussion section below)
Purpose:
~ Pollutant control only
D Hydromodification control only
D Combined pollutant control and hydromodification control D Pre-treatment/forebay for another structural BMP
D Other (describe in discussion section below)
Discussion (as needed):
The site is exempt from hydromodification requirements and a Biofiltration with Partial Retention Basin (BMP
PR-1 a) has been designed solely to address DMAs N 1 a and N 1 b for water quality purposes. The treatment will
be achieved as stormwater is filtered vertically through amended soils prior to infiltrating into native soils onsite.
OMA N 1 a combines with OMA N 1 b on Lot 4 and flows through the drainage easements on Lot 3 before
discharging into the City MS4 along the sites eastern perimeter. The total area within DMAs N 1 a and N 1 b is
13,552 sq-ft (38% impervious}, and it has been designed such that all of the proposed permeable areas and
impervious surfaces (i.e. house, sidewalks, and driveway) will drain to the Biofiltration with Partial Retention
Basin (BMP PR-1 a) to promote onsite infiltration.
The entire site is underlain by Hydrologic Soil Group B and Biofiltration with Partial Retention BMPs are an
appropriate measure for treating stormwater runoff. Design calculations for BMP PR-1 a are included under
SWQMP Attachment 1 e, and a summary is provided below:
1 85th percentile 24-hr storm depth from Figure B.1-1 d= 0.59 inches
2 Area tributary to BMP (s) A= 0.31 acres
3 Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1) C= 0.41 unitless
4 Tree wells volume reduction TCV= 0 cubic-feet
5 Rain barrels volume reduction RCV= 0 cubic-feet
Calculate DCV =
6 (3630 x C x d x A) -TCV -RCV DCV= 271.64 cubic-feet
The receiving permeable area is steeper than 5% and cannot be utilized for BMP SD-5, so there is not any
C-value reduction for DMAs Nla and Nlb. Furthermore, although the landscaping plans call out several
trees within the area, Tree Wells (BMP SD-1) have not been incorporated as measure for addressing the
DCV from these DMAs. As a result the DCV for DMAs Nla and Nlb has been determined to equal 271.64
cu-ft. A Biofiltration with Partial Retention Basin (PR-la) has been designed for OMA Nla and Nlb with a
retention capacity of 107 cu-ft which is more than adequate for treating 37.5% of the DCV of 272 cu-ft-->
107 cu-ft> {0.375 * 272 cu-ft) = 101.9 cu-ft--> OK
A Biofiltration with Partial Retention Basin (PR-1 a) was sized with sufficient capacity for addressing the DCV.
The Biofiltration with Partial Retention Basin includes a 6-inch ponding depth, 18-inches of amended soils and
12-inches of gravel on top of native soils with a surface area of 318 sq-ft, bottom area of 77 sq-ft and 3: 1 side
slopes, as detailed in the table below:
DMA A,BMP A, Inf. Inf. A,bot h,pond h,am h,gr V,BMP V,BMP > 0.375
req Rate Depth (retained) (retained) DCV?
Sf sf in/hr In sf ft ft ft cu-ft Fraction Water Quality
ofDCV Compliant?
Nla & Nlb 318 166 0.063 2.25 77 0.50 1.50 1.0 107 0.395 YES
The gravel, amended soil and ponding layers of the BMP combined retain 107 cubic-feet of volume (i.e.
volume retained = 107 cu-ft> 0.375 * DCV = 0.375 *272 cu-ft= 101.9 cu-ft 7 OK). Biofiltration BMPs
require an area of 3% of the OMA accounting for the C-value (i.e. 13,552 sq-ft * 0.41 * 0.03 = 166 sq-ft). As
noted PR-1 a provides 318 sq-ft which is larger than the area required (166 sq-ft), and therefore in compliance
with City requirements (i.e. area provided = 318 sq-ft > area required = 166 sq-ft 7 OK). Drawdown
calculation were performed using the Simple Sizing Method of Biofiltration BMPs as follows:
Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs
BMP ID IDs of Tributary DMAs IDs of Retention BMPs Treating the Same DMAs
PR-la DMAs Nla & Nlb N/A
Initial Information
la Total DCV of tributary DMAs 272 ft3
lb Volume reduction from implementation of retention BMPs 0 ft3
1 Remaining DCV after implementing retention BMPs (Line la -Line lb) 272 ft3
Partial Retention
2 Infiltration rate from Worksheet D.5-1 if partial infiltration is feasible 0.063 in/hr
3 Allowable drawdown time for aggregate storage below the underdrain 36 hr
4 Depth of runoff that can be infiltrated [Line 2 x Line 3] 2.25 in
5 Aggregate pore space 0.4 in/in
6 Required depth of gravel below the underdrain [Line 4/ Line 5] 5.63 in
7 Assumed surface area of the biofiltration BMP 318 ft2
8 Media retained pore storage 0.1 in/in
9 Volume retained by BMP [[[Line 4 + (Line 12 x Line 8)]/12] x Line 7] 107 ft3
10 DCV that requires biofiltration [Line 1-Line 9] 164 ft3
BMP Parameters
11 Surface Ponding [6 inch minimum, 12 inch maximum] 6 in
Soil Media Thickness [18 inches minimum], also add mulch layer thickness
12 to this line for sizing calculations 18 in
13 Aggregate Storage above underdrain invert 6 in
14 Soil Media available pore space 0.2 in/in
Soil Media filtration rate to be used for sizing (5 in/hr. with no outlet
control; if the filtration rate is controlled by the outlet use the outlet
15 controlled rate) 5 in/hr.
Baseline Calculations
16 Allowable Routing Time for sizing 6 hr
17 Depth filtered during storm [ Line 15 x Line 16] 30 in
Depth of Detention Storage
18 [Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)] 12 in
19 Total Depth Treated [Line 17 + Line 18] 42 in
Option 1-Biofilter 1.5 times the DCV
20 Required biofiltered volume [1.5 x Line 10] 246 ft3
21 Required Footprint [Line 20/ Line 19] x 12 70 ft2
Option 2 -Store 0.75 of remaining DCV in pores and ponding
22 Required Storage (surface+ pores) Volume [0.75 x Line 10] 239 ft3
23 Required Footprint [Line 22/ Line 18] x 12 239 ft2
Footprint of the BMP
24 Area draining to the BMP 13552 ft2
25 Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and B.2) 0.41
BMP Footprint Sizing Factor (Default 0.03 or an alternative minimum
26 footprint sizing factor from Worksheet B.5-2, Line 11) 0.03 unitless
27 Minimum BMP Footprint [Line 24 x Line 25 x Line 26] 166 ft2
28 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 27) 166 ft2
29 Calculate the fraction of the DCV retained by the BMP [Line 9/ Line 1] 0.395 unitless
30 Minimum required fraction of DCV retained for partial infiltration condition 0.375 unitless
Is the retained DCV > 0.375? If the answer is no increase the footprint sizing
31 factor in Line 26 until the answer is yes for this criterion @Yes D No
Notes
1. 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)
2. The DCV fraction of 0.375 is based on a 40% average annual percent capture and a 36-hour drawdown time.
3. The increase in footprint for volume reduction can be optimized using the approach presented in Appendix B.5.2. The
optimized footprint cannot be smaller than the alternative minimum footprint sizing factor from Worksheet B.5-2.
4. If the proposed biofiltration BMP footprint is smaller than the alternative minimum footprint sizing factor from Worksheet
B.5-2, but satisfies Option 1 or Option 2 sizing, it is considered a compact biofiltration BMP and may be allowed at the
discretion of the [City Engineer], if it meets the requirements in Appendix F.
Compliance Check for PR-1 a (Volume Retained > 0.375 * DCV}
Volume Retained= 107 cu-ft> 0.375 *DCV = 0.375* 272 cu-ft= 101.9 cu-ft 7 OK
Compliance Check for PR-1 a (Area Provided > Area Required}
Area Provided= 318 sq-ft> Area Required= 166 sq-ft 7 OK
In summary by incorporating Biofiltration with Partial Retention Basin (PR-1 a) into the site plan, DMAs N 1 a and
N 1 b have been designed in compliance with City water quality requirements. For further details, please refer to
the BMP Design Calculations included under Attachment 1e of this SWQMP.
Structural BMP Summary Information
Structural BMP ID No. SMA-1 (for OMA N1c)
DWG 483-68 Sheet No. 4 & 5
Type of structural BMP: D Retention by harvest and use (HU-1)
D Retention by infiltration basin (INF-1)
D Retention by bioretention (INF-2) D Retention by permeable pavement (INF-3)
D Partial retention by biofiltration with partial retention (PR-1)
D Biofiltration (BF-1) D 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) D Detention pond or vault for hydromodification management
[8J Other describe in discussion section below
Purpose:
[8J Pollutant control only
D Hydromodification control only D Combined pollutant control and hydromodification control D Pre-treatment/forebay for another structural BMP
[8J Other (describe in discussion section below)
Discussion (as needed):
The site is exempt from hydromodification requirements and the self-mitigating area (SMA-1) has been
designed solely to address OMA N 1 c for water quality purposes. The treatment will be achieved through
infiltration of stormwater onsite.
OMA N1 c is 0.014-acres along the western edge of Lot 3 and the southern portion of the western edge of Lot
2 and contains a drainage swale for conveying overflows from Lot 4 (i.e. flows from storms larger than the
851h percentile event) through Lot 3. OMA N1c will be vegetated and will not contain any impermeable
surfaces (i.e. 100% pervious). In order to comply with the City's Self-Mitigating Area requirements the
incidental impervious areas must be less than 5% of the total OMA.
1
2
3
4
5
6
Compliance Check for SMA-1 (impervious area < 5% of DMA):
impervious area = 0 7 0 < 5% 7 OK
SMA-1 as designed is compliant.
85th percentile 24-hr storm depth from Figure B.1-1 d= 0.59
Area tributary to BMP (s) A= 0.01
Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1) C= 0.10
Tree wells volume reduction TCV= 0
Rain barrels volume reduction RCV= 0
Calculate DCV =
(3630 x C x d x A) -TCV -RCV DCV= 2.97
inches
acres
unitless
cubic-feet
cubic-feet
cubic-feet
Please note that SMA-1 has been designed in compliance with City water quality requirements as a Self-
Mitigating DMA. Compliance Check for SMA-1 (imperv. area must be< 5%): imperv. area= 0 --> 0 < 5% --> OK
In summary, SMA-1 has been designed in compliance with City water quality requirements as a
Self-Mitigating OMA because it is completely permeable. For further details, please refer to the BMP Design
Calculations included under Attachment 1e of this SWQMP.
Structural BMP Summary Information
Structural BMP ID No. PR-1 b (for DMAs N2a and N2b)
DWG 483-6C Sheet No. 2
Type of structural BMP: D Retention by harvest and use (HU-1)
D Retention by infiltration basin (INF-1)
D Retention by bioretention (INF-2)
D Retention by permeable pavement (INF-3)
[8J Partial retention by biofiltration with partial retention (PR-1)
D Biofiltration (BF-1)
D 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)
D Detention pond or vault for hydromodification management
D Other (describe in discussion section below)
Purpose:
[8J Pollutant control only
D Hydromodification control only
D Combined pollutant control and hydromodification control
D Pre-treatment/forebay for another structural BMP
D Other (describe in discussion section below)
Discussion (as needed):
The site is exempt from hydromodification requirements and a Biofiltration with Partial Retention Basin (PR-1 b)
has been designed solely to address DMAs N2a and N2b for water quality purposes. The treatment will be
achieved as stormwater is filtered vertically through amended soils prior to infiltrating into native soils onsite.
OMA N2a combines with OMA N2b on Lot 5 and flows through the drainage easement on the southern edge of
Lot 1 before discharging to the City MS4, via the drainage easement along the eastern edge of Lots 2 and 3.
The total area within DMAs N2a and N2b is 13,586 sq-ft (36% impervious), and it has been designed such that
all of the proposed permeable areas and impervious surfaces (i.e. home, sidewalks, and driveway) will drain to
the Biofiltration with Partial Retention Basin (PR-1 b) to promote onsite infiltration.
The entire site is underlain by Hydrologic Soil Group B and Biofiltration with Partial Retention BMPs are an
appropriate measure for treating stormwater runoff. Design calculations for BMP PR-1 b are included under
SWQMP Attachment 1e, and a summa is provided below:
1 85th percentile 24-hr storm depth from Figure B.1-1 d= 0.59 inches
2 Area tributary to BMP (s) A= 0.31 acres
3 Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1) C= 0.39 unitless
4 Tree wells volume reduction TCV= 0 cubic-feet
5 Rain barrels volume reduction RCV= 0 cubic-feet
Calculate DCV =
6 (3630 x C x d x A) -TCV -RCV DCV= 259.77 cubic-feet
The receiving permeable area is steeper than 5% and cannot be utilized for BMP SD-5, so there is not any
C-value reduction for DMAs N2a and N2b. Furthermore, although the landscaping plans call out several trees
within the area, Tree Wells (BMP SD-1) have not been incorporated as measure for addressing the DCV from
these DMAs. As a result the DCV for DMAs N2a and N2b has been determined to equal 259.77 cu-ft. A
Biofiltration with Partial Retention Basin (PR-2a) has been designed for DMA N2a and N2b with a retention
capacity of 100 cu-ft which is more than adequate for treating 37.5% of the DCV =of 260 cu-ft--> 100 cu-ft>
(0.375 * 260 cu-ft)= 97.4 cu-ft--> OK
A Biofiltration with Partial Retention Basin (PR-1 b) was sized with sufficient capacity for addressing the DCV.
The Bioretention Basin includes a 6-inch ponding depth, 18-inches of amended soils and 12-inches of gravel
on top of native soils with a surface area of 297 sq-ft, bottom area of 72 sq-ft and 3: 1 side slopes, as detailed in
the table, below:
OMA A,BMP A, Inf. Inf. A,bot h,pond h,am h,gr V,BMP V,BMP > 0.375
req Rate Depth (retained) (retained) DCV?
Sf sf in/hr In sf ft ft ft cu-ft Fraction Water Quality
of DCV Compliant?
