HomeMy WebLinkAboutCT 16-02; OCEAN CONDOMINIUMS; PRIORITY DEVELOPMENT PROJET (PDP) STORM WATER QUALITY MANAGEMENT PLAN (SWQMP); 2020-11-20CITY OF CARLSBAD
PRIORITY DEVELOPMENT PROJECT (PDP) STORM WATER
QUALITY MANAGEMENT PLAN (SWQMP) FOR
OCEAN CONDOMINIUMS
CT16-02 / RPI6-08
GR2019-0028
DRAWING No. 519-5A
SWQMP No.519-5
ENGINEER OF WORK:
uI.?I5
cc No. 58274
Lriy R. Taylor, RCE, GE, QSD
RCE 58274, Expires 06.30.2022 ppcAi'
Prepared for.-
Carlsbad 17 GP, LLC
234 Venture Street, Suite 100
San Marcos, CA 92079
Prepared by:
TAYLOR GROUP, INC.
301 Mission Avenue, Suite 201
Oceanside, CA 92054
760.721.9990
TGI Project No. 19.00911-0700
November 20, 2020
RTT
D1 11 2020
LAN .....
EN(NErsiNG
TABLE OF CONTENTS
I Certificaton Page
Project Vicinity Map
FORM E-34 Storm Water Standard Questionnaire
I
Site Information
FORM E•-36 Standard Project Requirement Checklist
Summary of PDP Structural BMPs
I
Attachment 1: Backup for PDP Pollutant Control BMPs
Attachment la: DMA Exhibit
Attachment I b: Tabular Summary of DMAs and Design Capture Volume Calculations
Attachment ic: Harvest and Use Feasibility Screening (when applicable)
I Attachment Id: Categorization of Infiltration Feasibility Condition (when applicable)
Attachment le: Pollutant Control BMP Design Worksheets /Calculations
Attachment 2: Backup for PDP Hydromodification Control Measures
I Attachment 2a: Hydromodification Management Exhibit
Attachment 2b: Management of Critical Coarse Sediment Yield Areas
Attachment 2c: Geomorphic Assessment of Receiving Channels
I Attachment 2d: Flow Control Facility Design Attachment 3: Structural BMP Maintenance Thresholds and Actions
Attachment 4: Single Sheet BMP (SSBMP) Exhibit
CERTIFICATION PAGE
Project Name: OCEAN CONDOMINIUMS Project ID: CT 16-02 I RP 16-08
I hereby declare that I am the Engineer in Responsible Charge of design of storm water BMPs for
this project, and that I have exercised responsible charge over the design of the project as defined
in Section 6703 of the Business and Professions Code, and that the design is consistent with the
requirements of the BMP Design Manual, which is based on the requirements of SDRWQCB
Order No. R9-2013-0001 (MS4 Permit) or the current Order.
I have read and understand that the City Engineer has adopted minimum requirements for
managing urban runoff, including storm water, from land development activities, as described in
the BMP Design Manual. I certify that this SWQMP has been completed to the best of my ability
and accurately reflects the project being proposed and the applicable source control and site
design BMPs proposed to minimize the potentially negative impacts of this project's land
development activities on water quality. I understand and acknowledge that the plan check review
of this SWQMP by the City Engineer is confined to a review and does not relieve me, as the
Engineer in Responsible Charge of design of storm water BMPs for this project, of my
responsibilities for project design.
TAYLOR GROUP, INC.
Larry R. Taylor, RCE, GE, QSD
RCE 58274, Expires 06.30.2022
;04 oF ESSi0 vi AV
No. 58274
Date: November 20, 2020
Le1;Ai4 PROJECT VICINITY MAP XMapc4.5
Data use subject to license. W 2004 DeLorme. XMap® 4.5. 0 800 1600 2400 3200 4000
www.delorrne.com MN (0.0 W) Data Zoom 13-0
STORM WATER STANDARDS Development Services t City of QUESTIONNAIRE Land Development Engineering
C ar s1a1.1635 Faraday Avenue
E-34 (760) 602-2750
www.carlsbadca.gov
INSTRUCTIONS:
To address post-development pollutants that may be generated from development projects, the city requires that new
development and significant redevelopment priority projects incorporate Permanent Storm Water Best Management
Practices (BMPs) into the project design per Carlsbad BMP Design Manual (BMP Manual). To view the BMP Manual,
refer to the Engineering Standards (Volume 5).
This questionnaire must be completed by the applicant in advance of submitting for a development application
(subdivision, discretionary permits and/or construction permits). The results of the questionnaire determine the level of
storm water standards that must be applied to a proposed development or redevelopment project. Depending on the
outcome, your project will either be subject to 'STANDARD PROJECT' requirements or be subject to 'PRIORITY
DEVELOPMENT PROJECT' (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 sgned questionnaire is required when multiple development applications for the same project are
submitted concurrently.
PROJECT INFORMATION
PROJECT NAME: Ocean Condominiums PROJECT ID: CT 16-02IRP 16-08
ADDRESS: 2501 State Street APN: 155-200-10-00
The project is (check one): fl New Development FV1 Redevelopment
The total proposed disturbed area is: 42,700 ft2 (_0.980 ) acres
The total proposed newly created and/or replaced impervious area is: 21,565 ft2 (_0.495 ) 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 NA SWQMP#: NA
Then, go to Step 1 and follow the instructions. When completed, sign the form at the end and submit this with your
application to the city.
E-34 Page 1 of 4 REV 02/16
STEP
TO BE COMPLETED FOR ALL PROJECTS
To determine if your project is a "development project", please answer the following question:
YES NO
Is your project LIMITED TO routine maintenance activity and/or repair/improvements to an existing building FE71 M or structure that do not alter the size (See Section 1.3 of the BMP Design Manual for guidance)?
If you answered "yes" to the above question, provide justification below then go to Step 5, mark the third box stating "my
project is not a 'development project' and not subject to the requirements of the BMP manual" and complete applicant
information.
Justification/discussion: (e.g. the project includes only interior remodels within an existing building):
If you answered "no" to the above question, the project is a 'development project', go to Step 2.
STEP2
TOBE COMPLETED FOR ALL DEVELOPMENT PROJECTS
To determine if your project is exempt from PDP requirements pursuant to MS4 Permit Provision E.3.b.(3), please answer
the following questions:
Is your project LIMITED to one or more of the following:
YES NO
1. Constructing new or retrofitting paved sidewalks, bicycle lanes or trails that meet the following criteria:
Designed and constructed to direct storm water runoff to adjacent vegetated areas, or other non-
erodible permeable areas;
Designed and constructed to be hydraulically disconnected from paved streets or roads;
Designed and constructed with permeable pavements or surfaces in accordance with USEPA
Green Streets guidance?
2. Retrofitting or redeveloping existing paved alleys, streets, or roads that are designed and constructed in
accordance w th the USEPA Green Streets guidance?
3. Ground Moun'ed Solar Array that meets the criteria provided in section 1.4.2 of the BMP manual? LI E1
If you answered 'yes" to one or more of the above questions, provide discussion/justification below, then go to Step 5, mark
the second box stating my project is EXEMPT from PDP ..." and complete applicant information.
Discussion to justify exemption ( e.g. the project redeveloping existing road designed and constructed in accordance with
the USEPA Green Street guidance):
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 04/17
- :sTEp3 : -
TO BE COMPLETED FOR ALL NEW OR REDEVELOPMENT PROJECTS
To determine if your project is a POP, please answer the following questions (MS4 Permit Provision E.3.b.(1)):
YES NO
Is your project a new development that creates 10,000 square feet or more of impervious surfaces
collectively over the entire project site? This includes commercial, industrial, residential, mixed-use, LI
and public development projects on public or private land.
Is your project a redevelopment project creating and/or replacing 5,000 square feet or more of
impervious surface collectively over the entire project site on an existing site of 10,000 square feet or
more of impervious surface? This includes commercial, industrial, residential, mixed-use, and public
development projects on public or private land.
Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more
of impervious surface collectively over the entire project site and supports a restaurant? A restaurant is
a facility that sells prepared foods and drinks for consumption, including stationary lunch counters and LI L1
refreshment stands selling prepared foods and drinks for immediate consumption (Standard Industrial
Classification (SIC) code 5812).
Is your project a new or redevelopment project that creates 5,000 square feet or more of impervious
surface collectively over the entire project site and supports a hillside development project? A hillside LI
development project includes development on any natural slope that is twenty-five percent or greater.
Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more
of impervious surface collectively over the entire project site and supports a parking lot? A parking lot is El Z a land area or facility for the temporary parking or storage of motor vehicles used personally for
business or for commerce.
Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more
of impervious street, road, highway, freeway or driveway surface collectively over the entire project El R1 site? A street, road, highway, freeway or driveway is any paved impervious surface used for the
transportation of automobiles, other vehicles. _trucks, _motorcycles, _and
Is your project a new or redevelopment project that creates and/or replaces 2,500 square feet or more
of impervious surface collectively over the entire site, and discharges directly to an Environmentally
Sensitive Area (ESA)? "Discharging Directly to" includes flow that is conveyed overland a distance of LI
200 feet or less from the project to the ESA, or conveyed in a pipe or open channel any distance as an
isolated flow from the project to the ESA (i.e. not commingled with flows from adjacent lands). *
Is your project a new development or redevelopment project that creates and/or replaces 5,000 square
feet or more of impervious surface that supports an automotive repair shop? An automotive repair El Z shop is a facility that is categorized in any one of the following Standard Industrial Classification (SIC)
codes: 5013, 5014, 5541, 7532-7534, or 7536-7539.
Is your project a new development or redevelopment project that creates and/or replaces 5,000 square
feet or more of impervious area that supports a retail gasoline outlet (RGO)? This category includes El Z RGO's that meet the following criteria: (a) 5,000 square feet or more or (b) a project Average Daily
Traffic (AD T) of 100 or more vehicles per day.
Is your project a new or redevelopment project that results in the disturbance of one or more acres of land
and are expected to generate pollutants post construction?
Is your project located within 200 feet of the Pacific Ocean and (1) creates 2,500 square feet or more of
impervious surface or (2) increases impervious surface on the property by more than 10%? (CMC LI
21.203.040)
If you answered 'yes" to one or more of the above questions, your project is a PDP. If your project is a redevelopment
project, go to step 4. If your project is a new project, go to step 5, check the first box stating "My project is a PDP
and complete applicant information.
If you answered "no" to all of the above questions, your project is a 'STANDARD PROJECT.' Go to step 5, check the
second box stating "My project is a 'STANDARD PROJECT'..." and complete applicant information.
E-34 Page 3 of 4 REV 04/17
STEP
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) = 17.275 sq. ft. El Z
Total proposed newly created or replaced impervious area (B) = 21,565 sq. ft.
Percent impervious area created or replaced (B/A)*100 = 125 %
If you answered "yes", the structural BMPs 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 BMP'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.
STEP
* CHECK THE APPROPRIATE BOX AND COMPLETE APPLICANT INFORMATION
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.
LI 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.
LI My Project is NOT a 'development project' and is not subject to the requirements of the BMP Manual.
Applicant Information and Signature Box
Applicant Name: Larry trRGEGE, QSD Applicant Title: Consultant
Applicant November 20, 2020
FIVIFUI1FIlC1llLIY oerisiuve ,reas incivae out are not umitea to at uiean water ict section U(0) 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 PARE beneficial use by the State Water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1994) and
amendments); areas designated as preserves or their equivalent under the Multi Species Conservation Program within the Cities and County of San Diego; Habitat
Management Plan; and any other equivalent environmentally sensitive areas which have been identified by the City.
This Box for City Use On/v
City Concurrence:
YES NO
[I] [1
By:
Date:
Project ID:
E-34 Page 4 of 4 REV 04/17
SITE INFORMATION CHECKLIST
Project SUnmatyInformation,
Project Name Ocean Condominiums
Project ID C11602 I RP 16-08
Project Address 2501 State Street
Assessor's Parcel Number(s) (APN(s)) 155-200-10-00
Project Watershed (Hydrologic Unit) Carlsbad 904
Parcel Area
0.487 Acre (21,223 Square Feet)
Existing impervious Area
(subset of Parcel Area) 0.400 Acre (17.275 Square Feet)
Area to be disturbed by the project
(Project Area) 0.980 Acre (42,700 Square Feet)
Project Proposed Impervious Area
(subset of Project Area) 0.495Acre (21,565 Square Feet)
Project Proposed Pervious Area
(subset of Project Area) 0.113 Acre (4,935 Square Feet)
Note: Proposed Impervious Area + Proposed Pervious Area = Area to be Disturbed by the
Project.
This may be less than the Parcel Area.
Description of Existing Site Cohdition and Drainage Patterns
Current Status of the Site (select all that apply):
Existing development
LI Previously graded but not built out
El Agricultural or other non-impervious use
El Vacant, undeveloped/natural
Description I Additional
Information:
Existing Land Cover Includes (select all that apply):
Vegetative Cover
i• Nan-Vegetated Pervious Areas
l• Impervious Areas
Description /Additional Information:
Underlying Soil belongs to Hydrologic Soil Group (select all that apply):
El NRCS Type A
lZ NRCS Type B
El NRCS Type C
ZI NRCS Type D
Approximate Depth to Groundwater (GW):
El GW Depth < 5 feet
LI 5feet<GWDepth< lOfeet
Eli 10 feet < GW Depth <20 feet
GW Depth > 20 feet
Existing Natural Hydrologic Features (select all that apply):
El Watercourses
LI Seeps
LI Springs
El Wetlands
None
Description / Additional Information:
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 Site is trapezoidal in shape and consists of an existing parcel measuring approximately 220 feet
by 100 feet for a total of 0.49 acres. The subject parcel is located at 2501 State Street and is identified
as Assessor's Parcel Number 155-200-10-00. The project Site is bordered to the east by State
Street, to the south by an existing multi-family residential development, to the west by undeveloped
land and to the north by a commercial office building.
The Site is currently developed with a roughly 5,680 s.f. single story commercial office building, a
roughly 7,750 s.f. asphalt drive and parking lot and various hardscaped and landscaped areas. A 7-
foot high sound wall constructed of mechanically stabilized earth blocks extends across the westerly
property boundary and the westerly 40 feet of the southerly property boundary.
The Site slopes mildly down from the southwest to the northeast, with most of the site being relatively
level at a nominal elevation of El. 36 feet.
Existing drainage conveyance is urban and there are no offsite flows conveyed through the Site.
Runoff from approximately 94% of the Site flows from west to the east to State Street via surface
flow, roof downspouts and a sidewalk underdrain. Area drains capture the flow on portions of the
Site and convey it to a sidewalk underdrain. Once in the gutter of State Street, flow travels to the
northwest, where it enters existing storm drain piping at a curb inlet on the westerly side of State
Street approximately 250 feet northwest of the Site. The storm drain is a 66" pipe that discharges to
Buena Vista Lagoon approximately 80 feet northeast of the curb inlet.
A small portion of the site (approximately 0.03 acres, or 6% of the parcel area) flows to the adjacent
properties to the north and west.
Descriptiol ófPrOposedSite Development and Drainage lRafteens
Project Description / Proposed Land Use and/or Activities:
The proposed project will consist of demolition of all existing improvements at the Site and
construction of 17 residential condominium units in a single structure with three habitable stories
over a partially subterranean covered parking/storage level accessed from State Street.
List/describe proposed impervious features of the project (e.g., buildings, roadways, parking lots,
courtyards, athletic courts, other impervious features):
The majority of the Site will consist of the building structure which will have and overall projected
impervious area of 17,636 square feet. Onsite hardscape areas including exterior concrete stairs,
walks, equipment pads, curbs and walls will total 370 s.f. outside the rooftop footprint, making the
total onsite impervious area 18,530 square feet. The project will also replace existing curb, gutter,
sidewalk and AC pavement totaling approximately 1,925 square feet of replaced impervious surface
along the State Street frontage. Approximately 1,110 square feet of curb, AC driveway and a
concrete trash enclosure in easements on the adjacent property to the north in connection with
replacing existing sewer and water mains, for at total offsite replaced impervious area of 3,035
square feet.
List/describe proposed pervious features of the project (e.g., landscape areas):
Approximately 2,655 square feet of the ground floor of site outside the building footprint will consist
of permeable paver walkways and landscape. The northerly side yard will be a landscaped shallow
swale area that will sheet flow to State Street. Small disconnected landscaped areas and planters
will be located in the front yard area, inclufing a 70 square foot biofiltration planter in the southern
portion of the front yard. The southerly side yard will be paved primarily with a permeable paver
system. An area drain in the depressed lobby entry area at the southeast corner of the Site will drain
to a sump that will discharge to the aforementioned biofiltration planter at the southeast corner of the
Site which will have and underdrain discharging to gutter flow in State Street. This gutter flow in
State Street will then discharge to a tree well located in the right-of-way approximately 45 feet north
of the northerly boundary of the Site.
A total of twelve (12) raised landscaped planters with a combined surface area of 818 square feet
will be located on the second level podium deck of the structure and will function as a biofiltration
planter for treatment of runoff from 16,256 s.f (approximately 90%) of the area of the roof, the
exposed fourth floor walkway and most of the balconies on the 3rd and 41h floors of the structure.
Does the project include grading and changes to site topography?
Yes
El No
Description/ Additional Information:
The overall topography of the Site will not be substantially altered. Most of the ground floor level will
consist of a parking level (covered by the structure) that will have a finished floor elevation about 4
feet below the current nominal finished grade of the Site. The finished grade at the exterior of the
garage level will be roughly at the current grade.
Grading for the project will result in removal of the clayey fill soils from the Site and replacement with
select granular soils, resulting in a change of the effective Hydrologic Soil Group from Group "D" to
Group B".
Does the project include changes to site drainage (e.g., installation of new storm water
conveyance systems)?
