HomeMy WebLinkAboutCDP 2020-0044; GIBSON FAMILY RESIDENCE; STORM WATER QUALITY MANAGEMENT PLAN; 2021-05-17CITY OF CARLSBAD
PRIORITY DEVELOPMENT PROJECT (PDP)
STORM WATER QUALITY MANAGEMENT PLAN (SWQMP)
FOR
ENGINEER OF WORK:
GIBSON RESIDENCE
CDP2020-0044
DWG 530-2A
BRUCE RICE RCE 60676 EXP 12-31-2022 DATE
PREPARED FOR:
Gibson Family Trust
7089 Leeward Street
Carlsbad, CA 92011
760-823-0084
PREPARED BY:
bkA, Inc
land planning, civil engineering, surveying
5115 AVENIDA ENCINAS, SUITE L
CARLSBAD, CA 92008-4387
(760) 931-8700
DATE:
May 17, 2021
W.O. 1101-1456-600
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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, Impervious Area Exhibit
Attachment 1b: Tabular Summary of DMAs and Design Capture Volume Calculations
Attachment 1c: Harvest and Use Feasibility Screening (when applicable)
Attachment 1d: Categorization of Infiltration Feasibility Condition (when applicable)
Attachment 1e: Pollutant Control BMP Design Worksheets / Calculations
Attachment 2: Structural BMP Maintenance Thresholds and Actions
Attachment 3: Single Sheet BMP (SSBMP) Exhibit
Attachment 4: Geotechnical References
Project Name: Gibson Residence
Project ID: CDP2020-0044
CERTIFICATION PAGE
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.
~~ R.C.E. 60676 Exp. 12/31/2022
Engineer of Work's Signature, PE Number & Expiration Date
Bruce Rice
Print Name
bltA, Inc
land planning, civil engineering, suNeying
May 17, 2021
Date
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PROJECT VICINITY MAP
NO SCALE
VICINITY MAP
NOT TO SCALE
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C cityof
Carlsbad
STORM WATER STANDARDS
QUESTIONNAIRE
Development Services
Land Development Engineering
1635 FaradctY Avenue
(760) 602-2750
www.carlsbadca.gov
E-34
I INSTRUCTIONS:
To address post-development pollutants that. may be generated from development projects, the city requires that new
development and sig nifka nt redevelop men! priorrty projects incorporate Perman en! 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 submrtting for a development application
(subdivision, discretionary perm its and/a r construction perm its). The re su Its of the q uestio nna ire 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 e·ither 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 fin al assessment after submission of the d eve lopm en! application. If staff
determines that the questionnaire was incorrectly filled out and is subject to more stringent storm water standards th an
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 dy.
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 sa me project are
submrtted concurrently.
PROJECTINFORMATION
PROJECT NAME: Gibson Family Residence PROJECT ID
ADDRESS: S/W corner of Hillside Drive & Park Drive (new parcel-no address) APN: 206-160-15
The project is (check one):~New Development D Redevelopment
The total proposed disturbed area is: _24 ,1~_ ft2 L0:55_) acres
The total proposed newly created and/or replaced impervious area is: 10,943 fj2 ( 0.25 ) 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 in structions. When completed, sign the form at the end and submit this with your
application to the city._
E-34 Page1 o14 REV 02/16
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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 □ 4 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
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; □ {$ b) Designed and constructed to be hydraulically disconnected from paved streets or roads;
c) Designed and constructed with permeable pavements or surfaces in accordance with USEPA
Green Streets quidance?
2. Retrofitting or redeveloping existing paved alleys, streets, or roads that are designed and constructed in □ f$ accordance with the USEPA Green Streets guidance?
3. Ground Mounted Solar Array that meets the criteria provided in section 1.4.2 of the BMP manual? □ .,
If you answered "yes" to one or more of the above questions, provide discussion/justification below, then go to Step 5, mark
the second box stating "my project is EXEMPT from PDP ... " and complete applicant information.
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 REV04/17
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STEP3
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 surfaces
collectively over the entire project site? This includes commercial, industrial, residential, mixed-use, ~ □ and public development proiects 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 of impervious surface? This includes commercial, industrial, residential, mixed-use, and public
development projects on public or private land.
3. Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more
of impervious surface collectively over the entire project site and supports a restaurant? A restaurant is V 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 impervious
surface collectively over the entire project site and supports a hillside development project? A hillside □ {$
development project includes development on any natural slope that is twenty-five percent or Qreater.
5. Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more
of impervious surface collectively over the entire project site and supports a parking lot? A parking lot is □ ~ a land area or facility for the temporary parking or storage of motor vehicles used personally for
business or for commerce.
6. Is your project a new or redevelopment project that creates and/or replaces 5,000 square feet or more
of impervious street, road, highway, freeway or driveway surface collectively over the entire project □ ~ site? A street, road, highway, freeway or driveway is any paved impervious surface used for the
transportation of automobiles, trucks, motorcycles, and other vehicles.
7. Is your project a new or redevelopment project that creates and/or replaces 2,500 square feet or more
of impervious surface collectively over the entire site, and discharges directly to an Environmentally {$ Sensitive Area (ESA)? "Discharging Directly to" includes flow that is conveyed overland a distance of □ 200 feet or fess 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 comminqfed with flows from adjacent lands).•
8. Is your project a new development or redevelopment project that creates and/or replaces 5,000 square
feet or more of impervious surface that supports an automotive repair shop? An automotive repair □ {$ shop is a facility that is categorized in any one of the following Standard Industrial Classification (SIC)
codes.· 5013, 5014, 5541, 7532-7534, or 7536-7539.
9. Is your project a new development or redevelopment project that creates and/or replaces 5,000 square
feet or more of impervious area that supports a retail gasoline outlet (RGO)? This category includes □ V 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 dav.
10. 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?
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%? (CMC □ ~ 21203.040)
If you answered "yes" to one or more of the above questions, your project is a PDP. If your project is a redevelopment
project, go to step 4. If your project is a new project, go to step 5, check the first box stating "My project is a PDP . "
and complete applicant information.
If you answered "no" to all of the above questions, your project is a 'STANDARD PROJECT.' Go to step 5, check the
second box statinQ "My project is a 'STANDARD PROJECT' ... " and complete applicant information
E-34 Page 3 of 4 REV04/17
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STEP4
TO BE COMPLETED FOR REDEVELOPMENT PROJECTS THAT ARE PRIORITY DEVELOPMENT PROJECTS (PDP)
ONLY
Complete the questions below regarding your redevelopment project (MS4 Permit Provision E.3.b.(2)):
YES NO
Does the redevelopment project result in the creation or replacement of impervious surface in an amount
of less than 50% of the surface area of the previously existing development? Complete the percent
impervious calculation below
Existing impervious area (A) = 000 sq fl. □ ~
Total proposed newly created or replaced impervious area (B) = 10,943 sq. fl.
Percent impervious area created or replaced (B/A)*100 = %
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.
STEPS
CHECK THE APPROPRIATE BOX AND COMPLETE APPLICANT INFORMATION
-4 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 lime of application.
0 My project is a 'STANDARD PROJECT' OR EXEMPT from PDP and must only comply with 'STANDARD PROJECT'
stormwater requirements of the BMP Manual. As part of these requirements, I will submit a "Standard Project
Requirement Checklist Form E-36' and incorporate low impact development strategies throughout my project.
Note: For projects that are close to meeting the PDP threshold, staff may require detailed impervious area calculations
and exhibits to verify if 'STANDARD PROJECT' stormwater requirements apply.
D My Project is NOT a 'development project' and is not subject to the requirements of the BMP Manual.
Applicant Information and Signature Box
Applicant Name Curt Gibson Applicant Title Owner
Applicant Signature: Date:
EnVlronmentally Sensitive Areas include but are not hm1ted to all Clean Water Act Section 303(d) 1mpa1red Vvater bodtes, 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 'Nith the RARE beneficial use by the State Water Resoorces Cootrol 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 Only
YES NO
City Concurrence: □ □
By:
Date:
Project ID:
E-34 Page 4 of 4 REV04/17
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SITE INFORMATION CHECKLIST
Project Summary Information
Project Name GIBSON RESIDENCE.
Project ID Parcel 2 of MS2019-0001, CDP2019-0028
Project Address VACANT LOT
Assessor's Parcel Number(s) (APN(s)) 206-160-15
Project Watershed (Hydrologic Unit) Carlsbad 904
Project Hydrologic Unit Hydrologic Area Select One:
Loma Alta 904.1
Buena Vista Creek 904.2
Agua Hedionda 904.3
Encinas 904.4
San Marcos 904.5
Escondido Creek 904.6
Parcel Area
(total area of Assessor's Parcel(s)
associated with the project)
__0.40_ Acres (__17,548__ Square Feet)
Area to be disturbed by the project
(Project Area)
__0.55_ Acres (__24,144__ Square Feet)
Project Proposed Impervious Area
(subset of Project Area)
__0.25_ Acres (__10,943 _ Square Feet)
Project Proposed Pervious Area
(subset of Project Area)
__0.30__ Acres (_13,201_ Square Feet)
Note: Proposed Impervious Area + Proposed Pervious Area = Area to be Disturbed by the
Project.
This may be less than the Parcel Area.
1:8]
□
□
1:8]
□
□
□
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Description of Existing Site Condition and Drainage Patterns
Current Status of the Site (select all that apply):
Existing development
Previously graded but not built out
Agricultural or other non-impervious use
Vacant, undeveloped/natural
Description / Additional Information:
The existing site is currently vacant and undeveloped.
Existing Land Cover Includes (select all that apply):
Vegetative Cover
Non-Vegetated Pervious Areas
Impervious Areas
Description / Additional Information:
The site is currently a vacant lot.
Underlying Soil belongs to Hydrologic Soil Group (select all that apply):
NRCS Type A
NRCS Type B
NRCS Type C
NRCS Type D
The on-site soil classification is Type A and Type B from the USGS Web Soil Survey.
Approximate Depth to Groundwater (GW):
GW Depth < 5 feet
5 feet < GW Depth < 10 feet
10 feet < GW Depth < 20 feet
GW Depth > 20 feet
□
□
□
~
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Existing Natural Hydrologic Features (select all that apply):
Watercourses
Seeps
Springs
Wetlands
None
Description / Additional Information:
□
□
□
□
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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]:
Storm flows affecting the site are limited to the rainfall that lands directly on the property and an
area south of Hillside Drive along the northerly property line. A concrete spillway constructed
along the southerly curb in Hillside Drive directs 4.93 cfs of offsite flow from a 4.64 acres area
into the property. In the existing condition, the site drains to one (1) Point of Compliance (POC
1) located near the southeast corner of the property, near Park Drive. Surface runoff sheet
flows in a southeasterly direction towards the southeast corner of the property, where flow is
concentrated into an existing natural earthen channel. The lot to the west (Parcel 3 of Parcel
Map 21808) is currently being developed. Runoff from Parcel 3 will be diverted towards the
southwest corner of the property via a graded swale.
The on-site soil classification is Type A and Type B from USGS Web Soil Survey.
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Description of Proposed Site Development and Drainage Patterns
Project Description / Proposed Land Use and/or Activities:
The project proposes the development of single family residential lot with a pool. Proposed
drainage improvements consist of private yard drains and a biofiltration basin to treat the full
Design Capture Volume (DCV) of contributing area and discharge downstream into a 48-inch
storm drain in Hillside Drive at POC 2.
List/describe proposed impervious features of the project (e.g., buildings, roadways, parking
lots, courtyards, athletic courts, other impervious features):
The proposed impervious features of the project include on single family residential structure,
concrete and grouted pavers.
List/describe proposed pervious features of the project (e.g., landscape areas):
The proposed pervious features of the project include landscape areas.
Does the project include grading and changes to site topography?