N2a & N2b 297 159 0.063 2.25 72 0.50 1.50 1.0 100 0.386 YES
The gravel, amended soil and ponding layers of the BMP combined retain 100 cubic-feet of volume (i.e.
volume retained= 100 cu-ft> 0.375 * DCV = 0.375 *260 cu-ft= 97.4 cu-ft~ OK). Biofiltration BMPs require
an area of 3% of the OMA accounting for the C-value (i.e. 13,586 sq-ft * 0.39 * 0.03 = 159 sq-ft). As noted
PR-2a provides 297 sq-ft which is larger than the area required (159 sq-ft), and therefore in compliance with
City requirements (i.e. area provided = 297 sq-ft > area required = 159 sq-ft ~ OK). Drawdown calculation
were performed using the Simple Sizing Method of Biofiltration BMPs as follows:
Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs
BMPID IDs of Tributary DMAs IDs of Retention BMPs Treating the Same DMAs
PR-lb DMAs N2a & N2b N/A
Initial Information
la Total DCV of tributary DMAs 260 ft3
lb Volume reduction from implementation of retention BMPs 0 ft3
1 Remaining DCV after implementing retention BMPs (Line la -Line lb) 260 ft3
Partial Retention
2 Infiltration rate from Worksheet D.5-1 if partial infiltration is feasible 0.063 in/hr
3 Allowable drawdown time for aggregate storage below the underdrain 36 hr
4 Depth of runoff that can be infiltrated [Line 2 x Line 3] 2.25 in
5 Aggregate pore space 0.4 in/in
6 Required depth of gravel below the underdrain [Line 4/ Line 5] 5.63 in
7 Assumed surface area of the biofiltration BMP 297 ft2
8 Media retained pore storage 0.1 in/in
9 Volume retained by BMP [[[Line 4 + (Line 12 x Line 8)]/12] x Line 7] 100 ft3
10 DCV that requires biofiltration [Line 1-Line 9] 160 ft3
BMP Parameters
11 Surface Ponding [6 inch minimum, 12 inch maximum] 6 in
Soil Media Thickness [18 inches minimum], also add mulch layer
12 thickness to this line for sizing calculations 18 in
13 Aggregate Storage above underdrain invert 6 in
14 Soil Media available pore space 0.2 in/in
Soil Media filtration rate to be used for sizing (5 in/hr. with no outlet
control; if the filtration rate is controlled by the outlet use the outlet
15 controlled rate) 5 in/hr.
Baseline Calculations
16 Allowable Routing Time for sizing 6 hr
17 Depth filtered during storm [ Line 15 x Line 16] 30 in
Depth of Detention Storage
18 [Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)] 12 in
19 Total Depth Treated [Line 17 + Line 18] 42 in
Option 1-Biofilter 1.5 times the DCV
20 Required biofiltered volume [1.5 x Line 10] 239 ft3
21 Required Footprint [Line 20/ Line 19] x 12 68 ft2
Option 2 -Store 0.75 of remaining DCV in pores and ponding
22 Required Storage (surface+ pores) Volume [0.75 x Line 10] 223 ft3
23 Required Footprint [Line 22/ Line 18] x 12 223 ft2
Footprint of the BMP
24 Area draining to the BMP 13586 ft2
Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and
25 B.2) 0.39
BMP Footprint Sizing Factor (Default 0.03 or an alternative minimum
26 footprint sizing factor from Worksheet B.5-2, Line 11) 0.03 unitless
27 Minimum BMP Footprint [Line 24 x Line 25 x Line 26] 159 ft2
28 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 27) 159 ft2
29 Calculate the fraction of the DCV retained by the BMP [Line 9/ Line 1] 0.386 unitless
Minimum required fraction of DCV retained for partial infiltration
30 condition 0.375 unitless
Is the retained DCV > 0.375? If the answer is no increase the footprint
31 sizing factor in Line 26 until the answer is yes for this criterion @Yes D No
Notes
1. 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)
2. The DCV fraction of 0.375 is based on a 40% average annual percent capture and a 36-hour drawdown time.
3. The increase in footprint for volume reduction can be optimized using the approach presented in Appendix B.5.2. The
optimized footprint cannot be smaller than the alternative minimum footprint sizing factor from Worksheet B.5-2.
4. If the proposed biofiltration BMP footprint is smaller than the alternative minimum footprint sizing factor from
Worksheet B.5-2, but satisfies Option 1 or Option 2 sizing, it is considered a compact biofiltration BMP and may be
allowed at the discretion of the [City Engineer], if it meets the requirements in Appendix F.
Compliance Check for PR-1 b (Volume Retained > 0.375 * DCV)
Volume Retained= 100 cu-ft> 0.375 *DCV = 0.375 * 260 cu-ft= 97.4 cu-ft 7 OK
Compliance Check for PR-1 b (Area Provided > Area Required)
Area Provided = 297 sq-ft > Area Required = 159 sq-ft 7 OK
In summary by incorporating Biofiltration with Partial Retention Basin (PR-1 b) into the site plan, DMAs N2a and
N2b have been designed in compliance with City water quality requirements. For further details, please refer to
the BMP Design Calculations included under Attachment 1 e of this SWQMP.
Structural BMP Summary Information
Structural BMP ID No. SMA-2 (for OMA N2c)
DWG 483-68 Sheet No. 3 -----
Type of structural BMP: D Retention by harvest and use (HU-1)
D Retention by infiltration basin (INF-1)
D Retention by bioretention (INF-2) D Retention by permeable pavement (INF-3) D Partial retention by biofiltration with partial retention (PR-1)
D Biofiltration (BF-1) D 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)
D Detention pond or vault for hydromodification management
IZI Other describe in discussion section below
Purpose:
1Z1 Pollutant control only
D Hydromodification control only D Combined pollutant control and hydromodification control D Pre-treatment/forebay for another structural BMP
IZ] Other ( describe in discussion section below)
Discussion (as needed):
The site is exempt from hydromodification requirements and the self-mitigating area (SMA-2) has been
designed solely to address OMA N2c for water quality purposes. The treatment will be achieved through
infiltration of stormwater onsite.
OMA N2c is 0.011-acres along the western edge of Lot 1 and the northern portion of the western edge of Lot
2 and contains a drainage swale for conveying overflows from Lot 5 (i.e. flows from storms larger than the
851h percentile event) through Lot 1. OMA N2c will be vegetated and will not contain any impermeable
surfaces (i.e. 100% pervious). In order to comply with the City's Self-Mitigating Area requirements the
incidental impervious areas must be less than 5% of the total OMA.
1
2
3
4
5
6
Compliance Check for SMA-2 (impervious area < 5% of DMA):
impervious area = 0 ~ 0 < 5% ~ OK
SMA-2 as designed is compliant.
85th percentile 24-hr storm depth from Figure B.1-1 d= 0.59
Area tributary to BMP (s) A= 0.01
Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1) C= 0.10
Tree wells volume reduction TCV= 0
Rain barrels volume reduction RCV= 0
Calculate DCV =
(3630 x C x d x A) -TCV -RCV DCV= 2.38
inches
acres
unitless
cubic-feet
cubic-feet
cubic-feet
Please note that SMA-2 has been designed in compliance with City water quality requirements as a Self-
Mitigating OMA. Compliance Check for SMA-2 (imperv. area must be< 5%): imperv. area= 0 --> 0 < 5% --> OK
In summary, SMA-2 has been designed in compliance with City water quality requirements as a
Self-Mitigating OMA because it is completely permeable. For further details, please refer to the BMP Design
Calculations included under Attachment 1 e of this SWQMP.
Structural BMP Summary Information
Structural BMP ID No. SRA-1 (for OMA N3)
DWG 483-68 Sheet No. _5 ___ _
Type of structural BMP:
D Retention by harvest and use (HU-1)
D Retention by infiltration basin (INF-1)
D Retention by bioretention (INF-2) D Retention by permeable pavement (INF-3) D Partial retention by biofiltration with partial retention (PR-1)
D Biofiltration (BF-1)
D 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) D Detention pond or vault for hydromodification management
IZI Other (describe in discussion section below)
Purpose: IZI Pollutant control only
D Hydromodification control only
D Combined pollutant control and hydromodification control
D Pre-treatment/forebay for another structural BMP
IZ! Other (describe in discussion section below)
Discussion (as needed):
The site is exempt from hydromodification requirements and the self-retaining area (SRA-1) has been
designed solely to address OMA N3 for water quality purposes. The treatment will be achieved by dispersing
the runoff from the impervious areas to permeable areas (BMP SD-5) and incorporating Tree Wells (BMP
SD-1) into the site design to promote onsite infiltration.
OMA N3 contains the southern half of Lot 3, and the drainage easement and storm drain infrastructure that
coveys flows from DMAs N1 and N3 along the southern perimeter of Lot 3 prior to discharging to the City MS4.
OMA N3 has been designed such that its 2,202 sq-ft (61.7%) of proposed impervious surfaces (i.e. home,
sidewalks, and driveway) will drain to its 1,369 sq-ft (38.3%) of permeable/landscaped area to promote onsite
infiltration.
The entire site is underlain by Hydrologic Soil Group B, so in order to comply with the BMP SD-5 requirements
outlined in the City BMP Design Manual the impervious:pervious ratio for OMA N3 must be less than 1.0.
Compliance Check for SRA-1 {imp:perv ratio must be < 1.0):
imp:perv ratio= (0.617)/(0.383) = 1.608 7 1.608 > 1.0 7 SRA-1 requires additional BMPs
Since the impervious:pervious ratio for OMA N3 is larger than 1.0, additional BMPs are required for
compliance. First however, it is important to quantify the impacts of BMP SD-5 by adjusting the Runoff Factor
(C) as follows:
• Baseline C = LCxAx/1:Ax = ((0.9 * 0.051-ac) + (0.1 * 0.031-ac))/0.082-ac = 0.59 ~ Baseline C = 0.59.
• imp:perv ratio= (0.617)/(0.383) = 1.608 ~ 1.0 < 1.668 .s::; 4.0, since ratio > 1.0, compliance cannot be achieved
through BMP SD-5 alone, but since ratio< 4.0 7 C Factor adjustment can be claimed.
• Adjustment factors for hydrologic soil group 8 and a ratio of 1 = 0.0, ratio of 2 = 0.27 (Table 8.2-1 ).
• Linear interpolated adjustment factor for a ratio of 1.608 = 0.0 + (0.27 -0.0) I (2 -1) * (1.608 -1) = 0.16 7
adjustment factor= 0.16.
• Adjusted C = (0.9 * 0.16 * 0.051-ac + 0.1 * 0.031-ac /0.082-ac = 0.13 7 Adjusted C = 0.13
Next, the adjusted C factor is used to calculate the Design Capture Volume (DCV) which is equal to the volume
of runoff in excess of what can be treated through the implementation of BMP SD-5. The DCV may be
calculated simply as follows:
• DCV = C * d *A= 0.13 * 0.59 * 0.082-ac * 43,560 sq-ft/ac * 12-in/ft = 22.74 7 DCV = 22.7 cu-ft
Finally, a Tree Well (BMP SD-1) was incorporated into the site design to treat the DCV from OMA N3. Tree
wells can further reduce runoff and help to eliminate the DCV because of the water demands of the vegetation
and underlying roots. The Carlsbad BMP Design Manual allows for Tree Credit Volumes (TCV) of 10 cu-ft/tree
and 40 cu-ft/trees for proposed tree wells with 5-ft and 10-ft canopy diameters at maturity, respectively.
The project proposes one (1) new tree with a 10-ft canopy diameter at maturity to address the remaining DCV
(22. 7 cu-ft) from OMA N3. The final adjusted DCV is determined by simply subtracting DCV from TCV as
outlined in Worksheet B.2-1, below:
1 85th percentile 24-hr storm depth from Figure B.1-1 d= 0.59 inches
2 Area tributary to BMP (s) A= 0.08 acres
3 Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1) C= 0.13 unitless
4 Tree wells volume reduction TCV= 40 cubic-feet
5 Rain barrels volume reduction RCV= 0 cubic-feet
Calculate DCV =
6 (3630 x C x d x A) -TCV -RCV DCV= -17.26 cubic-feet
By Dispersing Runoff from Impervious Areas (SD-5) and with Hydrologic Soil Group B, and an
impervious:pervious ration< 1, the Runoff Factor (C = 0.59) was reduced significantly (adjusted C = 0.13). This
combined with one tree well (with an anticipated 10-ft diameter canopy) reduced the original Design Capture
Volume (DCV = 104 cu-ft) significantly such that the adjusted DCV is negative and does not require further
treatment (adjusted DCV = -17.26 cu-ft)--> DCV = -17.3 < 0--> OK
Compliance Check for SRA-1 (Final DCV < 0):
Final DCV = DCV-TCV = 22.74 cu-ft-40 cu-ft= -17.26 cu-ft "?Final DCV = -17.3 cu-ft
Final DCV = -17.3 < 0 7 SRA-1 as designed is compliant.
In summary by incorporating Impervious Area Dispersion (BMP SD-5) and a Tree Well (BMP SD-1),
into the site plan, SRA 3 has been designed in compliance with City water quality requirements as a
Self-Retaining OMA via qualifying Site Design BMPs. Please refer to the BMP Design calculations
included under SWQMP Attachment 1 e.
Structural BMP Summary Information
Structural BMP ID No. SRA-2 (for OMA N4)
DWG 483-68 Sheet No. 5
Type of structural BMP: D Retention by harvest and use (HU-1)
D Retention by infiltration basin (I NF-1)
D Retention by bioretention (INF-2)
D Retention by permeable pavement (INF-3)
D Partial retention by biofiltration with partial retention (PR-1) D Biofiltration (BF-1) D 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) D Detention pond or vault for hydromodification management
IZI Other (describe in discussion section below)
Purpose: IZI Pollutant control only
D Hydromodification control only
D Combined pollutant control and hydromodification control
D Pre-treatment/forebay for another structural BMP 1Z1 Other (describe in discussion section below)
Discussion (as needed):
The site is exempt from hydromodification requirements and the self-retaining area (SRA-4) has been
designed solely to address OMA N4 for water quality purposes. The treatment will be achieved by dispersing
the runoff from the impervious areas to permeable areas (BMP SD-5) and incorporating tree wells (BMP SD-1)
into the site design to promote onsite infiltration.
OMA N4 is 0.082-acres (49.9% impervious) and contains the northern half of Lot 3, and a swale and storm
drain that conveys runoff along the northern edge of Lot 3 prior to discharging to the City MS4. There is also a
drainage easement along the eastern perimeter of OMA N4 that accepts flows from Lots 1 and 2 and conveys
them to the back of the curb inlet on James Drive.
The total area within OMA N4 is 3,571 sq-ft (0.082-acres), and it has been designed such that its 1,782 sq-ft
(49.89) of proposed impervious surfaces (i.e. home and sidewalks) will drain to its 1,789 sq-ft (50.1%) of
permeable/landscaped area to promote onsite infiltration.
The entire site is underlain by Hydrologic Soil Group B, so in order to comply with the BMP SD-5 requirements
outlined in the City BMP Design Manual the impervious:pervious ratio for OMA N3 must be less than 1.0.
Compliance Check for SRA-2 {imp:perv ratio must be < 1.0):
imp:perv ratio= (0.499)/(0.501) = 0.996 7 0.996 < 1.0 7 OK
SRA-2 as designed is compliant.
