HomeMy WebLinkAboutPD 2020-0049; HOPE ELEMENTARY SCHOOL; PRIORITY DEVELOPMENT PROJECT STORM WATER QUALITY MANAGEMENT PLAN; 2022-06-05CITY OF CARLSBAD
PRIORITY DEVELOPMENT PROJECT (PDP)
STORM WATER QUALITY MANAGEMENT PLAN (SWQMP)
FOR
HOPE ELEMENTARY SCHOOL NEW CLASSROOM BUILDING / MODERNIZATION
PROJECT ID PD-2020-0049
GR 2020-0049
DRAWING No. 528-2A
ENGINEER OF WORK:
ALAN WING-CHI LEE, P.E. #C34971
PREPARED FOR:
CARLSBAD UNIFIED SCHOOL DISTRICT
6225 EL CAMINO REAL
CARLSBAD, CA 92009
(760) 331-5000
PREPARED BY: FPL AND ASSOCIATES, INC.
30 CORPORATE PARK, SUITE 401
IRVINE, CA 92606
(949) 252-1688
DATE:
JUNE 5, 2022
TABLE OF CONTENTS
Certification Page Project Vicinity Map FORM E-34 Storm Water Standard Questionnaire
Site Information FORM E-36 Standard Project Requirement Checklist Summary of PDP Structural BMPs
Attachment 1: Backup for PDP Pollutant Control BMPs Attachment 1a: DMA Exhibit Attachment 1b: Tabular Summary of DMAs and Design Capture Volume Calculations Attachment 1c: Harvest and Use Feasibility Screening (when applicable) Attachment 1d: Infiltration Feasibility Analysis (when applicable) Attachment 1e: Pollutant Control BMP Design Worksheets / Calculations
Attachment 1f: Trash Capture BMP Requirements Attachment 2: Backup for PDP Hydromodification Control Measures Attachment 2a: Hydromodification Management Exhibit Attachment 2b: Management of Critical Coarse Sediment Yield Areas Attachment 2c: Geomorphic Assessment of Receiving Channels Attachment 2d: Flow Control Facility Design Attachment 3: Structural BMP Maintenance Thresholds and Actions Attachment 4: Single Sheet BMP (SSBMP) Exhibit Attachment 5: Geotechnical Report
CERTIFICATION PAGE
PROJECT VICINITY MAP
PROJECT VICINITY MAP
FORM E-34
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, ‘STANDARD PROJECT’ with TRASH CAPTUREREQUIREMENTS, or be subject to ‘PRIORITY DEVELOPMENT PROJECT’ (PDP) requirements.
Your responses to the questionnaire represent an initial assessment of the proposed project conditions and impacts. City staff has responsibility for making the final assessment after submission of the development application. If staff determines
that the questionnaire was incorrectly filled out and is subject to more stringent storm water standards than initially assessed by you, this will result in the return of the development application as incomplete. In this case, please make the changes to the questionnaire and resubmit to the city.
If you are unsure about the meaning of a question or need help in determining how to respond to one or more of the
questions, please seek assistance from Land Development Engineering staff.
A completed and signed questionnaire must be submitted with each development project application. Only one completed and signed questionnaire is required when multiple development applications for the same project are submitted concurrently.
PROJECT INFORMATION
PROJECT NAME: APN:
ADDRESS:
The project is (check one): New Development Redevelopment
The total proposed disturbed area is: ft2 ( ) acres
The total proposed newly created and/or replaced impervious area is: ft2 ( ) 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 SWQMP #:
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.
This Box for City Use Only
City Concurrence:
YES NO Date: Project ID:
By:
E-34 Page 1 of 4 REV 02/22
Development Services
Land Development Engineering
1635 Faraday Avenue
442-339-2750
www.carlsbadca.gov
STORM WATER STANDARDS
QUESTIONNAIRE E-34
INSTRUCTIONS:
Hope ES Classroom Building / Modernization
3010 Tamarack Avenue, Carlsbad, CA 92010 1671011100
X
132,600 3.03
100,100 2.30
N/A
E-34 Page 2 of 4 REV 02/22
STEP 1 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 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 6, mark the 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.
STEP 2 TO BE COMPLETED FOR ALL DEVELOPMENT PROJECTS
To determine if your project is exempt from PDP requirements pursuant to MS4 Permit Provision E.3.b.(3), please answer the following questions:
Is your project LIMITED to one or more of the following: YES NO
1.Constructing new or retrofitting paved sidewalks, bicycle lanes or trails that meet the following criteria:a)Designed and constructed to direct storm water runoff to adjacent vegetated areas, or other non-erodible permeable areas; ORb)Designed and constructed to be hydraulically disconnected from paved streets or roads; OR
c)Designed and constructed with permeable pavements or surfaces in accordance with USEPAGreen Streets guidance?
2. Retrofitting or redeveloping existing paved alleys, streets, or roads that are designed and constructed inaccordance with the USEPA Green Streets guidance?
3. Ground Mounted Solar Array that meets the criteria provided in section 1.4.2 of the BMP manual?
If you answered “yes” to one or more of the above questions, provide discussion/justification below, then go to Step 6, 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.
X
X
X
X
E-34 Page 3 of 4 REV 02/22
* Environmentally Sensitive Areas include but are not limited to all Clean Water Act Section 303(d) impaired water bodies; areas designated as Areas of Special Biological Significance by the State Water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1994) and amendments); water bodiesdesignated with the RARE beneficial use by the State Water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1994) and amendments);areas designated as preserves or their equivalent under the Multi Species Conservation Program within the Cities and County of San Diego; Habitat ManagementPlan; and any other equivalent environmentally sensitive areas which have been identified by the City.