Yes
ENo
Description /Additional Information:
The planned development of the Site will not significantly alter the overall drainage pattern, with
essentially all the runoff continuing to discharge to State Street. However, existing discharge to the
adjacent property to the north will be eliminated. Runoff from most of the Site will be captured in
private onsite drainage piping and discharge to an existing storm drain in State Street via a new
storm drain connection. Runoff from a depressed area in the southeastern portion of the Site (near
the planned lobby entrance) will be collected in a sump and discharged at a curb core to gutter flow.
Rain falling on the roof and upper floor balconies of the building will be directed to twelve (12)
biofiltration planters to be constructed on the second floor podium deck and another biofiltration at
the street level in the southeast corner of the Site.
The podium deck planters will have underdrains and risers that will connect to drain piping through
the building to a 10" storm drain pipe that will connect to an existing 66" RCP storm drain in State
Street that discharges to Buena Vista Lagoon at a point located approximately 300 feet from the
point of connection.
The street level biofiltration planter will have an underdrain connected to a sidewalk underdrain that
will discharge to the gutter iin State Street. The gutter flow will be intercepted at an existing curb
inlet located approximately 225' north of the northern site boundary. The existing curb inlet will be
modified by removing an existing debris rack and installing a proposed membrane filter drain insert.
Identify whether any of the following features, activities, and/or pollutant source areas will be
present (select all that apply):
I On-site storm drain inlets
l Interior floor drains and elevator shaft sump pumps
Interior parking garages
Need for future indoor & structural pest control
1 Landscape/Outdoor Pesticide Use
Li Pools, spas, ponds, decorative fountains, and other water features
Li Food service
Refuse areas
LI Irdustrial processes
Li Outdoor storage of equipment or materials
Li Vehicle and Equipment Cleaning
Li Vehicle/Equipment Repair and Maintenance
Li Fuel Dispensing Areas
Li Loading Docks
Fire Sprinkler Test Water
Miscellaneous Drain or Wash Water
II 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):
Runoff from the Site will include:
a small amount of gutter flow in State Street and flows to the northwest, where it enters existing
storm drain piping at a curb inlet on the westerly side of State Street approximately 250 feet
northwest of the Site. The storm drain is a 66" pipe that discharges to Buena Vista Lagoon
approximately 80 feet northeast of the curb inlet.
flows in a 10" storm drain that will connected directly to the 66" storm drain pipe and discharge
to Buena Vista Lagoon
List any 303(d) impaired water bodies within the path of storm water from the project site to the
Pacific Ocean (or bay, lagoon, lake or reservoir, as applicable), identify the pollutant(s)/stressor(s)
causing impairment, and identify any TMDLs for the impaired water
bodies:
303(d) Impaired Water Body Pollutant(s)/Stressor(s) TMDLs
Buena Vista Lagoon Indicator bacteria, nutrients,
sedimentation/siltation
NA
Identification of Project Site Pollutants
Identify pollutants anticipated from the project site based on all proposed use(s) of the site (see
BMP Design Manual Appendix B.6):
Pollutant
Not Applicable to
the Project Site
I
Anticipated from the
Project Site
Also a Receiving
Water Pollutant of
Concern
Sediment V V
Nutrients V V
Heavy Metals V
Organic Compounds V
Trash & Debris V
Oxygen Demanding
Substances V
Oil & Grease V
Bacteria & Viruses V
Pesticides V
HydrornodificationManagenient Requirements
Do hydromodification management requirements apply (see Section 1.6 of the BMP Design
Manual)?
El Yes, hydromodification management flow control structural BMPs required.
El 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.
El 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.
ll 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):
Runoff from the Site to State Street is conveyed by the MS4 to Buena Vista Lagoon, which is
an exempt water body per the Carlsbad WMA WQIP.
CritiàâlCbarsSediñiéiitYiéld Areas*
*T his;", Section only required if hydromodufication management requirements apply
Based on the maps provided within the WMAA, do potential critical coarse sediment yield areas
exist within the project drainage boundaries?
DYes
ll No, No critical coarse sediment yield areas to be protected based on WMAA maps
If yes, have any of the optional analyses presented in Section 6.2 of the BMP Design Manual
been performed?
El 6.2.1 Verification of Geomorphic Landscape Units (GLUs) Onsite
El 6.2.2 Downstream Systems Sensitivity to Coarse Sediment
El 6.2.3 Optional Additional Analysis of Potential Critical Coarse Sediment Yield Areas Onsite
El 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?
El No critical coarse sediment yield areas to be protected based on verification of GLUs
onsite
El Critical coarse sediment yield areas exist but additional analysis has determined
that protection is not required. Documentation attached in Attachment 8 of the
SWQMP.
El Critical coarse sediment yield areas exist and require protection. The project will
implement management measures described in Sections 6.2.4 and 6.2.5 as applicable,
and the areas are identified on the SWQMP Exhibit.
Discussion /Additional Information:
I FIó COntrol fó Pot-PtojetRunofr
'This Section only required if hydromodification management requirements apply.
List and describe point(s) of compliance (POCs) for flow control for hydromodifiction
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.
Not Applicable
Has a geomorphic assessment been performed for the receiving channel(s)?
El No, the low flow threshold is 0.1Q2 (default low flow threshold)
El Yes, the result is the low flow threshold is O.1Q2
El Yes, the result is the low flow threshold is 0.302
El Yes, the result is the low flow threshold is 0.5Q2
If a geomorphic assessment has been performed, provide title, date, and preparer:
Not Applicable
Discussion /Additional Information: (optional)
. Other Site Requirements ndConstraints
When applicable, list other site requirements or constraints that will influence storm water
management design, such as zoning requirements including setbacks and open space, or City
codes governing minimum street width, sidewalk construction, allowable pavement types, and
drainage requirements.
The project is conditioned to replace a sewer main and a water main in easements on the adjacent
property to the north. This will require removal and replacement of approximately 1,100 square feet
of existing impervious surface (driveway, curb and trash enclosure) on the adjacent private property.
Optional Additional Information or Continuation of Previous Sections As Needed
This space provided for additional information or continuation of information from previous
sections as needed.
C"City of
Carlsbad
STANDARD PROJECT
REQUIREMENT
CHECKLIST
E-36
Development Services
Land Development Engineering
1635 Faraday Avenue
(760) 602-2750
www.carlsbadca.gov
Project Information,
Project Name: Ocean Condiminiums
Project ID: CT 16-02 I RP 16-08
DWG No. or Bu Iding Permit No.: 519-5A
Source Control BMPs
All development projects must implement source control BMPs SC-i through SC-6 where applicable and feasible. See
Chapter 4 and Appendix E.1 of the BMP Design Manual (Volume 5 of City Engineering Standards) for information to
implement source control BMPs shown in this checklist.
Answer each category below pursuan to the following.
"Yes" means the project will implement the source control BMP as described in Chapter 4 and/or Appendix E.1 of the
Model BMP Design Manual. Discussion/justification is not required.
'No" means the BMP is applicable to the project but it is not feasible to implement. Discussion/justification must be
provided. Please add attachments if more space is needed.
"N/A' means the BMP is not applicable at the project site because the project does not include the feature that is
addressed by the BMP (e.g., the project has no outdoor materials storage areas). Discussion/justification may be
provided.
Source Control Requirement Applied?
SC-I Prevention of Illicit Discharges into the MS4 El Yes 0 No 0 N/A
Discussion/justification if SC-1 not implemented:
SC-2 Storm Drain Stenciling or Signage 0 Yes 1 Li No 0 N/A
Discussion/justification if SC-2 not implemented:
SC-3 Protect Outdoor Materials Storage Areas from Rainfall Run-On Runoff, and Wind 0 Yes LI No N/A Dispersal
Discussion/justification if SC-3 not implemented:
E-36 Page 1 of 4 Revised 09/16
Source Control Requirement (continued) Applied?
SC-4 Protect Materials Stored in Outdoor Work Areas from Rainfall Run-On Runoff, and
Wind Dispersal DYes ONo MN/A
Discussion/justification if SC-4 not implemented:
SC-5 Protect Trash Storage Areas from Rainfall, Run-On, Runoff, and Wind Dispersal 9 Yes I 0 No 0 N/A
Discussion/justification if SC-5 not implemented:
Trash storage will be in a trash room in the partially subterranean garage lavel of the building that will
be fully protected from rainfall.
SC-6 AdditionEl 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).
lf On-site storm drain inlets E1Yes 0 No LEN/A
Interior floor drains and elevator shaft sump pumps 13'Yes 0 No 0 N/A
1 Interior parking garages I1 Yes 0 No 0 N/A
Need for future indoor & structural pest control Iff Yes 0 No 0 N/A
i Landscape/Outdoor Pesticide Use 11 Yes 0 No 0 N/A
Pools, spas, ponds, decorative fountains, and other water features 0 Yes 0 No 0 N/A
Food service Yes 0 No EJ N/A
I1 Refuse areas R1 Yes 0 No 0 N/A
E] Industrial processes D Yes 0 No 1 N/A
0 Outdoor storage of equipment or materials 0 Yes D No i N/A
0 Veh cle and Equipment Cleaning Yes 0 No EJ N/A
0 Veh cle/Equipment Repair and Maintenance Yes 0 No Rf N/A
El Fuel Dispensing Areas 0 Yes 0 No 1 N/A
0 Loading Docks Yes 0 No N/A
Fire Sprinkler Test Water IYes U No 0 N/A
Miscellaneous Drain or Wash Water EJ Yes 0 No 0 N/A
11 Plazas, sidewalks, and parking lots 0 Yes 0 No 0 N/A
For "Yes" answers, identify the additional BMP per Appendix E.1. Provide justification for "No' answers.
See attached narrative discussion, on next page
E-36 Page 2 of 4 Revised 09/16
Site Design BMPs
All development projects must implement site design BMPs SD-I through SD-8 where applicable and feasible. See
Chapter 4 and Appendix E.2 thru E.6 of the BMP Design Manual (Volume 5 of City Engineering Standards) 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.G of
the Model BMP Design Manual. Discussion /justification is not required.
"No" means the BMPs is applicable to the project but it is not feasible to implement. Discussion/justification must be
provided. Please add attachments if more space is needed.
"N/A" means the BMPs is not applicable at the project site because the project does not include the feature that is
addressed by the BMPs (e.g., the project site has no existing natural areas to conserve). Discussion/justification may be
provided.
Site Design Requirement Applied?
SD-I Maintain Natural Drainage Pathways and Hydrologic Features 0 Yes I 0 No I J N/A
Discussion/justification if SD-1 not implemented:
There are no natural drainage pathway or other hydrologic features at the site.
SD-2 Conserve Natural Areas, Soils, and Vegetation o Yes LI' No 0 N/A
Discussion/justification if SD-2 not implemented:
There is minimal existing vegetation on the Site. Trees along northerly property boundary will need to be removed to
replace a sewer main per the project conditions.
SD-3 Minimize Impervious Area Yes 0 No 0 N/A
Discussion/justification if SD-3 not implemented:
SD-4 Minimize Soil Compaction I El Yes RI No I 0 N/A
Discussion/justification if SD-4 not implemented:
The entire site will be graded to prepare the subgrade for the planned 4-story structure. All fill will need to be compacted to
90% relative compaction to provide suitable bearing capacity as per the project geotechnical recommendations
SD-5 Impervious Area Dispersion I Yes I 0 No I ON/A
Discussion/justification if SD-5 not implemented:
E-36 Page 3 of 4 Revised 09/16
Site Design Requirement (continued) Applied?
SD-6 Runoff Collection EJ Yes I 0 No I 0 N/A
Discussion/justification if SD-6 not implemented:
SD-7 Landscaping with Native or Drought Tolerant Species I l Yes I 0 No I 0 N/A
Discussion/justification if SD-7 not implemented:
SD-8 Harvestng and Using Precipitation 0 Yes I 11 No I 0 N/A
Discussion/justification if SD-8 not implemented:
Demand for harvested water for irrigation and other onsite use is insufficient to make harvesting and use a feasible option.
Use of biofiltration planters on the podium deck will make use of a portion of the runoff for landscape purposes.
E-36 Page 4 of 4 Revised 09/16
NarrativeDiscussióA of Soüre CñtroIBMPS
The following paragraphs summarize source control BMPs associated with the potential pollutant sources
identified under item SC-6 of Form E-36.
Onsite storm drain inlets - There will be a number on onsite area drain inlets including arra drain inlets in
hardscape areas and a channel drain at the base of the drive entrance ramp. All of these locations are indicated
on the grading plans. All of the inlets will be marked with "No Dumping" Flows to Bay" (or similar) stencils,
placards or signs that will be maintained for legibility. Storm water pollution prevention information will be
included on HOA documents and owner information packages.
Interior floor drains and elevator shaft sump pumps- The building will have an elevator. A sump pump
in the elevator shaft will be plumbed to sanitary sewer. The sump pump will be inspected and maintained
regularly to ensure proper operation. The building wall alsdo have an interior floor drain in the trash storage
room as discussed under item "G" below.
Interior parking garages - The partially subterranean garage level of the structure will have a small catch
basin to collect incidental water that will be plumbed to a sand-oil separator (clarifier) beneath the garage floor.
The clarifier will be plumbed to discharge to the storm sewer as directed by City of Carlsbad. The clarifier will
be inspected and maintained regularly to ensure proper operation.
Dl. Need for future indoor & structural pest control - Integrated Pest Management (IMP) information will
be provided to owners, lessees, and operators.
D2. Landscape/Outdoor Pesticide Use - The proposed development will remove all existing trees, shrubs
and ground cover from the Site. The proposed landscaping (except for biofiltration planters) will be designed
to feature drought-tolerant species to minimize irrigation and runoff, to promote surface infiltration where
appropriate, and to minimize the use of fertilizers and pesticides that can contribute to storm water pollution.
Landscape plans for the biofiltration planters will specify plants that are tolerant of periodic saturated soil
conditions. The landscape plan will specify plants that are appropriate to site soils, slopes, climate, sun, wind,
rain, land use, air movement, ecological consistency, and plant interactions and will consider using pest-
resistant plants, especially adjacent to hardscape.
G. Refuse areas - Site refuse and recycled materials will be handled and stored for pickup in an indoor trash
storage room at the covered garage level of the building as shown on the plans. A floor drain in the trash room
will be plumbed to the clarifier below the garage floor. Signs will be posted on or near dumpsters with the
words "Do not dump hazardous materials here" (or similar). The trash storage room will have the required
number of covered receptacles for trash and recycled waste based on occupancy load. The receptacles will be
inspected regularly and replaced of they are found to be leaky. The trash storage room will be cleaned regularly
as part of routine building maintenance. Spill control materials will be available in the storage room.
N. Fire Sprinkler Test Water - Fire sprinkler test water will be drained to the channel drain at the garage
entrance from where it will subsequently be discharged to a biofiltration planter via a sump pump.
0. Miscellaneous Drain or Wash Water - Miscellaneous drain or wash water sources for the project will
include: condensate drain lines; rooftop equipment; a drainage sump, and; roofing, gutters, and trim. All
condensate drain lines from air conditioning units will be plumbed to discharge to landscaped areas and/or
biofiltrarton planters. Other ooftop mounted equipment with potential to produce pollutants shall be roofed
and/or have secondary containment. The drainage sump at the southeast corner of the Site will have a
sediment sump to reduce the quantity of sediment in pumped water and will discharge to a biofiltration planter.
Roofing, gutters, and trim made will not be made of copper or other unprotected metals.
SUMMARY OF PDP STRUCTURAL BMPS
PDP StructuráIBMPs .
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
hydromcdification management can be achieved within the same structural BMP(s).
PDP structural BMPs must be verified by the City at the completion of construction. This may include
requiring the project owner or project owner's representative to certify construction of the structural BMPs
(see Section 1.12 of the BMP Design Manual). PDP structural BMPs must be maintained into perpetuity,
and the City must confirm the maintenance (see Section 7 of the BMP Design Manual).
Use this form to provide narrative description of the general strategy for structural BMP implementation
at the project site in the box below. Then complete the PDP structural BMP summary information sheet
for each structural BMP within the project (copy the BMP summary information page as many times as
needed to provide summary information for each individual structural BMP).
Describe the general strategy for structural BMP implementation at the site. This information must
describe how the steps for selecting and designing storm water pollutant control BMPs presented in
Section 5.1 of the BMP Design Manual were followed, and the results (type of BMPs selected). For
projects requiring hydromodification flow control BMPs, indicate whether pollutant control and flow
control BMPs are integrated together or separate.
The strategy for structural BMP implementation adopted in this plan follows the strategy and general
design ii the plan that was approved as part of the discretionary review of the project.
Self-Retaining DMAs
At the ground level, runoff will primarily be managed by routing to self-retaining areas in the
northerly and southerly side yards.
DMA 01 is a self-retaining area that includes the landscaped rear yard, the landscaped northerly
side yard, the landscaped northeasterly front yard area and a permeable paver walkway in the
northeast portion of the site. Runoff from an isolated rooftop area at the northeast corner of the
structure, a small upper floor balcony area and podium deck patios on the north and west sides of
the structure totaling 1,172 s.f. will discharge to this area. The impervious-to-pervious area ratio of
DMA 01 is 0.78:1.
DMA 02 is a self-retaining area that consists of permeable payers in the southerly side yard, the
ADA ramp in the southerly portion of the front yard and small impervious areas including concrete
stairs and a small portion of the podium deck that will drain to the permeable payers. Isolated areas
of the structure totaling approximately 58 s.f. will also discharge to DMA 02. The impervious-to-
pervious area ratio of DMA 02 is 0.06:1 (based on the ground floor pervious area, some of which is
overhur.g by roof elements)
It is noted that the existing subgrade soils at the site are dominated by clayey fill soils that are
categorized as Hydrologic Group D. The project proposes remedial grading that will remove these
soils and replace them with imported fill that will be Hydrologic Group B soils. The proposed
permeable paver walkways on the southerly portion of the site are considered as a site design BMP
to reduce the DCV. The basement wall for the parking level will be waterproofed to minimize the
potential for water intrusion into the proposed partially subterranean garage-level storage and utility
areas.