1 85th percentile 24-hr storm depth from Figure B.1-1 d= 0.59 inches
2 Area tributary to BMP (s) A= 0.08 acres
3 Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1) C= 0.50 unitless
4 Tree wells volume reduction TCV= 0 cubic-feet
5 Rain barrels volume reduction RCV= 0 cubic-feet
Calculate DCV =
6 (3630 x C x d x A) -TCV -RCV DCV= 87.65 cubic-feet
Please note that SRA 2 has been designed in compliance with City water quality requirements as a
Self-Retaining DMA via qualifying Site Design BMPs. Compliance Check for SRA-2 (imp:perv ratio must be<
1.0): imp:perv ratio= (0.499)/(0.501) = 0.996 --> 0.996 < 1.0 --> OK
In summary by incorporating Impervious Area Dispersion (BMP SD-5) into the site plan, SRA 2 has been
designed in compliance with City water quality requirements as a Self-Retaining OMA via Qualifying Site
Design BMPs. For further details, please refer to the BMP Design Calculations included under Attachment 1 e
of this SWQMP.
Structural BMP Summary Information
Structural BMP ID No. SRA-3 (for OMA NS)
DWG 483-68 Sheet No. _4...:._ __ _
Type of structural BMP:
D Retention by harvest and use (HU-1)
D Retention by infiltration basin (INF-1)
D Retention by bioretention (INF-2)
D Retention by permeable pavement (INF-3)
D Partial retention by biofiltration with partial retention (PR-1) D Biofiltration (BF-1)
D 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)
D Detention pond or vault for hydromodification management
~ Other (describe in discussion section below)
Purpose:
~ Pollutant control only
D Hydromodification control only
D Combined pollutant control and hydromodification control
D Pre-treatment/forebay for another structural BMP
~ Other (describe in discussion section below)
Discussion (as needed):
The site is exempt from hydromodification requirements and the self-retaining area (SRA-3) has been
designed solely to address OMA NS for water quality purposes. The treatment will be achieved by dispersing
the runoff from the impervious areas to permeable areas (BMP SD-S) and incorporating Tree Wells (BMP
SD-1) into the site design to promote onsite infiltration.
OMA NS is 0.082-acres contains the southern half of Lot 2, and a swale and storm drain that conveys runoff
along the southern edge of Lot 2 prior to discharging to the City MS4 (via the drainage easement along the
eastern edge of Lot 3). OMA NS has been designed such that its 2,309 sq-ft (64.7%) of proposed impervious
surfaces (i.e. home, sidewalks, and driveway) will drain to its 1,262 sq-ft (3S.3%) of permeable/landscaped
area to promote onsite infiltration.
The entire site is underlain by Hydrologic Soil Group B, so in order to comply with the BMP SD-S requirements
outlined in the City BMP Design Manual the impervious:pervious ratio for OMA N4 must be less than 1.0.
Compliance Check for SRA-3 {imp:perv ratio must be < 1.0):
imp:perv ratio = (0.647)/(0.353) = 1.830 7 1.830 > 1.0 7 SRA-3 requires additional BMPs
Since the impervious:pervious ratio for OMA NS is larger than 1.0, additional BMPs are required for
compliance. First however, it is important to quantify the impacts of BMP SD-S by adjusting the Runoff Factor
(C) as follows:
• Baseline C = LCxAxlLAx = ((0.9 * 0.053-ac) + (0.1 * 0.029-ac))/0.082-ac = 0.62 "7 Baseline C = 0.62.
• imp:perv ratio = (0.65)/(0.35) = 1.830 "7 1.0 < 1.830 < 4.0, since ratio > 1.0, compliance cannot be achieved
through BMP SD-5 alone, but since ratio< 4.0 "7 C Factor adjustment can be claimed.
• Adjustment factors for hydrologic soil group Band a ratio of 1 = 0.0, ratio of 2 = 0.27 (Table B.2-1 ).
• Linear interpolated adjustment factor for a ratio of 1.830 = 0.0 + (0.27 -0.0) I (2 -1) * (1.830 -1) = 0.22 7
adjustment factor= 0.22.
• Adjusted C = (0.9 * 0.22 * 0.053-ac + 0.1 * 0.029-ac I 0.082-ac = 0.17 7 Adjusted C = 0.17
Next, the adjusted C factor is used to calculate the Design Capture Volume (DCV) which is equal to the volume
of runoff in excess of what can be treated through the implementation of BMP SD-5. The DCV may be
calculated simply as follows:
• DCV = C * d *A= 0.09 * 0.59 * 0.082-ac * 43,560 sq-ft/ac * 12-in/ft = 29.09 7 DCV = 29.1 cu-ft
Finally, a Tree Well (BMP SD-1) was incorporated into the site design to treat the DCV from OMA N5. Tree
wells can further reduce runoff and help to eliminate the DCV because of the water demands of the vegetation
and underlying roots. The Carlsbad BMP Design Manual allows for Tree Credit Volumes (TCV) of 10 cu-ft/tree
and 40 cu-ft/trees for proposed tree wells with 5-ft and 10-ft canopy diameters at maturity, respectively.
The project proposes one (1) new tree with a 10-ft canopy diameter at maturity to address the remaining DCV
(29.1 cu-ft) from OMA N5. The final adjusted DCV is determined by simply subtracting DCV from TCV as
outlined in Worksheet 8.2-1, below:
1 85th percentile 24-hr storm depth from Figure B.1-1 d= 0.59 inches
2 Area tributary to BMP (s) A= 0.08 acres
3 Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1) C= 0.17 unitless
4 Tree wells volume reduction TCV= 40 cubic-feet
5 Rain barrels volume reduction RCV= 0 cubic-feet
Calculate DCV =
6 (3630 x C x d x A) -TCV -RCV DCV= -10.91 cubic-feet
By Dispersing Runoff from Impervious Areas (SD-5) and with Hydrologic Soil Group B, and an
impervious:pervious ration< 1, the Runoff Factor (C = 0.62) was reduced significantly (adjusted C = 0.17). This
combined with one tree well (with an anticipated 10-ft diameter canopy) reduced the Design Capture
Volume (DCV = 108 cu-ft) significantly such that the adjusted DCV is negative and does not require further
treatment (adjusted DCV = -10.91 cu-ft)--> DCV = -10.9 < 0 --> OK
Compliance Check for SRA-3 (Final DCV < 0):
Final DCV = DCV -TCV = 29.09 cu-ft -40 cu-ft = -10.91 cu-ft ~Final DCV = -10.9 cu-ft
Final DCV = -10.9 < 0 ~ SRA-3 as designed is compliant.
In summary by incorporating Impervious Area Dispersion (BMP SD-5) and Tree Wells (BMP SD-1),
into the site plan, SRA 3 has been designed in compliance with City water quality requirements as a
Self-Retaining OMA via qualifying Site Design BMPs. Please refer to the BMP Design calculations
included under SWQMP Attachment 1 e.
Structural BMP Summary Information
Structural BMP ID No. SRA-4 (for OMA N6)
DWG 483-68 Sheet No. _4-'-----
Type of structural BMP: D Retention by harvest and use (HU-1)
D Retention by infiltration basin (INF-1)
D Retention by bioretention (INF-2) D Retention by permeable pavement (INF-3)
D Partial retention by biofiltration with partial retention (PR-1)
D Biofiltration (BF-1) D 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)
D Detention pond or vault for hydromodification management
[8J Other ( describe in discussion section below)
Purpose:
[8J Pollutant control only D Hydromodification control only
D Combined pollutant control and hydromodification control D Pre-treatment/forebay for another structural BMP
[8J Other (describe in discussion section below)
Discussion (as needed):
The site is exempt from hydromodification requirements and the self-retaining area (SRA-4) has been
designed solely to address OMA N6 for water quality purposes. The treatment will be achieved by dispersing
the runoff from the impervious areas to permeable areas (BMP SD-5) and incorporating tree wells (BMP SD-1)
into the site design to promote onsite infiltration.
OMA N6 is 0.082-acres and contains the northern half of Lot 2 and a swale and storm drain that conveys runoff
along the northern edge of Lot 2 prior to discharging to the City MS4 (via the drainage easement along the
eastern edge of Lot 3). OMA N6 has been designed such that its 1,798 sq-ft (50.4%) of proposed impervious
surfaces (i.e. homes, sidewalks, and driveways) will drain to its 1,773 sq-ft (49.6%) of permeable/landscaped
area to promote onsite infiltration.
The entire site is underlain by Hydrologic Soil Group B, so in order to comply with the BMP SD-5 requirements
outlined in the City BMP Design Manual the impervious:pervious ratio for OMA N6 must be less than 1.0.
Compliance Check for SRA-4 (imp:perv ratio must be < 1.0):
imp:perv ratio= (0.504)/(0.496) = 1.014 ~ 1.014 > 1.0 ~ SRA-4 requires additional BMPs
Since the impervious:pervious ratio for OMA N6 is larger than 1.0, additional BMPs are required for
compliance. First however, it is important to quantify the impacts of BMP SD-5 by adjusting the Runoff Factor
(C) as follows:
• Baseline C = rcxAxlLAx = ((0.9 * 0.041-ac) + (0.1 * 0.041-ac))/0.082-ac = 0.50 7 Baseline C = 0.50.
• imp:perv ratio= (0.504)/(0.496) = 1.014 7 1.0 < 1.014 < 4.0, since ratio> 1.0, compliance cannot be
achieved through BMP SD-5 alone, but since ratio < 4.0 7 C Factor adjustment can be claimed.
• Adjustment factors for hydrologic soil group Band a ratio of 1 = 0.0, ratio of 2 = 0.27 (Table B.2-1).
• Linear interpolated adjustment factor for a ratio of 1.014 = 0.0 + (0.27 -0.0) I (2 -1) * (1.042 -1) = 0.004
~ adjustment factor= 0.004.
• Adjusted C = (0.9 * 0.004 * 0.041-ac + 0.1 * 0.041-ac I 0.082-ac = 0.05 ~ Adjusted C = 0.05
Next, the adjusted C factor is used to calculate the Design Capture Volume (DCV) which is equal to the volume
of runoff in excess of what can be treated through the implementation of BMP SD-5. The DCV may be
calculated simply as follows:
• DCV = C * d *A= 0.05 * 0.59 * 0.082-ac * 43,560 sq-ft/ac * 12-in/ft = 9.02 ~ DCV = 9.0 cu-ft
Finally, a Tree Well (BMP SD-1) was incorporated into the site design to treat the DCV from OMA N6. Tree
wells can further reduce runoff and help to eliminate the DCV because of the water demands of the vegetation
and underlying roots. The Carlsbad BMP Design Manual allows for Tree Credit Volumes (TCV) of 10 cu-ft/tree
and 40 cu-ft/trees for proposed tree wells with 5-ft and 10-ft canopy diameters at maturity, respectively.
The project proposes one (1) new tree with a 5-ft canopy diameter at maturity to address the remaining DCV
(10 cu-ft) from OMA N6. The final adjusted DCV is determined by simply subtracting DCV from TCV as outlined
in Worksheet 8.2-1, below:
1 85th percentile 24-hr storm depth from Figure B.1-1 d= 0.59 inches
2 Area tributary to BMP (s) A= 0.08 acres
3 Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1) C= 0.05 unitless
4 Tree wells volume reduction TCV= 10 cubic-feet
5 Rain barrels volume reduction RCV= 0 cubic-feet
Calculate DCV =
6 (3630 x C x d x A) -TCV -RCV DCV= -0.98 cubic-feet
By Dispersing Runoff from Impervious Areas (50-5) and with Hydrologic Soil Group B, and an
impervious:pervious ration< 1, the Runoff Factor (C = 0.50) was reduced significantly (adjusted C = 0.05). This
combined with one tree well (with an anticipated 5-ft diameter canopy) reduced the Design Capture Volume
(DCV = 88 cu-ft) significantly such that the adjusted DCV is negative and does not require further treatment
(adjusted DCV = -0.98 cu-ft)--> DCV = -0.98 < 0 --> OK
Compliance Check for SRA-4 (Final DCV = -0.98 cu-ft):
Final DCV = DCV -TCV = 9.02 cu-ft --10 cu-ft= -0.98 cu-ft ~Final DCV = -0.98 cu-ft
Final DCV = 0 ~ SRA-4 as designed is compliant.
In summary by incorporating Impervious Area Dispersion (BMP SD-5) and a Tree Well (BMP SD-1), into the
site plan, SRA 4 has been designed in compliance with City water quality requirements as a Self-Retaining
OMA via Qualifying Site Design BMPs. For further details, please refer to the BMP design calculations included
under SWQMP Attachment 1 e.
Structural BMP Summary Information
Structural BMP ID No. SRA-5 (for OMA N?)
DWG 483-68 Sheet No. _3=-----
Type of structural BMP: D Retention by harvest and use (HU-1)
D Retention by infiltration basin (INF-1)
D Retention by bioretention (INF-2) D Retention by permeable pavement (INF-3)
D Partial retention by biofiltration with partial retention (PR-1)
D Biofiltration (BF-1) D 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) D Detention pond or vault for hydromodification management
[gl Other (describe in discussion section below)
Purpose:
[gl Pollutant control only
D Hydromodification control only
D Combined pollutant control and hydromodification control
D Pre-treatment/forebay for another structural BMP
[gl Other ( describe in discussion section below)
Discussion (as needed):
The site is exempt from hydromodification requirements and the self-retaining area (SRA-5) has been
designed solely to address OMA N7 for water quality purposes. The treatment will be achieved by dispersing
the runoff from the impervious areas to permeable areas (BMP SD-5) and incorporating tree wells (BMP
SD-1) into the site design to promote onsite infiltration.
OMA N7 is 0.082-acres and contains the southern half of Lot 1, and the drainage easement and storm drain
infrastructure that coveys flows from DMAs N2 and N7 along the southern perimeter of Lot 1 prior to
discharging to the City MS4 (via the drainage easement along the eastern edge of Lots 2 and 3). OMA N7
has been designed such that its 2, 172 sq-ft (60.8%) of proposed impervious surfaces (i.e. homes, sidewalks,
and driveways) will drain to its 1,399 sq-ft (39.2%) of permeable/landscaped area to promote onsite
infiltration.
The entire site is underlain by Hydrologic Soil Group B, so in order to comply with the BMP SD-5
requirements outlined in the City of Carlsbad BMP Design Manual the impervious:pervious ratio for OMA N7
must be less than 1.0.
Compliance Check for SRA-5 (imp:perv ratio must be < 1.0):
imp:perv ratio = (0.608)/(0.392) = 1.553 ~ 1.553 > 1.0 ~ SRA-5 requires additional BMPs
Since the impervious:pervious ratio for OMA N7 is larger than 1.0, additional BMPs are required for
compliance. First however, it is important to quantify the impacts of BMP SD-5 by adjusting the Runoff
Factor (C) as follows:
• Baseline C = rcxAx!I:Ax = ((0.9 * 0.050-ac) + (0.1 * 0.032-ac))/0.082-ac = 0.59 ~ Baseline C = 0.59.
• imp:perv ratio = (0.608)/(0.392) = 1.553 7 1.0 < 1.553 < 4.0, since ratio> 1.0, compliance cannot be
achieved through 8MP SD-5 alone, but since ratio < 4.0 7 C Factor adjustment can be claimed.