STEP 3 TO BE COMPLETED FOR ALL NEW OR REDEVELOPMENT PROJECTS
To determine if your project is a PDP, please answer the following questions (MS4 Permit Provision E.3.b.(1)):
YES NO
1. Is your project a new development that creates 10,000 square feet or more of impervious surfacescollectively over the entire project site? This includes commercial, industrial, residential, mixed-use,and public development projects on public or private land.
2. Is your project a redevelopment project creating and/or replacing 5,000 square feet or more of impervious
surface collectively over the entire project site on an existing site of 10,000 square feet or more ofimpervious surface? This includes commercial, industrial, residential, mixed-use, and public
development projects on public or private land.
3. Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more ofimpervious 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 refreshment stands selling prepared foods and drinks for immediate consumption (Standard Industrial Classification (SIC) code 5812).
4. Is your project a new or redevelopment project that creates 5,000 square feet or more of impervioussurface collectively over the entire project site and supports a hillside development project? A hillsidedevelopment project includes development on any natural slope that is twenty-five percent or greater.
5. Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more ofimpervious surface collectively over the entire project site and supports a parking lot? A parking lot is a
land area or facility for the temporary parking or storage of motor vehicles used personally for business or for commerce.
6. Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or moreof impervious street, road, highway, freeway or driveway surface collectively over the entire projectsite? A street, road, highway, freeway or driveway is any paved impervious surface used for the
transportation of automobiles, trucks, motorcycles, and other vehicles. 7. Is your project a new or redevelopment project that creates and/or replaces 2,500 square feet or more ofimpervious 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 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).*
8.Is your project a new development or redevelopment project that creates and/or replaces 5,000 squarefeet or more of impervious surface that supports an automotive repair shop? An automotive repair
shop is a facility that is categorized in any one of the following Standard Industrial Classification (SIC)
codes: 5013, 5014, 5541, 7532-7534, or 7536-7539.
9. Is your project a new development or redevelopment project that creates and/or replaces 5,000 squarefeet or more of impervious area that supports a retail gasoline outlet (RGO)? This category includes
RGO’s that meet the following criteria: (a) 5,000 square feet or more or (b) a project Average Daily
Traffic (ADT) of 100 or more vehicles per day.
10. Is your project a new or redevelopment project that results in the disturbance of one or more acres of landand are expected to generate pollutants post construction?
11. Is your project located within 200 feet of the Pacific Ocean and (1) creates 2,500 square feet or more of
impervious surface or (2) increases impervious surface on the property by more than 10%? (CMC21.203.040)
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 6, 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, complete the trash capture questions..
X
X
X
X
X
X
X
X
X
X
X
E-34 Page 4 of 4 REV 02/22
STEP 4 TO BE COMPLETED FOR REDEVELOPMENT PROJECTS THAT ARE PRIORITY DEVELOPMENT PROJECTS (PDP) ONLY
Complete the questions below regarding your redevelopment project (MS4 Permit Provision E.3.b.(2)): YES NO
Does the redevelopment project result in the creation or replacement of impervious surface in an amount of less than 50% of the surface area of the previously existing development? Complete the percent impervious calculation below:
Existing impervious area (A) = sq. ft.
sq. ft.
%
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 6, 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 6, check the first box stating, “My project is a PDP …” and complete applicant information.
STEP 5 TO BE COMPLETED FOR STANDARD PROJECTS
Complete the question below regarding your Standard Project (SDRWQCB Order No. 2017-0077): YES NO
Is the Standard Project within any of the following Priority Land Use (PLU) categories?
R-23 (15-23 du/ac), R-30 (23-30 du/ac), PI (Planned Industrial), CF (Community Facilities), GC (General
Commercial), L (Local Shopping Center), R (Regional Commercial), V-B (Village-Barrio), VC (VisitorCommercial), O (Office), VC/OS (Visitor Commercial/Open Space), PI/O (Planned Industrial/Office), or
Public Transportation Station
If you answered “yes”, the ‘STANDARD PROJECT’ is subject to TRASH CAPTURE REQUIREMENTS. Go to step 6,
check the third box stating, “My project is a ‘STANDARD PROJECT’ subject to TRASH CAPTURE REQUIREMENTS
…” and complete applicant information.
If you answered “no”, your project is a ‘STANDARD PROJECT’. Go to step 6, check the second box stating, “My project is
a ‘STANDARD PROJECT’…” and complete applicant information. STEP 6 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) per E-35 template for submittal at time of application.
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.
My project is a ‘STANDARD PROJECT’ subject to TRASH CAPTURE REQUIREMENTS and must comply with TRASH CAPTURE REQUIREMENTS of the BMP Manual. I understand I must prepare a TRASH CAPTURE Storm Water Quality Management Plan (SWQMP) per E-35A template for submittal at time of application.
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.
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: Applicant Title:
Applicant Signature: Date:
209,950
100,100Total proposed newly created or replaced impervious area (B) =
Percent impervious area created or replaced (B/A)*100 = 48
X
X
Joe Litchfield Project Manager
6-5-2022
SITE INFORMATION CHECKLIST
SITE INFORMATION CHECKLIST
Project Summary Information
Project Name Hope ES New Classroom Building / Modernization
Project ID PD2020-0049
Project Address 3010 Tamarack Avenue
Carlsbad, CA 92010
Assessor's Parcel Number(s) (APN(s)) 1671011100
Project Watershed (Hydrologic Unit) Carlsbad 904
Parcel Area 13.25 Acres ( 577,381 Square Feet)
Existing Impervious Area
(subset of Parcel Area) 4.82 Acres ( 209,950 Square Feet)
Area to be disturbed by the project
(Project Area) 3.03 Acres ( 132,600 Square Feet)
Project Proposed Impervious Area
(subset of Project Area) 2.30 Acres ( 100,100 Square Feet)
Project Proposed Pervious Area
(subset of Project Area) 0.73 Acres ( 32,500 Square Feet)
Note: Proposed Impervious Area + Proposed Pervious Area = Area to be Disturbed by the
Project. This may be less than the Parcel Area.