Yes
No
Description / Additional Information:
Project grading will occur on approximately 0.55 acres of the project. The majority of stormwater
runoff from the project will be intercepted by private yard drains and conveyed into a biofiltration
basin near the northeast corner of the project near the street intersection of Hillside Drive and
Park Drive. The area between Hillside Drive and the graded pad will be graded to drain easterly
via a vegetated swale to a catch basin near the northeast corner of the project. The catch basin,
connected to the outlet storm drain for the biofiltration basin, will convey the runoff to a proposed
18-inch storm drain. The 18-inch storm drain will convey the combined offsite and onsite flow to
POC 2, a 48-inch storm drain in Hillside Drive. The southeast corner of the property, below the
graded pad will be graded to drain to a catch basin, which will convey the runoff to POC 1, a
proposed rip-rap. The graded fill slope along the southerly property line will daylight offsite onto
Parcel 1 per Parcel Map 21808. Post-development site flow will mimic existing drainage
conditions, and will discharge from the site near historical flow rates. See the “Drainage Report
for Gibson Family Residence, Hillside Drive” by BHA, Inc. dated May 2021 for post-development
drainage calculations. Impervious surfaces have been minimized where feasible.
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Does the project include changes to site drainage (e.g., installation of new storm water
conveyance systems)?
Yes
No
Description / Additional Information:
Storm water runoff from the proposed project site is routed to two (2) POCs. POC 1 is located
near the southeast corner of the property and POC 2 is located near the northeast corner of the
property. The proposed project drainage system will convey the collected stormwater into a
biofiltration basin for treatment of the DCV and detention, before releasing it downstream via a
storm drain to POC 2. Approximately 45.3% of the developed site will be impervious.
The project is not subject to hydromodification requirements based on the Hydromodification
Exemption Analysis Study approved by the City of Carlsbad titled “Hydromodification Exemption
Analyses for Select Carlsbad Watersheds” dated September 17, 2015 prepared by Chang
Consultants.
DMA 1 encompasses runoff from the proposed roof of the residential building, landscaping and
impervious areas draining to the biofiltration basin. .
The landscape areas around the residential building will be designed with native and/or drought
tolerant species
See Attachment 1b for qualifying site design BMP calculations.
~
□
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Identify whether any of the following features, activities, and/or pollutant source areas will be
present (select all that apply):
On-site storm drain inlets
Interior floor drains and elevator shaft sump pumps
Interior parking garages
Need for future indoor & structural pest control
Landscape/Outdoor Pesticide Use
Pools, spas, ponds, decorative fountains, and other water features
Food service
Refuse areas
Industrial processes
Outdoor storage of equipment or materials
Vehicle and Equipment Cleaning
Vehicle/Equipment Repair and Maintenance
Fuel Dispensing Areas
Loading Docks
Fire Sprinkler Test Water
Miscellaneous Drain or Wash Water
Plazas, sidewalks, and parking lots
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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):
From the project site, runoff flows to the Agua Hedionda Lagoon and to the Pacific Ocean.
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
Agua Hedionda Lagoon
(904.31)
Indicator bacteria
Invasive Species
Sedimentation/ Siltation
Identification of Project Site Pollutants
Identify pollutants expected 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
Expected from the
Project Site
Also a Receiving
Water Pollutant of
Concern
Sediment
Nutrients
Heavy Metals
Organic Compounds
Trash & Debris
Oxygen Demanding
Substances
Oil & Grease
Bacteria & Viruses
Pesticides
□ ~ ~
□ ~ ~
□ ~ □
□ ~ □
□ ~ ~
□ ~ ~
□ ~ □
□ ~ ~
□ ~ □
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Hydromodification Management Requirements
Do hydromodification management requirements apply (see Section 1.6 of the BMP Design
Manual)?
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):
The majority of the stormwater runoff from the project site is discharged in a natural earthen
channel flowing in a southerly direction along Park Drive. Ultimately the runoff in the natural
earthen channel is intercepted by a storm drain in Park Drive approximately 400 feet to the
south. Based on Section 1.6 of the City of Carlsbad BMP Design Manual, the City has the
discretion to exempt a PDP from hydromodification management requirements if discharge is
conveyed via a concrete lined system to an encased embayment (i.e. lagoon). Pursuant to the
study approved by the City of Carlsbad titled “Hydromodification Exemption Analyses for Select
Carlsbad Watersheds” dated September 17, 2015 prepared by Chang Consultants. The
hydrologic and hydraulic analyses performed showed that the hardened system downstream of
the project draining to the lagoon conveys the 10-year storm event, the discharge point has
proper energy dissipation and the outlet is within the 100-year flood limits.
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
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?
□ □
□
□
□
□
□
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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:
Hydromodification requirements are not required for this project.
□
□
□
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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.
Hydromodification requirements are not required for this project.
Has a geomorphic assessment been performed for the receiving channel(s)?
No, the low flow threshold is 0.1Q2 (default low flow threshold)
Yes, the result is the low flow threshold is 0.1Q2
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)
□
□
□
□
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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
local codes governing minimum street width, sidewalk construction, allowable pavement
types, and drainage requirements.
On-site soil classification from NRCS Web Soil Survey is Type A and Type B. Type A and
Type B soils have relatively high infiltration rates when thoroughly wet.
Infiltration at the proposed biofiltraion basin will increase the potential for geotechnical issues
such as water intrusion and ground settlement. Because the proposed biofiotration basin
cannot be sited adequately away from site structures, improvements, retaining walls,
foundations and top and toe of graded embankments, the biofiltration basin will be lined with
an impermeable liner (BF-1).
Optional Additional Information or Continuation of Previous Sections As Needed
21
C cityof
Carlsbad
STANDARD PROJECT
REQUIREMENT
CHECKLIST
E-36
Project Information
Project Name: Gibson Family Residence
Project ID: Parcel 2 of MS2019-0001, CDP2019-0028
DWG No. or Building Permit No.:
Source Control BMPs
Development Services
Land Development Engineering
1635 Faraday Avenue
(760) 602-2750
www.carlsbadca.gov
All development projects must implement source control BMPs SC-1 through SC-6 where applicable and feasible. See
Chapter 4 and Appendix E.1 of the BMP Design Manual (Volume 5 of City Engineering Standards) for information to
implement source control BMPs shown in this checklist.
Answer each category below pursuant to the following.
• "Yes" means the project will implement the source control BMP as described in Chapter 4 and/or Appendix E.1 of the
Model BMP Design Manual. Discussion/justification is not required.
• "No" means the BMP is applicable to the project but it is not feasible to implement. Discussion/justification must be
provided. Please add attachments if more space is needed.
• "N/A" means the BMP is not applicable at the project site because the project does not include the feature that is
addressed by the BMP (e.g., the project has no outdoor materials storage areas). Discussion/justification may be
provided.
Source Control Requirement I Applied?
SC-1 Prevention of Illicit Discharges into the MS4 I i. Yes I D No ID NIA
Discussion/justification if SC-1 not implemented:
SC-2 Storm Drain Stenciling or Signage I Iii Yes I D No ID NIA
Discussion/justification if SC-2 not implemented:
SC-3 Protect Outdoor Materials Storage Areas from Rainfall, Run-On, Runoff, and Wind I D Yes I D No I Iii N/A Dispersal
Discussion/justification if SC-3 not implemented:
E-36 Page 1 of 4 Revised 09/16
22
Source Control Requirement (continued) Aoolied?
SC-4 Protect Materials Stored in Outdoor Work Areas from Rainfall, Run-On, Runoff, and □ Yes □No Iii N/A Wind Dispersal
Discussion/justification if SC-4 not implemented:
SC-5 Protect Trash Storage Areas from Rainfall, Run-On, Runoff, and Wind Dispersal □Yes □No Iii N/A
Discussion/justification if SC-5 not implemented:
SC-6 Additional BMPs based on Potential Sources of Runoff Pollutants must answer for each source listed below and
identify additional BMPs. (See Table in Aooendix E.1 of BMP Manual for quidance).
□ On-site storm drain inlets Ii] Yes □No □ N/A
□ Interior floor drains and elevator shaft sump pumps □Yes □No Iii NIA
□ Interior parking garages □Yes □No Iii N/A
□ Need for future indoor & structural pest control Iii Yes □No D N/A
□ Landscape/Outdoor Pesticide Use Ill Yes □No D N/A
□ Pools, spas, ponds, decorative fountains, and other water features Ii] Yes □No □ N/A
□ Food service □Yes □No Iii N/A
□ Refuse areas □Yes □No Iii N/A
□ Industrial processes □Yes □No Iii N/A
□ Outdoor storage of equipment or materials □Yes □No Iii N/A
□ Vehicle and Equipment Cleaning □Yes □No Iii N/A
□ Vehicle/Equipment Repair and Maintenance □Yes □No Iii N/A
□ Fuel Dispensing Areas □Yes □No Iii N/A
□ Loading Docks □Yes □No 111 N/A
□ Fire Sprinkler Test Water □Yes □No Iii N/A
□ Miscellaneous Drain or Wash Water □Yes □No Iii N/A
□ Plazas, sidewalks, and parkinQ lots Ill Yes □No D N/A
For "Yes" answers, identify the additional BMP per Appendix E.1. Provide justification for "No" answers.
E-36 Page 2 of 4 Revised 09/16
23
Site Design BMPs
All development projects must implement site design BMPs SD-1 through SD-8 where applicable and feasible. See
Chapter 4 and Appendix E.2 thru E.6 of the BMP Design Manual (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.6 of
the Model BMP Design Manual. Discussion/ justification is not required.
• "No" means the BMPs is applicable to the project but it is not feasible to implement. Discussion/justification must be
provided. Please add attachments if more space is needed
• "N/A" means the BMPs is not applicable at the project site because the project does not include the feature that is
addressed by the BMPs (e.g., the project site has no existing natural areas to conserve). Discussion/justification may be
provided.
Site Design Requirement I Applied?
SD-1 Maintain Natural Drainage Pathways and Hydrologic Features I □Yes I □ No I ii NIA
Discussion/justification if SD-1 not implemented:
SD-2 Conserve Natural Areas, Soils, and Vegetation I D Yes I iii No I □ NIA
Discussion/justification if SD-2 not implemented:
Entire site will be graded as part of proposed preliminary grading plan.
SD-3 Minimize Impervious Area I Ill Yes I □ No I □ NIA
Discussion/justification if SD-3 not implemented:
SD-4 Minimize Soil Compaction I iii Yes I □No ID NIA
Discussion/justification if SD-4 not implemented:
SD-5 Impervious Area Dispersion I Iii Yes I □ No ID NIA
Discussion/justification if SD-5 not implemented:
Runoff from impervious walkway areas will be directed to landscape areas prior to discharging to the
MS4.
E-36 Page 3 of 4 Revised 09/16
24
Site Desian Requirement (continued) I Aoolied?
SD-6 Runoff Collection I Iii Yes I □ No I □ N/A
Discussion/justification if SD-6 not implemented:
SD-7 Landscaping with Native or Drought Tolerant Species I Iii Yes I □ No I □ N/A
Discussion/justification if SD-7 not implemented:
SD-8 Harvestinq and Usinq Precipitation I □Yes I □ No I Iii NIA
Discussion/justification if SD-8 not implemented:
No rain-water harvesting strategies proposed. Harvest and use is considered to be infeasible for the
project site .
E-36 Page 4 of 4 Revised 09/16
25
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 local jurisdiction 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 local jurisdiction 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 (page 3 of this form) 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 or separate.
For the purpose of this SWQMP, the proposed site condition has been divided into (1) Drainage
Management Area (DMA) draining to one biofiltration basin for pollutant control.
On-site soils classification from NRCS Web Soil Survey is Type A and Type B. Type A and Type B soils
have relatively high infiltration rates when thoroughly wet. However, based on the soils report prepared by
Vinje & Middleton, Inc. infiltration at the potential BMP locations will increase the potential for geotechnical
issues such as water intrusion and ground settlement. Because the proposed biofiltration basin cannot be
sited adequately away from site structures, improvements, retaining walls, foundations and top and toe of
graded embankments, the biofiltration basin will be lined with an impermeable liner (BF-1).
A portion of the proposed driveway (251 sf) in the City’s right-of way will be designed as a green street.
Green street infrastructure is an approach to stormwater that provides opportunities for using vegetation,
mulch, soils, and tree wells to provide some stormwater runoff retention into the soil. The proposed green
street area’s runoff will discharge onto a rip-rap and then continue in a vegetated swale. This method of
dispersion will provide opportunity for passive pollutant control before the runoff enters a proposed public
catch basin. In the catch basin, the runoff will confluence with flow from the proposed biofiltration basin.