• Adjustment factors for hydrologic soil group 8 and a ratio of 1 = 0.0, ratio of 2 = 0.27 (Table 8.2-1 ).
• Linear interpolated adjustment factor for a ratio of 1.553 = 0.0 + (0.27 -0.0) I (2 -1) * (1.553 -1) =
0.15 7 adjustment factor = 0.15.
• Adjusted C = (0.9 * 0.15 * 0.050-ac + 0.1 * 0.032-ac I 0.082-ac = 0.12 7 Adjusted C = 0.12
Next, the adjusted C factor is used to calculate the Design Capture Volume (DCV) which is equal to the
volume of runoff in excess of what can be treated through the implementation of 8MP SD-5. The DCV may
be calculated simply as follows:
• DCV = C * d *A= 0.12 * 0.59 * 0.082-ac * 43,560 sq-ft/ac * 12-in/ft = 21.227 DCV = 21.2 cu-ft
Finally, a Tree Well (8MP SD-1) was incorporated into the site design to treat the DCV from OMA N7. Tree
wells can further reduce runoff and help to eliminate the DCV because of the water demands of the
vegetation and underlying roots. The Carlsbad 8MP Design Manual allows for Tree Credit Volumes (TCV) of
10 cu-ft/tree and 40 cu-ft/trees for proposed tree wells with 5-ft and 10-ft canopy diameters at maturity,
respectively.
The project proposes one (1) new tree with a 10-ft canopy diameter at maturity to address the remaining
DCV (10 cu-ft) from OMA N7. The final adjusted DCV is determined by simply subtracting DCV from TCV as
outlined in Worksheet 8.2-1, below:
1 85th percentile 24-hr storm depth from Figure B.1-1 d= 0.59 inches
2 Area tributary to BMP (s) A= 0.08 acres
3 Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1) C= 0.12 unitless
4 Tree wells volume reduction TCV= 40 cubic-feet
5 Rain barrels volume reduction RCV= 0 cubic-feet
Calculate DCV =
6 (3630 x C x d x A) -TCV -RCV DCV= -18.78 cubic-feet
By Dispersing Runoff from Impervious Areas (SD-5) and with Hydrologic Soil Group B, and an
impervious:pervious ration < 1, the Runoff Factor {C = 0.59) was reduced significantly (adjusted C = 0.12). This
combined with one tree wells (with an anticipated 10-ft diameter canopy) reduced the Design Capture Volume
(DCV = 103 cu-ft) significantly such that the adjusted DCV is negative and does not require further treatment
(adjusted DCV = -18.78 cu-ft)--> DCV = -18.8 < 0 --> OK
Compliance Check for SRA-5 {Final DCV < 0):
Final DCV = DCV -TCV = 40 cu-ft-21.22 cu-ft= -18.78 cu-ft 7Final DCV = -18.78 cu-ft
Final DCV = -18. 78 cu-ft < 0 7 SRA-5 as designed is compliant.
In summary by incorporating Impervious Area Dispersion (BMP SD-5) and a Tree Well (BMP SD-1), into the
site plan, SRA 5 has been designed in compliance with City water quality requirements as a Self-Retaining
OMA via qualifying Site Design BMPs. Please refer to the BMP Design calculations included under SWQMP
Attachment 1e.
Structural BMP Summary Information
Structural BMP ID No. SRA-6 (for OMA N8)
DWG 483-68 Sheet No. _3=-----
Type of structural BMP: D Retention by harvest and use (HU-1) D Retention by infiltration basin (I NF-1) D Retention by bioretention (INF-2) D Retention by permeable pavement (INF-3)
D Partial retention by biofiltration with partial retention (PR-1)
D Biofiltration (BF-1)
D 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)
D Detention pond or vault for hydromodification management
~ Other ( describe in discussion section below)
Purpose:
~ Pollutant control only
D Hydromodification control only
D Combined pollutant control and hydromodification control D Pre-treatment/forebay for another structural BMP
~ Other ( describe in discussion section below)
Discussion (as needed):
The site is exempt from hydromodification requirements and the self-retaining area (SRA-6) has been
designed solely to address OMA N8 for water quality purposes. The treatment will be achieved by dispersing
the runoff from the impervious areas to permeable areas (BMP SD-5) and incorporating tree wells (BMP
SD-1) into the site design to promote onsite infiltration.
OMA N8 is 0.082-acres and contains the northern half of Lot 1 and a swale and storm drain that conveys
runoff along the northern edge of Lot 1 prior to discharging to the City MS4 (via the drainage easement along
the eastern edge of Lots 2 and 3). OMA N8 has been designed such that its 1,765 sq-ft (49.4%) of proposed
impervious surfaces (i.e. home and sidewalks) will drain to its 1,806 sq-ft (50.6%) of permeable/landscaped
area to promote onsite infiltration.
The entire site is underlain by Hydrologic Soil Group B, so in order to comply with the BMP SD-5
requirements outlined in the City of Carlsbad BMP Design Manual the impervious:pervious ratio for OMA N8
must be less than 1.0.
Compliance Check for SRA-6 (imp:perv ratio must be < 1.0):
imp:perv ratio = (0.494)/(0.506) = 0.977 7 0.977 < 1.0 7 OK
SRA-6 as designed is compliant.
1 85th percentile 24-hr storm depth from Figure B.1-1 d= 0.59 inches
2 Area tributary to BMP (s) A= 0.08 acres
3 Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1) C= 0.50 unitless
4 Tree wells volume reduction TCV= 0 cubic-feet
5 Rain barrels volume reduction RCV= 0 cubic-feet
Calculate DCV =
6 (3630 x C x d x A) -TCV -RCV DCV= 86.98 cubic-feet
Please note that SRA 6 has been designed in compliance with City water quality requirements as a
Self-Retaining DMA via qualifying Site Design BMPs. Compliance Check for SRA-6 (imp:perv ratio must be< 1.0):
imp:perv ratio= (0.494)/(0.506) = 0.977 --> 0.977 < 1.0 --> OK
In summary by incorporating Impervious Area Dispersion (BMP SD-5) into the site plan, SRA 6 has been
designed in compliance with City water quality requirements as a Self-Retaining OMA via Qualifying Site
Design BMPs. For further details, please refer to the BMP Design Calculations included under Attachment
1e of this SWQMP.
ATTACHMENT 1 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 a OMA Exhibit (Required) ~ Included
See OMA Exhibit Checklist on the
back of this Attachment cover sheet.
(24"x36" Exhibit typically required)
Attachment 1 b Tabular Summary of DMAs Showing D Included on OMA Exhibit in
OMA ID matching OMA Exhibit, OMA Attachment 1 a
Area, and OMA Type (Required)* ~ Included as Attachment 1 b,
*Provide table in this Attachment OR
separate from OMA Exhibit
on OMA Exhibit in Attachment 1 a
Attachment 1 c Form 1-7, Harvest and Use Feasibility D Included
Screening Checklist (Required unless ~ Not included because the entire
the entire project will use infiltration
BMPs)
project will use infiltration BMPs
Refer to Appendix 8.3-1 of the BMP
Design Manual to complete Form 1-7.
Attachment 1 d Form 1-8, Categorization of Infiltration ~ Included
Feasibility Condition (Required unless D 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 1e Pollutant Control BMP Design ~ Included
Worksheets I Calculations (Required)
Refer to Appendices B and E of the
BMP Design Manual for structural
pollutant control BMP design
guidelines
Use this checklist to ensure the required information has been included on the DMA Exhibit:
The OMA Exhibit must identify:
IZJ Underlying hydrologic soil group --B IZJ Approximate depth to groundwater -Greater than 15 ft IZJ Existing natural hydrologic features (watercourses, seeps, springs, wetlands) -NIA IZJ Critical coarse sediment yield areas to be protected (if present) -N/A
IZJ Existing topography and impervious areas -See OMA Exhibit
IZJ Existing and proposed site drainage network and connections to drainage offsite -See OMA
Exhibit IZJ Proposed grading -See OMA Exhibit
IZJ Proposed impervious features -See OMA Exhibit
IZJ Proposed design features and surface treatments used to minimize imperviousness -See OMA
Exhibit, IZJ Drainage management area (OMA) boundaries, OMA ID numbers, and OMA areas (square
footage or acreage), and OMA type (i.e., drains to BMP, self-retaining, or self-mitigating)
DMA Area (sq-ft) Type
Nla 1635 Drains to Structural BMP -Bioretention Basin PR-la
Nlb 11917 Drains to Structural BMP -Bioretention Basin PR-la
Nlc 605 Self-Mitigating Area (SMA-1)
N2a 1669 Drains to Structural BMP -Bioretention Basin PR-lb
N2b 11917 Drains to Structural BMP -Bioretention Basin PR-lb
N2c 484 Self-Mitigating Area (SMA-2)
N3 3571 Self-Retaining Area via Qualifying Site Design BMPs (SRA-1)
N4 3571 Self-Retaining Area via Qualifying Site Design BMPs (SRA-2)
NS 3571 Self-Retaining Area via Qualifying Site Design BMPs (SRA-3)
N6 3571 Self-Retaining Area via Qualifying Site Design BMPs (SRA-4)
N7 3571 Self-Retaining Area via Qualifying Site Design BMPs (SRA-5)
N8 3571 Self-Retaining Area via Qualifying Site Design BMPs (SRA-6)
IZJ Structural BMPs (identify location and type of BMP):
o PR-la for DMAs Nla and Nlb
o PR-lb for DMAs N2a and N2b
o SMA-1-Self-Mitigating Area for DMA Nlc
o SMA-2 -Self-Mitigating Area for DMA N2c
o SRA-1-Self-Retaining Area via Qualifying Site Design BMPs for DMA N3
o SRA-2 -Self-Retaining Area via Qualifying Site Design BMPs for DMA N4
o SRA-3 -Self-Retaining Area via Qualifying Site Design BMPs for DMA NS
o SRA-4 -Self-Retaining Area via Qualifying Site Design BMPs for DMA N6
o SRA-S -Self-Retaining Area via Qualifying Site Design BMPs for DMA N7
o SRA-6 -Self-Retaining Area via Qualifying Site Design BMPs for DMA N8
o TW-1-S-ft diameter canopy~ One (1) Tree Well on the north side of Lot 2 for DMA N6
o TW-2 -10-ft diameter canopy-3 total ~
• 1 on the south side of Lot 3 for DMA N3,
• 1 on the south side of Lot 2 for DMA NS, and
• 1 on the south side of Lot 1 for DMA N7.
ATTACHMENT 1A: OMA EXHIBIT
I
I
I_
I
I
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DWY _... L __ _
/ Hl~HLAND _ _QRIV_§
, _ -\ EX[)VYY
f I I IEX liJt_ Jtt;tWY ~j D~~
owx_,_ () '0s/"~-r •.. <oo//J ~J t 'C' -~L _.._,0:1~-{/~\ ~ l ~> ',h \
f / ~ Vllr --f:'77,/J '-~/ C: 11 VGARAGEj-
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t ~~---1-· wsop~-I ---. ----~ -I -@ID
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LEGEND
(E) : EXISTING , (N) : NEW I PROPOSED
-----(E) PROPERTY LINE
(E) MAJOR CONTOUR
(E) MINOR CONTOUR
·-==------·---(E)CURB & GUTIER
---(E) 12" RCP STORM DRAIN PIPE
(E) 18" RCP STORM DRAIN PIPE
(E) 48" RCP STORM DRAIN PIPE
(E) STORM DRAIN INLET
(E) RETAINING WALL CJ-(E)ACPAVEMENT
-~;?j (E) BUILDING
D -(E) CONCRETE
(E) VEGETATION
---DRAINAGE DIRECTION
--DMA BOUNDARY
@--
i!t>/ r I
--PROPOSED SITE
/
,:r
Q
1 (!)
5:
VICINITY MAP
NTS
~~
\~ ,i
j
\ \1 r
0 20 40 80 160
-c-.-:-~ I I
~===~======-=====-=~:==-~~=-:--============I=======::::;::::===---:===:-=:.... SCALE: 1" = 40 FEET --o-48" SD-~ 48" SD--SD-
~-"''\'\I\
PRE-DEVELOPMENT CONDITION
DRAINAGE AREA MAP
f J -EX ~L ~ 1-~~~---y--
-7--c"~'----"--J DWY l-11-__ _ ~JvL______ ---___J~ ---------Hlc/HLAND DRIVE
f I ftt
-I la I I _/
Q100 = 2.99 cfs
0D--O ---48" -~~~__: sF tJAt,J~DR1vE4s <;:T11 ------48" ~ I -
l
I ' -11 il-I
'ex 1--EX I~.,,\._
DWY ~--] DWY
EX
DWY 0 -·
1_
EX
DWY~
SD -48" SD-
LEGEND
(E) : EXISTING , (N) : NEW I PROPOSED
----(E) PROPERTY LINE
----------(E) MAJOR CONTOUR
(N) RETAINING WALL
-----------(N) EARTHEN SWALE FLOWLINE
Ji/<!ffi®iftllii>!'t~ (N)RIPRAPSWALE (E) MINOR CONTOUR
4" SD --(N)4"0SDPIPE
--611 SD --(N)6"0SDPIPE
(E) CURB & GUTIER
---(E) STRIPING
(N) MAJOR CONTOUR --8" SD --(N)8"0SDPIPE
--10" SD --(N)10"0SDPIPE ------------·---(N) MINOR CONTOUR
----12'' SD --(E)12"RCPSTORMDRAINPIPE --18" SD --(N)18"0SDPIPE -----18" SD --(E)18"RCPSTORMDRAINPIPE IJ (N) SD CATCH BASIN 4 8" SD---(E) 48" RCP STORM DRAIN PIPE
§ (E) STORM DRAIN INLET
~ ~~~-(E)RETAININGWALL 0 TREE WELL 10' CANOPY 0-TREE WELL 5' CANOPY
-DRAINAGE DIRECTION -(E) CONCRETE ----OMA BOUNDARY ~ (N) BIORETENTION BMP
~-(N) BUILDING c==i (N) HARDSCAPE GD DMALABEL ~
OMA AREA (SF) TYPE/NOTES
N1a 1,635 SF DRAINS TO STRUCTURAL BMP -BIORETENTION BASIN INF -2a
N1b 11,917 SF DRAINS TO STRUCTURAL BMP -BIORETENTION BASIN INF -2a
N1c 605SF SELF-MITIGATING AREA (SMA-1)
N2a 1,669 SF DRAINS TO STRUCTURAL BMP -BIORETENTION BASIN INF -2b
N2b 11,917 SF DRAINS TO STRUCTURAL BMP -BIORETENTION BASIN INF -2b
N2c 484SF SELF-MITIGATING AREA (SMA-2)
N3 3,571 SF SELF-RETAINING AREA VIA QUALIFYING SITE DESIGN BMPs (SRA-1)
N4 3,571 SF SELF-RETAINING AREA VIA QUALIFYING SITE DESIGN BMPs (SRA-2)
N5 3,571 SF SELF-RETAINING AREA VIA QUALIFYING SITE DESIGN BMPs (SRA-3)
N6 3,571 SF SELF-RETAINING AREA VIA QUALIFYING SITE DESIGN BMPs (SRA-4)
N7 3,571 SF SELF-RETAINING AREA VIA QUALIFYING SITE DESIGN BMPs (SRA-5)
N8 3,571 SF SELF-RETAINING AREA VIA QUALIFYING SITE DESIGN BMPs (SRA-6)
OMA EXHIBIT NOTES:
1. ENTIRE SITE IS UNDERLAIN WITH HYDROLOGIC SOIL GROUP B
2. THE APPROXIMATE DEPTH TO GROUNDWATER IS GREATER THAN 15 FT
3. THE SITE DOES NOT CONTAIN ANY EXISTING NATURAL HYDROLOGIC FEATURES (WATERCOURSES, SEEPS,
SPRINGS, WETLANDS)
4.