Description of Existing Site Condition and Drainage Patterns
Current Status of the Site (select all that apply):
X Existing development
Previously graded but not built out
Agricultural or other non-impervious use
Vacant, undeveloped/natural
Description / Additional Information:
The project area is located at 3010 Tamarack Avenue in Carlsbad, California, approximately
one‐half mile south of Highway 78, and approximately three miles east from the Pacific Ocean.
The developed portion of the site is at the higher elevations adjacent to Tamarack Avenue,
forming a plateau with sloped boundaries to the north, west, and south that are vegetated and
have some previous drainage swales to protect against erosion on the slopes. The existing site is
overlain with existing school buildings, asphalt surfaces for parking and play areas, and grass /
lawn areas. There is a significant undeveloped portion of the property (parcel) that is generally
open, natural space that also includes the natural drainage channels to the north, west, and south.
Drainage from the plateau area currently drains to all sides (north, south, east, and west), with the
concentration to the west per previous site improvements for the school. There are currently no
storm water quality controls on the campus as development occurred in 1986, prior to widespread
NPDES and water quality and hydromodification requirements.
Existing Land Cover Includes (select all that apply):
X Vegetative Cover
Non-Vegetated Pervious Areas
X Impervious Areas
Description / Additional Information:
The existing land cover is the elementary school which has impervious buildings and paving
(concrete and asphalt) as well as some open, vegetated, pervious areas.
Underlying Soil belongs to Hydrologic Soil Group (select all that apply):
NRCS Type A
NRCS Type B
NRCS Type C
X NRCS Type D
Approximate Depth to Groundwater (GW):
GW Depth < 5 feet
5 feet < GW Depth < 10 feet
10 feet < GW Depth < 20 feet
X GW Depth > 20 feet (60 to 78 BGS per geotechnical report)
Existing Natural Hydrologic Features (select all that apply):
X Watercourses
Seeps
Springs
Wetlands
None
Description / Additional Information:
The school site sits at a higher elevation / plateau on the parcel and is surrounded by lower
elevations of watercourses on the north, west, and south that are the natural drainage channels
for the school and surrounding area.
Description of Existing Site Topography and Drainage:
The developed portion of the site is at the higher elevations / plateau adjacent to Tamarack
Avenue, with sloped boundaries to the north, west, and south. The existing site is overlain with
existing school buildings, asphalt surfaces for parking and play areas, and grass / lawn areas.
There is a significant undeveloped portion of the property that is generally open, natural space that
also includes the natural drainage channels to the north, west, and south.
The existing drainage pattern of the developed site has outflow runoff from six different areas as
follows:
1. The south side of the developed portion of the parcel collects drainage on the surface via
sheet flow to an existing curb and gutter that spans the south end of the active campus
area. The drainage is then collected to an existing shallow catch basin and parkway drain
that discharges onto Tamarack Avenue. [Outflow #1]
2. The southern portion of the driveway / parking area discharges to the east directly onto
Tamarack Avenue. [Outflow #2]
3. The northern portion of the driveway / parking area discharges to the east directly onto
Tamarack Avenue. [Outflow #3]
4. A small portion of the existing site, the parkway between the public sidewalk and the
parking lot and also between the two lot entrances, discharges to the east directly onto
Tamarack Avenue via sheet flow across the public sidewalk. [Outflow #4]
5. The central / west portion of the site, which comprises the primary building pad area,
collects drainage runoff through multiple drain inlets, pipes, and surface swales and diverts
the drainage to the west side of the property, where a steep 18” diameter reinforced
concrete pipe (RCP) storm drain (18” RCP) directs drainage to a lower portion of the
canyon and outlets to a grouted rip rap to control erosion. [Outflow #5]
6. The north end of the property sheet flows across an existing grass / lawn area (multi-
purpose field) that is collected via an existing concrete curb and gutter at the north end of
the field to channel the runoff to an existing catch basin and 18” RCP storm drain that
outlets near the bottom of the canyon on a grouted rip rap surface to control erosion. An
additional bench drain is located on the northern portion of the parcel that collects runoff
from the northern slope and directs that drainage to a down drain that terminates at a
similar elevation in the canyon to the north. [Outflow #6]
There is no offsite run-on that drains through the site.
Description of Proposed Site Development and Drainage Patterns
Project Description / Proposed Land Use and/or Activities:
The proposed project is a modernization and expansion of the existing elementary school (Hope
Elementary School, a part of Carlsbad Unified School District). Four new classroom buildings
will be constructed, and one building will be expanded. A number of small portable classrooms
will be removed from the site. New play areas are included in the project, both on hardscape and
softscape.
List/describe proposed impervious features of the project (e.g., buildings, roadways, parking
lots, courtyards, athletic courts, other impervious features):
The new buildings as well as expanded main building, play areas, and sidewalks will all be
impervious and incorporate into the site drainage.
List/describe proposed pervious features of the project (e.g., landscape areas):
Some of the newly disturbed areas will be landscaped with lawn, primarily the removal of
relocatable buildings that were previously used for instruction. Tree wells and small landscaped
areas are included in the new site plan as a part of the new campus improvements.
Does the project include grading and changes to site topography?