Afterwards, the combined flow will be conveyed in a proposed 18 inch storm drain to an existing 48 inch
storm drain in Hillside Drive.
26
Structural BMP Summary Information
(Copy this page as needed to provide information for each individual proposed structural
BMP)
Structural BMP ID No. BMP-1
DWG CDP2020-0044 Sheet No. 1
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)
Partial retention by biofiltration with partial retention (PR-1)
Biofiltration (BF-1)
Flow-thru treatment control with prior lawful approval to meet earlier PDP requirements
(provide BMP type/description in discussion section below)
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)
Flow-thru treatment control with alternative compliance (provide BMP type/description in
discussion section below)
Detention pond or vault for hydromodification management
Other (describe in discussion section below)
Purpose:
Pollutant control only
Hydromodification control only
Combined pollutant control and
hydromodification control
Pre-treatment/forebay for another structural
BMP
Other (describe in discussion section below)
Discussion (as needed):
□
□
□
□
□ 1:8]
□
□
□
□
□
1:8]
□
□
□
□
27
ATTACHMENT 1
BACKUP FOR PDP POLLUTANT CONTROL BMPS
This is the cover sheet for Attachment 1.
Check which Items are Included behind this cover sheet:
Attachment
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)
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
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
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.
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
Included
~
□
~
~
□
~ □
~
28
Attachment 1a
DMA Exhibit
8')'6#6'&
59#.'
5&
241,'%6%*#4#%6'4+56+%5
.+�&5+6'&'5+)0
5174%'%10641.$/25
K:\Civil 3D\1456\_GIBSON PROJECT\DWG\SWQMP\1456_SWQMP.dwg, 5/21/2021 10:10:20 AM, DWG To PDF.pc3
( SD-3 ) MINIMIZE IMPERVIOUS AREA
( SD-4 ) MINIMIZE SOIL COMPACTION
( SD-5 ) IMPERVIOUS AREA DISPERSION
( SD-6 ) RUNOFF COLLECTION
! \
\
\
\
\
\
\
\
( SD-7 ) LANDSCAPING WITH NATIVE OR DROUGHT TOLERANT SPECIES
( SC-1 ) PREVENTION OF ILLICIT DISCHARGES INTO THE MS4
( SC-2 ) STORM DRAIN STENCILING AND SIGNAGE
\
I
ADDITIONAL BMPS BASED ON POTENTIAL RUNOFF POLLUTANTS:
( SC-6A) ON-SITE STORM DRAIN INLETS
( SC-6D) NEED FOR FUTURE INDOOR & STRUCTURAL PEST CONTROL
( SC-6E) LANDSCAPE/OUTDOOR PESTICIDE USE
\
\
\
\
I
\
\
\
\
\
\
\
\
( SC-6F) POOLS, SPAS, PONDS, DECORATIVE FOUNTAINS, AND OTHER WATER FEATURES
( SC-6Q) PLAZAS, SIDEWALKS, DRIVEWAYS, AND PARKING LOTS
-. "'4" . . .
. . . -----· . V . V . ,,, .,,,,,,,., .· .
-
LEGEND
DMA NAME
DMA AREA (SQ FT)
DMA BOUNDARY
PROPERTY LINE
----
POINT OF CONCENTRATION
FLOW DIRECTION
ROOF AREA
CONCRETE
PERVIOUS AREA
POOL AND SPA
-----
SYMBOL
OMA-I
16,609 SF
POC 1
-
v22Z21
1:·.<·· .. ·I
I· • • I
[y' Vy' Vy' V 'v Vy' Vy']
PROPOSED BIOFILTRATION BASIN (BF-1) tsSSS8
TYPE "G-1"
CATCH BASIN -------...
TG=74.98
7W 76.50
RETAINING
WALL
19.8" RISER INVERT
9" FREEBOARD
18" AMENDED SOIL MIN. INFILTRAnON RATE
51/HR (HANSON HEIDELBERG CEMENT GROUP
':4-1 BIO-RETENTION SOIL W/COMPOST MIX
#BA, PRODUCT CODE 804G)
6" LOWER ORIFICE
INVERT PONDING DEPTH)
,..--DEEP ROUTED, DENSE, DROUGHT TOLERANT
PLANnNG SUITABLE FOR WELL DRAINED SOIL
PER LANDSCAPE PLAN
•JO MIL LINER NOTE: JO-MIL IMPERMEABLE LINER FOR BIOREJENTION CONFORM TO THE FOLLOWING SPEC/FICA TIONS: SPECIFIC GRA \I/TY (AS1M D792): 1.2
(G/CC, MIN.); JENS/LE (AS1M D882): lJ (LB/IN-WIDTH, MIN); ELONGA TIDN AT BREAK (AS1M D882): JBD (%; MIN); MODULUS (AS1M D882): 30
(LB/IN-WIDTH, MIN.); AND TEAR STRENGTH (AS1M D1DD4): 8 (LB/IN, MIN); SEAM SHEAR STRENGTH (AS1M D882) 58.4 (LB/IN, MIN); SEAM PEEL STRENGTH
(AS1M D882) 15 (LB/IN, IN). SEE COLORADO LINING INTERNATIONAL PVC 30 HTTP: IIWWW.COLORADOLINING.COMIPRODUCTSIPVC.PDF) OR APPROVED EQUAL
BIOFIL TRATION BASIN DETAIL (SECTION c'-c')
NOT TO SCALE
BRUCE L RICE
NO. 80876
C!Vl\.
OF Ct."
I
I
I
I 'fi
I ':--/.1 · I I · .•.• I
I . I a1
I .!':. I
I I
j
PARCEL AREA 0.40ACRES
DISTURBED AREA 0.55 ACRES
PROPOSED IMPERVIOUS AREA 0.25 ACRES
PROPOSED PERVIOUS AREA 0.30ACRES
SOIL lYPE A&B
DEPTH TO GROUNDWATER 10 FEET< GW DEPTH > 20 FEET
1 o· s· o· 1 o· 20' 30'
b~A,lnc.
land planning, civil enginee~ng, survey
5115 AVENIDA ENCINAS
SUITE "L"
CARLSBAD, CA. 92008-4387
(760) 931-8700
SCALE: 1" = 10'
DMAEXHIBIT
GIBSON FAMILY
RESIDENCE
HILLSIDE DRIVE
(PARCEL 2 OF PM 21808)
CITY OF CARLSBAD, CALIFORNIA
SHEET 1 OF 1 SHEETS
29
Attachment 1b
Tabular Summary of DMAs and Design Capture Volume Calculations
Surface Name Surface Type Area (ft
2)
R1 Roof, Concrete Sidewalk and Concrete Driveway 10,834
10,834
Surface Name Surface Type Area (ft
2)
L1 Landscape 5,775
5,775
16,609
65%
B
0.62
0.59
508
DMA Surface Tabulation to Support Biofiltration of Design
Capture Volume (DCV) Determination
DMA Name
– DMA 1
DMA Impervious Area Tabulation
Total Pervious Area (ft2)
Total DMA (A)
Design Capture Volume (DVC) = (C)(I)(A) ∕ 12
Total Impervious Area (ft2) ∕ Total DMA (ft2) = Percent Impervious
Soil Type
DMA Runoff Factor “C” per Appendix B.1 and B.2
85th Percentile Rainfall (I)
Total Impervious Area (ft2)
DMA Pervious Area Tabulation
30
Surface Name Surface Type Area (ft2)
SM1 Landscape 1,471
1,471
Roof 0
PCC 0
0
1,471
0%
Subtotal Pervious Area
Subtotal Impervious Area
Total Self-Mitigating Area
Percent Impervious Area (Not to Exceed 5%)
Tabulation of Self-Mitigating DMAs
Surface Name Surface Type Area (ft2)
SM 2 Landscape 1,965
1,965
Roof 0
PCC 0
0
1,965
0%
Subtotal Impervious Area
Total Self-Mitigating Area
Percent Impervious Area (Not to Exceed 5%)
Tabulation of Self-Mitigating DMAs
Subtotal Pervious Area
31
Surface Name Surface Type Area (ft2)
DMIN 1 Landscape 142
142
Roof 0
PCC 109
109
251
Tabulation of De Minimis Areas
Subtotal Pervious Area
Subtotal Impervious Area
Total De Minimis Area
Percent Impervious Area (Not to Exceed 2% of 1.0% I
32
DMA Classification Quantity Subtotal DMA (ft2)Subtotal DMA (acres)
Self-Mitigating DMAs 2 3,436 0.079
Self-Retaining DMAs 0 0 0.000
Green Streets 1 3,473 0.080
HU-1: Cistern 0 0 0.000
INF-1: Infiltration Basins 0 0 0.000
INF-2: Bioretention 0 0 0.000
INF-3: Permeable Pavement (Pollutant Control) 0 0 0.000
PR-1: Biofiltration with Partial Retention 0 0 0.000
BF-1: Biofiltration 1 16,984 0.390
BF-2: Nutrient Sensitive Media Design 0 0 0.000
BF-3: Proprietary Biofiltration 0 0 0.000
FT-1: Vegetated Swales 0 0 0.000
FT-2: Media Filters 0 0 0.000
FT-3: Sand Filters 0 0 0.000
FT-4: Dry Extended Detention Basin 0 0 0.000
FT-5: Proprietary Flow-thru Treatment Control 0 0 0.000
De Minims DMAs 1 251 0.006
Total Project DMA 3 24,144 0.554
Total Parcel Area 17,548 0.403
Comment:
Summary of DMA Treatment Practices
33
Attachment 1c
Harvest and use is not considered to be infeasible per Form I-7 Checklist
Harvest and Us Feasibility Checklist
Form I-7
1. Is there a demand for harvested water (check all that apply) at the project site that is reliably present during the
wet season?
Toilet and urinal flushing
Landscape irrigation
Other: ______________
2. If there is a demand; estimate the anticipated average wet season demand over a period of 36 hours. Guidance
for planning level demand calculations for toilet/urinal flushing and landscape irrigation is provided in Section
B.3.2.
Modified ETWU = EToWet x [[∑(PF x HA)/E] + SLA] x 0.015
Using an average value for HA over the lot and Low Plant Water Use (per Table B.3-2);
Modified ETWU = 2.7 x [[(0.2 x 13,201)/0.9] + 0] x 0.015
Modified ETWU= 119
Note: Total Landscape Area = 13,201 sf
3. Calculate the DCV using worksheet B-2.1.
DCV = __506 (cubic feet)
3a. Is the 36 hour demand greater
than or equal to the DCV?
Yes / No
3b. Is the 36 hour demand greater than
0.25DCV but less than the full DCV?
Yes / No
3c. Is the 36 hour demand
less than 0.25DCV?
Yes
Harvest and use appears to be
feasible. Conduct more detailed
evaluation and sizing calculations to
confirm that DCV can be used at an
adequate rate to meet drawdown
criteria.
Harvest and use may be feasible.
Conduct more detailed evaluation and
sizing calculations to determine
feasibility. Harvest and use may only
be able to be used for a 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.
Harvest and use is considered
to be infeasible.
~
~
□
-
□ ~ □ ~ ~
34
Is harvest and use feasible based on further evaluation?
Yes, refer to Appendix E to select and size harvest and use BMPs.
No, select alternate BMPs
Harvest and use BMPs are considered infeasible. Drought tolerant landscape, as proposed in SD-7 in Form E-36,
requires low plant water use. Project will implement other LID strategies such as minimizing impervious area and
impervious area dispersion. The full DCV can be treated and detained in the proposed biofiltration basins.
□ ~
35
Attachment 1d
Form I-8, Categorization of Infiltration Feasibility Condition
Infiltration on the Gibson Residence project site is not considered feasible.
See Attachment 4: Geotechnical References
Geotechnical Investigation by Vinje & Middleton Engineering, Inc.