5.
6.
THE SITE DOES NOT CONTAIN ANY CRITICAL COARSE SEDIMENT YIELD AREAS TO BE PROTECTED
PROPOSED DESIGN FEATURES AND SURFACE TREATMENTS USED TO MINIMIZE IMPERVIOUSNESS INCLUDE TREE
WELLS (BMP SD-1) AND IMPERVIOUS AREA DISPERSION (BMP SD-5) SUCH THAT EACH OF THE DMAs N3 THOURGH N8
MAY BE CONSIDERED SELF RETAINING AREAS VIA QUALIFYING SITE DESIGN BMPS
STRUCTURAL BMPS WERE INCORPORATED TO MEET WATER QUALITY REQUIREMENTS FOR DMAs N1 & N2.
SCALE: 1" = 40 FEET
POST-DEVELOPMENT CONDITION
DRAINAGE AREA MAP
ATTACHMENT 18: DMA SUMMARY TABLE
Tabular Summary of DMAs Showing OMA ID matching OMA Exhibit, OMA Area, and OMA Type
(Required)*
DMAID AREA TYPE
(sq-ft)
Nla 1635 Drains to Structural BMP -Bioretention Basin PR-la
Nlb 11917 Drains to Structural BMP -Bioretention Basin PR-la
Nlc 605 Self-Mitigating Area (SMA-1)
N2a 1669 Drains to Structural BMP -Bioretention Basin PR-lb
N2b 11917 Drains to Structural BMP -Bioretention Basin PR-lb
N2c 484 Self-Mitigating Area (SMA-2)
N3 3571 Self-Retaining Area via Qualifying Site Design BMPs (SRA-1)
N4 3571 Self-Retaining Area via Qualifying Site Design BMPs (SRA-2)
NS 3571 Self-Retaining Area via Qualifying Site Design BMPs (SRA-3)
N6 3571 Self-Retaining Area via Qualifying Site Design BMPs (SRA-4)
N7 3571 Self-Retaining Area via Qualifying Site Design BMPs (SRA-5)
NS 3571 Self-Retaining Area via Qualifying Site Design BMPs (SRA-6)
ATTACHMENT 1C: FORM 1-7, HARVEST AND USE FEASIBILITY SCREENING CHECKLIST
1. Is there a demand for harvested water ( check all that apply) at the project site that is reliably present during the wet season?
181 Toilet and urinal flushing
181 Landscape irrigation
D Other: _____ _
2. 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.
•Toilet/Urinal Demand was determined using BMP Design Manual Table B.3-1 as follows:
o Assumptions -residential use, assumed 4 residents per household for each of the 5
proposed homes 7 18.5 flushes/person/day
o Toilet/Urinal Demand = 186 flushes * 1.6 gallons/flush = 297.6 gpd, which converts 446.4
gallons/36-hours or 59.7 cu-ft 7 36-Hour Toilet Demand= 59.7 cu-ft
• Landscape Demand was calculated using the Modified Estimated Total Water Use equation
outlined under BMP Manual Section B.3.2.2.1 as follows:
:Mxlified E1WU = (EToWet x (SUM(PPHA)/IE) + SIA) *0.015) I via Bl'vP l'v1mual page B-15
:Mxlified E1WU = Estimated daily average ooter use during \\et season
E10Wet= 2.8 in/month I via Bl'vP Mmual page B-15 using CIMi Zone 4 from Table G.1-1
Plant Factor (PF) = 0.5 via Bl'vP l\thnual Table B.3-2 using :Mxlerate plant ooter use
Hvdrozone Area (HA) = 27507 sq-ft (this analysis evaluates the ooter demand from all 5 lots combined)
Hydrozone Area (HA) = 0.63 acre
fuigation Efficiency (IE) 0.9 ass urned 90% oer Bl'vP l\thnual page B-16
Special landscaped Areas (SIA) = 0 *if reclaimed ooter is available then SIA= HA, if unavailable then SIA= 0
3-day irrigation shut down after rain (1 mo/30 days) *(Ift/12-in) *(7.48 gaVcu-ft) *(7 out of 10 days with irrigation
event= 0.015 demand in rainy season)
l'vbdi:fied E1WU = 641.83 Q"Od
36-hr landscape Cemand = 962.75 gallons
36-hr landscape Cemand = 128.7 cu-ft
The simplified planning level irrigation demand as outlined under Bl'vP Cesign l\thnual Section B.3.2.2.2.oos also used to check
the landscape Cemand calculations as follow,:
check via Simolified E1WU -site has 27,507 sq-ft (0.63 acres) of landscaping requiring irrigation
Hydrozone :Mxlerate plant ooter use = 1470 gallons per irrigated acre per 36-hour period via Table B.3-3
36-hr landscape Cemand = 928.27 gallons per 36-hour period
36-hr landscape Cemand = 124.1 cu-ft
To be conservative the higher value 36-hr landscape Cemand =962.75 cu-ft is used
o Total Landscape Demand = (EToWet x (SUM(PPHA)/IE) + SIA) *0.015) = (2.8x (SUM(0.5*27507)/0.9) +
0) *0.015) = 641.83 gallons per day \\hich converts to 962.75 gallon/36 hours or 128.7 cu-ft 7 36-Hour
Landscape Demand = 128. 7 cu-ft
• Other Demands = 0 N/A
Estimated Total 36-Hour Use = Toilet Demand + Landscape Demand + Other Demand =
59.7 cu-ft+ 128.7 cu-ft+ 0 cu-ft= 188.4 cu-ft~ Estimated Total 36-Hour Use= 188.4 cu-ft
3. Calculate the DCV using worksheet B-2 .1.
DCV= 1115 (cubic feet)
3a. Is the 36 hour demand greater than or 3b. Is the 36 hour demand greater than 3c. Is the 36 hour demand less than
equal to the DCV? c::> 0.25DCV but less than the full DCV? 0.25DCV?
D Yes/ [81 No D Yes I [81 No c::> [81 Yes
i i i
Harvest and use appears to be Harvest and use may be feasible. Harvest and use is considered to be
feasible. Conduct more detailed Conduct more detailed evaluation and 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, or
drawdown criteria. ( 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?
D Yes, refer to Appendix E to select and size harvest and use BMPs.
[81 No, select alternate BMPs.
ATTACHMENT 1 D: FORM 1-8, CATEGORIZATION OF INFILTRATION FEASIBILITY CONDITION
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
1
Screenin uestion
Is the estimated reliable infiltration rate below proposed facility
locations greater than 0.5 inches per hour? The response to this Screening
Question shall be based on a comprehensive evaluation of the factors
resented in A endix C.2 and A endix D.
Provide basis:
Yes No
X
An onsite percolation study was conducted on the subject property which indicates that the soils underneath
the proposed Biofiltration with Partial Retention Basin infiltrate at 0.125 inch/hour (please note that the soils
near the proposed tree wells infiltrate at significantly higher rates -from 2.9-up to 6.0 in/hr).
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
For further details, please refer to the Percolation Test Results prepared by Construction Testing &
Engineering, Inc. (March, 2016).
2
Can infiltration greater than 0.5 inches per hour be allowed without
increasing risk of geotechnical hazards (slope stability, groundwater
mounding, utilities, or other factors) that cannot be mitigated to an
acceptable level? The response to this Screening Question shall be based on a
com rehensive evaluation of the factors resented in A endix C.2.
Provide basis:
X
N/A --onsite percolation testing indicates that soils will not infiltrate at rates greater than 0.5-in/hr (rates
near BMP measured at 0.125 in/hr).
The project includes 5 proposed free-standing homes, their driveways, utility connections and a slope and
storm drain easement. The development of the site will produce a relatively small increase in the amount of
runoff which shall be addressed through the implementation of Site Design BMPs (specifically BMP SD-1 and
SD-5) and Biofiltration with Partial Retention Basins (PR-1). The site has been designed to direct runoff from
impervious surfaces to permeable areas onsite. It is not anticipated that the infiltration associated with the
selected BMPs will increase the risk of geotechnical hazards. The proposed Biofiltration with Partial
Retention Basins have been designed with vertical impermeable liners to direct the infiltration downward
and better protect the surrounding soils.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
For further details, please refer to the Percolation Test Results prepared by Construction Testing &
Engineering, Inc. (March, 2016).
3
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
com rehensive evaluation of the factors resented in A endix C.3.
Provide basis:
X
N/A --onsite percolation testing indicates that soils will not infiltrate at rates greater than 0.5-in/hr (rates
near BMP measured at 0.125 in/hr).
The actual depth to groundwater is not known. A Site Inspection was performed by Soil Testers, Inc., that
included borings up to 15 feet in depth without encountering groundwater. It is not anticipated that the
proposed infiltration will increase the risk of groundwater contamination.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
For further details, please refer to the Site Inspection prepared by Soil Testers, Inc. (September, 2005).
4
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 com rehensive evaluation of the factors resented in A endix C.3.
Provide basis:
X
N/A --onsite percolation testing indicates that soils will not infiltrate at rates greater than 0.5-in/hr (rates
near BMP measured at 0.125 in/hr).
The Geotechnical study did not evaluate potential water balance issues such as change of seasonality of
ephemeral streams or increased discharge of contaminated groundwater to surface waters; however it is not
anticipated to be problematic due to the relatively small amount of runoff generated by the project. It is
unlikely that implementing biofiltration with partial infiltration-based BMPs on this 1.14-acre will result in
water balance issues for the surrounding watershed.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
For further details, please refer to the Site Inspection prepared by Soil Testers, Inc. (September, 2005), and
the Percolation Test Results prepared by Construction Testing & Engineering, Inc. (March, 2016).
Part 1
Result*
If all answers to rows 1 - 4 are "Yes" a full infiltration design is potentially
feasible. The feasibility screening category is Full Infiltration
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
Infiltration may be possible
-continue to Part 2, below.
*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 Agency /Jurisdictions to substantiate findings.
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
5
Screenin Question
Do soil and geologic conditions allow for infiltration in any appreciable
rate or volume? The response to this Screening Question shall be based on a
comprehensive evaluation of the factors presented in Appendix C.2 and
A endixD.
Provide basis:
Yes No
X
As noted in the results from Part 1 above, the soils onsite are not conducive for a full infiltration design. An
onsite percolation study was conducted on the subject property which indicates that the soils underneath
the proposed BMP discharge locations infiltrate at 0.125 inch/hour (please note that the soils near the
proposed tree wells infiltrate at significantly higher rates -from 2.9-up to 6.0 in/hr).
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.
For further details, please refer to the Percolation Test Results prepared by Construction Testing &
Engineering, Inc. (March, 2016).
6
Can Infiltration in any appreciable quantity be allowed without
increasing risk of geotechnical hazards (slope stability, groundwater
mounding, utilities, or other factors) that cannot be mitigated to an
acceptable level? The response to this Screening Question shall be based on a
com rehensive evaluation of the factors resented in A endix C.2.
Provide basis:
X
As noted in the results from Part 1 above, the soils onsite are not conducive for a full infiltration design. An
onsite percolation study was conducted on the subject property which indicates that the soils underneath
the proposed BMP discharge locations infiltrate at 0.125 inch/hour. It is not anticipated that the infiltration
associated with the selected BMPs will increase the risk of geotechnical hazards. The proposed Biofiltration
with partial retention basins have been designed with vertical impermeable liners to direct the infiltration
downward and better protect the surrounding soils.
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.
For further details, please refer to the Percolation Test Results prepared by Construction Testing &
Engineering, Inc. (March, 2016).
7
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 resented in A endix C.3.
Provide basis:
X
As noted in the results from Part 1 above, the soils onsite are not conducive for a full infiltration design. An
onsite percolation study was conducted on the subject property which indicates that the soils underneath
the proposed BMP discharge locations infiltrate at 0.125 inch/hour. The actual depth to groundwater is not
known. A Site Inspection was performed by Soil Testers, Inc., that included borings up to 15 feet in depth
without encountering groundwater. It is not anticipated that the infiltration associated with the selected
BMPs will increase the risk of groundwater contamination.
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.
For further details, please refer to the Site Inspection prepared by Soil Testers, Inc. (September, 2005).
8
Can infiltration be allowed without violating downstream water rights?
The response to this Screening Question shall be based on a comprehensive
evaluation of the factors resented in A endix C.3.
Provide basis:
X
It is not anticipated that the infiltration associated with the selected BMPs will violate any downstream water
rights.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
Preliminary research into water rights downstream of the subject property did not yield results that could be
impacted by implementing the selected BMPs.
Part2
If all answers from row 1-4 are yes then partial infiltration design is potentially feasible.
The feasibility screening category is Partial Infiltration.
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.
Partial
Infiltration
*To be completed using gathered site information and best professional judgment considering the definition ofl\,fEP in the MS4
Permit. Additional testing and/ or studies may be required by Agency /Jurisdictions to substantiate findings.
ATTACHMENT 1E: POLLUTANT CONTROL BMP DESIGN CALCULATIONS
Summary Calculations
BMP 50-5
Compliance
OMA A A A,imp A,imp Check C d** DCV A,per A,per imp:perv (imp:perv <
sq-ft ac sq-ft ac sq-ft ac Ratio 1.0) in cu-ft
Nla 1635 0.04 352 0.01 1283 0.03 0.27 No* 0.27 0.59 21.9
Nlb 11917 0.27 4860 0.11 7057 0.16 0.69 No* 0.43 0.59 249.8
Nla + Nlb 13552 0.31 5212 0.12 8340 0.19 0.62 No* 0.41 0.59 271.6
Nlc 605 0.01 0 0.00 605 0.01 0.00 Yes 0.10 0.59 3.0
N2a 1669 0.04 361 0.01 1308 0.03 0.28 No* 0.27 0.59 22.4
N2b 11917 0.27 4545 0.10 7372 0.17 0.62 No* 0.41 0.59 237.4
N2a + N2b 13586 0.31 4906 0.11 8680 0.20 0.57 No* 0.39 0.59 259.8
N2c 484 0.01 0 0.00 484 0.01 0.00 Yes 0.10 0.59 2.4
N3 3571 0.08 2202 0.05 1369 0.03 1.61 No 0.59 0.59 104.2
N4 3571 0.08 1782 0.04 1789 0.04 1.00 Yes a.so 0.59 87.6
NS 3571 0.08 2309 0.05 1262 0.03 1.83 No 0.62 0.59 108.4
N6 3571 0.08 1798 0.04 1773 0.04 1.01 No a.so 0.59 88.3
N7 3571 0.08 2172 0.05 1399 0.03 1.55 No 0.59 0.59 103.0
N8 3571 0.08 1765 0.04 1806 0.04 0.98 Yes a.so 0.59 87.0
49653 1.14 22146 0.51 27507 0.63 0.81 0.46 0.59 1115.2
* = OMAs 1 and 2 meet the BMP SD-5 water quality requirement in terms of imp:perv ratio, however the OCV reduction associated with BMP 50-5 has
not been counted because a significant portion of the receiving permeable area is sloped greater than 5%.