[Continued from previous page]
Self-Mitigating DMAs
DMA 03 consists of a small (10 sq. ft.) isolated planter area in the front yard. DMA 04 consists of
a 90 s.f. area of landscape along the southerly property boundary above a retaining wall in the
easterly half of the south side yard.
All landscaped area will be planted with drought tolerant native species that do not require regular
applicaion of fertilizers or pesticides. The soil in these areas will be amended and aerated to
promote water retention characteristics equivalent to undisturbed native soil.
Onsite DMAs Routed to Pollutant Control BMPs
DMA 06 consists of an area of approximately 835 s.f. in the southeastern corner of the Site that
includes PCC and permeable paver pavement in walkways, a roof "eyebrow" detail, exposed upper
floor balconies and approximately 260 s.f. of PCC pavement in the drive entrance outside the
building footprint. The driveway ramp slopes down to the garage level and is contiguous with
another 488 s.f. portion of the drive entrance that is covered (within the building footprint). This
plan proposes to intercept the runoff from the drive entrance ramp in a channel drain at the base of
the ran-p that will discharge to a sump and sump pump from which the water will be discharged to
a biofiltration planter (BIO.09). The planter will have an underdrain that will connect to a sidewalk
underdrain to discharge to the gutter on State Street. This treated discharge will subsequently be
intercepted by a tree well located approximately 45 feet north of the northerly boundary of the
parcel.
DMAs 08 through 15 include all of the impervious rooftop, roof deck and upper floor balconies from
which runoff will be routed to the podium deck biofiltration planters. Lined biofiltration planters have
been specified rather than biofiltration basins based on the limited area outside the building
footprng and on geotechnical conditions. Remedial grading of the site will replace relatively
impermeable and highly expansive site soils with more permeable select fill, which could potentially
make biofiltration basins feasible. However, the geotechnical engineer has opined that while the
recommended import soils may possess favorable infiltration rates with respect to stormwater
BMPs in general, collection and transfer of stormwater runoff to limited areas for concentrated
infiltration in volumes exceeding that which would occur through natural precipitation or controlled
irrigation could result in: a) a perched water and saturated condition at the bottom of the select fill
soils, and; b) vertical and lateral migration of subsurface waters, which could adversely impact
onsite and adjacent offsite improvements through saturation and volume changes in expansive
soils (i.e. expansion and contraction). Based on these considerations, the use of infiltration-based
BMPs (such as infiltration basins) as pollutant control BMPs that are intended to infiltrate
concentrated quantities of stormwater into the underlying soils are not recommended for the Site.
A general routing diagram illustrating how runoff from structure surfaces will be routed to the
biofiltration planters is provided on Exhibit DMA-2. Drainage patterns and the locations of roof area
drama and downdrains that will route the runoff to the planters are also indicated on the exhibit.
Details of how the roof drains will be plumbed are to be provided in the architectural plans.
Discharge from the biofiltration planters will be from perforated PVC underdrain pipes and 6" PVC
risers that will connect to a common 6" rvc pipe mounted on the bottom of the concrete podium
deck (i.e., ceiling of the garage level). The 6" PVC pipe will connect to a proposed 10" PVC storm
drain beneath the northerly side yard that will be connected directly to an existing 66" RCP storm
drain in the State Street right-of-way.
The aforementioned 66" storm drain discharges directly to Buena Vista Lagoon at a point
approximately 300 feet northeast of the Site.
Offsite DMAs
There are two offsite DMAs.
DMA 05 consists of approximately 1,650 square feet of impervious AC pavement, PCC pavement
for sidewalk, the onsite driveway entrance, an offsite driveway entrance (2333 State Street), curb
and gutter, and minor landscaped areas within the public right-of-way that will be replaced along
the project frontage on State Street. Runoff from this area will flow to the north as gutter flow and
will be intercepted by an existing curb inlet with a proposed filter insert (Fl.01) located about 225
feet north of the northerly property boundary.
DMA 07 consists of 2,233 square feet of land that will be disturbed in connection with replacement
of water and sewer mains in public rights of way on the adjacent parcel. The disturbed area in the
easements will include replacement of AC pavement in a driveway, PCC curb and PCC pavement
for an existing trash enclosure. The total of replaced impervious surface in DMA 07 is 1,154 square
feet. The remaining 1,1079 square feet within DMA 07 will be landscaped area above the grade of
the replaced pavement. This DMA consists entirely of land in public easements of private property
owned by others. Based on this and the drainage patters within the DMA it is not feasible to capture
or treat the runoff form DMA 07.
Structural BMP Summary Information
Structural BMP ID No. BIO.OIA
DWG519-5A Sheet No. 5 and 8
Type of structural BMP:
El Retention by harvest and use (HU-l)
El Retention by infiltration basin (INF-I)
LI Retention by bioretention (INF-2)
El Retention by permeable pavement (INF-3)
LI Partial retention by biofiltration with partial retention (PR-1)
Biofiltration (BF-1)
El Flow-thru treatment control included as pre-treatm e nt/fore bay 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)
El Detention pond or vault for hydromodification management
LI Other (describe in discussion section below)
Purpose:
Pollutant control only
El Hydromodification control only
El Combined pollutant control and hydromodification control
El Pre-treatm ent/fore bay for another structural BMP
El Other (describe in discussion section below)
Discussion (as needed):
BI0.01A is a biofiltration planter located on a podium deck patio area adjacent to the northerly side
yard. The planter will have a 6" thick gravel drainage layer (4.5" gravel with 1.5" pea gravel choker
layer) and 18" thick bioretention soil media layer. The planter will have a surface area of 90 square
feet and allow for 6" ponding depth. The total storage (detention) capacity of B10.01A will be 110
cubic feet of water.
The drainage layer will have a 4" perforated PVC pipe underdrain connected to a 6" riser/weir and a
6" PVC discharge pipe that will connect directly to a 10" PVC storm drain pipe beneath the
landscaped northerly side yard. The 10" storm drain line will discharge to an existing 66" RCP storm
drain in State Street.
BI0.01A is intended accept runoff from 2,992 s.f. of of impervious roof/roof deck and exposed upper
floor balcony area in the northeasterly portion of the building.
Structural BMP Summary Information
Structural BMP ID No. BIO.OIB
DWG519-5A Sheet No. 5 and 8
Type of structural BMP:
Li Retention by harvest and use (HU-l)
Li Retention by infiltration basin (lNF-l)
Li Retention by bioretention (INF-2)
Li Retention by permeable pavement (INF-3)
LI Partial retention by biofiltration with partial retention (PR-1)
0 Biofiltration (BF-1)
LI Flow-thru treatment control included as pre-treatm ent/fore bay for an onsite
retention or biofiltration BMP (provide BMP type/description and indicate which
onsite retention or biofiltration BMP it serves in discussion section below)
Li Detention pond or vault for hydromodification management
Li Other (describe in discussion section below)
Purpose:
II Pollutant control only
Li Hydromodification control only
Li Combined pollutant control and hydromodification control
Li Pre-treatment/forebay for another. structural BMP
Li Other (describe in discussion section below)
Discussion (as needed):
13I0.01 B is a small biofiltration planter located on a podium deck patio area adjacent to the northerly
side yard. The planter will have a 6" thick gravel drainage layer (4.5" gravel with 1.5" pea gravel
choker layer) and 18" thick bioretention soil media layer. The planter will have a surface area of 18
square feet and allow for 6" ponding depth. The total storage (detention) capacity of 1310.01 B will be
22 cubic feet of water.
The drainage layer will have a 4" perforated PVC pipe underdrain connected to a 6" riser/weir and a
6" PVC discharge pipe that will connect directly to a 10" PVC storm drain pipe beneath the
landscaped northerly side yard. The 10" storm drain line will discharge to an existing 66" RCP storm
drain in State Street.
1310.01 B is intended accept runoff from 286 s.f. of of impervious roof and upper floor balcony area in
the north-central portion of the building.
StructuraI BMP Summary. Information
' ., • .
Structural BMP ID No. BIO.OIC
DWG519-5A Sheet No. 5 and 8
Type of structural BMP:
El Retention by harvest and use (HU-1)
El Retention by infiltration basin (INF-1)
El Retention by bioretention (INF-2)
El Retention by permeable pavement (INF-3)
El Partial retention by biofiltration with partial retention (PR-1)
Biofiltration (BF-1)
El 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)
El Detention pond or vault for hydromodification management
El Other (describe in discussion section below)
Purpose:
Pollutant control only
El Hydromodification control only
El Combined pollutant control and hydromodification control
El Pre-treatment/forebay for another structural BMP
El Other (describe in discussion section below)
Discussion (as needed):
BI0.01C is a small biofiltration planter located on a podium deck patio area adjacent to the northerly
side yard. The planter will have a 6" thick gravel drainage layer (4.5" gravel with 1.5" pea gravel
choker layer) and 18" thick bioretention soil media layer. The planter will have a surface area of 34
square feet and allow for 6" ponding depth. The total storage (detention) capacity of 13I0.01C will be
42 cubic feet of water.
The drainage layer will have a 4" perforated PVC pipe underdrain connected to a 6" riser/weir and a
6" PVC discharge pipe that will connect directly to a 10" PVC storm drain pipe beneath the
landscaped northerly side yard. The 10" storm drain line will discharge to an existing 66" RCP storm
drain in State Street.
B10.01C is intended accept runoff from 725 s.f. of of impervious roof and upper floor balcony area in
the north-central portion of the building.
Structural BMP Summary Information
Structural BMP ID No. 1310.011)
DWG519-5A Sheet No. 5 and 8
Type of structural BMP:
LI Retention by harvest and use (HU-I)
LI Retention by infiltration basin (INF-1)
LI Retention by bioretention (INF-2)
LI Retention by permeable pavement (INF-3)
LI Partial retention by biofiltration with partial retention (PR-1)
FZ Biofiltration (BF-1)
LI Flow-thru treatment control included as pre-treatm e nt/fore bay for an onsite
retention or biofiltration BMP (provide BMP type/description and indicate which
onsite retention or biofiltration BMP it serves in discussion section below)
LI Detention pond or vault for hydromodification management
LI Other (describe in discussion section below)
Purpose:
ZI Pollutant control only
LI Hydromodification control only
LI Combined pollutant control and hydromodification control
LI Pre-treatment/forebay for another structural BMP
LI Other (describe in discussion section below)
Discussion (as needed):
BIO.01 D is a biofiltration planter located on a patio area at the northwest corner opf the podium deck
level of the building. The planter will have a 6" thick gravel drainage layer (4.5" gravel with 1.5" pea
gravel choker layer) and 18" thick bioretention soil media layer. The planter will have a surface area
of 94 square feet and allow for 6" ponding depth. The total storage (detention) capacity of 13I0.01 D
will be 115 cubic feet of water.
The drainage layer will have a 4" perforated PVC pipe underdrain connected to a 6" riser/weir and a
6" PVC discharge pipe that will connect directly to a 10" PVC storm drain pipe beneath the
landscaped northerly side yard. The 10" storm drain line will discharge to an existing 66" RCP storm
drain in State Street.
BIO.01D is intended accept runoff from 2,774 s.f. of of impervious roof and upper floor balcony area
in the northwestern portion of the building.
Structural BMP Summary Information
Structural BMP ID No. 13I0.02
DWG519-5A Sheet No. 8
Type of structural BMP:
LI Retention by harvest and use (HU-1)
LI Retention by infiltration basin (INF-1)
LI Retention by bioretention (INF-2)
LI Retention by permeable pavement (INF-3)
LI Partial retention by biofiltration with partial retention (PR-1)
Biofiltration (BF-1)
LI Flow-thru treatment control included as pre-treatment/forebay for an onsite
retention or biofiltration BMP (provide BMP type/description and indicate which
onsite retention or biofiltration BMP it serves in discussion section below)
LI Detention pond or vault for hydromodification management
LI Other (describe in discussion section below)
Purpose:
II Pollutant control only
LI Hydromodification control only
LI Combined pollutant control and hydromodification control
LI Pre-treatment/forebay for another structural BMP
LI Other (describe in discussion section below)
Discussion (as needed):
13I0.02 is a biofiltration planter on the south-central edge of 2nd story concrete podium deck. The
facility will have a 6" thick gravel drainage layer, 2" thick choker course and 18" thick bioretention soil
media layer. The planter will have a surface area of 216 square feet and allow for a 10" ponding
depth. The total storage (detention) capacity of 13I0.02 will be 351 cubic feet of water.
The drainage layer will have a 4" perforated PVC pipe underdrain connected to a 6" riser/weir and a
6" PVC discharge pipe that will connect to a 6" PVC collector pipe mounted on the bottom of the
podium deck (ceiling of garage level). The collector pipe will connect to a 10" PVC storm drain pipe
beneath the landscaped northerly side yard that will discharge to an existing 66" RCP storm drain in
State Street.
1310.02 is intended accept runoff from 763 s.f. of of impervious surfaces including rooftops of two
stairwell/elevator penthouses on the southeast and southwest portions of the roof and concrete
walkways on the south-central portion of the fourth floor that are open to the sky.
13I0.02 is significantly oversized with respect to the DCV required for pollutant control and will provide
detention volume to reduce the peak discharge from the proposed site development for the 100-year
storm event to less than existing peak discharge.
Structural BMP Summary Information
Structural BMP ID No. 13I0.03
DWG519-5A Sheet No. 8
Type of structural BMP:
Li Retention by harvest and use (HU-1)
Li Retention by infiltration basin (INF-1)
Li Retention by bioretention (INF-2)
Li Retention by permeable pavement (INF-3)
Li Partial retention by biofiltration with partial retention (PR-1)
I Biofiltration (BF-1)
Li Flow-thru treatment control included as pre-treatm e nt/fore bay for an onsite
retention or biofiltration BMP (provide BMP type/description and indicate which
onsite retention or biofiltration BMP it serves in discussion section below)
Li Detention pond or vault for hydromodification management
Li Other (describe in discussion section below)
Purpose:
Pollutant control only
Li Hydromodification control only
Li Combined pollutant control and hydromodification control
Li Pre-treatment/fore bay for another structural BMP
Li Other (describe in discussion section below)
Discussion (as needed):
13I0.03 is a biofiltration planter on south-central portion of the 2nd story concrete podium deck. The
facility will have a 6" thick gravel drainage layer (4.5" of 3/4' gravel and 1.5" of 3/8" choker course)
and 18" thick bioretention soil media layer. The planter will have a surface area of 101 square feet
and allow for a 6" ponding depth. The total storage (detention) capacity of BIO.03 will be 124 cubic
feet of water.
The drainage layer will have a 4" perforated PVC pipe underdrain connected to a 6" riser/weir and a
6" PVC discharge pipe that will connect to a 6" PVC collector pipe mounted on the bottom of the
podium deck (ceiling of garage level). The collector pipe will connect to a 10" PVC storm drain pipe
beneath the landscaped northerly side yard that will discharge to an existing 66" RCP storm drain in
State Street.
BlO.03 is intended accept runoff from 1,612 s.f. of impervious surface on the south-central portion
roof deck and concrete walkways on the fourth floor that are open to the sky.
Structural BMP Summary Information
Structural BMP ID No. 113I0.04
DWG519-5A Sheet No. 8
Type of structural BMP:
Li Retention by harvest and use (HU-1)
liii Retention by infiltration basin (INF-l)
Li Retention by bioretention (INF-2)
Li Retention by permeable pavement (INF-3)
Li Partial retention by biofiltration with partial retention (PR-1)
FX1 Biofiltration (BF-1)
Li Flow-thru treatment control included as pre-treatm e nt/fore bay for an onsite
retention or biofiltration BMP (provide BMP type/description and indicate which
onsite retention or biofiltration BMP it serves in discussion section below)
Li Detention pond or vault for hydromodification management
Li Other (describe in discussion section below)
Purpose:
J Pollutant control only
Li Hydromodification control only
Li Combined pollutant control and hydromodification control
Li Pre-treatment/forebay for another structural BMP
Li Other (describe in discussion section below)
Discussion (as needed):
BIO.04 is a biofiltration planter on the southeastern portion of the 2nd story concrete podium deck.
The facility will have a 6" thick gravel drainage layer (4.5" of %" gravel and 1.5" of 3/8" choker course)
and 18" thick bioretention soil media layer. The planter will have a surface area of 92 square feet
and allow for a 6" ponding depth. The total storage (detention) capacity of 1310.04 will be 113 cubic
feet of water.
The drainage layer will have a 4" perforated PVC pipe underdrain connected to a 6" riser/weir and a
6" PVC discharge pipe that will connect to a 6" PVC collector pipe mounted on the bottom of the
podium deck (ceiling of garage level). The collector pipe will connect to a 10" PVC storm drain pipe
beneath the landscaped northerly side yard that will discharge to an existing 66" RCP storm drain in
State Street.
BIO.04 is intended accept runoff from 3,030 s.f. of impervious roof/roof deck surface.
Structural BNIP Summary Information
Structural BMP ID No. B10.05
DWG519-5A Sheet No. 8
Type of structural BMP:
Li Retention by harvest and use (HU-I)
Li Retention by infiltration basin (INF-l)
Li Retention by bioretention (INF-2)
Li Retention by permeable pavement (lNF-3)
LI Partial retention by biofiltration with partial retention (PR-1)
Biofiltration (BF-1)
Li Flow-thru treatment control included as pre-treatm ent/fore bay for an onsite
retention or biofiltration BMP (provide BMP type/description and indicate which
onsite retention or biofiltration BMP it serves in discussion section below)
Li Detention pond or vault for hydromodification management
Li Other (describe in discussion section below)
Purpose:
Z Pollutant control only
Li Hydromodification control only
Li Combined pollutant control and hydromodification control
Li Pre-treatment/fore bay for another structural BMP
Li Other (describe in discussion section below)
Discussion (as needed):
BIO.05 is a biofiltration planter in the south-central portion of the 2nd story concrete podium deck.