X Yes
No
Description / Additional Information:
The majority of the proposed grading is remedial grading for structural stability of the proposed
buildings at the request of the geotechnical engineer (4 feet depth of over-excavation up to 3 feet
outside of all foundations). The remainder of the grading is import fill to bring the grade up
sufficiently around the buildings to allow for fairly level areas in and around the buildings for ease
of access (accessibility requirements for the Division of State Architect on school campuses).
Other grading changes are incorporated to properly implement the proposed BMPs as discussed
later in this report. The need for the treatment ponds and tree wells to be fairly level to
adequately treat surface storm water requires some small grade changes along the BMPs to
properly tie into the surrounding grades of the campus.
Does the project include changes to site drainage (e.g., installation of new storm water
conveyance systems)?
X Yes
No
Description / Additional Information:
The new stormwater conveyance systems are primarily new catch basins and underground
piping that collect and convey stormwater from the newly disturbed areas to the eastern portion
of the project site. This is due to the site parameters and topography that necessitated
placement of the proposed BMPs at the eastern edge of the project due to size of the required
ponds, infiltration characteristics, locations near the top of slopes, and current degradation of the
slope on the west side of the project. Essentially all new disturbed areas were purposely
separated hydrologically and hydraulically from the previous drainage system(s) and diverted to
the new BMPs. The only exception to this methodology was the southern portion of the project
site that did not introduce new piping, but instead sheet flows in a similar manner as it does now
and introducing tree well and treatment pond BMPs for treatment control and hydromodification.
The southern portion of the site (DMAs 1 and 2) drains to SSD-BMP tree wells (self-retaining)
and a biofiltration / partial retention treatment pond (BMP A), respectively, for storm water
treatment and hydromodification. Overflow from these BMPs discharges via an overflow
structure and is piped via an 8” HDPE pipe down to an existing catch basin on Tamarack
Avenue.
The central / northern portion of the project site (DMA 3 and 4) drains to the east where BMP B
that utilizes biofiltration / partial retention treatment pond to meet the water quality and
hydromodification requirements. Overflow from this pond is via a catch basin structure with an
18” HDPE pipe outlet that drains to the to the existing curb inlet catch basin at the furthest north
portion of the project, ultimately discharging to an 18” RCP drain that is at a nearly 40% slope
down the hill to the natural drainage channel.
The west area that is disturbed (DMA 5) incorporates tree wells as a SSD-BMP, with overflow
discharging via a catch basin overflow structure and 8” HDPE pipe to the same existing curb inlet
catch basin at the furthest north portion of the project, ultimately discharging to the same steep
18” RCP drain.
Identify whether any of the following features, activities, and/or pollutant source areas will be
present (select all that apply):
X On-site storm drain inlets
Interior floor drains and elevator shaft sump pumps
Interior parking garages
Need for future indoor & structural pest control
X Landscape/Outdoor Pesticide Use
Pools, spas, ponds, decorative fountains, and other water features
X Food service
X Refuse areas
Industrial processes
Outdoor storage of equipment or materials
Vehicle and Equipment Cleaning
Vehicle/Equipment Repair and Maintenance
Fuel Dispensing Areas
Loading Docks
X Fire Sprinkler Test Water
Miscellaneous Drain or Wash Water
X Plazas, sidewalks, and parking lots
Identification of Receiving Water Pollutants of Concern
Describe path of storm water from the project site to the Pacific Ocean (or bay, lagoon, lake or
reservoir, as applicable):
Runoff from the project site drains to natural drainage courses to Buena Vista Creek, Buena
Vista Lagoon, and the Pacific Ocean Shoreline.
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 Creek Sediment Toxicity, Selenium
Buena Vista Lagoon Indicator Bacteria, Nutrients,
Sedimentation / Siltation
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
Anticipated from the
Project Site
Also a Receiving
Water Pollutant of
Concern
Sediment
X X
Nutrients
X X
Heavy Metals
X
Organic Compounds
X
Trash & Debris
X
Oxygen Demanding
Substances
X
Oil & Grease
X
Bacteria & Viruses
X
Pesticides
X
Anticipated and Potential Pollutants Generated by Land Use Type
General Pollutant Categories
Priority
Project
Categories
Sediment Nutrients Heavy
Metals
Organic
Compounds
Trash &
Debris
Oxygen
Demanding
Substances
Oil &
Grease
Bacteria &
Viruses Pesticides
Detached
Residential
Development
X X X X X X X
Attached
Residential
Development
X X X P(1) P(2) P X
Commercial
Development
>one acre
P(1) P(1) X P(2) X P(5) X P(3) P(5)
Heavy
Industry X X X X X X
Automotive
Repair Shops X X(4)(5) X X
Restaurants X X X X P(1)
Hillside
Development
>5,000 ft2
X X X X X X
Parking Lots P(1) P(1) X X P(1) X P(1)
Retail
Gasoline
Outlets
X X X X X
Streets,
Highways &
Freeways
X P(1) X X(4) X P(5) X X P(1)
X = anticipated
P = potential
(1) A potential pollutant if landscaping exists onsite.
(2) A potential pollutant if the project includes uncovered parking areas.
(3) A potential pollutant if land use involves food or animal waste products.
(4) Including petroleum hydrocarbons.
(5) Including solvents.
Hydromodification Management Requirements
Do hydromodification management requirements apply (see Section 1.6 of the BMP Design
Manual)?
X Yes, hydromodification management flow control structural BMPs required.
No, the project will discharge runoff directly to existing underground storm drains
discharging directly to water storage reservoirs, lakes, enclosed embayments, or the Pacific
Ocean.
No, the project will discharge runoff directly to conveyance channels whose bed and bank
are concrete-lined all the way from the point of discharge to water storage reservoirs, lakes,
enclosed embayments, or the Pacific Ocean.