** d is the depth of precipitation produced by the 85th percentile storm event (P85 = 0.59 inches)
Linear Interpolation for C Factor Adjustment --Hydrologic Soils Group B)
DMA imp:perv imp:perv imp:perv Adjustment Adjustment Adjustment
Ratio Ratio <=1 Ratio =2 Factor --Low Factor --High Factor
Nla 0.27 0.00 0.27 1 2 0.000
Nlb 0.69 0.00 0.27 1 2 0.000
Nla + Nlb 0.62 0.00 0.27 1 2 0.000
Nlc 0.00 0.00 0.27 1 2 0.000
N2a 0.28 0.00 0.27 1 2 0.000
N2b 0.62 0.00 0.27 1 2 0.000
N2a + N2b 0.57 0.00 0.27 1 2 0.000
N2c 0.00 0.00 0.27 1 2 0.000
N3 1.61 0.00 0.27 1 2 0.164
N4 1.00 0.00 0.27 1 2 0.000
NS 1.83 0.00 0.27 1 2 0.224
N6 1.01 0.00 0.27 1 2 0.004
N7 1.55 0.00 0.27 1 2 0.149
N8 0.98 0.00 0.27 1 2 0.000
Summary Calculations Continued
Adj. DCV
(via SD-
OMA Adj. Adj. C 5)
imp:perv
Ratio Factor cu-ft
Nla 0.00 N/A, slopes too steep for SD-5 21.88
Nlb 0.00 N/A, slopes too steep for SD-5 249.75
Nla + Nlb 0.62 N/A, slopes too steep for SD-5 271.64
Nlc 0.00 N/A, slopes too steep for SD-5 2.97
N2a 0.00 N/A, slopes too steep for SD-5 22.41
N2b 0.00 N/A, slopes too steep for SD-5 237.36
N2a + N2b 0.57 N/A, slopes too steep for SD-5 259.77
N2c 0.00 N/A, slopes too steep for SD-5 2.38
N3 1.61 0.16 0.13 22.74
N4 1.00 N/A, SD-5 alone is sufficient 87.65
NS 1.83 0.22 0.17 29.09
NG 1.01 0.00 0.05 9.02
N7 1.55 0.15 0.12 21.22
N8 0.98 N/A, SD-5 alone is sufficient 86.98
Total Adjusted DCV = 793
Total TCV = 130 cu-ft which is less than 25% of DCV
-25% of DCV = 0.25 * DCV = 0.25* 1115 cu-ft--> 25% of DCV =
Total TCV = 150 cu-ft which is also less than 25% of the Adjusted DCV
-25% of Adjusted DCV = 0.25 * DCV = 0.25* 793 cu-ft--> 25% of DCV =
Bioretention BMP Summary
Inf. Rate Inf. Depth
DMA A,BMP A,req 3%
sf sf Check in/hr In
Nla + Nlb 318 166 OK 0.063 2.25
N2a + N2b 297 159 OK 0.063 2.25
Adj.
Trees TCV DCV
Trees TCV {d = (d = 10 Total (via
(d = 5ft) (d = 5 ft) 10ft) ft) TCV SD-5) WQ Compliant?
cu-cu-
# ft/tree # ft/tree cu-ft cu-ft
N/A, DMA Nla is treated by BMP PR-la
N/A, DMA Nlb is treated by BMP PR-la
N/A, DMAs Nla and Nlb are treated by BMP PR-la
N/A, DMA Nlc is a Self-Mitigated Area --SMA-1
N/A, DMA N2a is treated by BMP PR-lb
N/A, DMA N2b is treated by BMP PR-lb
N/A, DMAs N2a and N2b are treated by BMP PR-lb
N/ A, DMA N2c is a Self-Mitigated Area --SMA-2
1.00 40.00 40.00 -17.26 Yes
N/A, DMA N4 is fully treated by BMP SD-5 (Impervious Area Dispersion)
1.00 40.00 40.00 -10.91 Yes
1.00 10.00 10.00 -0.98 Yes
1.00 40.00 40.00 -18.78 Yes
N/A, DMA NS is fully treated by BMP SD-5 (Impervious Area Dispersion)
cu-ft TotalTCV= i Bo.oo cu-ft
278.80 cu-ft > TCV = 130 cu-ft --> OK
198.36 cu-ft > TCV = 130 cu-ft --> OK
V,BMP V,BMP > 0.375 *
A,bot h,pond h,am h,gr (retained) (retained) DCV?
sf ft ft ft cu-ft Fraction of DCV WQ Compliant?
77 a.so 1.5 1 107 0.395 Yes
72 a.so 1.5 1 100 0.386 Yes
Table 4. DMA Summary
Nla 0 D D D D 1635 0.04 352 0.01 0.22 1283 0.03 0.78 0.272
Nlb 0 D D D D 11917 0.27 4860 0.11 0.41 7057 0.16 0.59 0.426
Nla + Nlb 0 D D D D 13552 0.31 5212 0.12 0.38 8340 0.19 0.62 0.408
Nlc D D 0 D D 605 0.01 0 0.00 0.00 605 0.01 1.00 0.100
N2a 0 D D D D 1669 0.04 361 0.01 0.22 1308 0.03 0.78 0.273
N2b 0 D D D D 11917 0.27 4545 0.10 0.38 7372 0.17 0.62 0.405
N2a + N2b 0 D D D D 13586 0.31 4906 0.11 0.36 8680 0.20 0.64 0.389
N2c D D 0 D D 484 0.01 0 0.00 0.00 484 0.01 1.00 0.100
N3 D D D D 0 3571 0.08 2202 0.05 0.62 1369 0.03 0.38 0.593
N4 D D D D 0 3571 0.08 1782 0.04 0.50 1789 0.04 0.50 0.499
NS D D D D 0 3571 0.08 2309 0.05 0.65 1262 0.03 0.35 0.617
N6 D D D D 0 3571 0.08 1798 0.04 0.50 1773 0.04 0.50 0.503
N7 D D D D 0 3571 0.08 2172 0.05 0.61 1399 0.03 0.39 0.587
N8 D D D D 0 3571 0.08 1765 0.04 0.49 1806 0.04 0.51 0.495
49653 1.14 22146 0.51 0.45 27507 0.63 0.55 0.457
1. See BMP Design Manual Section 5.2.1 for characteristics required to qualify.
2. See BMP Design Manual Section 5.2.2 for characteristics required to qualify.
3. See BMP Design Manual Section 5.2.3. If this option is selected, the site design BMPs must be shown to achieve a DCV of O using the
DMA Summary Worksheet
Table 6. Structural BMP Summary Table
BMP-PR-la Biofiltration with Partial Retention (PR-la) 0 a Nla & Nlb DWG 483-6C, Sheet No. 2
BMP-PR-lb Biofiltration with Partial Retention (PR-lb) 0 a N2a & N2b DWG 483-6C, Sheet No. 2
Structural BMP Types:
• Harvest and use (HU-1) • Biofiltration (without retention) (BF-1)
• Infiltration basin (INF-1) • Biofiltration with Nutrient Sensitive Media Design (BF-2)
• Bioretention (INF-2)
• Permeable pavement (INF-3)
• Biofiltration with partial retention (PR-1)
Notes
• Detention pond or vault for hydromodification management
• Other (describe)
• Proprietary Biofiltration (BF-3) can only be used if it meets the requirements of Appendix F
• Flow-thru treatment control BMPs, unless used solely for pre-treatment, may only be used as part of an alternative compliance
program. See Section 1.8 of the BMP Design Manual for more information.
Pre-treatment BMPs
All structural BMPs that will be used for pre-treatment purposes only are described below, including the type of BMP and
which of the BMPs from the table above it provides pre-treatment for. Sizing calculations are included in Appendix E.
There are not any Pretreatment BMPs proposed at the project.
Appendix C.3 DMA Design Capture Volume Calculations
85th Percentile Rainfall (inches): I o.s9 I
B
B
Impervious: sidewalks, driveway
draining to BMP
Pervious: Landscape draining to BMP
352
1,283
Total DMA Area (ft2) I 1,635 I
85th Percentile Rainfall (inches): I o.~;i
B I Impervious: building, sidewalks,
driveway draining to BMP I 4,860 I
--
B I Pervious: Landscape draining to BMP I 7,057 I
Total DMA Area (ft2) I 11,917
0.90
0.10
0.90
0.10
None Claimed N/A 1 0.9 N/A N/A 16
None Claimed N/A 1 0.1 N/A N/A 6
Weighted Average C Factor for DMA I 0.27 Total DCV for DMA (ft3) 22 ___ _,
None Claimed N/A 1 0.9 N/A N/A 215
None Claimed N/A 1 0.1 N/A N/A 35
Weighted Average C Factor for DMA I 0.43 Total DCV for DMA (ft3) ___ .... 250
85th Percentile Rainfall (inches): I o.59]
B I Impervious: building, sidewalks,
driveway draining to BMP 5,212 0.90
B I Pervious: Landscape draining to BMP 8,340 0.10
Total OMA Area (ft2) I 13,552 I
85th Percentile Rainfall (inches): I 0.591
B Impervious: N/A 0 0.90
B Pervious: Landscaping 605 0.10
Total OMA Area (ft2) .__ ___ ....... 605
None Claimed N/A 1
None Claimed N/A 1
Weighted Average C Factor for OMA I
Runoff Dispersion
(SD-5)
None Claimed
0.00
N/A
1
1
0.9
0.1
0.41
0.9
0.1
Weighted Average C Factor for OMA I 0.10
N/A N/A I 231
N/A N/A I 41
I Total OCV for OMA (ft3) I 272
N/A N/A 0
N/A N/A 3
Total OCV for OMA (ft3) .__ __ ..... 3
It is important to note that the ai:ap ratio for DMA Nlc is less than 1 and therefore the DMA can be fully treated with Impervious Dispersion (BMP SD-5)
85th Percentile Rainfall (inches): I o.;~ I
B I Impervious: sidewalks, driveway
draining to BMP 361 0.90 None Claimed N/A 1 0.9 N/A N/A I 16
B I Pervious: Landscape draining to BMP 1,308 0.10 None Claimed N/A 1 0.1 N/A N/A I 6
Total OMA Area (ft2) 1,669 Weighted Average C Factor for OMA 0.27 Total OCV for OMA (ft3) I 22
85th Percentile Rainfall (inches): I 0.591
B I Impervious: building, sidewalks,
driveway draining to BMP 4,545 0.90 None Claimed N/A 1 0.9 N/A N/A 201
B I Pervious: Landscape draining to BMP 7,372 0.10 None Claimed N/A 1 0.1 N/A N/A 36
Total OMA Area (ft2) I 11,917 Weighted Average C Factor for OMA I 0.41 Total OCV for OMA (ft3) ,__ __ _. 237
85th Percentile Rainfall (inches): [ 0.591
B I Impervious: building, sidewalks,
driveway draining to BMP I 4,906 I
--
B I Pervious: Landscape draining to BMP I 8,680 I
Total OMA Area (ft2) I 13,586
85th Percentile Rainfall (inches): [~~~o~
B Impervious: N/A 0
B Pervious: Landscaping 484
Total OMA Area (ft2) ...._ ___ __, 484
0.90
0.10
0.90
0.10
None Claimed N/A 1 0.9
None Claimed N/A 1 0.1
Weighted Average C Factor for OMA I 0.39
Runoff Dispersion
(SD-5)
None Claimed
0.00
N/A
1 0.9
1 0.1
Weighted Average C Factor for OMA I 0.10
N/A N/A
N/A N/A
Total OCV for OMA (ft3)
N/A N/A
N/A N/A
Total OCV for OMA (ft3)
It is important to note that the ai:ap ratio for DMA N2c is less than 1 and therefore the DMA can be fully treated with Impervious Dispersion (BMP SD-5)
217
43
260 ----
0
2
2 ----
85th Percentile Rainfall (inches):
B I Impervious: building, sidewalks,
driveway draining to BMP
B I Pervious: Landscaping
Total DMA Area (ft2)
85th Percentile Rainfall (inches):
B
B
Impervious: building & sidewalks
draining to BMP
Pervious: Landscaping
I a.591
2,202
1,369
3,571
I o.59 I
1,782
1,789
Total DMA Area (ft2) I 3,571 I
0.90
0.10
0.90
0.10
Runoff Dispersion 1.608 0.16 (SD-5)
NA (Pervious) N/A N/A
Weighted Average C Factor for DMA
Runoff Dispersion
(SD-5)
NA (Pervious)
0.996
N/A
1.00
N/A
I 0.15
0.1
0.13
0.90
0.1
Weighted Average C Factor for DMA I 0.50
I 40.00 I N/A I -24
N/A I N/A I 7
Total DCV for DMA (ft3) I -17
N/A N/A 79
N/A N/A 9
Total DCV for DMA (ft3) L-----' 88
It is important to note that the ai:ap ratio for DMA N4 is less than 1 and therefore the DMA can be fully treated with Impervious Dispersion (BMP SD-5)
85th Percentile Rainfall (inches):
B I Impervious: building, sidewalks,
driveway draining to BMP
B I Pervious: Landscaping
Total DMA Area (ft2)
85th Percentile Rainfall (inches):
B
B
Impervious: building & sidewalks
draining to BMP
Pervious: Landscaping
c~· 0.591
2,309
1,262
3,571
I 0.591
1,798
1,773
Total DMA Area (ft2) l 3,571 l
0.90
0.10
0.90
0.10
Runoff Dispersion 1.83 0.22 {SD-5)
NA (Pervious) N/A N/A
Weighted Average C Factor for DMA
Runoff Dispersion
(SD-5)
NA (Pervious)
1.01
N/A
0.004
N/A
0.20
0.1
0.17
0.00
0.1
Weighted Average C Factor for DMA I 0.05
40.00 N/A -17
N/A N/A I 6
Total DCV for DMA (ft3} I -11
10.00 N/A -10
N/A N/A 9
Total DCV for DMA (ft3) ,__ __ ~ -1
85th Percentile Rainfall (inches):
B
B
Impervious: building, sidewalks,
driveway draining to BMP
Pervious: Landscaping
Total DMA Area (ft2)
85th Percentile Rainfall (inches):
B I Impervious: building & sidewalks
draining to BMP
B I Pervious: Landscaping
I o.59 1
2,172 0.90
1,399 0.10
3,571 -----
1 ·· ~~~ ~o.59]
1,765 0.90
1,806 0.10
Runoff Dispersion
(SD-5)
NA (Pervious)
1.55
N/A
0.15 0.14
N/A 0.1
Weighted Average C Factor for DMA I 0.12
Runoff Dispersion 0.977 I N/A I 0.9 (SD-5)
NA (Pervious) N/A I N/A 0.1
40.00 N/A -26
N/A N/A 7
Total DCV for DMA (ft3) .__ __ ..., -19
I N/A I N/A I 2
N/A I N/A I 9
Total DMA Area (ft2) 3,571 Weighted Average C Factor for DMA 0.50 Total DCV for DMA (ft3) I 87
It is important to note that the ai:ap ratio for DMA N8 is less than 1 and therefore the DMA can be fully treated with Impervious Dispersion (BMP SD-5)
Notes
1. If the area is pervious or if runoff dispersion site design BMPs are not proposed, enter "NA".
2. If the area is pervious or if runoff dispersion site design BMPs are not proposed, enter "1" in this column.
3. Include a separate line item in this table for each street tree and its tributary drainage area, or include supplemental information to demonstrate
that the 85th percentile runoff of the impervious area draining to each street tree does not exceed the volume reduction credit being claimed for
each street tree. Also include supplemental information documenting the mature tree canopy size of the street tree. Trees must be implemented
in accordance with SD-1. Total tree volume reduction must be less than 0.25 times the DCV for the entire project, and each single tree volume
credit must be less than 400 cu-ft (see Appendix B.2.2.1 for more information).