The facility will have a 6" thick gravel drainage layer (4.5" of %" gravel and 1.5" of 3/8" choker course)
and 18" thick bioretention soil media layer. The planter will have a surface area of 77 square feet
and allow for a 6" ponding depth. The total storage (detention) capacity of BIO.05 will be 94 cubic
feet of water.
The drainage layer will have a 4" perforated PVC pipe underdrain connected to a 6" riser/weir and a
6" PVC discharge pipe that will connect to a 6" PVC collector pipe mounted on the bottom of the
podium deck (ceiling of garage level). The collector pipe will connect to a 10" PVC storm drain pipe
beneath the landscaped nor.herly side yard that will discharge to an existing 66" RCP storm drain in
State Street.
BIO.05 is intended accept runoff from 1,755 s.f. of impervious roof/roof deck surface on the north-
central portion of the building.
Structural BMP Summary Information
.
. . .
Structural BMP ID No. 1310.06
DWG519-5A Sheet No. 8
Type of structural BMP:
LI Retention by harvest and use (HU-I)
LI Retention by infiltration basin (INF-I)
LI Retention by bioretention (lNF-2)
LI Retention by permeable pavement (INF-3)
LI Partial retention by biofiltration with partial retention (PR-1)
Biofiltration (BF-1)
LI Flow-thru treatment control included as pre-treatment/forebay for an onsite
retention or biofiltration BMP (provide BMP type/description and indicate which
onsite retention or biofiltration BMP it serves in discussion section below)
LI Detention pond or vault for hydromodification management
LI Other (describe in discussion section below)
Purpose:
Xl Pollutant control only
LI Hydromodification control only
LI Combined pollutant control and hydromodification control
LI Pre-treatment/forebay for another structural BMP
LI Other (describe in discussion section below)
Discussion (as needed):
1310.06 is a small biofiltration planter on the south-central portion of the 2nd story concrete podium
deck. The facility will have a 6" thick gravel drainage layer (4.5" of 3/4 gravel and 1.5" of 3/8" choker
course) and 18" thick bioretention soil media layer. The planter will have a surface area of 16 square
feet and allow for a 6" ponding depth. The total storage (detention) capacity of B10.06 will be 20
cubic feet of water.
The drainage layer will have a 4" perforated PVC pipe underdrain connected to a 6" riser/weir and a
6" PVC discharge pipe that will connect to a 6" PVC collector pipe mounted on the bottom of the
podium deck (ceiling of garage level). The collector pipe will connect to a 10" PVC storm drain pipe
beneath the landscaped northerly side yard that will discharge to an existing 66" RCP storm drain in
State Street.
B10.06 is intended accept runoff from 515 s.f. of impervious roof/roof deck surface in the
southwestern portion of the building.
I
I
I
I
Structural BMP Summary. Information
Structural BMP ID No. 13I0.07
DWG 519-5A Sheet No. 8
Type of structural BMP:
L] Retention by harvest and use (HU-1)
Li Retention by infiltration basin (INF-I)
LI Retention by bioretention (lNF-2)
Li Retention by permeable pavement (INF-3)
Li Partial retention by biofiltration with partial retention (PR-1)
Biofiltration (BF-1)
Li Flow-thru treatment control included as pre-treatment/forebay for an onsite
retention or biofiltration BMP (provide BMP type/description and indicate which
onsite retention or biofiltration BMP it serves in discussion section below)
Li Detention pond or vault for hydromodification management
Li Other (describe in discussion section below)
Purpose:
Pollutant control only
Li Hydromodification control only
Li Combined pollutant control and hydromodification control
Li Pre-treatment/forebay for another structural BMP
Li Other (describe in discussion section below)
Discussion (as needed):
1310.07 is a small biofiltration planter on the west-central portion of the 2nd story concrete podium
deck. The facility will have a 6" thick gravel drainage layer (4.5" of 3/4" gravel and 1.5" of 3/8" choker
course) and 18" thick bioretention soil media layer. The planter will have a surface area of 56 square
feet and allow for a 6" ponding depth. The total storage (detention) capacity of 1310.07 will be 69
cubic feet of water.
The drainage layer will have a 4" perforated PVC pipe underdrain connected to a 6" riser/weir and a
6" PVC discharge pipe that will connect to a 6" PVC collector pipe mounted on the bottom of the
podium deck (ceiling of garage level). The collector pipe will connect to a 10" PVC storm drain pipe
beneath the landscaped northerly side yard that will discharge to an existing 66" RCP storm drain in
State Street.
1310.07 is intended accept runoff from 1,863 s.f. of impervious roof/roof deck surface on the
southwestern portion of the building and a small portion of the exposed 4th story walkway.
Structural BNIP Summary Information
Structural BMP ID No. 810.08
DWG 519-5A Sheet No. 8
Type of structural BMP:
Li Retention by harvest and use (HU-1)
Li Retention by infiltration basin (INF-1)
Li Retention by bioretention (lNF-2)
Li Retention by permeable pavement (INF-3)
Li Partial retention by biofiltration with partial retention (PR-1)
Zi Biofiltration (BF-1)
Li Flow-thru treatment control included as pre-treatm e nt/fore bay for an onsite
retention or biofiltration BMP (provide BMP type/description and indicate which
onsite retention or biofiltration BMP it serves in discussion section below)
Li Detention pond or vault for hydromodification management
Li Other (describe in discussion section below)
Purpose:
Pollutant control only
Li Hydromodification control only
Li Combined pollutant control and hydromodification control
Li Pre-treatment/forebay for another structural BMP
Li Other (describe in discussion section below)
Discussion (as needed):
13I0.08 is a small biofiltration planter on the west-central portion of the 2nd story concrete podium deck. The facility will have a 6" thick gravel drainage layer (4.5" of 3/4 gravel and 1.5" of 3/8" choker
course) and 18" thick bioretention soil media layer. The planter will have a surface area of 24 square
feet and allow for a 6" ponding depth. The total storage (detention) capacity of BlO.07 will be 29
cubic feet of water.
The drainage layer will have a 4" perforated PVC pipe underdrain connected to a 6" riser/weir and a
6" PVC discharge pipe that will connect to a 6" PVC collector pipe mounted on the bottom of the
podium deck (ceiling of garage level). The collector pipe will connect to a 10" PVC storm drain pipe
beneath the landscaped northerly side yard that will discharge to an existing 66" RCP storm drain in
State Street.
BlO.08 is intended accept runoff from 180 s.f. of impervious surface on a small portion of the exposed
4th story walkway.
Structural BMP Summary Information
Structural BMP ID No. 131009
DWG519-5A Sheet No. 5 and 8
Type of structural BMP:
E Retention by harvest and use (HU-l)
E Retention by infiltration basin (INF-I)
III Retention by bioretention (lNF-2)
LI Retention by permeable pavement (INF-3)
LI Partial retention by biofiltration with partial retention (PR-1)
l Biofiltration (BF-1)
LI Flow-thru treatment control included as pre-treatment/forebay for an onsite
retention or biofiltration BMP (provide BMP type/description and indicate which
onsite retention or biofiltration BMP it serves in discussion section below)
LI Detention pond or vault for hydromodification management
LI Other (describe in discussion section below)
Purpose:
Pollutant control only
LI Hydromodification control only
LI Combined pollutant control and hydromodification control
LI Pre-treatment/forebay for another structural BMP
LI Other (describe in discussion section below)
Discussion (as needed):
13I0.09 is a biofiltration planter at street level in the southeastern corner of the Site. The facility will
have a 6" thick gravel drainage layer (4.5" of %" gravel and 1.5" of 3/8" choker course) and 18" thick
bioretention soil media layer. The planter will have a surface area of 70 square feet and allow for a
6" ponding depth. The total storage (detention) capacity of BI0.09 will be 86 cubic feet of water.
The drainage layer will have a 4" perforated PVC pipe underdrain connected to a 6" riser/weir and a
3" PVC discharge pipe that will connect to sidewalk underdrain (per SDRSD D-27) that will discharge
to the gutter in State Street.
B10.09 is intended accept runoff from 557 s.f. of impervious surface on upper level balconies and a
"eyebrow" roof detail at the southeast corner of the building.
-
Structural BMP Summary Information
Structural BMP ID No. FI.01
DWG519-5 Sheet No. 3
Type of structural BMP:
LI Retention by harvest and use (HU-1)
LI Retention by infiltration basin (lNF-1)
LI Retention by bioretention (INF-2)
LI Retention by permeable pavement (INF-3)
LI Partial retention by biofiltration with partial retention (PR-1)
LI Biofiltration (BF-1)
LI Flow-thru treatment control included as pre-treatment/forebay for an onsite
retention or biofiltration BMP (provide BMP type/description and indicate which
onsite retention or biofiltration BMP it serves in discussion section below)
LI Detention pond or vault for hydromodification management
Xi Other (describe in discussion section below)
Purpose:
M Pollutant control only
LI Hydromodification control only
LI Combined pollutant control and hydromodification control -
LI Pre-freatment/forebay for another structural BMP
LI Other (describe in discussion section below)
Discussion (as needed):
FI.01 is a media filter insert to be installed in an existing Type B curb inlet located in the right-of-way
approximately 225 feet north of the northerly property boundary. The proposed filter is a Bio Clean
Curb Inlet Filter consisting of an insertable curb inlet basin filter system designed to capture fine to
coarse sediments, floatable trash, debris, and other pollutants conveyed in stormwater runoff. The
proposed filter system is the Kraken type media filter insert. The Kraken filter cartridges are
removable and reusable after spray cleaning with a typical garden hose. The system woth the media
filter cartridges addresses a wide array of pollutants including trash and debris, sediments, TSS,
nutrients, metals, and hydrocarbonsn (Sediment and nutrients are pollutants of concern for the
receiving waters).
The expandable trough system is designed to convey water quality design flows through the filter
basket while allowing peak flows to bypass over the trough without resuspending captured pollutants.
F1.01 is intended accept runoff from approximately 1,650 s.f. of replaced impervious AC and PCC
pavement and minor landscaped areas in the right-of-way along the project frontage of State Street.
It is noted that a planned sump at the lobby entrance will discharge flow from a channel drain at the
drive entrance (DMA 06) and possible underilow from the permeable paver walkway in the southerly
side yard (DMA 02) to a biofiltration planter (13I0.09) that will in turn discharge to the State Street
gutter via a sidewalk underdrain. Although discharge from the biofiltration planter will be intercepted
by the curb inlet with the proposed filter inset. Even though discharge from the sump/biofiltration
planter will consist of treated runoff that will also arrive at the curb inlet following the "first flush" from
a storm event, it was considered in sizing calculations for FI.01.
The proposed filter insert has a media treatmet flow capacity of 0.11 cfs and unlimited bypass flow
capacity. The calculated design flow for the Site DMA's discharging to the inlet is 0.01 cfs.
ATTACHMENT I
BACKUP FOR PDP POLLUTANT CONTROL BMPS
This is the cover sheet for Attachment 1.
Check which Items are Included behind this cover sheet:
Attachment Contents Checklist Sequence Attachment 1 DMA Exhibit (Required) 0 Included
See DMA Exhibit Checklist on the back
of this Attachment cover sheet.
(24"x36" Exhibit typically required)
Attachment lb Tabular Summary of DMAs Showing 0 Included on DMA Exhibit in
DMA ID matching DMA Exhibit, DMA Attachment la Area, and DMA Type (Required)* LI Included as Attachment ib,
separate from DMA Exhibit
*Provide table in this Attachment OR
on DMA Exhibit in Attachment 1 a
Attachment lc Form 1-7, Harvest and Use Feasibility Z Included
Screening Checklist (Required unless E Not included because the entire the entire project will use infiltration project will use infiltration BMPs BMPs)
Refer to Appendix B.3-1 of the BMP
Design Manual to complete Form 1-7.
Attachment ld Form 1-8, Categorization of Infiltration 0 Included
Feasibility Condition (Required unless Z Not included because the the project will use harvest and use entire project will use harvest BMPs) and use BMPs
Refer to Appendices C and D of the
BMP Design Manual to complete Form
Attachment le Pollutant Control BMP Design Z Included
Worksheets / 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 DMA Exhibit must identify:
Underlying hydrologic soil group
Approximate depth to groundwater
Existing natural hydrologic features (watercourses, seeps, springs, wetlands)
IZI Critical coarse sediment yield areas to be protected (if present)
Existing topography and impervious areas
IZI Existing and proposed site drainage network and connections to drainage offsite
IZI Proposed grading
Z Proposed impervious features
ZI Proposed design features and surface treatments used to minimize imperviousness
Drainage management area (DMA) boundaries, DMA ID numbers, and DMA areas
(squarefootage or acreage), and DMA type (i.e., drains to BMP, self-retaining, or self-
mitigating)
ZI Structural BMPs (identify location and type of BMP)
tug ft
I. Is there a demand for harvested water (check all that apply) at the project site that is reliably present during the wet season?
[J Toilet and urinal flushing
[i Landscape irrigation
U Other:_____________
If there is a demand; estimate the anticipated average wet season demand over a period of 36 hours. Guidance for planning level
demand calculations for toilet/urinal flushing and landscape irrigation is provided in Section B.3.2.
[Provide a summary of calculations here]
SEE ATTACHED CALCULATIONS
Calculate the DCV using worksheet B.2-1. DCV = 876 (cubic feet)
3a. Is the 36 hour demand greater than 3b. Is the 36 hour demand greater than 3c. Is the 36 hour demand less than
or equal to the DCV? 0.25DCV but less than the full DCV? 0.25DC17?
o Yes / Il No 0 Yes / il No Il Yes
Harvest and use appears to be feasible. Harvest and use may be feasible. Conduct Harvest and use is considered to be
Conduct more detailed evaluation and more detailed evaluation and sizing infeasible.
sizing calcuations to confirm that calculations to determine feasibility. Harvest
DCV can b2 used at an adequate rate and use may only be able to be used for a
to meet drawdown criteria, portion of the site, or (optionally) the storage
may need to be upsized to meet long term
capture targets while draining in longer than
• 36 hours.
Is harvest and use feasible based on further evaluation?
0 Yes, refer to Appendix E to select and size harvest and use BMPs.
No, select alternate MIN.
Project Name
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Client Name. i'7 ,p Prepared by: C GeocienlnetimgCnsullii1s
Date: 6 Checked by: Page / of / pages
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Part 1- Full Infiltration Feasibility Screening Criteria
Would infiltration of the full design volume be feasible from a physical perspective without any undesirable
consequences that cannot be reasonably mitigated?
Criteria Screening Question Yes No
Is the estimated reliable infiltration rate below proposed
facility locations greater than 0.5 inches per hour? The response
1 to this Screening Question shall be based on a comprehensive
evaluation of the factors presented in Appendix C.2 and Appendix
D.
Provide basis:
Existing soils at site include undocumented fill composed of clay soils with very high
expansion potential and very low infiltration rates (<0.1 in/hr). With proposed remedial
grading, imported soil may be specified that will provide an infiltration rate of more than
0.25 in./hr. Import soil will need to be tested to verify the design infiltration rate.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
SEE ATTACHED NARRATIVE DISCUSSION AND EXCERPTS FROM GEOTECHNICAL REPORT.
Can infiltration greater than 0.5 inches per hour be allowed
without increasing risk of geotechnical hazards (slope stability,
2 groundwater mounding, utilities, or other factors) that cannot
be mitigated to an acceptable level? The response to this
Screening Question shall be based on a comprehensive evaluation of
the factors presented in Appendix C.2.
Provide basis:
With remedial grading, expansive soils will remain offsite, including beneath combination
retaining/site wall footings along southerly boundary. Infiltration-based BMPs would create
an unacceptable risk of damage to adjacent improvements unless lateral infiltration is
prevented.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
SEE ATTACHED NARRATIVE DISCUSSION AND EXCERPTS FROM GEOTECHNICAL REPORT.
Cnteri Screening Question Yes No a
Can infiltration greater than 0.5 inches per hour be allowed
without increasing risk of groundwater contamination (shallow
water table, storm water pollutants or other factors) that cannot
be mitigated to an acceptable level? The response to this
- Screening Question shall be based on a comprehensive evaluation of
the factors presented in Appendix C.3.
Provide basis:
Groundwater is more than 20 feet deep. No beneficial use of groundwater
Summarize findings of studies, provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
SEE ATTACHED NARRATIVE DISCUSSION AND EXCERPTS FROM GEOTECHNICAL REPORT.
Can infiltration greater than 0.5 inches per hour be allowed
without causing potential water balance issues such as change
of seasonality of ephemeral streams or increased discharge of
contaminated groundwater to surface waters? The response to
this Screening Question shall be based on a comprehensive
evaluation of the factors presented in Appendix C.3.
Provide basis:
No nearby ephemeral streams and no known groundwater contamination at or immediately
adjacent to the site
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
SEE ATTACHED NARRATIVE DISCUSSION AND EXCERPTS FROM GEOTECHNICAL REPORT.
If all answers to rows 1 - 4 are "Yes" a full infiltration design is potentially feasible.
Part 1 The feasibility screeaing category is Full Infiltration
Result f any answer from row 1-4 is "No", infiltration may be possible to some extent but J
vould not generally be feasible or desirable to achieve a "full infiltration" design!
[Proceed to Part 2
*To be completed using gathered site information and best professional judgment considering the definition of MEP in
the MS4 Permit. Additional testing and/or studies may be required by the City to substantiate findings.
I
Part 2— Partial Infiltration vs. No Infiltration Feasibility Screening Criteria
Would infiltration of water in any appreciable amount be physically feasible without any negative
consequences that cannot be reasonably mitigated?
Criteria Screening Question Yes No
Do soil and geologic conditions allow for infiltration in any
5 appreciable rate or volume? The response to this Screening
Question shall be based on a comprehensive evaluation of the
factors presented in Appendix C.2 and Appendix D.