No, the project will discharge runoff directly to an area identified as appropriate
for an exemption by the WMAA for the watershed in which the project resides.
Description / Additional Information (to be provided if a 'No' answer has been selected above):
Critical Coarse Sediment Yield Areas*
*This Section only required if hydromodification management requirements apply
Based on the maps provided within the WMAA, do potential critical coarse sediment yield areas
exist within the project drainage boundaries?
Yes
X No, No critical coarse sediment yield areas to be protected based on WMAA maps
If yes, have any of the optional analyses presented in Section 6.2 of the BMP Design Manual
been performed?
6.2.1 Verification of Geomorphic Landscape Units (GLUs) Onsite
6.2.2 Downstream Systems Sensitivity to Coarse Sediment
6.2.3 Optional Additional Analysis of Potential Critical Coarse Sediment Yield Areas Onsite
No optional analyses performed, the project will avoid critical coarse sediment yield areas
identified based on WMAA maps
If optional analyses were performed, what is the final result?
No critical coarse sediment yield areas to be protected based on verification of GLUs onsite
Critical coarse sediment yield areas exist but additional analysis has determined that
protection is not required. Documentation attached in Attachment 8 of the SWQMP.
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:
See attached map for CCSYA near the project site. There are some areas directly across the
canyon from the project site, but are not disturbed or a part of the project drainage boundaries.
Flow Control for Post-Project Runoff*
*This Section only required if hydromodification management requirements apply
List and describe point(s) of compliance (POCs) for flow control for hydromodification
management (see Section 6.3.1). For each POC, provide a POC identification name or number
correlating to the project's HMP Exhibit and a receiving channel identification name or number
correlating to the project's HMP Exhibit.
Point of Compliance No. 1 – existing catch basin along Tamarack Avenue south of the project
area / campus. A new 8” HDPE pipe conveys both low flows from the underdrain of the BMP A
treatment pond as well as the overflow (100-year return storm flow) from the BMP A treatment
pond and the SSD-BMP Tree Wells from DMA 1. The new 8” HDPE pipe will be connected to
the back of the existing storm drain. The receiving channel is ultimately a natural drainage
course on the south side of campus. The existing runoff pipe drains down to the natural
drainage course and ultimately to Buena Vista Creek. Hydromodification of the outflows from
the site at POC-1 is accomplished via Tree Well SSD-BMPs (for DMA 1) and via the additional
size of the biofiltration / partial retention treatment pond for DMA 2 through the relatively small
orifice (0.25” diameter) on the underdrain from the pond.
Point of Compliance No. 2 – existing curb inlet catch basin and 18” RCP down drain to an
existing natural watercourse on the north side of campus. No modifications are proposed to
this drainage structure beyond the connection of the new 18” HDPE and 8” HDPE that convey
water from the site BMPs. The natural drainage course at the bottom of the existing 18” RCP
drain ultimately flows to Buena Vista Creek. Hydromodification at POC-2 is accomplished via
orifice control of the underdrain at BMP B (DMA 3 and DMA 4) as well as the retention of the
tree well SSD-BMP for DMA 5.
All other outflows from the project site are from undisturbed areas and/or are self-mitigating,
and therefore do not require hydromodification control and a named POC.
Has a geomorphic assessment been performed for the receiving channel(s)?
X No, the low flow threshold is 0.1Q2 (default low flow threshold)
Yes, the result is the low flow threshold is 0.1Q2
Yes, the result is the low flow threshold is 0.3Q2
Yes, the result is the low flow threshold is 0.5Q2
If a geomorphic assessment has been performed, provide title, date, and preparer:
Discussion / Additional Information: (optional)
Other Site Requirements and Constraints
When applicable, list other site requirements or constraints that will influence storm water
management design, such as zoning requirements including setbacks and open space, or City
codes governing minimum street width, sidewalk construction, allowable pavement types, and
drainage requirements.
None.
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.
CITY STANDARD PROJECT REQUIREMENT
CHECKLIST
FORM E-36
E-36 Page 1 of 4 Revised 02/22
Development Services
Land Development Engineering
1635 Faraday Avenue
442-339-2750
www.carlsbadca.gov
STANDARD PROJECT
REQUIREMENT CHECKLIST
E-36
Project Information
Project Name:
Project ID:
DWG No. or Building Permit No.:
Baseline BMPs for Existing and Proposed Site Features
Complete the Table 1 - Site Design Requirement to document existing and proposed site features and the BMPs to be
implemented for them. All BMPs must be implemented where applicable and feasible. Applicability is generally assumed if a feature exists or is proposed.
BMPs must be implemented for site design features where feasible. Leaving the box for a BMP unchecked means it will not be implemented (either partially or fully) either because it is inapplicable or infeasible. Explanations must be provided in the area below. The table provides specific instructions on when explanations are required.
Table 1 - Site Design Requirement
A.Existing Natural Site Features (see Fact Sheet BL-1)
1.Check the boxes below for each existing feature on
the site.
1.Select the BMPs to be implemented for each identified feature. Explain
why any BMP not selected is infeasible in the area below.
SD-G Conserve natural features
SD-H Provide buffers around waterbodies
Natural waterbodies Natural storage reservoirs & drainage corridors -- Natural areas, soils, & vegetation (incl. trees) --
B.BMPs for Common Impervious Outdoor Site Features (see Fact Sheet BL-2)
1.Check the boxes below for each
proposed feature.
2. Select the BMPs to be implemented for each proposed feature. If neither BMP SD-B nor
SD-I is selected for a feature, explain why both BMPs are infeasible in the area below.