4. To be granted a credit here, rain barrels must meet the standards described in Section B.2 and fact sheet SD-8. Enter credit in cubic feet, not
gallons.
5. DCV = (Final C Factor) x (85th Percentile Rainfall)/12 x (Area of Surface Type) -(Street Tree Volume Reduction) -(Rain Barrel Volume Reduction).
Note that only one Site Design volume reduction credit can be applied for each area, however. For example, runoff dispersion and rain barrel
volume reduction cannot both be claimed for the same line item area.
Table D.5-1: Suitability Assessment Related Considerations for Infiltration Facility Safety Factors
Assessment methods
(see explanation
below)
Texture Class
Site soil variability
Depth to
Use of soil survey maps or
simple texture analysis to
estimate short-term
infiltration rates
Use of well permeameter
or borehole methods
without accompanying
continuous boring log
Relatively sparse testing
with direct infiltration
methods
Silty and clayey soils with
significant fines
Highly variable soils
indicated from site
assessment, or
Unknown variability
Use of well permeameter
or borehole methods with
accompanying continuous
boring log
Direct measurement of
infiltration area with
localized infiltration
measurement methods
(e.g., infiltrometer)
Moderate spatial
resolution
Loamy soils
Soil borings/test pits
indicate moderately
homogeneous soils
groundwater/ 5-15 ft below facility
Direct measurement with
localized (i.e., small-scale)
infiltration testing methods at
relatively high resolution1
or
Use of extensive test pit
infiltration measurement
methods2
Granular to slightly loamy
soils
Soil borings/test pits indicate
relatively homogeneous soils
impervious layer <5 ft below facility bottom bottom >15 below facility bottom
1 -Localized (i.e., small scale) testing refers to methods such as the double-ring infiltrometer and
borehole tests. A relatively high resolution generally means two or more tests directly within the
proposed BM P's footprint.
2 -Extensive infiltration testing refers to methods that include excavating a significant portion of the
proposed infiltration area, filling the excavation with water, and monitoring drawdown. The excavation
should be to the depth of the proposed infiltration surface and ideally be at least 30 to 100 square feet.
Form 1-9/Worksheet D.5-1: Factor of Safety and Design Infiltration Rate Worksheet
A
B
Factor Category
Suitability
Assessment
Design
Factor Description
Soil assessment methods
Predominant soil texture
Site soil variability
Depth to groundwater I impervious layer
Suitability Assessment Safety Factor, SA= Ip
Level of pretreatment/ expected sediment
loads
Redundancy/ resiliency
Compaction during construction
Design Safety Factor, S8 = Ip
Combined Safety Factor, S1ata1= SAX Ss
Observed Infiltration Rate, inch/hr, Kabserveci
(corrected for test-specific bias)
Design Infiltration Rate, in/hr, Kdesi n = Kabserved / S1a1a1
Supporting Data
Briefly describe infiltration test and provide reference to test forms:
Assigned Factor Weight Value1 (v) (w)
0.25 3
0.25 3
0.25 2
0.25 2
0.5 3
0.25 3
0.25 3
Product
(p)
p=wx
V
0.75
0.75
0.5
0.5
2.5
1.5
0.75
0.75
3
2
0.125
0.0625
Although the analysis indicates that the safety factor should be 7.5, the BMP Design Manual (Appendix
D.5.4 recommends a maximum safety factor of 2.0, which has been implemented into the design).
Additionally, an onsite percolation study was conducted on the subject property which indicates that
the soils underneath the proposed Biofiltration with Partial Retention Basin infiltrate at 0.125 inch/hour
(please note that the soils near the proposed tree wells infiltrate at significantly higher rates -from 2.9-
up to 6.0 in/hr). For further details, please refer to the Percolation Test Results prepared by
Construction Testing & Engineering, Inc. (March, 2016), included under Appendix E of this SWQMP.
Note
1. Factor values are assigned per Table D.5-1 in the BMP Design Manual.
Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs
BMP ID IDs of Tributary DMAs IDs of Retention BMPs Treating the Same DMAs
PR-la DMAs Nla & Nlb N/A
Initial Information
la Total DCV of tributary DMAs
lb Volume reduction from implementation of retention BMPs
1 Remaining DCV after implementing retention BMPs (Line la -Line lb)
Partial Retention
2 Infiltration rate from Worksheet 0.5-1 if partial infiltration is feasible
3 Allowable drawdown time for aggregate storage below the underdrain
4 Depth of runoff that can be infiltrated [Line 2 x Line 3]
5 Aggregate pore space
6 Required depth of gravel below the underdrain [Line 4/ Line SJ
7 Assumed surface area of the biofiltration BMP
8 Media retained pore storage
9 Volume retained by BMP [[[Line 4 + (Line 12 x Line 8)]/12] x Line 7]
10 DCV that requires biofiltration [Line 1 -Line 9]
BMP Parameters
11 Surface Ponding [6 inch minimum, 12 inch maximum]
Soil Media Thickness [18 inches minimum], also add mulch layer thickness
12 to this line for sizing calculations
13 Aggregate Storage above underdrain invert
14 Soil Media available pore space
Soil Media filtration rate to be used for sizing (S in/hr. with no outlet
control; if the filtration rate is controlled by the outlet use the outlet
15 controlled rate)
Baseline Calculations
16 Allowable Routing Time for sizing
17 Depth filtered during storm [ Line 15 x Line 16]
Depth of Detention Storage
18 [Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)]
19 Total Depth Treated [Line 17 + Line 18]
Option 1-Biofilter 1.5 times the DCV
20 Required biofiltered volume [1.5 x Line 10]
21 Required Footprint [Line 20/ Line 19] x 12
272 ft3
0 ft3
272 ft3
0.063 in/hr
36 hr
2.25 in
0.4 in/in
5.63 in
318 ft2
0.1 in/in
107 ft3
164 ft3
6 in
18 in
6 in
0.2 in/in
5 in/hr.
6 hr
30 in
12 in
42 in
246 ft3
70 ft2
Option 2 -Store 0.75 of remaining DCV in pores and ponding
22 Required Storage (surface+ pores) Volume [0.75 x Line 10] 239 ft3
23 Required Footprint [Line 22/ Line 18] x 12 239 ft2
Footprint of the BMP
24 Area draining to the BMP 13552 ft2
25 Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and B.2) 0.41
BMP Footprint Sizing Factor (Default 0.03 or an alternative minimum
26 footprint sizing factor from Worksheet B.5-2, Line 11) 0.03 unitless
27 Minimum BMP Footprint [Line 24 x Line 25 x Line 26] 166 ft2
28 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 27) 166 ft2
29 Calculate the fraction of the DCV retained by the BMP [Line 9/ Line 1] 0.395 unitless
30 Minimum required fraction of DCV retained for partial infiltration condition 0.375 unitless
Is the retained DCV > 0.375? If the answer is no increase the footprint sizing
31 factor in Line 26 until the answer is yes for this criterion @Yes D No
Notes
1. 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)
2. The DCV fraction of 0.375 is based on a 40% average annual percent capture and a 36-hour drawdown time.
3. The increase in footprint for volume reduction can be optimized using the approach presented in Appendix B.5.2. The
optimized footprint cannot be smaller than the alternative minimum footprint sizing factor from Worksheet B.5-2.
4. If the proposed biofiltration BMP footprint is smaller than the alternative minimum footprint sizing factor from Worksheet
B.5-2, but satisfies Option 1 or Option 2 sizing, it is considered a compact biofiltration BMP and may be allowed at the
discretion of the [City Engineer], if it meets the requirements in Appendix F.
Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs
BMPID IDs of Tributary DMAs IDs of Retention BMPs Treating the Same DMAs
PR-lb DMAs N2a & N2b N/A
Initial Information
la Total DCV of tributary DMAs
lb Volume reduction from implementation of retention BMPs
1 Remaining DCV after implementing retention BMPs (Line la -Line lb)
Partial Retention
2 Infiltration rate from Worksheet D.5-1 if partial infiltration is feasible
3 Allowable drawdown time for aggregate storage below the underdrain
4 Depth of runoff that can be infiltrated [Line 2 x Line 3]
5 Aggregate pore space
6 Required depth of gravel below the underdrain [Line 4/ Line SJ
7 Assumed surface area of the biofiltration BMP
8 Media retained pore storage
9 Volume retained by BMP [[[Line 4 + (Line 12 x Line 8)]/12] x Line 7]
10 DCV that requires biofiltration [Line 1-Line 9]
BMP Parameters
11 Surface Ponding [6 inch minimum, 12 inch maximum]
Soil Media Thickness [18 inches minimum], also add mulch layer
12 thickness to this line for sizing calculations
13 Aggregate Storage above underdrain invert
14 Soil Media available pore space
Soil Media filtration rate to be used for sizing (S in/hr. with no outlet
control; if the filtration rate is controlled by the outlet use the outlet
15 controlled rate)
Baseline Calculations
16 Allowable Routing Time for sizing
17 Depth filtered during storm [ Line 15 x Line 16]
Depth of Detention Storage
18 [Line 11 + (Line 12 x Line 14) + (Line 13 x Line S)]
19 Total Depth Treated [Line 17 + Line 18]
Option 1-Biofilter 1.5 times the DCV
20 Required biofiltered volume [1.5 x Line 10]
21 Required Footprint [Line 20/ Line 19] x 12
260 ft3
0 ft3
260 ft3
0.063 in/hr
36 hr
2.25 in
0.4 in/in
5.63 in
297 ft2
0.1 in/in
100 ft3
160 ft3
6 in
18 in
6 in
0.2 in/in
5 in/hr.
6 hr
30 in
12 in
42 in
239 ft3
68 ft2
Option 2 -Store O. 75 of remaining DCV in pores and ponding
22 Required Storage (surface+ pores) Volume [0.75 x Line 10) 223 ft3
23 Required Footprint [Line 22/ Line 18) x 12 223 ft2
Footprint of the BMP
24 Area draining to the BMP 13586 ft2
Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and
25 B.2) 0.39
BMP Footprint Sizing Factor (Default 0.03 or an alternative minimum
26 footprint sizing factor from Worksheet B.5-2, Line 11) 0.03 unit less
27 Minimum BMP Footprint [Line 24 x Line 25 x Line 26) 159 ft2
28 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 27) 159 ft2
29 Calculate the fraction of the DCV retained by the BMP [Line 9/ Line 1) 0.386 unitless
Minimum required fraction of DCV retained for partial infiltration
30 condition 0.375 unitless
Is the retained DCV > 0.375? If the answer is no increase the footprint
31 sizing factor in Line 26 until the answer is yes for this criterion @Yes D No
Notes
1. 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)
2. The DCV fraction of 0.375 is based on a 40% average annual percent capture and a 36-hour drawdown time.
3. The increase in footprint for volume reduction can be optimized using the approach presented in Appendix B.5.2. The
optimized footprint cannot be smaller than the alternative minimum footprint sizing factor from Worksheet B.5-2.
4. If the proposed biofiltration BMP footprint is smaller than the alternative minimum footprint sizing factor from
Worksheet B.5-2, but satisfies Option 1 or Option 2 sizing, it is considered a compact biofiltration BMP and may be
allowed at the discretion of the [City Engineer], if it meets the requirements in Appendix F.
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 IZI Included
Exhibit (Required) See Hydromodification Management
Exhibit Checklist on the back of this
Attachment cover sheet.
Attachment 2b Management of Critical Coarse IZI 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)
See Section 6.2 of the BMP Design Optional analyses for Critical Coarse
Manual. Sediment Yield Area Determination
D 6.2.1 Verification of Geomorphic
Landscape Units Onsite
D 6.2.2 Downstream Systems
Sensitivity to Coarse Sediment
D 6.2.3 Optional Additional Analysis
of Potential Critical Coarse
Sediment Yield Areas Onsite
Attachment 2c Geomorphic Assessment of Receiving !ZI Not performed
Channels (Optional) D Included
See Section 6.3.4 of the BMP Design
Manual.
Attachment 2d Flow Control Facility Design and D Included
Structural BMP Drawdown IZI N/A Calculations (Required)
See Chapter 6 and Appendix G of the
BMP Design Manual
ATTACHMENT 2A: HYDROMODIFICATION MANAGEMENT EXHIBIT
Please note that the site is located in a hydromodification exempt area and is therefore exempt from the
City's hydromod requirements. Any of the typical items required on the Hydromodification Management
Exhibit that are relevant to this project have been included on the OMA Exhibit under SWQMP
Attachment 1A. For further details, please refer to the Hydromodification Exemption Exhibits below:
-• ~ DRAtlA(I; 8ASfh BCU()MY
'LOW ,-4fH
// alllllOll(llflCA-»I DH?1 MO
Source: Hydromodification Exemption Analyses for select Carlsbad Watersheds prepared by Chang Consultants
(September, 2015).
-e..mpt ~ I.act. ..
~ds.o.e.r .......