August 18, 2020
36
Attachment 1e
Pollutant Control BMP Design Worksheets / Calculations
37
Category # Description i ii iii iv v vi vii viii ix x Units
1 Drainage Basin ID or Name 1 unitless
2 85th Percentile 24-hr Storm Depth 0.59 inches
3 Impervious Surfaces Not Directed to Dispersion Area (C=0.90) 10,834 sq-ft
4 Semi-Pervious Surfaces Not Serving as Dispersion Area (C=0.30) sq-ft
5 Engineered Pervious Surfaces Not Serving as Dispersion Area (C=0.10) 5,775 sq-ft
6 Natural Type A Soil Not Serving as Dispersion Area (C=0.10) sq-ft
7 Natural Type B Soil Not Serving as Dispersion Area (C=0.14) sq-ft
8 Natural Type C Soil Not Serving as Dispersion Area (C=0.23) sq-ft
9 Natural Type D Soil Not Serving as Dispersion Area (C=0.30) sq-ft
10 Does Tributary Incorporate Dispersion, Tree Wells, and/or Rain Barrels? No No No No No No No No No No yes/no
11 Impervious Surfaces Directed to Dispersion Area per SD-B (Ci=0.90) sq-ft
12 Semi-Pervious Surfaces Serving as Dispersion Area per SD-B (Ci=0.30) sq-ft
13 Engineered Pervious Surfaces Serving as Dispersion Area per SD-B (Ci=0.10) sq-ft
14 Natural Type A Soil Serving as Dispersion Area per SD-B (Ci=0.10) sq-ft
15 Natural Type B Soil Serving as Dispersion Area per SD-B (Ci=0.14) sq-ft
16 Natural Type C Soil Serving as Dispersion Area per SD-B (Ci=0.23) sq-ft
17 Natural Type D Soil Serving as Dispersion Area per SD-B (Ci=0.30) sq-ft
18 Number of Tree Wells Proposed per SD-A #
19 Average Mature Tree Canopy Diameter ft
20 Number of Rain Barrels Proposed per SD-E #
21 Average Rain Barrel Size gal
22 Total Tributary Area 16,609 0 0 0 0 0 0 0 0 0 sq-ft
23 Initial Runoff Factor for Standard Drainage Areas 0.62 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 unitless
24 Initial Runoff Factor for Dispersed & Dispersion Areas 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 unitless
25 Initial Weighted Runoff Factor 0.62 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 unitless
26 Initial Design Capture Volume 506 0 0 0 0 0 0 0 0 0 cubic-feet
27 Total Impervious Area Dispersed to Pervious Surface 0 0 0 0 0 0 0 0 0 0 sq-ft
28 Total Pervious Dispersion Area 0 0 0 0 0 0 0 0 0 0 sq-ft
29 Ratio of Dispersed Impervious Area to Pervious Dispersion Area n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a ratio
30 Adjustment Factor for Dispersed & Dispersion Areas 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 ratio
31 Runoff Factor After Dispersion Techniques 0.62 n/a n/a n/a n/a n/a n/a n/a n/a n/a unitless
32 Design Capture Volume After Dispersion Techniques 506 0 0 0 0 0 0 0 0 0 cubic-feet
33 Total Tree Well Volume Reduction 0 0 0 0 0 0 0 0 0 0 cubic-feet
34 Total Rain Barrel Volume Reduction 0 0 0 0 0 0 0 0 0 0 cubic-feet
35 Final Adjusted Runoff Factor 0.62 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 unitless
36 Final Effective Tributary Area 10,298 0 0 0 0 0 0 0 0 0 sq-ft
37 Initial Design Capture Volume Retained by Site Design Elements 0 0 0 0 0 0 0 0 0 0 cubic-feet
38 Final Design Capture Volume Tributary to BMP 506 0 0 0 0 0 0 0 0 0 cubic-feet
False
False
Automated Worksheet B.1: Calculation of Design Capture Volume (V2.0)
Dispersion
Area, Tree
Well & Rain
Barrel Inputs
(Optional)
Standard
Drainage
Basin Inputs
Results
Tree & Barrel
Adjustments
Initial Runoff
Factor
Calculation
Dispersion
Area
Adjustments
No Warning Messages
38
Category # Description i ii iii iv v vi vii viii ix x Units
1 Drainage Basin ID or Name 1 - - - - - - - - - unitless
2 85th Percentile Rainfall Depth 0.59 - - - - - - - - - inches
3 Predominant NRCS Soil Type Within BMP Location A unitless
4 Is proposed BMP location Restricted or Unrestricted for Infiltration Activities? Restricted unitless
5 Nature of Restriction Slopes unitless
6 Do Minimum Retention Requirements Apply to this Project? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes yes/no
7 Are Habitable Structures Greater than 9 Stories Proposed? No yes/no
8 Has Geotechnical Engineer Performed an Infiltration Analysis? No yes/no
9 Design Infiltration Rate Recommended by Geotechnical Engineer in/hr
10 Design Infiltration Rate Used To Determine Retention Requirements 0.000 - - - - - - - - - in/hr
11 Percent of Average Annual Runoff that Must be Retained within DMA 4.5% - - - - - - - - - percentage
12 Fraction of DCV Requiring Retention 0.02 - - - - - - - - - ratio
13 Required Retention Volume 10 - - - - - - - - - cubic-feet
False
False
Automated Worksheet B.2: Retention Requirements (V2.0)
Advanced
Analysis
Basic Analysis
Result
No Warning Messages
39
Category # Description i ii iii iv v vi vii viii ix x Units
1 Drainage Basin ID or Name 1 ---------sq-ft
2 Design Infiltration Rate Recommended 0.000 ---------in/hr
3 Design Capture Volume Tributary to BMP 506 ---------cubic-feet
4 Is BMP Vegetated or Unvegetated?Vegetated unitless
5 Is BMP Impermeably Lined or Unlined?Lined unitless
6 Does BMP Have an Underdrain?Underdrain unitless
7 Does BMP Utilize Standard or Specialized Media?Standard unitless
8 Provided Surface Area 375 sq-ft
9 Provided Surface Ponding Depth 6 inches
10 Provided Soil Media Thickness 18 inches
11 Provided Gravel Thickness (Total Thickness)12 inches
12 Underdrain Offset 3 inches
13 Diameter of Underdrain or Hydromod Orifice (Select Smallest)6.00 inches
14 Specialized Soil Media Filtration Rate in/hr
15 Specialized Soil Media Pore Space for Retention unitless
16 Specialized Soil Media Pore Space for Biofiltration unitless
17 Specialized Gravel Media Pore Space unitless
18 Volume Infiltrated Over 6 Hour Storm 0 0 0 0 0 0 0 0 0 0 cubic-feet
19 Ponding Pore Space Available for Retention 0.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 unitless
20 Soil Media Pore Space Available for Retention 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 unitless
21 Gravel Pore Space Available for Retention (Above Underdrain)0.00 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 unitless
22 Gravel Pore Space Available for Retention (Below Underdrain)0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 unitless
23 Effective Retention Depth 2.10 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 inches
24 Fraction of DCV Retained (Independent of Drawdown Time)0.13 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 ratio
25 Calculated Retention Storage Drawdown Time 120 0 0 0 0 0 0 0 0 0 hours
26 Efficacy of Retention Processes 0.15 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 ratio
27 Volume Retained by BMP (Considering Drawdown Time)76 0 0 0 0 0 0 0 0 0 cubic-feet
28 Design Capture Volume Remaining for Biofiltration 430 0 0 0 0 0 0 0 0 0 cubic-feet
29 Max Hydromod Flow Rate through Underdrain 1.4948 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 cfs
30 Max Soil Filtration Rate Allowed by Underdrain Orifice 172.21 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 in/hr
31 Soil Media Filtration Rate per Specifications 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00 in/hr
32 Soil Media Filtration Rate to be used for Sizing 5.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 in/hr
33 Depth Biofiltered Over 6 Hour Storm 30.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 inches
34 Ponding Pore Space Available for Biofiltration 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 unitless
35 Soil Media Pore Space Available for Biofiltration 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 unitless
36 Gravel Pore Space Available for Biofiltration (Above Underdrain)0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 unitless
37 Effective Depth of Biofiltration Storage 13.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 inches
38 Drawdown Time for Surface Ponding 1 0 0 0 0 0 0 0 0 0 hours
39 Drawdown Time for Effective Biofiltration Depth 3 0 0 0 0 0 0 0 0 0 hours
40 Total Depth Biofiltered 43.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 inches
41 Option 1 - Biofilter 1.50 DCV: Target Volume 644 0 0 0 0 0 0 0 0 0 cubic-feet
42 Option 1 - Provided Biofiltration Volume 644 0 0 0 0 0 0 0 0 0 cubic-feet
43 Option 2 - Store 0.75 DCV: Target Volume 322 0 0 0 0 0 0 0 0 0 cubic-feet
44 Option 2 - Provided Storage Volume 322 0 0 0 0 0 0 0 0 0 cubic-feet
45 Portion of Biofiltration Performance Standard Satisfied 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 ratio
46 Do Site Design Elements and BMPs Satisfy Annual Retention Requirements?Yes ---------yes/no
47 Overall Portion of Performance Standard Satisfied (BMP Efficacy Factor)1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 ratio
48 Deficit of Effectively Treated Stormwater 0 n/a n/a n/a n/a n/a n/a n/a n/a n/a cubic-feet
Biofiltration
Calculations
False
False
False
False
Result
False
False
No Warning Messages
Retention
Calculations
Automated Worksheet B.3: BMP Performance (V2.0)
False
False
BMP Inputs
40
ATTACHMENT 2
BACKUP FOR PDP HYDROMODIFICATION CONTROL MEASURES
Project is not subject to Hydromodification requirements.
41
ATTACHMENT 3
Structural BMP Maintenance Information
Use this checklist to ensure the required information has been included in the Structural
BMP Maintenance Information Attachment:
Preliminary Design/Planning/CEQA level submittal:
Attachment 3 must identify:
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)
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)
Manufacturer and part number for proprietary parts of structural BMP(s) when
applicable
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.)
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
42
Draft Maintenance Agreement
I. Purpose and Scope
This section was prepared based on the Chapter 7 of City of Carlsbad BMP Design Manual The
goal is to insure that the Project proponent accepts responsibility for all facilities maintenance,
repair, and replacement from the time they are constructed until the ownership and maintenance
responsibilities is formally transferred to the new owner. Facilities shall be maintained in perpetuity
and comply with the City’s self-inspection, reporting, and verification requirements.
II. Inspection, Maintenance Log and Self-Verification Forms
Fill the forms on the following pages for each BMP using the maintenance schedule here and the
inspection-maintenance checklists in Section VII. These forms shall be signed by the responsible
party and retained for at least (5) years. Use the DMA Exhibit for the location of BMPs. (Make
duplicate copies of these forms and fill out those, not the original ones.)
III. Updates, Revisions and Errata
This maintenance plan is a living document and based on the changes made by maintenance
personnel, such as replacement of mechanical equipment, addition maintenance procedure shall
be added and maintenance plan shall be kept up to date.
Please add the revisions and updates to the maintenance plan to this section if any, these
revisions maybe transmitted to the City at any time. However, at a minimum, updates to the
maintenance plan must accompany the annual inspection report.
IV. Introduction
The Gibson Family Residence project is a 0.56-acre project that includes the development of
single family residential structure and pool. The project is located at southwest corner of street
intersection of Hillside Drive and Park Drive.
Storm flows affecting the site are limited to the rainfall that lands directly on the property and an
area south of Hillside Drive along the northerly property line. The project drains to one (1) Point
of Compliance (POC 1) located near the southeast corner of the property, near Park Drive.
Surface runoff sheet flows in a southeasterly direction towards the southeast corner of the
property, where flow is concentrated into an existing natural earthen channel. The lot to the
west (Parcel 3 of Parcel Map 21808) is currently being developed. Runoff from Parcel 3 will be
diverted towards the southwest corner of the property via a graded swale.
The on-site soil classification is Type A and Type B from USGS Web Soil Survey.
The majority of stormwater runoff from the project will be intercepted by private yard drains and
conveyed into a biofiltration basin near the northeast corner of the project near the street
intersection of Hillside Drive and Park Drive. The area between Hillside Drive and the graded
43
pad will be graded to drain easterly via a vegetated swale to a catch basin near the northeast
corner of the project. The catch basin will convey the intercepted runoff to a 48-inch storm drain
in Hillside Drive. The southeast corner of the property, below the graded pad will be graded to
drain to a catch basin that is connected to the outlet storm drain for the biofiltration basin. The
graded fill slope along the southerly property line will daylight offsite onto Parcel 1 per Parcel Map
21808. Post-development site flow will mimic existing drainage conditions, and will discharge
from the site near historical flow rates. See the “Drainage Report for Gibson Family Residence,
Hillside Drive” by BHA, Inc. dated November 2020 for post-development drainage calculations.