Provide basis:
Existing soils at site include undocumented fill composed of clay soils with very high
expansion potential and very low infiltration rates (<0.1 in/hr). With proposed remedial
grading to remove existing fill in the upper 10-13' and replacement with imported select fill
meeting specified performance criteria, infiltration of modereate rates and volumes
can be allowed. Imported fill is specified to provide an infiltration rate of more than 0.25
in./hr. Import soil will need to be tested to verify the design infiltration rate.
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.
SEE ATTACHED NARRATIVE DISCUSSION AND EXCERPTS FROM GEOTECHNICAL REPORT.
Can Infiltration in any appreciable quantity be allowed
without increasing risk of geotechnical hazards (slope
6 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 comprehensive
evaluation of the factors presented in Appendix C.2.
Provide basis:
With removal of existing fill in the upper 10-13' and replacement with select fill meeting
specified performance criteria, infiltration of modereate quantity of runoff will not pose risk if
geotechnical hazards.
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.
SEE ATTACHED NARRATIVE DISCUSSION AND EXCERPTS FROM GEOTECHNICAL REPORT.
Criteria Screening Question Yes No
Can Infiltration in any appreciable quantity be allowed
without posing significant risk for groundwater related
concerns (shallow water table, storm water pollutants or other
factors)? The response to this Screening Question shall be based
on a comprehensive evaluation of the factors presented in
Appendix C.3.
Provide basis:
Groundwater is more than 20 feet deep. No beneficial use of groundwater
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.
SEE ATTACHED NARRATIVE DISCUSSION AND EXCERPTS FROM GEOTECHNICAL REPORT.
Can infiltration be allowed without violating downstream
8 water rights? The response to this Screening Question shall be
based on a comprehensive evaluation of the factors presented in
Appendix C.3.
Provide basis:
No nearby ephemeral streams and no known groundwater contamination at or immediately
adjacent to the site
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data sourc applicability and why it was not feasible to mitigate low infiltration rates.
SEE ATTACHED NARRATIVE DISCUSSION AND EXCERPTS FROM GEOTECHNICAL REPORT.
If all answers from row 5-8 are yes then partial infiltration design is potentially feasible.
Part 2 The feasibility screening category is Partial Infiltration.
Result*
i If any answer from row 5-8 s no, then infiltration of any volume is considered to be
infeasible within the drainage area. The feasibility screening category is No Infiltration.
*To be completed using gathered site information and best professional judgment considering the definition of MEP in
the M54 Permit. Additional testhig and/or studies may be required by the City to substantiate findings.
MEMO i n n I I i i ~Ms i bij i I igMyyJ 10CM 1-8 6,0n(
q
M lition
The following narrative discussion is based on informattion from the geotechnical desi'n report prepared
by TGI datedAprll24, 2020. Applicable portions of the report are attached on the following pages.
The subject site is underlain by 5 to 10 feet of undocumented fill composed of highly to very highly
expansive clay fill soils. These existing fine-grained fill materials are categorized as Soil Hydrologic Group
"D" soils with low infiltration rates that are unsuitable for infiltration-based BMPs. The clayey fill soils may
also extend offsite and exist below adjacent properties. The clayey fill soils are underlain by predominately
granular terrace deposits that correlate to Soil Hydrologic Group "B" soils.
TGI has recommended that all the expansive soils be completely removed within the limits of the site and
replaced with select import fill complying with Section 6.3.6 of the Geotechnical Report (TGl, 2020) as
reiterated below.
Any soil that is to be imported for use as structural fill shall meet the following specifications:
Expansion Index < 10
Plasticity Index <5
No Organic Material
Less than 25 percent gravel larger than Xinch
Less than 15 percent rock larger than 2-1/2 inches
No rocks larger than 4 inches
Corrosivity characteristics suitable for the proposed construction materials
Select fill meeting the above requirements can be expected to be categorized as Soil Hydrologic Group
"A" or 'B' soils with infiltration rates in the range of 0.2 to 2 inches/hour or more. Testing of imported fill
shall be required to verify its conformance with the above specifications and to verify a design infiltration
rate of at least 0.25 inch per hour. Subgrade soils with infiltration rates greater than 0.25 inch/hour are
judged to be suitable for the use of permeable pavements as a site design BMP.
While the recommended import soils can be expected to possess more favorable infiltration rates than
existing fill soils with respect to stormwater BMPs in general, it is TGl's opinion that collection and transfer
of stormwater runoff to limited areas for concentrated infiltration in volumes exceeding what would fall on
the same area through natural precipitation or controlled irrigation could result in the following:
a perched water and saturated condition at the bottom of the select fill soils, and;
vertical and lateral migration of subsurface waters, which could adversely impact onsite and adjacent
offsite improvements through saturation and expansive soil related effects (i.e. expansion and
contraction).
Based on these considerations, the use of infiltration-based BMPs (such as infiltration basins, bioretention
facilities, dry wells or storm water chambers) as pollutant control BMPs that are intended to infiltrate
concentrated quantities of stormwater into the underlying soils are not recommended for the Site. Pollutant
control BMPs at the site should be designed so that water is not allowed to percolate or infiltrate into the
underlying site soils. This would be expected to include fully-lined biofiltration planters.
1impJ!8
However, it is TGI's professional opinion the soil conditions at the Site following remedial grading will be
suitable for low impact development (LID) site design BMPs such as permeable pavements to be utilized to
retain runoff to a level equivalent to pervious ground and act as self-retaining areas.
Summary prepared by: /Of ESS,0
L rry R. Taylor, RC , QS-
Exp. 06/30/2022
GE 2602, Expires 06/30/2022
TGI Project No. 19.00911
2501 State Street, Carlsbad, California
September 20, 2019
Revised February 24, 2020
2 SUBSURFACE INVESTIGATION
2.1 EXPLORATORY BORINGS
The site was explored by TGI on April 8 and 11, 2019 by excavating four exploratory borings. The borings
were advanced to depths between approximately 16.25 and 20 feet using a truck mounted drilling machine
equipped with 8-inch diameter hollow stem augers. The borings were generally located within the footprint
of the planned structure..
All excavation and sampling operations were performed under the supervision of a professional engineer
experienced in the performance of geotechnical field investigations. TGl's on-site personnel visually
classified and logged the materials encountered in the exploratory borings and obtained relatively
undisturbed samples and bulk samples at various depths for observation and laboratory testing. The boring
locations are shown on the enclosed Figure 2a - Plot Plan, and the boring logs are included in Appendix A
of this report. The boring depths and surface elevations are summarized in Table 2.1 below.
Table v Summary Exploratory Borings
Boring No.
Approx. Surface Elevation*
. (feet)
Depth of Boring
(feet)
Bi 34.5 20
B2 35.5 16.25
B3 35.3 20
B4 35.2 20
*Datum: NAVD88.
Drive samples were obtained in the borings at various depths using a 3-inch O.D. by 2.5-inch I.D. ring-lined
Modified California (Mod Cal) split spoon sampler. The sampler was driven using a 140-pound hammer
dropped approximately 30 inches. The hammer system consisted of an automatic trip hammer. Samples
obtained using the Mod Cal sampler were placed in plastic bags and then into 6-inch long PVC tubes. The
ends of the tubes were then capped and taped. Bulk samples from selected depths were placed in plastic
bags.
2.2 EARTH MATERIALS
The field investigation performed by TGI encountered undocumented fill soils underlain by weathered native
soils and Pleistocene age older terrace deposits. These geologic units are described in more detail below,
in order from youngest to oldest.
2.2.1 Fill
ap p roximately- 5 and 107
ct blow the ground surface .jhejill predominantlyconsistsof-sandyto sty clays which arej
6N~~m_brownandTh rownin color, moist firm and occasionally inliide 1ense57
layersandinclusionsof silty iiákIdingphalt, concrete;
- —.1 ,-Abridk',',wood, and-plastic fillils:-
i/JJ Page 14
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I
TGI Project No. 19.00911
I 2501 State Street, Carlsbad, California
September 20, 2019
Revised February 24, 2020
2.2.2 Weathered Native Soils
I Weathered native soils were encountered below the fill soils in all' of the borings performed by TGI.
These soils generally consist of highly weathered terrace deposits and/or residual natural soils.
They were observed to extend to depths between approximately 10 to 13 feet below the ground
I surface.
sands -sands-silts-and clayswhich-are light j
I (gray V, dark gray,41ight browiit67. brOWd'bsionally exhibit yellowishand/6 dfige sfiningj 1. - - W weathered native sofls are generally moist medium dense or firm and predominantly fine
dl -
2.2.3 Older Terrace Deposits
I Older terrace deposits were observed below the weathered native soils at depths between 10 and
13 feet below the ground surface The derterrac&dep6itwere obrtö orii of silt9
jands which are light brown to brown toyery moist and fine to coarse
ciirThe'older terrace deposits are slightly to moderately weathered and occasionally exhibit' I ôfcmentation3 - -
2.3
UNDERGROUND OBSTRUCTIONS
Borings Bi, B2, and B3 performed by TGI encountered a reinforced concrete slab below the surface asphalt
pavement. The concrete slabs were on the order of 6-inches thick. A 4-inch thick concrete slab is also
noted on boring log BA-3 in the geotechnical report by (AGS, 2016).
2.4 GROUNDWATER AND CAVING
Groundwater was not observed in the borings on the Site to a maximum depth of 20 feet below the ground
surface. Based on TGl's experience in the vicinity of the site, groundwater is estimated to be at elevations
on the order of 5 to 10 feet relative to MSL, or approximately 25 to 30 feet below the ground surface.
Seasonal variation of groundwater level may occur, and shallower zones of perched groundwater may
occasionally exist beneath the Site.
Caving of the boreholes could not be directly observed during exploration because the boreholes were
cased during drilling and caving was not possible. However, some of the subsurface soil conditions
encountered during exploration were consistent with those where caving would be more likely to occur in
shallow open excavations. This would include (but may not be limited to) areas where cohesionless sandy
soils are present.
2.5 GEOTECH N ICAL LABORATORY TESTING
Samples that were obtained during the field investigation were transported to TGl's lab for geotechnical
laboratory testing. The laboratory testing program performed for this investigation included tests to evaluate
moistu-e content, dry density, expansion character, shear strength, consolidation, soil resistivity, corrosivity,
and pH. The testing performed is summarized in the following Table 2.2.
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IGI Project No. 19.00911
2501 State Street, Carlsbad, California
September 20, 2019
Revised February 24, 2020
5 CEOTECHNICAL AND CLIMATIC CONSIDERATIONS
5.1 GEOTECHNICAL CONSIDERATIONS
5.1.1 Expansive Soils
Expansive soils pose a significant hazard to foundations for light buildings. Swelling clays derived
from residual soils can exert large uplift pressures which can do considerable damage to lightly-
loaded wood-frame structures. Expansive soils owe their characteristics to the presence of "active"
clay minerals. As they get wet, the clay minerals absorb water molecules and expand; conversely,
as they dry they shrink, leaving large voids in the soil. Swelling clays can control the behavior of
virtually any type of soil if the percentage of clay is more than about 5 percent by weight. Soils with
smectite clay minerals, such as montmorillonite, exhibit the most profound swelling properties.
Expansive soils can damage foundations by uplift as they swell with moisture increases. Swelling
soils lift up and crack lightly-loaded, continuous strip footings, and frequently cause distress in floor
slabs. Because building loads vary on different portions of a structure's foundation, the resultant
uplift will vary in different areas. The exterior corners of a uniformly-loaded rectangular slab
foundation may only exert about one-fourth of the bearing pressure of that exerted at the central
portion of the slab. As a result, the corners tend to be lifted up relative to the central portion. This
phenomenon can be exacerbated by moisture differentials within soils at the edge of the slab. Such
differential movement of the foundation can, in turn, cause distress to the framing of a structure.
Potentially expansive soils can be identified in the lab by their plastic properties. Inorganic clays of
high plasticity, generally those with liquid limits exceeding 50 percent and plasticity index over 30,
usually have high inherent swelling capacity. Expansion of soils can also be measured in the lab
directly, by immersing a remolded soil sample and measuring its volume change.
Laboratory expansion index testing performed by TGI (ASTM D 4829) of the upper undocumented
fill soils encountered in TGI's borings indicates an expansion index (El) between 112 and 192.
Therefore, the soils are in the high to very high expansion category. Similar testing by (AGS, 2016)
indicated an El of 103 (high expansion category).
UBased expansicharaterofthesitesoilstheTecommendationsprovidedhereinare
ided to mitigate the potential effects from expansive soils by removing them from the Site
5.1.2 Collapsible Soils/Hydroconsolidation
Hydroconsolidation, or soil collapse, typically occurs in soils that were recently (e.g., Holocene age)
deposited in and or semi-arid environments. Soils prone to collapse are commonly associated with
poorly-compacted man-made fill, wind-laid sands and silts, and alluvial fan and mudflow sediments
deposited during flash floods. The soil particles may be partially bonded by clay or silt, or chemically
cemented with carbonates. When saturated, collapsible soils undergo a rearrangement of their
grains and the water removes the cohesive (or cementing) material, resulting in often rapid and
substantial settlement. An increase in surface water infiltration from irrigation, infiltration of surface
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TGI Project No. 19.00911
2501 State Street, Carlsbad, California
September 20, 2019
Revised February 24, 2020
I
In the planned location, the permanent shoring wall will also serve as temporary shoring for the
recommended remedial grading activities. It is recommended the wall designer specify the permanent
construction materials that will be utilized for construction of the permanent soldier pile wall. This should
I include considerations for corrosion protection of buried steel and use of suitable permanent wall materials.
I
3EARTFWOR k RECOMMENDATlON'S
The following earthwork recommendations are provided for areas where fill or recompaction will be required
for the project. This is expected to include the area of the proposed condominium structure, as well as
I areas to be finished with exterior concrete flatwork or pavements. Earthwork should be performed in
accordance with the guidelines for earthwork summarized in the following sections and the Earthwork
Guidelines provided in Appendix D of this report.
6.3.1 Demolition, Clearing, and Site Preparation, and Grading
I Demolition should include complete removal of any remaining elements of previous structures,
foundations, concrete slabs, hardscape and underground piping systems. The Site should be
cleared of all surface and subsurface deleterious materials including any pavements, buried utility
I and irrigation lines, fill soils, debris, trees, shrubs, vegetation and associated root systems. All such
materials should be removed from the Site and properly disposed.
I An approximate 6-inch thick reinforced concrete slab should be expected to be encountered during
grading throughout much of the site. The slab was encountered below the asphalt pavement in
three of the borings performed by TGI. It is not known if the slab extends below the existing
- structures on the site. The slab should be completely removed during the grading operation.
6.3.2 Remedial Grading
In order to provide uniform support for the proposed condominium structure, it is recommended the
proposed structure be supported on conventional foundations bearing in a newly placed compacted
fill pad. The proposed floor slab-on-grade may also be supported on the newly placed fill pad. The
recommended fill pad shall be constructed in accordance with the following:
•
u urfaceexploratiorrperformed by
Therneatherednaturalsoilsbelow1he.undocumentedfillshould thflbe:removed -until the
at th bottoiiof tiëexcavationBased on
the subsurface exploration performed by TGI if Fs antiEilFated1h6'.oldenterrace deposits will? be:encountered;atdepsbetweenapproximately1 0-and-13 feet below the ground surface
This would correspond to elevations between approximately 23 and 25 feet relative to MSL.
The subgrade at the bottom of the excavation should be observed and approved by TGI,
then prepared as discussed in Section 6.3.3 below.
The excavated weathered natural soils may then be moisture conditioned and placed as
newly compacted fill in accordance with these earthwork guidelines. All compacted fill
should be compacted to a relative compaction of at least 90 percent as determined by
ASTM D1557.
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TGI Project No. 19.00911
2501 State Street, Carlsbad, California
September 20, 2019
Revised February 24, 2020
Select import soils complying with Section 6.3.6 of this report shall then be placed as
compacted fill up to the proposed subgrade elevation.
The compacted fill pad shall extend laterally beyond the edge of the perimeter foundations
to the property lines, where feasible.
The depth to competent terrace deposits should be expected to vary across the site. The remedial
grading operation and construction of the recommended fill pad should be observed by a
representative of the geotechnical engineer during construction. The bottom of all removals shall
be observed and approved by a representative of the geotechnical engineer. Additional and/or
deeper removals may be necessary in some areas of the site should existing unsuitable soils be
encountered during grading. All compacted fill shall be observed and tested by a representative of
the geotechnical engineer.
All excavations shall be made in general accordance with Section 6.6 of this report. It is anticipated
that the material encountered may be excavated using conventional earthmoving equipment,
however, if concretions or cemented areas are encountered, they could require some heavy ripping.
A bulking factor of 30% should be considered for material handling and stockpiling.
The moisture content in the subgrade shall be maintained during construction to prevent drying of
the soil in areas to be improved.
6.3.3 Subgrade Preparation
Soil exposed at the bottom of excavations to receive structural fill should be scarified to a depth of
at least 6 inches, moisture conditioned and compacted to relative compaction of at least 90 percent
as determined byASTM D1557.
6.3.4 Acceptable Materials for Compacted Fill
lt - . - - isjecommended thexistlng expansive - clay-fiIlsoils underlying-the-site -not -be, re-used as..
- - -- . - cpacted fill Itis recommended these existing clayey fill materials be excavated removed frj'
thete'and pro 'dispJ
The weathered native soils underlying existing fill soils are considered to be satisfactory for re-use
in compacted fill, provided any debris and/or deleterious materials (including roots and organic
materials) are removed prior to placement of compacted fill. Import soils complying with the
requirements of Section 6.3.6 may also be utilized as compacted fill on the Site. Materials larger
than 6 inches in maximum dimension shall not be used in the fill.
6.3.5 Compaction
Structural fill, backfill and subgrade soils should be compacted to a relative compaction of 90
percent or more as determined by ASTM D 1557. Prior to compaction, fill soils should be thoroughly
mixed and moisture conditioned to bring the moisture content to within about 2 percent of the
optimum moisture content and spread in uniform lifts of less than 8 inches (uncompacted
thickness).