'"-9'""-. ---· -..... ---.---Conffyanc:··-----.. OGfM'JVICII'~ .... bid an:fbank .. ~
__ .. __
~ ............ GflilNxllllld CINClld..., ...... ~ ... --
HYDROMODIFICATION MANAGEMENT EXEMPTION MAP
Carlsbad Watershed Manaoement Area
HU 904.00, 211 mi2
•• -J Receiving Waters and Conveyance Systems Exempt
from Hydromodification Management Requirements Gcosynccci> 1;j1ijj O ~
!llhibil Dale: S.pl t 2014 ~
Source: Receiving Waters and Conveyance Systems Exempt form hydromodification Management Requirements prepared by
Geosyntec and Consultants and Rick Engineering (09/08/2014) included under Attachment 8.4 of the Carlsbad Watershed
Management Area Analysis (WMAA)
ATIACHMENT 28: CRITICAL COARSE SEDIMENT YEILD AREA MAP
Please note that the site is located outside of the noted critical coarse sediment yield areas and therefore
exempt from the City's critical coarse sediment yield requirements. For further details, please refer to the
Critical Coarse Sediment Yield Area Map below:
Critical Coarse Sediment Yield Area Map
()otential Critical Coarse Sediment Yield Areas
:arlsbad Watershed -HU 904.00, 211 mi2
.... 3 • -1•f
Gcosyntcc0 •;1119 a r-!xhlbit Date: sept a, 2014 ~
Source: Potential Critical Coarse Sediment Yield Areas Map prepared by Geosyntec and Consultants and Rick Engineering
(09/08/2014) included under Attachment A.4 of the Carlsbad Watershed Management Area Analysis (WMAA)
ATTACHMENT 3
City Standard Single Sheet BMP (SSBMP) Exhibit
,_
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3990 HIGHLAND DR
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20
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EX
DWY
3971 JAMES DRIVE
/
/
SCALE: 1" = 20 FEET
LEGEND
(E): EXISTING , (N): NEW I PROPOSED
(E) PROPERTY LINE
(E) MAJOR CONTOUR
(E) MINOR CONTOUR
(N) MAJOR CONTOUR
(N) MINOR CONTOUR
(E) CURB & GUTTER
---6" ss - -6" ss -(E) 6" SANITARY SEWER
(E) STRIPING
--12" SD - -12" SD -(E) 12" RCP STORM DRAIN PIPE
--18" SD--18" SD-(E)18"RCPSTORMDRAINPIPE
--48" SD--48" SD-(E) 48" RCP STORM DRAIN PIPE
§ (E) STORM DRAIN INLET
---4" SS --4" ss -(E) SANITARY SEWER ~--------........----.. -...------------.-..-.. (E) RETAINING WALL
(N) BIORETENTION BMP
, I -(E) CONCRETE
[~~=J--~;z:a -:~: ~~::~~:ION
'., " .. 1-------~-t-:·~-
----4" SD
----6" SD
----8" SD
----10" SD
----18" SD
(N) HARDSCAPE
(N) LANDSCAPE
(N) EARTHEN SWALE FLOWLINE
(N) RIPRAP SWALE
(N) 4" 0 SD PIPE
(N) 6" 0 SD PIPE
(N) 8" 0 SD PIPE
(N) 1 O" 0 SD PIPE
(N) 18" 0 SD PIPE
IJ (N) SD CATCH BASIN
"SP (N) BMP SIGN
/~',,,-"1
, 0 (N) TREE WELL 10' CANOPY ,,
'''~-(N) TREE WELL 5' CANOPY
LOCAL
DEPRESSION 0 ---(N) STREET TREE (IN PUBLIC ROW
-8--(E) POWER POLE
DRAINAGE DIRECTION
-I --I --DMABOUNDARY
Nl
DMALABEL
## ac
EASEMENT NOTES
® PUBLIC 5' WIDE DRAINAGE EASEMENT DEDICATED TO THE
CITY OF CARLSBAD
® INDICATES A COVENANT FOR PRIVATE STORM DRAIN
EASEMENT TO BENEFIT REMAINDER PARCEL
@ INDICATES A COVENANT FOR PRIVATE STORM DRAIN
EASEMENT TO BENEFIT LOTS 1, 2, AND REMAINDER PARCEL
@ INDICATES A COVENANT FOR PRIVATE STORM DRAIN
EASEMENT TO BENEFIT LOT 1 AND REMAINDER PARCEL
SWQMP NO,: 16-28
PARTY RESPONSIBLE FOR MAINTENANCE:
NAME ELIZABETH TEMPLE
ADDRESS 3276 HIGHLAND DRIVE
CARLSBAD, CA, 92008
EMAIL elizabethtemple@gmail.com
PHONE NO. (619) 204 • 4903
PLAN PREPARED BY:
NAME PHILLIP PATAGUE
COMPANY TERRAMAR ENGINEERING
ADDRESS 2888 LOKER AVENUE EAST
SUITE 303
CARLSBAD CA 92010
PHONE NO. 760 • 603 • 1900 __ _
ADDITIONAL OMA NOTES:
. , --, ~
\
SIGNATURE
CERTIFICATION ____ _
1. DMA N1c CONVEYS FLOWS FROM N1 ll& N1 CITO THE PRIVATE
STORM DRAIN SYSTEM.
2. DMA N2c CONVEYS FLOW FROM N2 n & N2 0 TO THE PRIVATE
STORM DRAIN SYSTEM.
BEST MANAGEMENT PRACTICE (BMP) TABLE
-
BMPID# BMPTYPE SYMBOL CITY BMP# QUANTITY DRAWING NO. INSPECTION I MAINTENANCE FREQUENCY
-·---
~r-r-· MONTHLY -INSPECT FOR ERODED SOILS & BUil T UP TRASH AND DEBRIS.
PR-1A BIORETENTION r-!f./.J:/:j. PR-1 318 SF DETAIL 1 HEREON tN , ... t1-, SEMI-ANNUALLY· INSPECT/REMOVE/REPLACE DAMAGED/DEAD VEGETATION, VEGETATIVE COVER r,.._ ,!:r-1:'l·.f:!
'
DAMAGED BY EROSION.
SEMI-ANNUALLY -REMOVE BUILT-UP SEDIMENTS, RE-MULCH VOIDED AREAS, TREAT VEGETATION, ,f:rJ)~r-r-:{/ PR-18 BIORETENTION Y"f' r-1'-rJ ... PR-1 297 SF DETAIL 1 HEREON MOW TURF AREAS, REPAIR EROSION AT INFLOW POINTS, REPAIR DAMAGES TO OUTFLOW t-,t-r:7./1:Ef:'rJ STRUCTURE, UNCLOG UNDER-DRAIN AND REGULATE SOIL pH ON AN AS-NEEDED BASIS.
·-·---
SMA-1 SELF-MITIGATING I 'I i I SD-5 605 SF N/A NOT APPLICABLE -SITE DESIGN BMP AREA-1 ' . ------·-----
SMA-2 SELF-MITIGATING I! z. 'I SD-5 484 SF N/A NOT APPLICABLE -SITE DESIGN BMP AREA·2 --. ----
SRA-1 SELF-RETAINING 1·,'.·I SD-5 3,571 SF N/A NOT APPLICABLE -SITE DESIGN BMP AREA-1
SRA-2 SELF-RETAINING L-·J SD-5 3,571 SF N/A NOT APPLICABLE -SITE DESIGN BMP AREA-2 .
SELF-RETAINING 1·.·._:J SRA-3 AREA-3 SD-5 3,571 SF N/A NOT APPLICABLE -SITE DESIGN BMP
-------
~l SRA-4 SELF-RETAINING SD-5 3,571 SF N/A NOT APPLICABLE -SITE DESIGN BMP AREA-4 .
-
SRA-5 SELF-RETAINING 1--· . · l SD-5 3,571 SF N/A NOT APPLICABLE -SITE DESIGN BMP AREA-5 ------
SRA-6 SELF-RETAINING 1·,·.-1 SD-5 3,571 SF N/A NOT APPLICABLE -SITE DESIGN 8MP AREA-6
--
TW-5' TREE WELL 8 SD-1 1 EACH DWG 483-68 (DET 1 SHT 2) & NOT APPLICABLE -SITE DESIGN BMP S'CANOPY DETAIL 2 HEREON ..
TW-10' TREE WELL (·) SD-1 3EACH DWG 483-66 (DET 1 SHT 2) & NOT APPLICABLE -SITE DESIGN BMP 10' CANOPY DETAIL 2 HEREON ------· ·-. .
HYDROMODIFICATION & TREATMENT CONTROL ADDITIONAL BMP NOTES:
HYDROMODIFICATION: SITE IS LOCATED IN AN AREA THAT IS HYDROMODIFICATION EXEMPT. 1. THESE BMPS ARE MANDATORY TO BE INSTALLED PER
MANUFACTURER"5 RECOMMENDATIONS OR THESE PLANS.
TREATMENT CON TROL: TREATMENT CONTROL IS ATTAINED THROUGH A COMBINATION OF SITE DESIGN BMPS
(SD-1 , SD-5, TW-5L& TW-10~AND STRUCTURAL BMPS (PR-1A & PR-1 B).
2. NO CHANGES TO THE PROPOSED BMPS ON THIS SHEET
WITHOUT PRIOR APPROVAL FROM THE CITY ENGINEER.
LOW IMPACT DESIGN (L.I.D.)
3. NO SUBSTITUTIONS TO THE MATERIAL OR TYPES OR
PLANTING TYPES WITHOUT PRIOR APPROVAL FROM THE
CITY ENGINEER.
WATER QUALITY COMPLIANCE IS BEING ADDRESSED THROUGH A COMBINATION OF SITE DESIGN BMPS (SD-1,
SD-5, TW-5L& TW-10:)J AND STRUCTURAL BMPS (PR-1A & PR-18). 4. NO OCCUPANCY WILL BE GRANTED UNTIL THE CITY
INSPECTION STAFF HAS INSPECTED THIS PROJECT FOR
APPROPRIATE BMP CONSTRUCTION AND INSTALLATION. SOURCE CONTROL
BMP ID# BMPTYPE
G) TRASH STORAGE
0 INTERIOR GARAGE
@ INDOOR PEST
CONTROL
8) OUTDOOR PEST
CONTROL
® INLET STENCILING
/SIGNAGE -----·-----
30 MIL
IMPERMEABLE
LINER (VERTICAL)
PREVAILING WIND ____ ,.
TURF AREAS ONLY: ARBOR GUARD -~
MODEL #AG8-4
--
SYMBOL
[LJlJ
• • •
N/A
SECTION VIEW
CITY BMP#
SC-5
SC-BA
SC-6B
SC-6C
SC-2
QUANTITY DETAIL INSPECTION
NO. FREQUENCY
5 EACH NIA AS NEEDED (1 PER HOUSE)
5 EACH N/A AS NEEDED (1 PER HOUSE) I
--
SEACH NIA AS NEEDED (1 PER HOUSE) -----·--
SEACH N/A AS NEEDED (1 PER HOUSE)
11 EACH DETAIL3 AS NEEDED
-·
PLAN VIEW -----·--
TREE TIE NOTE: ---~
MAINTENANCE
FREQUENCY
AS NEEDED
AS NEEDED
AS NEEDED
AS NEEDED
AS NEEDED
5. REFER TO MAINTENANCE AGREEMENT DOCUMENT.
6. SEE PROJECT SWMP FOR ADDITIONAL INFORMATION .
CATCH BASIN STENCIUNG/SIGNAGE ~3 SCALE:SCALE ~.:.J_j
NOTES: PLACARD MUST HAVE SIMILAR WORDING" NO -
DUMPING! DRAINS TO OCEAN". MUST BE CITY APPROVED.
AMENDED SOILS NOTE:
(BY VOLUME: 65% SAND, 20% SANDY LOAM, 15% COMPOST IN ACCORDANCE WITH THE
SAN DIEGO COUNTY BIORETENT!ON SOIL MEDJA EXAMPLE SPECIFICATION AVAILABLE
ONLINE)
BIORETENTION BMP (PR-1) DETAIL
·scALE:NTS
TREE WELL NOTES
[2J TREE CANOPY
0 (2) CINCH TIES, TACK TO STAKE 'NITH GALVAf·JIZED NAILS TO PREVENT SLIPPING
(2)2' DIA. X 8' LONG UNTREATED LODGEPOLE PINE STAKES FOR 5 GAL. TREES,
OR
(2) 2' DIA. X 10' LONG UNTREATED LODGEPOLE PINET AKES FOR 15 GAL.-36' BOX TREES,
SET STAKES OUTSIDE ROOTBALL. ANGLE TOP OF STAKE A'NAY FROM BRANCH STRUCTURE.
TREE TRUNK
1 X4 DOUG. FIR BRACE, TACK TO LODGEPOLE STAKES WITH G.ALV. NAILS
t INSTALL TREE TIES AND STAKES ONLY TO PROPER LEVEL TO HOLD
TREE UPRIGHT PROPER HEIGHT IS 6" ABOVE POINT WHERE THE TREE
WILL SNAP TO AN UPRIGHT POSITION BY ITSELF IF TOP IS PULLED TO
ONE SIDE AS IF l/1'IND LOADED AND THEN RELEASED. QQ_ NOT TOP
TREES IN ORDEH TO REDUCE SIZE OR WEIGHT OF TREE CROWN,
CONT ACT LANDSCAPE ARCHITECT PRIOR TO ANY PRUMING OF TREES.
ROOT BALL, DO NOT PENETRATE WITH STAKE.
USE AMENDED SOIL WI TH MINIMUM DEPTH OF 3' + 1' IN ALL DIRECTI ONS OF ROOT BALL PER
CITY'S BMP MANUAL APPENDIX PG. E-18.
TREE WELL DETAIL ~2 SCALE:NTS ~
:===.=+;=-~~:--_-_ -_ ---~---------~~~~~==--=---=-----_-__ -+-;-~~--::-~~--+----_ -_ -+-+--_ -_ __,-l I SH1EET J -CITY OF CARLSBAD
ENGINEERING DEP ARTMENT
1------1---+-------------------------+----1-----::===::'...':====================-===~
---~----!------------------+----+----+----+-----<
----r--------------------t-----t------1------t----1
1------1----+-------·--·--------------+-----+---+------+---t
1---~----1--------------------+----+----+----+---
SINGLE-SHEET BMP PLAN FO R
HIGHLAND JAMES SUBDIVISION
(JAMES DRIVE PORTION)
3980 HIGHLAND DR
CARLSBAD, CA, 92008
+------------------+-------·--·t----t---J :===R=E=c=o=R=D=c=o=p=y==::;-;=c=c==p~==0=J~==-~==T=~1==~=6~1
:==D=A=TE=:=l=N=IT=IA=L:=====-----=-~-=------_---_-_--.:_-.:_-::-.:__-.:_-.:_-.:_-.:_-.:_-.:_-::__-----+--D-A-TE-+-IN-!T-IA-L--+-D-A-TE-+-"-"T-IA_L_1 4( C, ~ l -DRAW-IN G NO. I
ENGINEER OF WORK REVISION DESC RIP TION OTHER APPROVAL CI TY APP l10VAL ~ __ IN_I_TI_AL ______ D_A_TE __ --j 4 83~ 6SW