Impervious surfaces have been minimized where feasible.
V. Responsibility for Maintenance
A. General
Owner will enter into a Stormwater Facilities Maintenance Agreement (SWFMA) with the City
of Carlsbad to maintain designated facilities herein this section for the Gibson Family
Residence Project.
The SWFMA will serve as the mechanism to ensure that proper inspection and maintenance
is done in an efficient and timely manner.
Responsible Party/Owner
Gibson Family Trust
7089 Leeward Street
Carlsbad, CA 92011
(619) 823-0084
Owner will have the direct responsibility for maintenance of Stormwater controls.
Whenever the property is sold and whenever designated individual change, immediately the
updated contact information must be provided to the City of Carlsbad.
B. Staff Training Program
Staff training and education program shall be carried out twice a year, once prior to the rainy
season (October 1st) and once during the early dry season (April 30th).
The inspection and maintenance training program consists of the operation and function of
the biofiltration basin. Please refer to the BMP Maintenance Fact Sheet for biofiltration basin
for fact sheets and checklists.
It is the responsibility of Owner to convey the maintenance and inspection information to the
employees. Maintenance personnel must be qualified to properly maintain stormwater
management facilities. Inadequately trained personnel can cause additional problems
resulting in additional maintenance costs.
44
C. Records
Owner shall retain education, inspection, and maintenance forms and documents for at least
five (5) years.
D. Safety
Keep safety considerations at the forefront of inspection procedures at all times. Likely
hazards should be anticipated and avoided. Never enter a confined space (outlet structure,
manhole, etc) without proper training or equipment. A confined space should never be
entered without at least one additional person present.
If a toxic or flammable substance is discovered, leave the immediate area and contact the
local Sheriff at 911.
Potentially dangerous (e.g., fuel, chemicals, hazardous materials) substances found in the
areas must be referred to the local Sheriff’s Office immediately for response by the Hazardous
Materials Unit. The emergency contact number is 911.
Vertical drops may be encountered in areas located within and around the facility. Avoid
walking on top of retaining walls or other structures that have a significant vertical drop
VI. Summary of Drainage Areas and Stormwater Facilities
A. Drainage Areas
The proposed project drainage system will convey the collected stormwater into a biofiltration
basin for treatment of the DCV and detention, before releasing it downstream via a storm drain
to POC 1. Treated flow from the biofiltration basin will be released downstream into an existing
earthen channel with a rip rap energy dissipater.
DMA 1 encompasses the majority of the grading pad. Proposed roof runoff from the single
family residential structure, adjacent landscaping and impervious areas drain into the
biofiltration basin via a private storm drain system.
B. Treatment and Flow-Control Facilities
Stormwater runoff will be treated by the biofiltration basins. Flows will discharge from the
biofiltration cells via an orifice outlet within the gravel layer or surface slots within the riser
structure. The top of the riser will act as a spillway, such that peak flows can be safely
discharged to the receiving storm drain system. A perforated under-drain pipe will be located
at the bottom of the basins and will connect to the proposed storm drain system. Treated flow
45
from the biofiltration basin will be released downstream into an existing earthen channel with
a rip rap energy dissipater.
See the DMA Exhibit for the location of BMPs.
VII. Facility Documentation
Please see the following pages regarding the BMPs details and maintenance fact sheets.
VIII. Maintenance Schedule and Checklist
Fill out the Checklists in the following pages for each BMP. The required maintenance activities
are at the end of this section. At the discretion of the Project proponent, a qualified Stormwater
company may be hired to perform the required inspection and maintenance and provide
necessary reports.
46
BMP MAINTENANCE FACT SHEET
FOR
STRUCTURAL BMP BF-1 BIOFILTRATION
BF-1
Biofiltration
Biofiltration facilities are vegetated surface water systems that filter water through vegetation, and soil or
engineered media prior to discharge via underdrain or overflow to the downstream conveyance system.
Biofiltration facilities have limited or no infiltration. They are typically designed to provide enough hydraulic head
to move flows through the underdrain connection to the storm drain system. Typical biofiltration components
include:
• Inflow distribution mechanisms (e.g., perimeter flow spreader or filter strips)
• Energy dissipation mechanism for concentrated inflows (e.g., splash blocks or riprap)
• Shallow surface ponding for captured flows
• Side slope and basin bottom vegetation selected based on climate and ponding depth
• Non-floating mulch layer
• Media layer (planting mix or engineered media) capable of supporting vegetation growth
• Filter course layer consisting of aggregate to prevent the migration of fines into uncompacted native soils
or the aggregate storage layer
• Aggregate storage layer with underdrain(s)
• Impermeable liner or uncompacted native soils at the bottom of the facility
• Overflow structure
Normal Expected Maintenance
Biofiltration requires routine maintenance to: remove accumulated materials such as sediment, trash or debris;
maintain vegetation health; maintain infiltration capacity of the media layer; replenish mulch; and maintain
integrity of side slopes, inlets, energy dissipators, and outlets. A summary table of standard inspection and
maintenance indicators is provided within this Fact Sheet.
Non-Standard Maintenance or BMP Failure
If any of the following scenarios are observed, the BMP is not performing as intended to protect downstream
waterways from pollution and/or erosion. Corrective maintenance, increased inspection and maintenance, BMP
replacement, or a different BMP type will be required.
• The BMP is not drained between storm events. Surface ponding longer than approximately 24 hours
following a storm event may be detrimental t o vegetation health, and surface ponding longer than
approximately 96 hours following a storm event poses a risk of vector (mosquito) breeding. Poor drainage
can result from clogging of the media layer, filter course, aggregate storage layer, underdrain, or outlet
structure. The specific cause of the drainage issue must be determined and corrected.
• Sediment, trash, or debris accumulation greater than 25% of the surface ponding volume within one
month. This means the load from the tributary drainage area is too high, reducing BM P function or
clogging the BMP. This would require pretreatment measures within the tributary area draining to the
BMP to intercept the materials. Pretreatment components, especially for sediment, will extend the life of
components that are more expensive to replace such as media, filter course, and aggregate layers.
• Erosion due to concentrated storm water runoff flow that is not readily corrected by adding erosion
control blankets, adding stone at flow entry points, or minor re-grading to restore proper drainage
according to the original plan. If the issue is not corrected by restoring the BMP to the original plan and
grade, the [City Engineer] shall be contacted prior to any additional repairs or reconstruction.
BF-1 Page 1 of 11
January 12, 2017
47
Other Special Considerations
BF-1
Biofiltration
Biofiltration is a vegetated structural BMP. Vegetated structural BMPs that are constructed in the vicinity of, or
connected to, an existing jurisdictional water or wetland could inadvertently result in creation of expanded waters
or wetlands. As such, vegetated structural BMPs have the potential to come under the jurisdiction of the United
States Army Corps of Engineers, SDRWQCB, California Department of Fish and Wildlife, or the United States Fish
and Wildlife Service. This could result in the need for specific resource agency permits and costly mitigation to
perform maintenance of the structural BMP. Along with proper placement of a structural BMP, routine
maintenance is key to preventing this scenario.
BF-1 Page 2 of 11
January 12, 2017
48
BF-1
Biofiltration
SUMMARY OF STANDARD INSPECTION AND MAINTENANCE FOR BF-1 BIOFILTRATION
The property owner is responsible to ensure inspection, operation and maintenance of permanent BM Ps on their property unless responsibility has been formally transferred to
an agency, community facilities district, homeowners association, property owners association, or other special district.
Maintenance frequencies listed in this table are average/typical frequencies. Actual maintenance needs are site-specific, and maintenance may be required more frequently.
Maintenance must be performed whenever needed, based on maintenance indicators presented in this table. The BMP owner is responsible for conducting regular inspections
to see when maintenance is needed based on the maintenance indicators. During the first year of operation of a structural BMP, inspection is recommended at least once prior
t o August 31 and then monthly from September through May. Inspection during a storm event is also recommended. After the initial period of frequent inspections, the
minimum inspection and maintenance frequency can be determined based on the results of the first year inspections.
Threshold/Indicator Maintenance Action Typical Maintenance Frequency
Accumulation of sediment, litter, or debris Remove and properly dispose of accumulated materials, • Inspect monthly. If the BMP is 25% full' or more in
without damage to the vegetation or compaction of the one month, increase inspection frequency to monthly
media layer. plus after every 0.1-inch or larger storm event.
• Remove any accumulated materials found at each
inspection.
Obstructed inlet or outlet structure Clear blockage. • Inspect monthly and after every 0.5-inch or larger
storm event.
• Remove any accumulated materia Is found at each
inspection.
Damage to structural components such as weirs, inlet or Repair or replace as applicable • Inspect annually.
outlet structures • Maintenance when needed.
Poor vegetation establishment Re-seed, re-plant, or re-establish vegetation per original • Inspect monthly.
plans. • Maintenance when needed.
Dead or diseased vegetation Remove dead or diseased vegetation, re-seed, re-plant, • Inspect monthly.
or re-establish vegetation per original plans. • Maintenance when needed.
Overgrown vegetation Mow or trim as appropriate. • Inspect monthly.
• Maintenance when needed.
2/3 of mulch has decomposed, or mulch has been Remove decomposed fraction and top off with fresh • Inspect monthly.
removed mulch to a total depth of 3 inches. • Replenish mulch annually, or more frequently when
needed based on inspection.
*"25% full" 1s defined as¼ of the depth from the design bottom elevation to the crest of the outflow structure (e.g., 1f the height to the outflow opening 1s 12 inches from the
bottom elevation, then the materials must be removed when there is 3 inches of accumulation -this should be marked on t he outf low structure).
BF-1 Page 3 of 11
January 12, 2017
49
BF-1
Biofiltration
SUMMARY OF STANDARD INSPECTION AND MAINTENANCE FOR BF-1 BIOFILTRATION (Continued from previous page)
Threshold/Indicator
Erosion due to concentrated irrigation flow
Erosion due to concentrated storm water runoff flow
Standing water in BMP for longer than 24 hours
following a storm event
Surface ponding longer than approximately 24 hours
following a storm event may be detrimental to
vegetation health
Presence of mosquitos/larvae
For images of egg rafts, larva, pupa, and adult
mosquitos, see
htt~:awww.mosguito.orgLbiolog~
Underdrain clogged
Maintenance Action
Repair /re-seed/re-plant eroded areas and adjust the
irrigation system.
Repair /re-seed/re-plant eroded areas, and make
appropriate corrective measures such as adding erosion
control blankets, adding stone at flow entry points, or
minor re-grading to restore proper drainage according
to the original plan. If the issue is not corrected by
restoring the BM P to the original plan and grade, the
[City Engineer] shall be contacted prior to any additional
repairs or reconstruction.
Make appropriate corrective measures such as adjusting
irrigation system, removing obstructions of debris or
invasive vegetation, clearing underd rains, or
repairing/replacing clogged or compacted soils.
If moscuitos/larvae are observed: first, immediately
remove any standing water by dispersing to nearby
landscaping: second, make corrective measures as
applicable to restore BMP drainage to prevent standing
water.
If mosquitos persist following corrective measures to
remove standing water, or if the BMP design does not
meet the 96-hour drawdown criteria due to release
rates controlled by an orifice installed on the
underdrain, the [City Engineer] shall be contacted to
determine a solution. A different BMP type, or a Vector
Management Plan prepared with concurrence from the
County of San Diego Department of
Health, may be required.
Clear blockage.
BF-1 Page 4 of 11
January 12, 2017
Environmental
Typical Maintenance Frequency
• Inspect monthly.
• Maintenance when needed.
• Inspect after every 0.5-inch or larger storm event. If
erosion due to storm water flow has been observed,
increase inspection frequency to after every 0.1-inch
or larger storm event.
• Maintenance when needed. If the issue is not
corrected by restoring the BMP to the original plan
and grade, the [City Engineer) shall be contacted prior
to any additional repairs or reconstruction.
• Inspect monthly and after every 0.5-inch or larger
storm event. If stand ing water is observed, increase
inspection frequency to after every 0.1-inch or larger
storm event.
• Maintenance when needed.