SD-B Direct runoff to pervious areas
SD-I Construct surfaces from permeable materials
Minimize size of impervious areas
Streets and roads Check this box to confirm
that all impervious areas on
the site will be minimized
where feasible.
If this box is not checked,
identify the surfaces that
cannot be minimized in area
below, and explain why it is
Sidewalks & walkways
Parking areas & lots
Driveways
Patios, decks, & courtyards
Hardcourt recreation areas
Hope Elementary School New Classroom Building / Modernization
X
X
PD-2020-0049, GR 2020-049
DWG 528-2A
E-36 Page 2 of 4 Revised 02/22
Other: _______________ infeasible to do so.
C. BMPs for Rooftop Areas: Check this box if rooftop areas are proposed and select at least one BMP
below.
If no BMPs are selected, explain why they are infeasible in the area below.
(see Fact Sheet BL-3)
SD-B Direct runoff to pervious areas
SD-C Install green roofs
SD-E Install rain barrels
D. BMPs for Landscaped Areas: Check this box if landscaping is proposed and select the BMP below
SD-K Sustainable Landscaping
If SD-K is not selected, explain why it is infeasible in the area below.
(see Fact Sheet BL-4)
Provide discussion/justification for site design BMPs that will not be implemented (either partially or fully):
Baseline BMPs for Pollutant-generating Sources
All development projects must complete Table 2 - Source Control Requirement to identify applicable requirements for documenting pollutant-generating sources/ features and source control BMPs.
BMPs must be implemented for source control features where feasible. Leaving the box for a BMP unchecked means it will not be implemented (either partially or fully) either because it is inapplicable or infeasible. Explanations must be provided in the area below. The table provides specific instructions on when explanations are required.
Table 2 - Source Control Requirement
A.Management of Storm Water Discharges
1.Identify all proposed outdoor
work areas below
Check here if none are proposed
2. Which BMPs will be used to preventmaterials from contacting rainfall orrunoff? (See Fact Sheet BL-5)
Select all feasible BMPs for each work area
3.Where will runoff from thework area be routed?
(See Fact Sheet BL-6)
Select one or more option for each
work area SC-A Overhead covering
SC-B Separation flows from adjacent areas
SC-C Wind protection
SC-D Sanitary sewer
SC-E Containment system
Other
Trash & Refuse Storage Materials & Equipment Storage
The school project is approved by the Division of State Architect and the plans were approved with no rooftop BMPsas a part of the plan. However, all roof drainage is collected and diverted to appropriate structural BMPs, either biofiltration with partial retention treatment ponds or tree wells (SSD-BMPs).
The school site was designed and approved by the Division of State Architect prior to requiring water quality requirements, and the site is constrained due to required classrooms and accessibility requirements. The design is incorporating structural BMPs to treat the stormwater from areas indicated above.
X X X X X
X
X
E-36 Page 3 of 4 Revised 02/22
Loading & Unloading Fueling Maintenance & Repair Vehicle & Equipment Cleaning Other: _________________
B.Management of Storm Water Discharges (see Fact Sheet BL-7)
Select one option for each feature below:
•Storm drain inlets and catch basins … are not proposed will be labeled with stenciling or signage to discourage dumping (SC-F)
•Interior work surfaces, floor drains &
sumps …
are not proposed will not discharge directly or indirectly to the MS4 or receiving waters
•Drain lines (e.g. air conditioning, boiler,
etc.) …
are not proposed will not discharge directly or indirectly to the MS4 or receiving waters
•Fire sprinkler test water … are not proposed will not discharge directly or indirectly to the MS4 or receiving waters
Provide discussion/justification for source control BMPs that will not be implemented (either partially or fully):
X
X
X
X
E-36 Page 4 of 4 Revised 02/22
Form Certification
This E-36 Form is intended to comply with applicable requirements of the city’s BMP Design Manual. I certify that it has been completed to the best of my ability and accurately reflects the project being proposed and the applicable BMPs proposed to minimize the potentially negative impacts of this project's land development activities on water quality. I understand and acknowledge that the review of this form by City staff is confined to a review and does not relieve me as the person in charge of overseeing the selection and design of storm water BMPs for this project, of my responsibilities for project design. Preparer Signature: Date:
Print preparer name: Joe Litchfield
6-5-2022
SUMMARY OF PDP STRUCTURAL BMPs
PDP Structural BMPs
All PDPs must implement structural BMPs for storm water pollutant control (see Chapter 5 of
the BMP Design Manual). Selection of PDP structural BMPs for storm water pollutant control
must be based on the selection process described in Chapter 5. PDPs subject to
hydromodification management requirements must also implement structural BMPs for flow
control for hydromodification management (see Chapter 6 of the BMP Design Manual). Both
storm water pollutant control and flow control for hydromodification management can be
achieved within the same structural BMP(s).
PDP structural BMPs must be verified by the City at the completion of construction. This may
include requiring the project owner or project owner's representative to certify construction of
the structural BMPs (see Section 1.12 of the BMP Design Manual). PDP structural BMPs must
be maintained into perpetuity, and the City must confirm the maintenance (see Section 7 of the
BMP Design Manual).
Use this form to provide narrative description of the general strategy for structural BMP
implementation at the project site in the box below. Then complete the PDP structural BMP
summary information sheet for each structural BMP within the project (copy the BMP summary
information page as many times as needed to provide summary information for each individual
structural BMP).
Describe the general strategy for structural BMP implementation at the site. This information
must describe how the steps for selecting and designing storm water pollutant control BMPs
presented in Section 5.1 of the BMP Design Manual were followed, and the results (type of
BMPs selected). For projects requiring hydromodification flow control BMPs, indicate whether
pollutant control and flow control BMPs are integrated together or separate.