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TGI Project No. 19.00911
2501 State Street, Carlsbad, California
September 20, 2019
Revised February 24, 2020
6jedj
Any soil that is to be imported for use as structural fill shall meet the following specifications:
Expansion Index < 10
Plasticity Index < 5
No Organic Material
Less than 25 percent gravel larger than 1/4 inch
Less than 15 percent rock larger than 2-1/2 inches
No rocks larger than 4 inches
Corrosivity characteristics suitable for the proposed construction materials
o
in addition, import soils utilized in the building pad area shall meet the following minimum shear
strength characteristics when compacted to a minimum of 90 percent of the maximum density as
determined byASTM D 1557:
Angle of Internal Friction (phi) = 33 degrees or greater
Cohesion = 50 psf or greater
TGI shall be notified at least four working days in advance of importation in order to sample and
test the proposed import material. No imported materials shall be delivered for use on site without
prior sampling, testing, and evaluation by the geotechnical consultant.
6.3.7 Surface and Subsurface Drainage
Final grading of the site must facilitate positive surface drainage away from foundations to prevent
ponding of water. The minimum slope adjacent to structures should be 2 percent. We recommend
the use of a sealed local area drain system around the perimeter of the structure to facilitate
drainage, if possible. The discharge of downdrains from roof gutters and rooftop deck drains should
be plumbed directly into an area drain system where possible.
It is recognized that project's storm water management requirements and design may be in conflict
with the geotechnical recommendations. If infiltration devices are planned for the site, it is strongly
recommended that site drainage and storm water BMP design should prevent ponding of water,
infiltration, or saturation of soils adjacent to structure footings.
6.3.8 Carlsbad Opportunistic Beach Fill Program (COBFP)
The City of Carlsbad encourages developers who plan to export soils from development sites to
test the potential export soil material and evaluate if the soils are suitable for sand replenishment
at local beaches.
The proposed project will include export of the upper existing undocumented fill soils and import of
select fill soil complying with Section 6.3.6 of this report. Based on the results of TGl's site
exploration and laboratory testing, the soils to be exported would not be suitable for beach
replenishment materials. The export soils are expected to consist of clayey soils, with fines content
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TGl Project No. 19.00911
2501 State Street, Carlsbad, California
September 20, 2019
Revised February 24, 2020
6.8 SEISMIC DESIGN PARAMETERS
The proposed structure should be designed to resist earthquake toads in accordance with the minimum
standards of the 2016 California Building Code (CBC). Seismic design parameters for the Site were
evaluated using the USGS U.S. Seismic Design Maps Tool. Seismic design parameters were calculated
based on the following input parameters:
Site Location: Latitude = 33.164816 °N Longitude = 117.353682 ow
Site Class: D (Stiff Soil)
Seismic Risk Category: I/Il/Ill
Table 6.4 lists mapped, site modified and design spectral response accelerations for 0.2 second and 1
second periods. Program output including MCE, Site Modified and Design Response Spectrum data are
included in Appendix C.
- .. 69STORMjIVATER jAmGATIQN BESLMANAGEM ENT2RACTICES)
The subject site is underlain by 5 to 10 feet of undocumented fill composed of highly to very highly expansive
clay fill soils. These soils may also extend offsite and exist below adjacent properties. As discussed herein,
TGI recommends that all the expansive soils be completely removed within the limits of the site and replaced
with select import fill complying with Section 6.3.6. Select fill meeting the requirements of Section 6.3.6
may be expected to exhibit infiltration rates in the range of 0.25 to 2 inches/hour, whereas the clayey site
soils are judged to have very low infiltration rates that would otherwise be unsuitable for infiltration-based
BMPs.
While the recommended import soils may possess favorable infiltration rates with respect to stormwater
BMPs in general, it is TGI's opinion that collection and transfer of stormwater runoff to limited areas for
concentrated infiltration in volumes exceeding what would fall on the same area through natural precipitation
or controlled irrigation could result in the following:
a perched water and saturated condition at the bottom of the select fill soils, and
vertical and lateral migration of subsurface waters, which could adversely impact onsite and
adjacent offsite improvements through saturation and expansive soil related effects (i.e. expansion
End contraction).
Based on these considerations, the use of infiltration-based BMPs (such as infiltration basins, bioretention
facilities, dry wells or storm water chambers) as pollutant control BMPs that are intended to infiltrate
concentrated quantities of stormwater into the underlying soils are not recommended for the Site. Pollutant
control BMPs at the site should be designed so that water is not allowed to percolate or infiltrate into the
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TGI Project No. 19.00911
2501 State Street, Carlsbad, California
September 20, 2019
Revised February 24, 2020
underlying site soils. This would be expected to include fully-lined biofiltration planters. However, it is TGl's
opinion the soil conditions at the Site following remedial grading will be suitable for low impact development
(LID) site design BMPs (such as permeable payers) used to retain runoff to a level equivalent to pervious
ground and act as self-retaining areas.
Where utilized, permeable paver sections not subject to vehicle traffic should consist of at least 3-inch thick
payers underlain by a minimum of 1-inch clean bedding sand placed above a minimum of 6-inches of open
graded aggregate base. The thickness and gradation of the aggregate base should be specified by the
engineer providing the LID design. It is anticipated the thickness and gradation will be dependent on the
required storage capacity of the LID.
6.10 PLAN REVIEW
TGI should review the final foundation plans, civil plans, shoring plans and specifications to evaluate
conformance with the recommendations presented in this report and to assess whether additional analyses
or recommendations are necessary based on the final design of planned improvements.
Soil and rock are highly variable materials. Subsurface conditions at a given site can vary spatially and can
vary over time. While the geotechnical findings and recommendations presented in this report are based
on interpretation and extrapolation of site-specific subsurface investigation, testing and analysis, it is not
feasible to perform a geotechnical investigation that allows for assessment of all conditions that may be
encountered during construction at any site. Consequently, observation and documentation of conditions
encountered during grading is an integral and critical element of all earthwork projects.
All earthwork associated with this project should be performed under the observation of a qualified
geotechnical engineer and/or geologist from our office to assure that the recommendations presented in
this report are followed, to verify that conditions encountered during construction are consistent with the
design assumptions inherent in TGI's recommendations and to identify the need for any additional or
revised recommendations based on conditions encountered during construction.
At this time, the following geotechnical observations and or tests are recommended during construction:
observation of drilled shoring pile shafts
observation during excavation to the subgrade bottom
observation of lagging installation
observation and approval of exposed subgrades prior to placement of fills
to thë rf6Finance standardjor LID stormwater BMPs per.
observation and testing of all structural fill, including fill placed in the building pad, utility trenches,
and any fill that will support surficial improvements such as exterior flatwork or pavement
observation of retaining wall subdrainage devices
observation and approval of all foundation excavations
observation and testing of base materials
observation of miscellaneous temporary excavations
I
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_ eiix Ij 1RW
Assigned Factor Product (p) Factor Category Factor Description
Weight (w) Value (v) p = w x v
Soil assessment methods 0.25 1 0.25
Predominant soil texture 0.25 1 0.25
Suitability Site soil variability 0.25 2 0.50 A
Depth to groundwater / impervious
Assessment
layer 0.25 1 0.25
Suitability Assessment Safety Factor, SA Ep 1.25
Level of pretreatment! expected
sediment loads 0.5 2 1.00
B Design Redundancy/resiliency 0.25 2 0.50
Compaction during construction 0.25 2 0.50
Design Safety Factor, SB = Ep 2.00
Combined Safety Factor, Stotai= SAX SB 3.25
Observed Infiltration Rate, inch/hr, Kobseed
(corrected for test-specific bias) 0.80
Design Itiflitration Rate, in/hr, Kobserved / StoOl 0.25
Supporting Data
Briefly describe infiltration test and provide reference to test forms:
A minimum infiltration rate of 0.8 inch/hour is specified for near -surface fill soil to be imported to the site following remadial grading. Infiltration rate to be confirmed by laboratory testing of proposed import and field testing of fill following placement. Weighting factors may change based on the amount of testing and geotecj=hnical evaluation of imported fill (soil type(s) and variability).
DESIGN CAPTURE VOLUME WORKSHEET
BMP Identification: BIO.OIA
Description: Biofiltration planter in north side yard
85th percentile 24-hr storm depth from Figure B.1-1 d= 0.58 inches
2 Area tributary to BMP (s) A= 0.061 acre
3 Area weighted runoff factor (estimate using Appendix
B.1.1 and B.2.1)
C= 0.99 unitless
4 Tree wells volume reduction TCV= 0.00 cubic-feet
5 Rain barrels volume reduction RCV= 0.00 cubic-feet
6 Calculate DCV =
(3630 x C x d x A) — TCV - RCV
DCV= 128 cubic-feet
BMP Identification:
[ Description:
BIO.OIB
Biofiltration planter in north side yard
th 85 percentile 24-hr stormdepthfromFigureB.1-1 d= 0.58 inches
2 AreatributarytoBMP(s) A= 0.007 acre
3 Area weighted runoff factor (estimate using Appendix
B.1.1andB.2.1)
C= 1.00 unitless
4 Tree wells volume reduction TCV= 0.00 cubic-feet
5 Rain barrels volume reduction RCV= 0.00 cubic-feet
6 Calculate DCV =
(3630 x C x d x A) - TCV - RC\f
DCV= 14 cubic-feet
BMP Identification:
Description:
BIO.OIC
113iofiltration planter in north side yard
8sh percentile 24-hr storm depth from Figure B.1 -1 d= 0.58 inches
2 Area tributary to BMP (s) A= 0.017 acre
3 Area weighted runoff factor (estimate using Appendix
B.1.1 and B.2.1)
C= 0.99 unitless
4 Tree wells volume reduction TCV= 0.00 cubic-feet
5 Rain barrels volume reduction RCV= 0.00 cubic-feet
6
-
Calculate DCV =
(3630xCxdx A)- TCV -RCV
DCV= 35 cubic-feet
BMP Identification:
Description:
BIO.OID
Biofiltration planter in north side yard
85 th percentile 24-hr storm depth from Figure B.1-1 d= 0.58 inches
2 Area tributary to BMP (s) A= 0.064 acre
3 Area weighted runoff factor (estimate using Appendix
B.1.1 and B.2.1)
0= 1.00 unitless
4 Tree wells volume reduction TCV= 0.00 cubic-feet
5 Rain barrels volume reduction RCV= 0.00 cubic-feet
6
-
Calculate DCV =
(3630 x C x d x A) — TCV - RCV
DCV=
_____
134 cubic-feet
DESIGN CAPTURE VOLUME WORKSHEET
BMP Identification: 13I0.02
Description: Biofiltration planter on podium deck
1 85th percentile 24-hr storm depth from Figure B.1-1 d= 0.58 inches
2 Area tributary to BMP (s) A= 0.023 acre
3 Area weighted runoff factor (estimate using Appendix C= 0.82 unitless
B.1.1 and B.2.1)
4 Tree wells volume reduction TCV= 0.00 cubic-feet
5 Rain barrels volume reduction RCV= 0.00 cubic-feet
6 Calculate DCV = DCV= 39 cubic-feet
-
(3630 x C x d x A) - TCV - RCV
DESIGN CAPTURE VOLUME WORKSHEET
BMP Identification: 13I0.03
Description: Biofiltration planter on podium deck
1 85th percentile 24-hr storm depth from Figure B.1-1 d= 0.58 inches
2 Area tributary to BMP (s) A= 0.039 acre
3 Area weighted runoff factor (estimate using Appendix
B.1.1 and B.2.1)
C= 0.95 unitless
4 Tree wells volume reduction TCV= 0.00 cubic-feet
5 Rain barrels volume reduction RCV= 0,00 cubic-feet
6 Calculate D =
(3630 x C x d x A) - TCV - RCV
DCV= 79 cubic-feet
DESIGN CAPTURE VOLUME WORKSHEET
BMP Identification: 13I0.04
Description: Biofiltration planter on podium deck
77
85 th percentile 24-hr storm depth from Figure B.1-1 d= 0.58 inches
2 Area tributary to BMP (s) A= 0.072 acre
3 Area weighted runoff factor (estimate using Appendix C= 0.98 unitless
B.1.1 and B,2.1)
4 Tree wells volume reduction TCV= 0.00 cubic-feet
5 Rain barrels volume reduction RCV= 0.00 cubic-feet
6 Calculate DCV = DCV= 147 cubic-feet
(3630 x C x d x A) — TCV - RCV
DESIGN CAPTURE VOLUME WORKSHEET
BMP Identification: 13I0.05
Description: Biofiltration planter on podium deck
1 85th percentile 24-hr storm depth from Figure B.1-1 d= 0.58 inches
2 Area tributary to BMP (s) A= 0.042 acre
3 Area weighted runoff factor (estimate using Appendix
B.1.1 and 8.2.1)
C= 0.97 unitless
4 Tree wells volume reduction TCV= 0.00 cubic-feet
5 Rain barrels volume reduction RCV= 0.00 cubic-feet
6
-
Calculate DCV =
(3630 x C x d x A) — TCV - RCV
DCV= 86 cubic-feet
DESIGN CAPTURE VOLUME WORKSHEET
BMP Identification: 13I0.06
Description: Biofiltration planter on podium deck
I 85 th percentile 24-hr storm depth from Figure B.1-1 d= 0.58 inches
2 Area tributary to BMP (s) A= 0.012 acre
3 Area weighted runoff factor (estimate using Appendix
B.1.1 and B.2.1)
C= 0.98 unitless
4 Tree wells volume reduction TCV= 0.00 cubic-feet
5 Rain barrels volume reduction RCV= 0.00 cubic-feet
6 Calculate DCV =
(3630 x C x d x A) — TCV - RCV
DCV= 25 cubic-feet
DESIGN CAPTURE VOLUME WORKSHEET
BMP Identification: 13I0.07
Description: 113iofiltration planter on podium deck
1 --
85th percentile 24-hr storm depth from Figure B.1-1 0.58 inches
2 Area tributary to BMP (s) A= 0.044 acre
3 Area weighted runoff factor (estimate using Appendix C= 0.98 unitless
B.1.1 and B.2.1)
4 Tree wells volume reduction TCV= 0.00 cubic-feet
5 Rain barrels volume reduction RCV= 0.00 cubic-feet
6 Calculate DCV = DCV= 91 cubic-feet
-
(3630 x C x d x A) — TCV - RCV
DESIGN CAPTURE VOLUME WORKSHEET
BMP Identification: 13I0.08
Description: 113iofiltration planter on podium deck
-77
1 85k" percentile 24-hr storm depth from Figure al-i d= 0.58 inches
2 Area tributary to BMP (s) Az 0.005 acre
3 Area weighted runoff factor (estimate using Appendix 0= 0.91 unitless
B.1.1 and B.2.i)
4 Tree wells volume reduction TCV= 0.00 cubic-feet
5 Rain barrels volume reduction RCV= 0.00 cubic-feet
6 Calculate DCV = DCV= 9 cubic-feet
-
(3630 x C x d x A) — TCV - RCV
DESIGN CAPTURE VOLUME WORKSHEET
BMP Identification: 13I0.09
Description: Biofiltration planter at street level
85th percentile 24-hr storm depth from Figure B.1-1 d= 0.58 inches
2 Area tributary to BMP (s) A= 0.015 acre
3 Area weighted runoff factor (estimate using Appendix 0= 0.91 unitless
B.1.1 and 8.2.1)
4 Tree wells volume reduction TCV= 0.00 cubic-feet
5 Rain barrels volume reduction RCV= 0.00 cubic-feet
6 Calculate DCV = DCV= 28 cubic-feet
-
(3630 x C x d x A) — TCV - RCV
FLOW-THRU DESIGN FLOW WORKSHEET
BMP Identification: FI.01
Description: Curb inlet filter insert (media filter type)
1 DCV DCV 114 cubic-feet
2 DCV retained DCVretained 0 cubic-feet
3 DCV biofiltered DCVbiofiltered 0 cubic-feet
4 DCV requiring flow-thru
(Line 1-Line 2 - 0.67 x Line 3)
DCV flow-thru 114 cubic-feet
5 Adjustment factor (Line 4/Line 1:* AF= 1.00 unitless
6 Design rainfall intensity i= 0.20 in/hr
7 Area Tributary to BMP A= 0.08 acres
8 Area-weighted runoff factor C= 0.90 unitless
9 Calculate flow rate - Afx(C x I xA) Q= 0,015 cfs
DMA 02 CONTRIBUTION
1 85th percentile 24-hr storm depth from Figure 13.1-1 d= 0.58 inches
2 Area tributary to BMP (s) A= 0.024 acre
3 Area weighted runoff factor (estimate using Appendix C= 0.24 unitless
4 Tree wells volume reduction TCV= 2.00 cubic-feet
5 Rain barrels volume reduction RCV= 0.00 cubic-feet
6 Calculate DCV = DCV= 10 cubic-feet
DMA 05 CONTRIBUTION
85 th percentile 24-hr storm depth from Figure 13.1-1 d= 0.58 inches
2 Area tributary to BMP (s) A= 0.038 acre
3 Area weighted runoff factor (estimate using Appendix C= 0.95 unitless
4 Tree wells volume reduction TCV= 0.00 cubic-feet
5 Rain barrels volume reduction I RCV= 1 0.00 cubic-feet
6 Calculate DCV I DCV= 1 76 cubic-feet
DMA 06 CONTRIBUTION
85th percentile 24-hr storm depth from Figure B.1-1 d= 0.58 inches
2 Area tributary to BMP (s) A= 0.019 acre
3 Area weighted runoff factor (estimate using Appendix C= 0.70 unitless
4 Tree wells volume reduction TCV= 0.00 cubic-feet
5 Rain barrels volume reduction I RCV= 1 0.00 cubic-feet
6 Calculate DCV = I DCV= 1 28 Icubic4eet
Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs
BMP IDENTIFICATION: BIO.OIA
I I
1 1 Remaining DCV after implementing retention BMPs 128 j cubic-feet
Partial Retention
2 Infiltration rate from Form 1-9 if partial infiltration is feasible in/hr.
3 Allowable drawdown time for aggregate storage below the underdrain 36 hours
4 Depth of runoff that can be infiltrated [Line 2 x Line 3] inches
5 Aggregate pore space 0.40 in/in
6 Required depth of gravel below the underdrain [Line 4/ Line 5] 0 inches
7 Assumed surface area of the biofiltration BMP 90 sq-ft
8 Media retained pore storage 0.1 in/in
9 JVolume retained by BMP [[Line 4 + (Line 12x Line 8)]/12] x Line 7 13.5 cubic-feet
10 1 DCV that requires biofiltration [Line 1 - Line 9] 114.5 cubic-feet
BMP Parameters
11 Surface Ponding [6 inch minimum, 12 inch maximum] 6 inches
12 Media Thickness [18 inches minimum], also add mulch layer thickness to
this line for sizing calculations 18
inches
13 Aggregate Storage above underdrain invert (12 inches typical) - use 0
inches for sizing if the aggregate is not over the entire bottom surface area 6 inches
14 Media available pore space 0.2 in/in
15 Media filtration rate to be used for sizing (5 in/hr. with no outlet control;
if the filtration is controlled by the outlet, use the outlet controlled rate)
5 in/hr.