• Inspect monthly and after every 0.5-inch or larger
storm event. If mosquitos are observed, increase
inspection frequency to after every 0.1-inch or larger
storm event.
• Maintenance when needed.
• Inspect if standing water is observed for longer than
24-96 hours following a storm event.
• Maintenance when needed.
50
References
American Mosquito Control Association.
http://www.mosguito.org/
California Storm Water Quality Association (CASQA). 2003. Municipal BMP Handbook.
https ://www. casga .org/resou rces/b mp-handbooks/mun ici pa I-b mp-hand book
County of San Diego. 2014. Low Impact Development Ha ndbook.
http://www.sandiegocounty.gov/content/sdc/dpw/watersheds/susmp/lid.html
San Diego County Copermittees. 2016. Model BMP Design Manual, Appendix E, Fact Sheet BF-1.
http://www. p roj ectcl ea nwate r .org/i nde x. p hp ?opti on=com cont en t&view=a rticle &id= 250&1 tern id= 220
BF-1 Page 5 of 11
January 12, 2017
BF-1
Biofiltration
51
Page Intentionally Blank for Double-Sided Printing
BF-1 Page 6 of 11
January 12, 2017
BF-1
Biofiltration
52
Date:
Permit No.:
Property/ Development Name:
Property Address of BMP:
Threshold/Indicator
Accumulation of sediment, litter, or debris
Maintenance Needed?
□ YES
□ NO
□ N/A
Poor vegetation establishment
Maintenance Needed?
□ YES
□ NO
□ N/A
I Inspector: I BMP ID No.:
I APN(s):
Responsible Party Name and Phone Number:
Responsible Party Address:
INSPECTION AND MAINTENANCE CHECKLIST FOR BF-1 BIOFILTRATION PAGE 1 of 5
BF-1
Biofiltration
Maintenance Recommendation Date Description of Maintenance Conducted
D Remove and properly dispose of
accumulated materials, without damage
to the vegetation
D If sediment, litter, or debris accumulation
exceeds 25% of the surface ponding
volume within one month (25%full•),
add a forebay or other pre-treatment
measures within the tributary area
draining to the BMP to intercept the
materials.
□Other/ Comments:
□ Re-seed, re-plant, or re-establish
vegetation per original plans
□Other/ Comments:
'"25%full" is defined as¼ of the depth from the design bottom elevation to the crest of the outflow structure (e.g., if the height to the outflow opening is 12 inches from the
bottom elevation, then the materials must be removed when there is 3 inches of accumulation -this should be marked on the outflow structure).
BF-1 Page 7 of 11
January 12, 2017
53
Date:
Permit No.:
Threshold/Indicator
Dead or diseased vegetation
Maintenance Needed?
□ YES
□ NO
□ N/A
Overgrown vegetation
Maintenance Needed?
□ YES
□ NO
□ N/A
2/3 of mulch has decomposed,
been removed
Maintenance Needed?
□ YES
□ NO
□ N/A
Inspector:
APN(s):
BMP ID No.:
BF-1
Biofiltration
INSPECTION AND MAINTENANCE CHECKLIST FOR BF-1 BIOFILTRATION PAGE 2 of 5
or mulch has
Maintenance Recommendation
□ Remove dead or diseased vegetation, re-
seed, re-plant, or re-establish vegetation
per original plans
□Other/ Comments:
□ Mow or trim as appropriate
□Other/ Comments:
□ Remove decomposed fraction and top off
with fresh mulch to a total depth of 3
inches
D Other/ Comments:
BF-1 Page 8 of 11
January 12, 2017
Date Description of Maintenance Conducted
54
Date: Inspector:
Permit No.: APN(s):
BMP ID No.:
BF-1
Biofiltration
INSPECTION AND MAINTENANCE CHECKLIST FOR BF-1 BIOFILTRATION PAGE 3 of 5
Threshold/Indicator
Erosion due to concentrated irrigation flow
Maintenance Needed?
□ YES
□ NO
□ N/A
Erosion due to concentrated storm water runoff
flow
Maintenance Needed?
□ YES
□ NO
□ N/A
Maintenance Recommendation
□ Repair/re-seed/re-plant eroded areas and
adjust the irrigation system
D Other/ Comments:
□ Repair/re-seed/re-plant eroded areas,
and make appropriate corrective
measures such as adding erosion
control blankets, adding stone at flow
entry points, or minor re-grading to
restore proper drainage according to
the original plan
D If the issue is not corrected by restoring
the BMP to the original plan and grade,
the [City Engineer] shall be contacted
prior to any additional repairs or
reconstruction
□Other/ Comments:
BF-1 Page 9 of 11
January 12, 2017
Date Description of Maintenance Conducted
55
Date: Inspector:
Permit No.: APN(s):
BMP ID No.:
BF-1
Biofiltration
INSPECTION AND MAINTENANCE CHECKLIST FOR BF-1 BIOFILTRATION PAGE 4 of 5
Threshold/Indicator
Obstructed inlet or outlet structure
Maintenance Needed?
□ YES
□ NO
□ N/A
Underdrain clogged (inspect underdrain if
standing water is observed for longer than 24-96
hours following a storm event)
Maintenance Needed?
□ YES
□ NO
□ N/A
Damage to structural components such as weirs,
inlet or outlet structures
Maintenance Needed?
□ YES
□ NO
□ N/A
Maintenance Recommendation
□ Clear blockage
D Other/ Comments:
D Clear blockage
D Other/ Comments:
□ Repair or replace as applicable
□Other/ Comments:
BF-1 Page 10of11
January 12, 2017
Date Description of Maintenance Conducted
56
Date: Inspector:
Permit No.: APN(s):
BMP ID No.:
BF-1
Biofiltration
INSPECTION AND MAINTENANCE CHECKLIST FOR BF-1 BIOFILTRATION PAGE 5 of 5
Threshold/Indicator Maintenance Recommendation Date Description of Maintenance Conducted
Standing water in BMP for longer than 24-96 □ Make appropriate corrective measures
hours following a storm event* such as adjusting irrigation system,
Surface ponding longer than approximately 24 removing obstructions of debris or
invasive vegetation, clearing hours following a storm event may be underdrains, or repairing/replacing detrimental to vegetation health clogged or compacted soils
Maintenance Needed? □Other/ Comments:
□ YES
□ NO
□ N/A
Presence of mosquitos/larvae D Apply corrective measures to remove
standing water in BMP when standing
For images of egg rafts, larva, pupa, and adult water occurs for longer than 24-96
mosquitos, see hours following a storm event.**
http://www.mosg u ito.or g/biology D Other/ Comments:
Maintenance Needed?
□ YES
□ NO
□ N/A
*Surface ponding longer than approximately 24 hours following a storm event may be detrimental to vegetation health, and surface pond mg longer than approximately 96 hours
following a storm event poses a risk of vector (mosqurto) breeding. Poor drainage can result from clogging of the media layer, filter course, aggregate storage layer, underdrain,
or outlet structure. The specific cause of the drainage issue must be determined and corrected.
**If mosquitos persist following corrective measures to remove standing water, or if the BMP design does not meet the 96-hour drawdown criteria due to release rates
controlled by an orifice installed on the underdrain, the [City Engineer] shall be contacted to determine a solution. A different BMP type, or a Vector Management Plan prepared
with concurrence from the County of San Diego Department of Environmental Health, may be required.
BF-1 Page 11 of 11
January 12, 2017
57
ATTACHMENT 3
City standard Single Sheet BMP (SSBMP) Exhibit
8')'6#6'&
59#.'
5&
/#+06'0#0%'+0&+%#6145#0&#%6+105(14
$+1(+.64#6+10$/25
TYPICAL MAINTENANCE INDICATORS TYPICAL MAINTENANCE ACTIONS
ACCUMULATION OF SEDIMENT (OVER 2
INCHES DEEP OR COVERS VEGETATION),
LITTER, OR DEBRIS
REMOVE AND PROPERLY DISPOSE OF
ACCUMULATED MATERIALS WITHOUT
DAMAGE TO THE VEGETATION. CONFIRM
THAT SOIL IS NOT CLOGGING AND THAT THE
AREA DRAINS AFTER STORM EVENT. TILL OR
REPLACE SOIL AS NECESSARY.
POOR VEGETATION ESTABLISHMENT ENSURE VEGETATION IS HEALTHY AND
DENSE ENOUGH TO PROVIDE FILTERING AND
TO PROTECT SOILS FROM EROSION.
REPLENISH MULCH AS NECESSARY (IF LESS
THAN 3 INCHES DEEP), REMOVE FALLEN
LEAVES AND DEBRIS, PRUNE LARGE SHRUBS
OR TREES, AND MOW TURF AREAS.
OVERGROWN VEGETATION-WOODY
VEGETATION NOT PART OF DESIGN IS
PRESENT AND GRASS EXCESSIVELY TALL
(GREATER THAN 10 INCHES)
MOW OR TRIM AS APPROPRIATE, BUT NOT
LESS THAN THE DESIGN HEIGHT OF THE
VEGETATION (TYPICALLY 4-6 INCHES FOR
GRASS). CONFIRM THAT IRRIGATION IS
ADEQUATE AND NOT EXCESSIVE AND THAT
SPRAYS DO NOT DIRECTLY ENTER
OVERFLOW GRATES. REPLACE DEAD PLANTS
AND REMOVE NOXIOUS AND INVASIVE
WEEDS.
EROSION DUE TO CONCENTRATED
IRRIGATION FLOW
REPAIR/RE-SEED ERODED AREAS AND
ADJUST THE IRRIGATION.
EROSION DUE TO CONCENTRATED
STORMWATER RUNOFF FLOW
REPAIR/RE-SEED ERODED AREAS AND MAKE
APPROPRIATE CORRECTIVE MEASURES SUCH
AS ADDING EROSION CONTROL BLANKETS,
ADDING STONE AT ENTRY POINTS, OR
RE-GRADING WHERE NECESSARY. REMOVE
OBSTRUCTIONS AND SEDIMENT
ACCUMULATIONS SO WATER DISPERSES.
STANDING WATER (BMP NOT DRAINING). IF
MOSQUITO LARVAE ARE PRESENT AND
PERSISTENT, CONTACT THE SAN DIEGO
VECTOR CONTROL PROGRAM AT (858)
694-2888. MOSQUITO LARVICIDES SHOULD
BE APPLIED ONLY WHEN ABSOLUTELY
NECESSARY AND THEN ONLY BY A LICENSED
INDIVIDUAL CONTRACTOR.
WHERE THERE IS AN UNDERDRAIN, SUCH AS
IN PLANTER BOXES AND MANUFACTURED
BIOFILTERS, CHECK THE UNDERDRAIN PIPING
TO MAKE SURE IT IS INTACT AND
UNOBSTRUCTED. ABATE ANY POTENTIAL
VECTORS BY FILLING HOLES IN THE GROUND
IN AND AROUND THE BIOFILTER FACILITY
AND BY INSURING THAT THERE ARE NO
AREAS WHERE WATER STANDS LONGER
THAN 96 HOURS FOLLOWING A STORM.
OUTLET INLET OR OUTLET STRUCTURE CLEAR OBSTRUCTIONS.
DAMAGE TO STRUCTURAL COMPONENTS
SUCH AS WEIRS, INLET, OR OUTLET
STRUCTURES
REPAIR OR REPLACE AS APPLICABLE.
BEFORE THE WET SEASON AND AFTER RAIN
EVENTS: REMOVE SEDIMENT AND DEBRIS
FROM SCREENS AND OVERFLOW DRAINS
AND DOWNSPOUTS: ENSURE PUMPS ARE
FUNCTIONING, WHERE APPLICABLE; CHECK
INTEGRITY OF MOSQUITO SCREENS; AND;
CHECK THAT COVERS ARE PROPERLY SEALED
AND LOCKED.
WHERE CISTERNS ARE PART OF THE SYSTEM
1. THE BIOFILTRATION BMPS WILL INCLUDE AMENDED SOILS, SUBSURFACE GRAVEL LAYER,
AND AN UNDERDRAIN.
2. GRATED LIDS ON CATCH BASINS CAN BE REMOVED FOR INSPECTING ALL UNDERGROUND
COMPONENTS THAT REQUIRE INSPECTION AND MAINTENANCE.