The general strategy for selection of structural BMPs on this site had the following challenges in
implementing BMPs:
- the nature of the previously approved State grading plan (Division of State Architect) that
did not originally incorporate water quality or hydromodification requirements
- the site topography has limited relatively flat areas to incorporate infiltration / retention
BMPs
- limited infiltration capacity per geotechnical investigations (Soil Class D)
- preserving multi-use field play areas
- minimize cost and duration of construction due to school schedule
The project site is an existing school campus that is being partially redeveloped for some new
buildings, remove the portable / relocatable buildings, and increase the hardscape play areas for
the students. The general strategy was to implement water quality and hydromodification BMPs
to as minimal extent possible on the usable areas on campus due the high value of the area for
school district and their partners’ use. With how the school site is located in a plateau setting with
slopes on all sides of the campus, the proposed BMPs would need to be located directly on the
relatively flat portion of the campus and could not be located on a slope or within the natural
drainage channel as it would become a treatment for a much larger area (offsite flow) that would
not be practical.
The initial step was to do a site-specific infiltration test in order to determine the potential for
retention of storm water through infiltration. Results of this geotechnical report showed the
potential for infiltration / retention, but at a fairly low rate (less than 0.3 in / hour generally),
resulting in the suggested use of biofiltration with partial retention as the general strategy for
treatment of storm water prior to discharge from the project site.
The desire was to locate the BMPs near the outer edges of the existing campus, and the existing
drainage patterns were difficult to manipulate due to the school’s need for relatively flat slopes as
well as the fact that it was previously approved by the Division of State Architect, so modification
would require changes at the State level as well.
Once the general locations were selected, which were at the existing lower areas of the site prior
to discharge from the site, multiple options were investigated to meet the full water quality and
hydromodification control.
Ultimately, two primary strategies were implemented to meet both of these requirements and
applied to the Drainage Management Areas: Tree Well SSD-BMPs (Significant Site Design Best
Management Practices) as well as Biofiltration with Partial Retention Treatment Ponds (PR-1).
Both BMPs have the ability to treat the proper Design Control Volume as well as provide
hydromodification control. For the Tree Well SSD-BMP, the size of the tree well is increased by a
factor to handle the additional hydromodification requirements. For the Biofiltration with Partial
Retention Pond, the size of the overall pond (storage volume) combined with a controlled outlet
via an orifice on the underdrain allows the BMP to meet the water quality and hydromodification
requirements within the BMP.
A detailed drainage study (hydrology and hydraulics) was prepared to understand the precise flow
locations from the State-approved grading. This allowed for selecting the precise locations of the
BMPs on the site, minimizing impact as much as possible. Further, grading at the locations was
modified to flatten the areas further to maximize the effectiveness of each BMP.
One aspect of this project is that the site is within the 50% rule, meaning that only the project area
requires treatment and hydromodification prior to discharge from the site. The remaining property
(parcel) area that is not disturbed may continue to drain as it previously did. This did inform the
design in that diversion of some of the site drainage structures was modified to direct storm water
to the east vs. the west as it traditionally had done. This does have a two-part positive effect: it
does allow for proper treatment and hydromodification of the diverted water from disturbed areas,
but it also lowers the total flow to the west side of campus that exhibited fairly severe erosion on
the slopes below the campus in the natural drainage watercourse. By diverting the drainage, it
effectively provided some level of hydromodification to the west side of campus. It is not to a pre-
development level, but the side positive impact that is not technically required from the
undisturbed area of campus is noted as a benefit for this project.
Once the Drainage Management Areas (DMAs) and preferred locations were identified, sizing
spreadsheets (County of San Diego Automated Stormwater Pollutant Control Worksheets Version
2.0: B-1, B-2, and B-3; and County of San Diego Automated Worksheets for Significant Site
Design BMPs (SSD-BMP) SD-A Tree Wells Version 1.0: I-1 and I-3) were used to determine the
exact size of ponds and number of tree wells required to meet the full retention, treatment, and
hydromodification parameters. Sizing factors were incorporated into both the tree well SSD-BMPs
as well as the Biofiltration with Partial Retention treatment ponds to create BMPs that serves both
treatment and hydromodification control.
The final layout included Tree Well SSD-BMPs used for DMA 1 and 5, and treatment ponds for
DMAs 2, 3, and 4. The BMPs were designed to be at the lower elevations below the DMAs
treated, and overflow structures incorporated to bypass the 100-year flows to the outlet locations
(Points of Compliance No. 1 and No. 2).
DMA 6 is self-mitigating as it is open, pervious space and not disturbed as a part of this project.
DMA 7 is a small area that drains to the existing northern parking lot (Outflow #3 per the Drainage
report). Since adding a separate BMP for this small area is not readily feasible, the project is
incorporating an equivalent area that is treated within DMA 3 that is an equivalent size on a
portion of the asphalt parking lot that is existing, but will not be disturbed as a part of this project.
The area is treated with the flows from DMA 3 at BMP B.
Structural BMP Summary Information
Structural BMP ID No. A
DWG 528-2A Sheet No. 2, 10
Type of structural BMP:
Retention by harvest and use (HU-1)
Retention by infiltration basin (INF-1)
Retention by bioretention (INF-2)
Retention by permeable pavement (INF-3)
X Partial retention by biofiltration with partial retention (PR-1)
Biofiltration (BF-1)
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)
Detention pond or vault for hydromodification management
Other (describe in discussion section below)
Purpose:
Pollutant control only
Hydromodification control only
X Combined pollutant control and hydromodification control
Pre-treatment/forebay for another structural BMP
Other (describe in discussion section below)
Discussion (as needed):
BMP A treats water from DMA 2. The design storm and parameters are derived from the 85th
percentile 24-hour storm depth as prescribed by the City of Carlsbad BMP Design Manual.