Baseline Calculations
16 Allowable Routing Time for sizing 6 hours
17 Depth filtered during storm [Line 15 x Line 16] 30 inches
18 Depth of Detention Storage
[Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)] 12 inches
19 Total Depth Treated [Line 17 + Line 18] 42 inches
Option I - Biofilter 1.5 times the DCV
20 Required biofiltered volume [1.5 x Line 10] 172 cubic-feet
21 Required Footprint [Line 20/ Line 19] x 12 49 sq-ft
Option 2 - Store 0.75 of remaining DCV in pores and ponding
22 Required Storage (surface + pores) Volume [0.75 x Line 10]
] 86 cubic-feet
23 Required Footprint [Line 22/ Line 18] x 12 86 sq-ft
Footprint of the BMP
24 Area draining to the BMP 3015 sq-ft
25 Adjusted Runoff Factor for drainage area (Refer to Appendix 13.1 and 13.2) 0.99
26 Minimum BMP Footprint [Line 24 x Line 25 x 0.03] 90 sq-ft
27 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 26) 90 sq-ft
Note: Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to
the required biofiltration footprint (either Line 21 or Line 23)
Worksheet 13.5-1: Simple Sizing Method for Biofiltration BMPs
BMP IDENTIFICATION: BIO.OIB
17
1 Remaining DCV after implementing retention BMPs 1 14 f cubic-feet
Partial Retention
2 Infiltration rate from Form 1-9 if partial infiltration is feasible in/hr.
3 Allowable drawdown time for aggregate storage below the underdrain 36 hours
4 Depth of runoff that can be infiltrated [Line 2 x Line 3] inches
5 Aggregate pore space 0.40 in/in
6 Required depth of gravel below the underdrain [Line 41 Line 51 0 inches
7 Assumed surface area of the biofiltration BMP 18 sq-ft
8 Media retained pore storage 0.1 in/in
9 Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 2.7 cubic-feet
10 DCV that requires biofiltration [Line 1 - Line 9] 11.3 cubic-feet
BMP Parameters
11 Surface Ponding [6 inch minimum, 12 inch maximum] 6 inches
12 Media Thickness [18 inches minimum], also add mulch layer thickness to
this line for sizing calculations 1 8 inches
13
-
Aggregate Storage above underdrain invert (12 inches typical) - use 0
inches for sizing if the aggregate is not over the entire bottom surface area 6 inches
14 Media available pore space 0.2 in/in
15 Media filtration rate to be used for sizing (5 in/hr. with no outlet control;
if the filtration is controlled by the outlet, use the outlet controlled rate)
5 in/hr.
Baseline Calculations
16 Allowable Routing Time for sizing 6 hours
17 Depth filtered during storm [Line 15 x Line 16] 30 inches
18 Depth of Detention Storage
[Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)] 12 inches
19 Total Depth Treated [Line 17 + Line 18] 42 inches
Option I - Biofilter 1.5 times the DCV
20 Required biofiltered volume [1.5x Line 10] 17 cubic-feet
21 Required Footprint [Line 20/ Line 19] x 12 5 sq-ft
Option 2 - Store 0.75 of remaining DCV in pores and ponding
22 Required Storage (surface + pores) Volume [0.75 x Line 10] 8 cubic-feet
23 Required Footprint [Line 22/ Line 18] x 12 8 sq-ft
Footprint of the BMP
24 Area draining to the BMP 286 sq-ft
25 Adjusted Runoff Factor for drainage area (Refer to Appendix 13.1 and 13.2) 1
26 Minimum BMP Footprint [Line 24 x Line 25 x 0.03] 9 sq-ft
27 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 26) 18 sq-ft Note. Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to
the required biofiltration footprint (either Lin9 21 or Line 23)
Worksheet 13.5-1: Simple Sizing Method for Biofiltration BMPs
BMP IDENTIFICATION: BIO.OIC
1 1 I Remaining DCV after implementing retention BMPs 35 cubic-feet
Partial Retention
2 Infiltration rate from Form 1-9 if partial infiltration is feasible in/hr.
3 Allowable drawdown time for aggregate storage below the underdrain 36 hours
4 Depth of runoff that can be infiltrated [Line 2 x Line 31 inches
5 Aggregate pore space 0.40 in/in
6 Required depth of gravel below the underdrain [Line 4/ Line 5] 0 inches
7 Assumed surface area of the biofiltration BMP 34 sq-ft
8 Media retained pore storage 0.1 in/in
9 Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 5.1 cubic-feet
10 DCV that requires biofiltration [Line 1 - Line 9] 29.9 cubic-feet
BMP Parameters
11 Surface Ponding [6 inch minimum, 12 inch maximum] 6 inches
12 Media Thickness [18 inches minimum], also add mulch layer thickness to
this line for sizing calculations 18 inches
13 Aggregate Storage above underdrain invert (12 inches typical) - use 0
inches for sizing if the aggregate is not over the entire bottom surface area 6 inches
14 Media available pore space 0.2 in/in
15 Media filtration rate to be used for sizing (5 in/hr. with no outlet control;
if the filtration is controlled by the outlet, use the outlet controlled rate)
5 in/hr.
Baseline Calculations
16 Allowable Routing Time for sizing 6 hours
17 Depth filtered during storm [Line 15 x Line 16] 30 inches
18 Depth of Detention Storage
[Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)]
12 inches
19 Total Depth Treated [Line 17 + Line 18] 42 inches
Option I - Biofilter 1.5 times the DCV
20 Required biofiltered volume [1.5 x Line 10] 45 L cubic-feet
21 Required Footprint [Line 20/ Line 19] x 12 13 [ sq-ft
Option 2 - Store 0.75 of remaining DCV in pores and ponding
22J Required (surface + pores) Volume [0.75 x Line 10] _Storage 22 cubic-feet
23 Required [Line 22/ Line 18] x 12 _Footprint 22 sq-ft
Footprint of the BMP
24 Area draining to the BMP 737 sq-ft
25 Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and 13.2) 0.99
26 Minimum BMP Footprint [Line 24 x Line 25 x 0.03] 22 sq-ft
27 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 26) 34 sq-ft Note: Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to
the required bio flitration footprint (either Line 21 or Line 23)
Worksheet 13.5-1: Simple Sizing Method for Biofiltration BMPs
BMP IDENTIFICATION: BIO.OID
I,
1 jRemaining DCV after implementing retention BMPs 135 cubic-feet
Partial Retention
2 Infiltration rate from Form 1-9 if partial infiltration is feasible in/hr.
3 Allowable drawdown time for aggregate storage below the underdrain 33 hours
4 Depth of runoff that can be infiltrated [Line 2 x Line 3] inches
5 Aggregate pore space 0.40 in/in
6 Required depth of gravel below the underdrain [Line 41 Line 5] 0 inches
7 Assumed surface area of the biofiltration BMP 94 sq-ft
8 Media retained pore storage 0.1 in/in
9 Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 14,1 cubic-feet
10 DCV that requires biofiltration [Line 1 - Line 9] 120.9 cubic-feet
BMP Parameters
11 Surface Ponding 16 inch minimum, 12 inch maximum] 6 inches
12 Media Thickness [18 inches minimum], also add mulch layer thickness to
this line for sizing calculations 18 inches
13 Aggregate Storage above underdrain invert (12 inches typical) - use 0
inches for sizing if the aggregate is not over the entire bottom surface area 6 inches
14 Media available pore space 0.2 in/in
15 Media filtration rate to be used for sizing (5 in/hr. with no outlet control;
if the filtration is controlled by the outlet, use the outlet controlled rate)
5 in/hr.
Baseline Calculations
16 Allowable Routing Time for sizing 6 hours
17 Depth filtered during storm [Line 15 x Line 16] 30 inches
18 Depth of Detention Storage
[Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)]
12 inches
19 Total Depth Treated [Line 17 + Line 18] 42 inches
Option I - Biofilter 1.5 times the DCV
20 Required biofiltered volume [1.5 x Line 10] 181 cubic-feet
21 Required Footprint [Line 201 Line 19] x 12 52 sq-ft
Option 2 - Store 0.75 of remaining DCV in pores and ponding
22 Required (surface + pores) Volume [0.75x Line 101 _Storage 91 cubic-feet
23 Required Footprint [Line 22/ Line 18] x 12 91 sq-ft
Footprint of the BMP
24 Area draining to the BMP 2792 sq-ft
25 Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and 13.2) 1
26 Minimum BMP Footprint [Line 24 x Line 25 x 0.03] 84 sq-ft
27 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 26) 94 sq-ft
Note : Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to
the required biofiltration footprint (either Line 21 or Line 23)
I Worksheet 13.5-1: Simple Sizing Method for Biofiltration BMPs
BMP IDENTIFICATION: BIO.02
1
1 jRemaining DCV after implementing retention BMPs I 43 f cubic-feet
Partial Retention
2 Infiltration rate from Form 1-9 if partial infiltration is feasible in/hr.
3 Allowable drawdown time for aggregate storage below the underdrain 36 hours
4 Depth of runoff that can be infiltrated [Line 2 x Line 3] inches
5 Aggregate pore space 0.40 in/in
6 Required depth of gravel below the underdrain [Line 4/ Line 5] 0 inches
7 Assumed surface area of the biofiltration BMP 216 sq-ft
8 Media retained pore storage 0.1 in/in
9 Ivolume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 32.4 cubic-feet
10 1 DCV that requires biofiltration [Line 1 - Line 9] 10.6 cubic-feet
BMP Parameters
11 Surface Ponding [6 inch minimum, 12 inch maximum] 10 inches
12 Media Thickness [18 inches minimum], also add mulch layer thickness to
this line for sizing calculations 18 inches
13 Aggregate Storage above underdrain invert (12 inches typical) - use 0
inches for sizing if the aggregate is not over the entire bottom surface area 8 inches
14 Media available pore space 0.2 in/in
15
-
Media filtration rate to be used for sizing (5 in/hr. with no outlet control;
if the filtration is controlled by the outlet, use the outlet controlled rate)
5 in/hr.
Baseline Calculations
16 Allowable Routing Time for sizing 6 hours
17 Depth filtered during storm [Line 15 x Line 16] 30 inches
18 Depth of Detention Storage
[Line 11 + (Line 12 x Line 14) ± (Line 13 x Line 5)] 16.8 inches
19 Total Depth Treated [Line 17 + Line 18] 47 inches
Option I - Biofilter 1.5 times the DCV
20 Required biofiltered volume [1.5 x Line 10] 16 cubic-feet
21 Required Footprint [Line 20! Line 19] x 12 4 sq-ft
Option 2 - Store 0.75 of remaining DCV in pores and ponding
22 Required Storage (surface + pores) Volume [0.75x Line 10] J 8 cubic-feet
23 Required Footprint [Line 22/ Line 18] x 12 6 sq-ft
Footprint of the BMP
24 Area draining to the BMP 982 sq-ft
25 Adjusted Runoff Factor for drainage area (Refer to Appendix 13.1 and 13.2) 0.82
26 Minimum BMP Footprint [Line 24 x Line 25 x 0.03] 24 sq-ft
27 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 26) 219 sq-ft
Note: Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to
the required biofiltration footprint (either Line 21 or Line 23)
Worksheet 13.5-1: Simple Sizing Method for Biofiltration BMPs
BMP IDENTIFICATION: BIO.03
LWAT TT II!•![Ir 1 Remaining DCV after implementing retention BMPs 179 cubic-feet
Partial Retention
2 Infiltration rate from Form 1-9 if partial infiltration is feasible in/hr.
3 Allowable drawdown time for aggregate storage below the underdrain 36 hours
4 Depth of runoff that can be infiltrated [Line 2 x Line 3] inches
5 Aggregate pore space 0.40 in/in
6 Required depth of gravel below the underdrain [Line 4/ Line 51 0 inches
7 Assumed surface area of the biofiltration BMP 100 sq-ft
8 Media retained pore storage 0.1 in/in
9 Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 15 cubic-feet
10 DCV that requires biofiltration [Line 1 - Line 9] 64 cubic-feet
BMP Parameters
11 Surface Ponding [6 inch minimum, 12 inch maximum] 6 inches
12
-
Media Thickness [18 inches minimum], also add mulch layer thickness to
this line for sizing calculations 18 inches
13
-
Aggregate Storage above underdrain invert (12 inches typical) - use 0
inches for sizing if the aggregate is not over the entire bottom surface area 6 inches
14 Media available pore space 0.2 in/in
15
-
Media filtration rate to be used for sizing (5 in/hr. with no outlet control;
if the filtration is controlled by the outlet, use the outlet controlled rate)
5 in/hr.
Baseline Calculations
16 Allowable Routing Time for sizing 6 hours
17 Depth filtered during storm [Line 15 x Line 16] 30 inches
18 Depth of Detention Storage
[Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)]
12 inches
19 Total Depth Treated [Line 17 + Line 18] 42 inches
Option I - Biofilter 1.5 times the DCV
20 Required biofiltered volume (1.5x Line 10] 96 J cubic-feet
21 Required Footprint [Line 20/ Line 19] x 12 27 sq-ft
Option 2 - Store 0.75 of remaining DCV in pores and ponding
22 Required _Storage (surface + pores) Volume [0.75x Line 10] 48 cubic-feet
23 Required _Footprint [Line 22! Line 18] x 12 48 sq-ft
Footprint of the BMP
24 Area draining to the BMP 1713 sq-ft
25 Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and 13,2) 0.95
26 Minimum BMP Footprint [Line 24 x Line 25 x 0.03] 49 sq-ft
27 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 26) 101 sq-ft Note Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to the required biofiltration footprint (either Line 21 or Line 23)
Worksheet 13.5-1: Simple Sizing Method for Biofiltration BMPs
BMP IDENTIFICATION: BIO.04
1 1 Remaining DCV after implementing retention BMPs 147 cubic-feet
Partial Retention
2 Infiltration rate from Form 1-9 if partial infiltration is feasible in/hr.
3 Allowable drawdown time for aggregate storage below the underdrain 36 hours
4 Depth of runoff that can be infiltrated [Line 2 x Line 3] inches
5 Aggregate pore space 0.40 in/in
6 Required depth of gravel below the underdrain [Line 4/ Line 51 inches
7 Assumed surface area of the biofiltration BMP 92 sq-ft
8 Media retained pore storage 0.1 in/in
9 lVolume retained by BMP [[Line 4 + (Line 12 x Line 8)1/12] x Line 7 13.8 cubic-feet
10 1 DCV that requires biofiltration [Line I - Line 9] 1332 cubic-feet
BMP Parameters
11 Surface Ponding [6 inch minimum, 12 inch maximum] 6 inches
12 Media Thickness [18 inches minimum], also add mulch layer thickness to
this line for sizing calculations 18 inches
13 Aggregate Storage above underdrain invert (12 inches typical)
- use 0
inches for sizing if the aggregate is not over the entire bottom surface area 6 inches
14 Media available pore space 0.2 in/in
15 Media filtration rate to be used for sizing (5 in/hr. with no outlet control;
if the filtration is controlled by the outlet, use the outlet controlled rate)
5 in/hr.
Baseline Calculations
16 Allowable Routing Time for sizing 6 hours
17 Depth filtered during storm [Line 15 x Line 16] 30 inches
18 Depth of Detention Storage
[Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)] 1 2 inches
19 Total Depth Treated [Line 17 + Line 181 42 inches
Option I - Biofilter 1.5 times the DCV
20 Required biofiltered volume [1.5 x Line 10] 200 cubic-feet
21 Required Footprint [Line 20/ Line 19] x 12 57 sq-ft
Option 2 - Store 0.75 of remaining DCV in pores and ponding
22 Required Storage (surface + pores) Volume [0.75 x Line 10] 100 cubic-feet
23 Required Footprint [Line 22/ Line 18] x 12 100 sq-ft
Footprint of the BMP
24 Area draining to the BMP 3115 sq-ft
25 Adjusted Runoff Factor for drainage area (Refer to Appendix 13.1 and B.2) 0.98
26 Minimum BMP Footprint [Line 24 x Line 25 x 0.03] 92 sq-ft
27 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 26) 92 sq-ft
Note. Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to
the required biofiltration footprint (either Line 21 or Line 23)
Worksheet 13.5-1: Simple Sizing Method for Biofiltration BMPs
BMP IDENTIFICATION: BIO.05
1 Remaining DCV after implementing retention BMPs 86 cubic-feet
Partial Retention
2 lnfiltraticn rate from Form 1-9 if partial infiltration is feasible in/hr.