3. THE BIOFILTRATION BMPS REQUIRES ROUTINE LANDSCAPE MAINTENANCE USING THE
SAME EQUIPMENT THAT IS USED FOR GENERAL LANDSCAPE MAINTENANCE.
4. REFER TO MAINTENANCE INDICATORS AND ACTIONS TABLE FOR MAINTENANCE
THRESHOLDS AND ACTIONS.
)'0'4#./#+06'0#0%'016'5
K:\Civil 3D\1456\_GIBSON PROJECT\DWG\SWQMP\1456_SWQMP.dwg, 5/21/2021 10:09:15 AM, DWG To PDF.pc3
\
\
I
\
I
\
\
\
' ' ' ' ' '
\
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' ' ' ' ' ' '
\
\
\
I
\
\
\
I
I
\
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\
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I
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\
BMPTABLE
BMP
ID# BMPTYPE SYMBOL CSDBMPDM QUANTITY DRAWING
NO.
SOURCE CONTROL
ON-SITE
CD STORM DRAIN
INLETS
FUTURE
CD INDOOR&
STRUCTURE
PEST CONTROL
LANDSCAPE
CTI /OUTDOOR
PESTICIDE USE
POOLS, SPAS,
PONDS,
DECORATIVE
(I) FOUNTAINS,
AND OTHER
WATER
FEATURES
PLAZAS,
SIDEWALKS,
Cz) DRIVEWAYS
AND PARKING
LOTS
lg SC-6A 23 N/A
SC-6D N/A
SC-6E N/A
SC-6F N/A
SC-6Q 4531 SF N/A
-
SHEET
NO.{S)
1
1
1
1
1
INSPECTION
FREQUENCY
ANNUALLY
ANNUALLY
ANNUALLY
ANNUALLY
ANNUALLY
\
\ .· '.
-----
MAINTENANCE
FREQUENCY
ANNUALLY
ANNUALLY
ANNUALLY
ANNUALLY
ANNUALLY
2
SQ --SO
\
------
2
so --0
so ---
--so so
BMPTABLE
BMP
ID# BMPTYPE SYMBOL CSDBMPDM QUANTITY
LOW IMPACT DESIGN (LID)
SIDEWALK □ ® DRAINS TO
LANDSCAPING
SD-5
ROOF DRAIN ~ ® TO
LANDSCAPING
SD-5
TREATMENT CONTROL
(D BIOFILTRATION ~
BASIN l8iH:)'.;1 BF-1 375SF
CSDBMPDM-COUNTY OF SAN DIEGO BMP DESIGN MANUAL
DRAWING
NO.
N/A
N/A
N/A
SHEET
NO.{S)
1
1
1
INSPECTION
FREQUENCY
ANNUALLY
ANNUALLY
QUARTERLY
MAINTENANCE
FREQUENCY
ANNUALLY
ANNUALLY
ANNUALLY
1 o· 5' o· 1 o· 20' 30' -------SCALE: 1" = 10'
BRUCE L RICE
NO. 80876
C!Vl\.
OF CJ.:
PARTY RESPONSIBLE FOR MAINTENANCE:
NAME GIBSON FAMILY RESIDENCE
ADDRESS S/W CORNER OF HILLSIDE DR.
& PARK DR.
CARLSBAD. CA 92008
PHONE NO. /619) 823-0084
PLAN PREPARED BY:
NAME BRUCE RICE
COMPANY~B~H~A~l~NC~-~-----
ADDRESS 5115AVENIDA ENCINAS
SUITE L
CARLSBAD CA 92008
PHONE NO. /76Dl 931-8700
BMPNOTES:
CONTACT --"'C,.,URL>JTwG,.,IB..,S.,,O..,N'----
SIGNATURE
CERTIFICATION RCE 60676
1. THESE BMPS ARE MANDATORY TO BE INSTALLED PER MANUFACTURER'S
RECOMMENDATIONS OR THESE PLANS.
2. NO CHANGES TO THE PROPOSED BMPS ON THIS SHEET WITHOUT PRIOR
APPROVAL FROM THE CITY ENGINEER.
3. NO SUBSTITUTIONS TO THE MATERIAL OR TYPES OR PLANTING TYPES
WITHOUT PRIOR APPROVAL FROM THE CITY ENGINEER.
4. NO OCCUPANCY WILL BE GRANTED UNTIL THE CITY INSPECTION STAFF
HAS INSPECTED THIS PROJECT FOR APPROPRIATE BMP CONSTRUCTION
AND INSTALLATION.
5. REFER TO MAINTENANCE AGREEMENT DOCUMENT.
6. SEE PROJECT SWMP FOR ADDITIONAL INFORMATION.
b~A,lnc.
BMPEXHIBIT
GIBSON FAMILY
RESIDENCE
HILLSIDE DRIVE
(PARCEL 2 OF PM 21808)
CITY Or CARLSBAD, CALIFORNIA
land planning, civil enginee~ng, survey
5115 AVENIDA ENCINAS
SUITE "L"
CARLSBAD, CA. 92008-4387
(760) 931-8700
SHEET 1 OF 1 SHEETS
58
Attachment 4
Geotechnical References
59
\ID
Vinje & Middleton Engineering, Inc.
GEOTECHNICAL INVESTIGATION
PROPOSED RESIDENTIAL DEVELOPMENT
SOUTHWEST CORNER OF HILLSIDE DRIVE & PARK DRIVE
CARLSBAD, CALIFORNIA
August18,2020
Prepared For:
Curt Gibson
7089 Leeward Street
Carlsbad, CA 92011
Prepared By:
VINJE & MIDDLETON ENGINEERING, INC.
2450 Auto Park Way
Escondido, California 92029
Job #20-178-P
2450 Auto Park Way· Escondido, California 92029 · 760-743-1214 · Fax 760-739-0343
60
TABLE OF CONTENTS
PAGE NO.
I. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
II. SITE DESCRIPTION . . . . . • • . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Ill. PROPOSED DEVELOPMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
IV. SITE INVESTIGATION ............................................ 2
V. GEOTECHNICAL CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
A. Earth Materials . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
B. Groundwater and Surface Drainage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
C. Slope Stability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
D. Regional Geology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
E. Faults/Seismicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
F. Site Classification for Seismic Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
G. Seismic Ground Motion Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
H. Geologic Hazards . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . 7
I. Field and Laboratory Test and Test Results............................ 9
VI. SITE CORROSION ASSESSMENT ................................. 12
VII. HYDRO MODIFICATIONS ........................................ 13
VIII. CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
IX. RECOMMENDATIONS ........................................... 16
A. Grading & Earthwork............................................. 16
B. Footings and Slab-on-Grade Floor Foundations . . . . . . . . . . . . . . . . . . . . . . . 21
C. Soil Design Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
D. Swimming Pool/Spa Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
E. Exterior Concrete Slabs and Flatwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
F. Pavement Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
G. General Recommendations ......................................... 27
X. GEOTECHNICAL ENGINEER OF RECORD (GER) . . . . . . . . . . . . . . . . . . . . 29
XI. LIMITATIONS .................................................. 30
PLATE NO.
Vicinity Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Geotechnical Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
TestPits1-5 ...................................................... 3-7
Geologic Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
61
TABLE OF CONTENTS (continued)
Geologic Cross-Sections • . • . • . . . . . . . . . . . . • . . . • . • . . . . . . . . • . . . . . . . . . . . . . 9
Fault-Epicenter Map . . . . . . . . . . . . . . . • . . . . • • . . . . . . . . . . . • . . • . . . . . . . . . . . • 1 O
FEMA Map ....................•.•..............•............••...•• 11
Tsunami Inundation Map ••..........••.......•......•....•.••.•...... 12
Isolation Joints & Re-Entrant Corner Reinforcement .••...............•..•• 13
Retaining Wall Drain Detail. . . . . . . . . . . . . . . . . . . . . . • • . . . . . . . . . . . . . . . . . . . . 14
Attachment A: U.S. Seismic Design Map
62
GEOTECHNICAL INVESTIGATION
PROPOSED RESIDENTIAL DEVELOPMENT
SOUTHWEST CORNER OF HILLSIDE DRIVE & PARK DRIVE
CARLSBAD, CALIFORNIA
I. INTRODUCTION
The subject property investigated herein consists of a vacant corner lot located southwest
of the intersection of Hillside Drive and Park Drive within the City of Carlsbad. The site
location is shown on a Vicinity Map attached as Plate 1.The approximate site coordinates
are 33. 0 N latitude and 117. 0W longitude.
We understand that the property is planned for the support of a single-family residential
development and associated improvements. Consequently, this investigation was initiated
to determine geotechnical conditions at the site and to ascertain their influence upon the
proposed development. Testing pit digging, soil/rock sampling, and laboratory testing were
among the activities conducted in conjunction with this effort which has resulted in the
grading and foundation recommendations presented in the following sections.
II. SITE DESCRIPTION
A Geotechnical Map, reproduced from the available Precise Grading Plan, showing existing
topographic conditions and the proposed development is attached as Plate 2.The generally
rectangular-shaped lot is characterized by largely natural terrain that descends gently in
a southeasterly direction. Minor fill slopes (2: 1 gradients) that ascend to Hillside Drive and
Park Drive mark the north and east property margins respectively.
Surface areas range from recently brushed to ice plant and weeds. A large protected
Torrey Pine is in the southeast site corner and a large eucalyptus (to be removed) is in the
northeast corner.
Site drainage flows in a southeasterly direction to offsite areas. Offsite drainage from
Hillside Drive is currently directed into the property from a concrete spillway constructed
on the southerly curb line. Site drainage will be improved to disallow offsite runoff from
entering the property. Excessive scouring or erosion is not in evidence.
111. PROPOSED DEVELOPMENT
As shown on Plate 2,much of the property will be utilized for the support of a large
residential dwelling. A small additional dwelling unit (ADU) is planned in the southwesterly
corner of the property. Improvements will include an access driveway from Hillside Drive,
a pool and on-grade flatwork.
\;'1NJE &'_ M IDDLETON [NG!NEUUNG, lNC. • 2-t50 Amo Park \Var • Estondido, Caitfr)rrn;1 92029-1129 • Phone {760) 743-f2 l4
63
GEOTECHNICAL INVESTIGATION
HILLSIDE DRIVE & PARK DRIVE, CARLSBAD, CALIFORNIA
AUGUST 18, 2020
PAGE2
Site grading will consist of remedial grading of on site soils and importing fill soil to construct
a building pad at approximate street elevations. Significant graded embankments are not
planned. Vertical fills will generally approach 10 feet maximum and cuts are currently not
proposed.
Building foundation plans and details are not yet developed. However, future building
construction is expected to consist of a conventional wood-framed structure with exterior
stucco supported on shallow stiff continuous strip and spread pad footings, and slab-on-
grade floor foundations.
IV. SITE INVESTIGATION
Geotechnical and subsurface conditions at the property were chiefly determined by the
excavation of 5 test pits dug with a track-mounted John Deere excavator. All the test pit
excavations were logged by our project geologist who also directed sampling of
representative soil and rock for laboratory testing.
Test pit locations are indicated on the Geotechnical Map, Plate 2. Logs of the test pits are
included as Plates 3-7. Laboratory test results of selected samples are provided in a
following section.
V. GEOTECHNICAL CONDITIONS
The study property consists of largely natural, gentle terrain underlain at shallow depths
by sandstone deposits. The Geologic Map of the San Diego 30' x 60' Quadrangle,
California (Michael P. Kennedy and Siang S. Tan, 2008) indicates the site is underlain by
the Eocene age Santiago Formation as shown on Plate 8. However, site specifically, the
property is underlain by Pleistocene age Old Paralic Deposits typical of Carlsbad coastal
areas. The Santiago Formation is expected to occur at depth beneath the Old Paralic
Deposits.
Geologic Cross-Sections depicting subsurface conditions and the proposed development
are included as Plate 9. The following earth materials are recognized :
A. Earth Materials
Old Paralic Deposits (Qop2-4): The project property is underlain at shallow
depths by Old Paralic Deposits dominated by fine-grained sandstone. Site
sandstone deposits were typically found in massive, weathered friable, and medium
dense conditions in upper exposures becoming moderately cemented and uniformly
dense at depth. Clay-bearing sandstone deposits were locally encountered, and are
expected to be in minor quantities overall.