BMP A comprises a biofiltration with partial retention planter. It will be installed just south of the
existing fence of the current campus on school property. Inflow occurs by bypassing the current
catch basin inlet and removing the existing curb that previously created the sump condition for
the old catch basin. Water is dissipated via a gravel energy dissipator and allowed to pool in the
pond surface and naturally infiltrate into the medium and gravel. The 6” HDPE underdrain
carries water to the overflow structure and is installed with a low-flow orifice (0.25” diameter) for
hydromodification control.
The basin is sized per the County of San Diego Automated Stormwater Pollutant Control
Worksheets (B.1, B.2, and B.3) as well as BMP Sizing Spreadsheet V3.1 that includes a
calculation to determine the low-flow orifice for the underdrain.
The pond includes an overflow structure (catch basin) with an 8” outlet pipe that discharges to an
existing catch basin on Tamarack Avenue.
Calculations provide for the following basin parameters:
• Basin FG = 219.00
• 3:1 side slopes
• Basin bottom footprint: 350 sf
• Distance between basin FG to lowest opening in riser structure: 12 inches
• Riser rim elevation: 220.00
• Riser structure type: 12" x 12" Brooks Box (or equivalent)
• 3 inches mulch evenly distributed across basin footprint
• 18 inches engineered soil media
• 6 inches filter course
• 12 inches gravel
• 6-inch diameter perforated underdrain, offset nine inches from bottom of gravel layer
(invert at elevation 216.50)
• Hydromod orifice diameter (placed at interface between underdrain and riser structure):
0.25 inches
Structural BMP Summary Information
Structural BMP ID No. B
DWG 528-2A Sheet No. 4, 10
Type of structural BMP:
Retention by harvest and use (HU-1)
Retention by infiltration basin (INF-1)
Retention by bioretention (INF-2)
Retention by permeable pavement (INF-3)
X Partial retention by biofiltration with partial retention (PR-1)
Biofiltration (BF-1)
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)
Detention pond or vault for hydromodification management
Other (describe in discussion section below)
Purpose:
Pollutant control only
Hydromodification control only
X Combined pollutant control and hydromodification control
Pre-treatment/forebay for another structural BMP
Other (describe in discussion section below)
Discussion (as needed):
BMP B treats water from DMA 3 and 4.
BMP B comprises a biofiltration with partial retention planter. It will be installed on the
southeastern side of the multi-use field just north of BMP C. Inflow is from an 18” HDPE across
a gravel dissipator at the surface of the pond, which is approximately five to seven feet below
adjacent grades on the multi-use field, as well as sheet flow from the newly paved asphalt play
area and a smaller 8” pipe that collects drainage from smaller areas to the west. Slopes on the
side of the pond will be 2:1 minimum and have a fence at the top of the slope to keep people out
of the area. Water is dissipated via a gravel energy dissipator and allowed to pool in the pond
surface and naturally infiltrate into the medium and gravel. The 6” HDPE underdrain carries
water to the overflow structure and is installed with a low-flow orifice (0.75” diameter) for
hydromodification control. An additional 1.75” diameter orifice is cored into the side of the
overflow riser structure at 12” above the basin finished grade.
The pond includes an overflow structure (catch basin) with an 18” outlet pipe that discharges to
an existing curb inlet catch basin at the north side of campus.
Calculations and modeling provide for the following basin parameters:
• Basin FG = 216.00
• 2:1 side slopes
• Basin bottom footprint: 3,204 sf
• Distance between basin FG to lowest opening in riser structure: 12 inches
• Diameter of lowest surface opening in riser structure: 1.75 inches
• Riser rim elevation: 219.08
• Riser structure type: 3-ft x 3-ft Brooks Box (or equivalent)
• 3 inches mulch evenly distributed across basin footprint
• 18 inches engineered soil media
• 12-inch gravel layer with top 6 inches comprised of filter course, bottom 6 inches
comprised of clean washed aggregate
• 6-inch diameter perforated underdrain, offset three inches from bottom of gravel
layer (invert at elevation 213.50)
• Hydromod orifice diameter (placed at interface between underdrain and riser
structure): 0.75 inches
ATTACHMENT 1
ATTACHMENT 1
BACKUP FOR PDP POLLUTANT CONTROL BMPS
Attachment
Sequence
Contents Checklist
Attachment 1a DMA Exhibit (Required)
See DMA Exhibit Checklist on the
back of this Attachment cover sheet.
(24”x36” Exhibit typically required)
X Included
Attachment 1b Tabular Summary of DMAs Showing
DMA ID matching DMA Exhibit, DMA
Area, and DMA Type (Required)*
*Provide table in this Attachment OR
on DMA Exhibit in Attachment 1a
X Included on DMA
Exhibit in Attachment 1a
Included as Attachment 1b,
separate from DMA Exhibit
Attachment 1c Form I-7, Harvest and Use Feasibility
Screening Checklist (Required unless
the entire project will use infiltration
BMPs)
Refer to Appendix B.3-1 of the BMP
Design Manual to complete Form I-7.
Included
X Not included because the
entire project will use infiltration
BMPs
Attachment 1d Form I-8, Categorization of Infiltration
Feasibility Condition (Required unless
the project will use harvest and use
BMPs)
Refer to Appendices C and D of the
BMP Design Manual to complete
Form I-8.
X Included
Not included because the entire
project will use harvest and use
BMPs
Attachment 1e Pollutant Control BMP Design
Worksheets / Calculations (Required)
Refer to Appendices B and E of the
BMP Design Manual for structural
pollutant control BMP design
guidelines
X Included
DMA EXHIBIT