3 Allowable drawdown time for aggregate storage below the underdrain 36 hours
4 Depth of runoff that can be infiltrated [Line 2 x Line 3] inches
5 Aggregate pore space 0.40 in/in
6 Required depth of gravel below the underdrain [Line 4/ Line 51 0 inches
7 Assumed surface area of the biofiltration BMP 77 sq-ft
8 Media retained pore storage 0.1 in/in
9 Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 11.55 cubic-feet
10 DCV that requires bioffitration [Line 1 - Line 9] 74.45 cubic-feet
BMP Parameters
11 Surface Ponding [6 inch minimum, 12 inch maximum] 6 inches
12 Media Thickness [18 inches minimum], also add mulch layer thickness to
this line for sizing calculations 18 inches
13 Aggregate Storage above underdrain invert (12 inches typical) - use 0
inches for sizing if the aggregate is not over the entire bottom surface area 6 inches
14 Media available pore space 0.2 in/in
15
-
Media fitration rate to be used for sizing (5 in/hr. with no outlet control;
if the filt-ation is controlled by the outlet, use the outlet controlled rate)
5 in/hr.
Baseline Calculations
16 Allowable Routing Time for sizing 6 hours
17 Depth fi tered during storm [Line 15 x Line 16] 30 inches
18 Depth of Detention Storage
[Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)] 12
inches
19 Total Depth Treated [Line 17 + Line 18] 42 inches
Option I - Biofilter 1.5 times the DCV
_JRequired biofiltered volume [1.5x Line 10] 112 cubic-feet
21 jRequired Footprint [Line 20/ Line 19] x 12 32 sq-ft
Option 2 - Store 0.75 of remaining DCV in pores and ponding
22 Required Storage (surface + pores) Volume [0.75 x Line 10] 56 cubic-feet
23 Required Footprint [Line 22/ Line 18] x 12 56 sq-ft
Footprint of the BMP
24 Area draining to the BMP 1832 sq-ft
25 Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and B.2) 0.97
26 Minimum BMP Footprint [Line 24 x Line 25 x 0.03] 53 sq-ft
27 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 26) 77 sq-ft
Note: Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to
the required blotitration footprint (either Line 21 or Line 23)
Worksheet 13.5-1: Simple Sizing Method for Biofiltration BMPs
BMP IDENTIFICATION: BIO.06
Fl 1 jRemaining DCV after implementing retention BMPs 25 ] cubic-feet
Partial Retention
2 Infiltration rate from Form 1-9 if partial infiltration is feasible in/hr.
3 Allowable drawdown time for aggregate storage below the underdrain 36 hours
4 Depth of runoff that can be infiltrated [Line 2 x Line 3] inches
5 Aggregate pore space 0.40 in/in
6 Required depth of gravel below the underdrain [Line 4/ Line 5] 0 inches
7 Assumed surface area of the biofiltration BMP 16 sq-ft
8 Media retained pore storage 0.1 in/in
9 Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 2.4 cubic-feet
10 DCV that requires biofiltration [Line 1 - Line 9] 22.6 cubic-feet
BMP Parameters
11 Surface Ponding [6 inch minimum, 12 inch maximum] 6 inches
12 Media Thickness [18 inches minimum], also add mulch layer thickness to
this line for sizing calculations 18 inches
13 Aggregate Storage above underdrain invert (12 inches typical) - use 0
inches for sizing if the aggregate is not over the entire bottom surface area 6 inches
14 Media available pore space 0.2 in/in
15 Media filtration rate to be used for sizing (5 in/hr. with no outlet control;
if the filtration is controlled by the outlet, use the outlet controlled rate)
5 in/hr.
Baseline Calculations
16 Allowable Routing Time for sizing 6 hours
17 Depth filtered during storm [Line 15 x Line 16] 30 inches
18 Depth of Detention Storage
[Line 11 + (Line 12 xLine 14) + (Line 13 x Line 5)] lL inches
19 Total Depth Treated [Line 17 + Line 18] 42 inches
Option I - Biofilter 1.5 times the DCV
20 Required biofiltered volume [1.5x Line 10] 34 cubic-feet
21 Required Footprint [Line 20/ Line 19] x 12 10 sq-ft
Option 2 - Store 0.75 of remaining DCV in pores and ponding
Required Storage (surface + pores) Volume [0.75x Line 10]
1 17 cubic-feet
23f Required [Line 22/ Line 18] x 12 _Footprint 17 sq-ft
Footprint of the BMP
24 Area draining to the BMP 531 sq-ft
25 Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and 13.2) 0.98
26 Minimum BMP Footprint [Line 24 x Line 25 x 0.03] 16 sq-ft
27 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 26) 16 sq-ft
Note: Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to
the required biofiltration footprint (either Line 21 or Line 23)
Worksheet 13.5-1: Simple Sizing Method for Biofiltration BMPs
BMP IDENTIFICATION: BIO.07
1 Remaining DCV after implementing retention BMPs 91 { cubic-feet
Partial Retention
2 Infiltration rate from Form 1-9 if partial infiltration is feasible 0 in/hr.
3 Allowable drawdown time for aggregate storage below the underdrain 36 hours
4 Depth of runoff that can be infiltrated [Line 2 x Line 31 inches
5 Aggregate pore space 0.40 in/in
6 Required depth of gravel below the underdrain [Line 4/ Line 51 0 inches
7 Assumed surface area of the biofiltration BMP 56 sq-ft
8 Media retained pore storage 0.1 in/in
9 IVolume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 8.4 cubic-feet
10 1 DCV that requires biofiltration [Line 1 - Line 9] 82.6 cubic-feet
BMP Parameters
11 Surface Ponding [6 inch minimum, 12 inch maximum] 6 inches
12
-
Media Thickness [18 inches minimum], also add mulch layer thickness to
this line for sizing calculations 18 inches
13
-
Aggregate Storage above underdrain invert (12 inches typical) - use 0
inches for sizing if the aggregae is not over the entire bottom surface area 6 inches
14 Media available pore space 0.2 in/in
15 Media filtration rate to be used for sizing (5 in/hr. with no outlet control;
if the filtration is controlled by the outlet, use the outlet controlled rate)
5 in/hr.
Baseline Calculations
16 Allowable Routing Time for sizing 6 hours
17 Depth filtered during storm [Line 15 x Line 16] 30 inches
18 Depth of Detention Storage
[Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)] 12 inches
19 Total Depth Treated [Line 17 + Line 18] 42 inches
Option I - Biofilter 1.5 times the DCV
20 Required biofiltered volume [1.5 x Line 10] 124 cubic-feet
21 Required Footprint [Line 20/ Line 19] x 12 35 sq-ft
Option 2 - Store 0.75 of remaining DCV in pores and ponding
_____ ___________ 22 Required Storage (surface + pores) Volume [0.75 x Line 10] 62 cubic-feet
23 Required Footprint [Line 22/ Line 18] x 12 62 sq-ft
Footprint of the BMP
24 Area draining to the BMP 1913 sq-ft
25 Adjusted Runoff Factor for drainage area (Refer to Appendix 8.1 and 8.2) 0.98
26 Minimum BMP Footprint [Line 24 x Line 25 x 0.03] 56 sq-ft
27 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 26) 56 sq-ft
Note: Line 7 is used to estimate the amou.t of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to
the required biofiltration footprint (either Lire 21 or Line 23)
Worksheet 13.5-1: Simple Sizing Method for Biofiltration BMPs
BMP IDENTIFICATION: BIO.08
:
1 Remaining DCV after implementing retention BMPs I9 cubic-feet
Partial Retention
2 Infiltration rate from Form 1-9 if partial infiltration is feasible in/hr.
3 Allowable drawdown time for aggregate storage below the underdrain 36 hours
4 Depth of runoff that can be infiitrated [Line 2 x Line 31 inches
5 Aggregate pore space 0.40 in/in
6 Required depth of gravel below the underdrain [Line 4/ Line 51 0 inches
7 Assumed surface area of the biofiltration BMP 23 sq-ft
8 Media retained pore storage 0.1 in/in
9 Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]!12] x Line 7 345 cubic-feet
10 1 DCV that requires biofiltration [Line 1 - Line 9] 5.55 cubic-feet
BMP Parameters
11 Surface Ponding [6 inch minimum, 12 inch maximum] 6 inches
12 Media Thickness [18 inches minimum], also add mulch layer thickness to
this line for sizing calculations 18 inches
13 Aggregate Storage above underdrain invert (12 inches typical) - use 0
inches for sizing if the aggregate is not over the entire bottom surface area 6 inches
14 Media available pore space 0.2 in/in
15 Media filtration rate to be used for sizing (5 in/hr. with no outlet control;
if the filtration is controlled by the outlet, use the outlet controlled rate)
5 in/hr.
Baseline Calculations
16 Allowable Routing Time for sizing 6 hours
17 Depth filtered during storm [Line 15 x Line 16] 30 inches
18 Depth of Detention Storage
[Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)]
12 inches
19 Total Depth Treated [Line 17 + Line 18] 42 inches
Option 1 - Biofilter 1.5 times the DCV
20 Required biofiltered volume [1.5x Line 10] 8 cubic-feet
Required Footprint [Line 20/ Line 19] x 12 2 sq-ft
Option 2 - Store 0.75 of remaining DCV in pores and ponding
22 Required Storage (surface + pores) Volume [0.75 x Line 10] 4 cubic-feet
23 Required Footprint [Line 22/ Line 18] x 12 4 sq-ft
Footprint of the BMP
24 Area draining to the BMP 203 sq-ft
25 Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and B.2) 0.91
26 Minimum BMP Footprint [Line 24 x Line 25 x 0.03] 6 sq-ft
27 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 26) 6 sq-ft Note: Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to
the required bid filtration footprint (either Line 21 or Line 23)
Worksheet 13.5-1: Simple Sizing Method for Biofiltration BMPs
BMP IDENTIFICATION: BlO.09
1 Remaining DCV after implementing retention BMPs 38 cubic-feet
Partial Retention
2 infiltration rate from Form 1-9 if partial infiltration is feasible in/hr.
3 Allowable drawdown time for aggregate storage below the underdrain 36 hours
4 Depth of runoff that can be infiltrated [Line 2 x Line 3] 0 inches
5 Aggregate pore space 0.40 in/in
6 Required depth of gravel below the underdrain [Line 4/ Line 5] inches
7 Assumed surface area of the biofiltration BMP 75 sq-ft
8 Media retained pore storage 0.1 in/in
9 Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 11.25 cubic-feet
10 DCV that requires biofiltration [Line 1 - Line 9] 26.75 cubic-feet
BMP Parameters
11 Surface Ponding [6 inch minimum, 12 inch maximum] 6 inches
12 Media Thickness [18 inches minimum], also add mulch layer thickness to
this line for sizing calculations 18 inches
13
-
Aggregate Storage above underdrain invert (12 inches typical) - use 0
inches for sizing if the aggregate is not over the entire bottom surface area 6 inches
14 Media available pore space 0.2 in/in
15 Media filtration rate to be used for sizing (5 in/hr. with no outlet control;
if the filtration is controlled by the outlet, use the outlet controlled rate)
5 in/hr.
Baseline Calculations
16 Allowable Routing Time for sizing 6 hours
17 Depth filtered during storm [Line 15 x Line 16] 30 inches
18 Depth of Detention Storage
[Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)]
12 inches
19 Total Depth Treated [Line 17 + Line 181 42 inches
Option I - Biofilter 1.5 times the DCV
20 Required biofiltered volume [1.5x Line 10] 40 cubic-feet
21 Required Footprint [Line 20/ Line 19] x 12 11 sq-ft
Option 2 - Store 0.75 of remaining DCV in pores and ponding
22 Required Storage (surface + pores) Volume [0.75 x Line 10] 20 cubic-feet
23 Required Footprint [Line 22/ Line 181 x 12 20 sq-ft
Footprint of the BMP
24 Area draining to the BMP 632 sq-ft
25 Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and 8.2) 0.91
26 Minimum BMP Footprint [Line 24 x Line 25 x 0.03] 17 sq-ft
27 Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 26) 75 sq-ft
Note: Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to the required biofiltration footprint (either Line 21 or Line 23)
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 LI 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
El 6.2.1 Verification of
Geomorphic Landscape Units
Onsite
U 6.2.2 Downstream Systems
Sensitivity to Coarse
Sediment
U 6.2.3 Optional Additional
Analysis of Potential Critical
Coarse Sediment Yield Areas
Onsite
Attachment 2c Geomorphic Assessment of Receiving LI Not performed
Channels (Optional) LI Included
See Section 6.3.4 of the BMP Design
Manual. Attachment 2d Flow Control Facility Design and LI Included
Structural BMP Drawdown
Calculations (Required)
See Chapter 6 and Appendix G of the
BMP Design Manual
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_
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IF
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El
3.1 1 Wttt'rshed iIusiu;;ri:i&•tit Aru iisI
All of the Carlsbad WMA Responsible Agendas have participated in the development of a Watershed
Management Area Analysis (WMAA) see Appendix E. The purpose of the WMAA is to:
Characterize the WMA through identification of physical characteristics and compilation of the
data into Geographical Information System (GIS) mapping,-
Use the WMA characterization as a resource for identification of potential candidate projects for
Offsite Alternative Compliance (OAC) options for fulfilling applicable Land Development
requirements of the MS/I permit;
Use the WMA characterization as a resource for identifying areas within the WMA where
exemptions from hydromodification management requirements Would be appropriate.
C,orefrfiztzUun
The attached Carlsbad WMAA provides GIS mapping that characterize the WMAs by providing the
following:
Description of dominant hydrologic processes1 such as areas where infiltration or overland flow
likely dominates;
Description of existing streams in the watershed, Including bed material and composition, and if
they are perennial or ephemeral;
Current and anticipated future land uses;
Potential coarse sediment yield areas; and
Locations of existing flood control structures and channel structures, such as stream armoring,
constrictions, grade control structures, and hydromodification or flood management basins.
Offs ftc AIt,ngsffi,a compliance
Completion of a WMAA is a required step prior to allowing O1fsite Alternative Compliance (OAC) as an
option for development/redevelopment projects. Although the WMAA has been completed, Responsible
Agencies have not yet developed OAC programs. It Is anticipated that those Responsible Agencies that
elect to have OAC programs will develop and implement those programs in the coming years and are
identified in the optional strategies in each focus area where applicable.
The Responsible Agencies are also required to develop a list of candidate projects that could potentially
be used as alternative compliance options in lieu of land development onsite structural I3MP prforrnance
requirements. The current candidates list is provided as Appendix F. Since the Responsible Agencies are
not intending to implement OAC progi'anis until 2016 at the earliest, the candidates list Is currently not
comprehensive and is anticipated to be amended In coming years.
F Eenip lions frnm ilydmrnOdijkotion Management Requirvrn;nts
—The WM—Agii—iclu—de—s—a"2es—cniTti'5n—ontie recommend! exemptions from hydromodification management
requirements as summarized below. Future proposed l-lydrornodific.atlon Management Plan exemptions
would need to be approved through the WOIP Annual Update process,
Exempt River Reaches
There are no river reaches currently recommended for exemption from hydromodification
management requirements In the Carlsbad WMA. However, Escondido Creek is currently being
evaluated to assess whether a hydromodificatlon management exemption could apply to this
waterbocly. Based on the findings of the evaluation, the San Elijo Lagoon may also be evaluated. The
'1 results of these studies will be included In future Carlsbad WMAA Update.
Stabilized Conveyance Systems Draining to Exempt Water Bodies
There are no stabilized conveyance systems currently recommended for exemption from
hydromodification management requirements In the Carlsbad WMA.
Strategies
21
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Highly Impervious/Highly Urbanized Watersheds and Urban Infill
No areas within the Carlsbad WMA are currently recommended fDr highly impervious/highly
urbanized watershed, or urban mull exemption.
Tidally Influenced Lagoons
Based on a City of Carlsbad study5, there are several tidally Influenced areas recommended for
exemption including:
Areas tributary to Buena Vista Lagoon -
Several tributary areas to Agua Hedionda tagoon
One tributary area to t3atiquitos Lagoon
The San tiiijo lagoon and other tidally Influenced waterboclies may also be evaluated for exemption
hi future analyses.
Hydromodification Exemption Analyses for Select Carlsbad Watersheds, Chang Consultants (September 11, 2015)
Strategies
22
HYDROMODIHCATION EXEMPTION MAP
(Per County of San Diego Google Earth KMZ file)
Exempt Water Body
I
Ocean Condominiums
ATTACHMENT 2b
CCSYA MAP
SWQMP
CCSVA MAP
(Per County of San Diego Google Earth KMZ file)
CCSVA (none present)
ATTACHMENT 3
Structural BMP Maintenance Information
Use this checklist to ensure the required information has been included in the Structural
BMP Maintenance Information Attachment:
Preliminary Design/Plan ning/CEQA level submittal:
Attachment 3 must identify:
0 Typical maintenance indicators and actions for proposed structural BMP(s) based
on Section 7.7 of the BMP Design Manual
Final Design level submittal:
Attachment 3 must identify:
Specific maintenance indicators and actions for proposed structural BMP(s). This
shall be based on Section 7.7 of the BMP Design Manual and enhanced to reflect
actual proposed components of the structural BMP(s)
IZI How to access the structural BMP(s) to inspect and perform maintenance
Features that are provided to facilitate inspection (e.g., observation ports,
cleanouts, silt posts, or other features that allow the inspector to view necessary
components of the structural BMP and compare to maintenance thresholds)
U Manufacturer and part number for proprietary parts of structural BMP(s) when
applicable
M Maintenance thresholds for BMPs subject to siltation or heavy trash(e.g., silt level
posts or other markings shall be included in all BMP components that will trap and
store sediment, trash, and/or debris, so that the inspector may determine how full
the BMP is, and the maintenance personnel may determine where the bottom of the
BMP is. If required, posts or other markings shall be indicated and described on
structural BMP plans.)
!J Recommended equipment to perform maintenance
When applicable, necessary special training or certification requirements for
inspection and maintenance personnel such as confined space entry or
hazardous waste management
ATTACHMENT 4
City standard Single Sheet BMP (SSBMP) Exhibit
[Use the City's standard Single Sheet BMP Plan.]
U
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