64
GEOTECHNICAL INVESTIGATION
HILLSIDE DRIVE & PARK DRIVE. CARLSBAD, CALIFORNIA
AUGUST 18, 2020
PAGE3
Project dense Old Paralic Deposits are considered stable and competent deposits
that will provide adequate support for new fills, structures, and improvements.
Topsoil: Site Old Paralic Deposits are mantled by a relatively thin layer of topsoil.
The topsoil typically consists of silty fine sand that was found in very dry to damp,
loose, and root-laden conditions overall.
Site surficial soils and weathered loose Old Paralic Deposits are not suitable for
structural support in their present condition and should be removed and reworked
as recommended in following sections.
B. Groundwater and Surface Drainage
Subsurface water was not encountered in our test pits to the depths explored and
is not expected to impact the future performance of the graded building pad.
Drainage will be improved to disallow runoff from street areas onto the site.
Like all graded building sites, the proper control of site surface drainage and efficient
irrigation techniques are critical components to overall stability of the project graded
surfaces and embankments, as well as continued performance of the new
developed sites. Surface water should not pond upon graded surfaces, and irrigation
water should not be excessive. All graded embankments should be provided with
brow ditches.
C. Slope Stability
Large slopes are not present, nor are any planned. Existing perimeter fill slopes will
be filled against to create a level building pad at near street level. Consequently,
slope stability will not be a significant geotechnical concern in the site development.
D. Regional Geology
The subject property is located in the Costal Plains subdivision of the Peninsular
Ranges geomorphic province of San Diego. The coastal plain area is characterized
by Pleistocene marine terrace landforms. These surfaces are relatively flat erosional
platforms that were shaped by wave action along former coastlines. The step-like
elevation of the marine terraces was caused by changes in sea level throughout the
Pleistocene by seismic activity along the Rose Canyon Fault Zone located west of
the coastline. The Rose Canyon Fault Zone is one of many northwest trending , sub-
parallel faults and fault zones that traverse the nearby vicinity. Several of these
faults, including the Rose Canyon Fault Zone, are considered active faults. Further
discussion of faulting in regards to the site is provided in the Faults and Seismicity
section of this report.
\!1N)L & ivllDDLETON ENGINEERING. fr-.:c. • .2450 Auw Park \\:1r • Estondido, Cafiforni:i 92029~1229 • P/ioi1l' <_760) 743-J 21 -t
65
GEOTECHNICAL INVESTIGATION
HILLSIDE DRIVE & PARK DRIVE. CARLSBAD. CALIFORNIA
AUGUST 18, 2020
PAGE4
E. Faults/Seismicity
Faults or significant shear zones are not indicated on or near proximity to the project
site.
As with most areas of California, the San Diego region lies within a seismically active
zone; however, coastal areas of the county are characterized by low levels of
seismic activity relative to inland areas to the east. During a 40-year period (1934-
1974), 37 earthquakes were recorded in San Diego coastal areas by the California
Institute of Technology. None of the recorded events exceeded a Richter magnitude
of 3.7, nor did any of the earthquakes generate more than modest ground shaking
or significant damages. Most of the recorded events occurred along various offshore
faults which characteristically generate modest earthquakes.
Historically, the most significant earthquake events which affect local areas originate
along well known, distant fault zones to the east and the Coronado Bank Fault to the
west. Based upon available seismic data, compiled from California Earthquake
Catalogs, the most significant historical event in the area of the study site occurred
in 1800 at an estimated distance of 10.5 miles from the project area. This event,
which is thought to have occurred along an offshore fault, reached an estimated
magnitude of 6.5 with estimated bedrock acceleration values of 0.125g at the project
site. The following list represents the most significant faults which commonly impact
the region. Estimated ground acceleration data compiled from Digitized California
Faults (Computer Program EQ Fault Version 3.00 updated) typically associated with
the fault is also tabulated.
TABLE 1
MAXIMUM
PROBABLE
FAULT ZONE DISTANCE FROM SITE ACCELERATION (R.H.)
Rose Canyon Fault 5.2 Miles 0.241g
Newport-Inglewood Fault 6.0 Miles 0.222g
Elsinore-Julian Fault 24.0 Miles 0.143g
Coronado Bank Fault 21.3 Miles 0.183a
The location of significant faults and earthquake events relative to the study site are
depicted on a Fault -Epicenter Map attached to this report as Plate 10.
VINJE &. ~1l roOLL TON E NG!NU:R1r-..'G, INC.• 1450 Auro P.u:k \Vay• Escondido, C:tli!Ornia 92029-1229 • Phom· (76l)) 743~121-t
66
GEOTECHNICAL INVESTIGATION
HILLSIDE DRIVE & PARK DRIVE, CARLSBAD, CALIFORNIA
AUGUST 18, 2020
PAGES
More recently, the number of seismic events which affect the region appears to have
heightened somewhat. Nearly 40 earthquakes of magnitude 3.5 or higher have been
recorded in coastal regions between January 1984 and August 1986. Most of the
earthquakes are thought to have been generated along offshore faults. For the most
part, the recorded events remain moderate shocks which typically resulted in low
levels of ground shaking to local areas. A notable exception to this pattern was
recorded on July 13, 1986. An earthquake of magnitude 5.3 shook County coastal
areas with moderate to locally heavy ground shaking resulting in $700,000 in
damages, one death, and injuries to 30 people. The quake occurred along an
offshore fault located nearly 30 miles southwest of Oceanside.
A series of notable events shook County areas with a (maximum) magnitude 7.4
shock in the early morning of June 28, 1992. These quakes originated along related
segments of the San Andreas Fault approximately 90 miles to the north. Locally high
levels of ground shaking over an extended period of time resulted; however,
significant damages to local structures were not reported. The increase in
earthquake frequency in the region remains a subject of speculation among
geologists; however, based upon empirical information and the recorded seismic
history of County areas, the 1986 and 1992 events are thought to represent the
highest levels of ground shaking which can be expected at the study site as a result
of seismic activity.
In recent years, the Rose Canyon Fault has received added attention from
geologists. The Rose Canyon Fault is a significant structural feature in metropolitan
San Diego which is characterized by a complex zone of strike-slip, oblique, reverse,
and normal faults that extend onshore from La Jolla Cove south to San Diego Bay.
Test trenching along the fault in Rose Canyon indicated that at that location the fault
was last active 6,000 to 9,000 years ago. More recent work suggests that segments
of the fault are younger having been last active 1000 -2000 years ago.
Consequently, the fault has been classified as active and included within an Alquist-
Priolo Special Studies Zone established by the State of California. A more recent
study of the Newport-Inglewood I Rose Canyon Fault system concluded that the
coastal region of San Diego may experience earthquakes up to magnitudes 7.3 and
7.4 (Sahakian et al, 2017). Work on the fault system also indicates that 6.5 to 6.8
magnitude earthquakes may occur along the Rose Canyon Fault every 1,000 to
1,500 years
Fault zones tabulated in the preceding table are considered most likely to impact the
region of the study site during the lifetime of the project. The faults are periodically
active and capable of generating moderate to locally high levels of ground shaking
at the site. Ground separation as a result of seismic activity is not expected at the
property.
67
GEOTECHNICAL INVESTIGATION
HILLSIDE DRIVE & PARK DRIVE, CARLSBAD, CALIFORNIA
F. Site Classification for Seismic Design
AUGUST 18, 2020
PAGES
The Site Class is based on the average conditions present within 100 feet of the
ground surface, and are designated as A-F. Class A is classified as hard rock and
Class F as potentially liquefiable or collapsible soils, and is based on shear wave
velocity. For the A and B classification, it is preferable to measure the shear wave
velocity onsite. Site Classes C, D and E can be determined by seismic methods or
typical Standard Penetration Test (SPT-N) results (based on Section 20.4.2 of
ASCE 7-16) conducted during drilling. Site Classification is then established based
on Table 20.3-1 of ASCE 7-16. Site Class Dis typically used conservatively as a
default, unless otherwise noted. However, the Building Code does allow the design
condition to be estimated by a geotechnical engineer, engineering geologist, or
seismologist with knowledge of specific geologic formations and conditions
(considering weathering and fracturing).
G. Seismic Ground Motion Values
Seismic design values were determined as part of this investigation in accordance
with Chapter 16, Section 1613 of the 2019 California Building Code (CBC) and
ASCE 7-16 Standard. Presented values are generated using the web-based
SEAOC/OSHPD (Structural Engineers Association of America/California's Office of
Statewide Health Planning and Development) ground motion calculator. Generated
results at the site are summarized in the enclosed Appendix.
Requirements provided below are also applicable and should be incorporated in the
project design where appropriate:
1. Site specific hazard analysis is required (see Section 11 .4.8) in accordance with
Chapter 21 .2 of ASCE 7-16 for structures on Site Class E sites with values of Ss
greater than or equal to 1.0g, and structures on Site Class D and E sites with
values of S1 greater than or equal to 0.2g. However, the following 3 exceptions
are permitted for Equivalent Lateral Force design (ELF) using conservative
values of seismic design parameters in lieu of performing a site specific ground
motion analysis:
• Structures on Site Class E sites with Ss greater than or equal to 1.0, provided
the site coefficient Fa is taken as equal to that of Site Class C.
V1Nft: & MrnnLJ'TON ENGINU JUNG. !NC.• 2.J50 Auto Park\Vay • Es,ond,do, California 92029-1129 • Phone (i60) i .J..\-121-i
68
GEOTECHNICAL INVESTIGATION
HILLSIDE DRIVE & PARK DRIVE, CARLSBAD, CALIFORNIA
AUGUST 18, 2020
PAGE 7
• For structures on Site Class D sites with S1 greater than or equal to 0.2, a
long period coefficient (Fv) of 1.7 may be utilized for calculation of Ts,
provided that the value of Seismic Response Coefficient (Cs) is determined
by Equation (12.8-2) for values of the fundamental period of the building (T)
less than or equal to 1.5Ts, and taken as 1.5 times the value computed in
accordance with either Equation 12.8-3 for T greater than 1.5 Ts and less
than or equal to TL or Equation 12.8-4 for T greater than TL.
• Structures on Site Class E sites with S1 greater than or equal to 0.2, provided
that Tis less than or equal to Ts and the equivalent static force procedure is
used for the design.
2. Where Site Class B is recommended, and a site specific measurement is not
provided, the site coefficients Fa, Fv, and FPGA shall be taken as unity (1 .0) in
accordance to Section 11.4.3 of ASCE 7-16.
3. Where Site Class D is selected as the default site class per Section 11.4.3 of
ASCE 7-16, the value of Fa shall not be less than 1.2. Where the simplified
procedure of Section 12.4 is used, the value of Fa shall be determined in
accordance with Section 12.14.8.1 , and the values of Fv, SMS and SM1 need not
to be determined.
H. Geologic Hazards
Potential geologic hazards at the project study site were evaluated as part of this
effort in accordance with the Title 24, California Code of Regulations, 2019
California Building Code (CBC) and California Geologic Survey (CGS) Note 48
guidelines:
1. Seismicity: Moderate to locally heavy levels of ground shaking can be
anticipated during rare events along an active fault over the lifetime of the
development. Details of the project's seismic environment are given in a
preceding section.
2. Faulting: Faults or significant shear zones are not indicated within the project
site. The project is not located in proximity to Alquist -Priolo earthquake fault
zone areas associated with active faults discussed above.
3. Flood Inundation: In order to determine general site flooding potential, we
obtained pertinent copies of the available Flood Insurance Rate Map produced
by the Federal Emergency Management Agency (FEMA). According to the
FEMA map, the project site is located in Zone X as depicted on the enclosed
Plate 11. Zone X, by definition, is an area outside the 500-year flood plain.
VJSJE & MIDIH.ElOS EsGINEEIUNG. INC. • 2450 Auw Park War • Escondido, C.,lifornia 92029-1229 • Phone (760 ) 743-1214
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GEOTECHNICAL INVESTIGATION
HILLSIDE DRIVE & PARK DRIVE, CARLSBAD, CALIFORNIA
AUGUST 18, 2020
PAGES
Dams, or other significant water retention structures are not within sufficient
distance to the study site. Site flood inundation, a catastrophic erosion or related
hazards are considered unlikely to remote. Site flooding due to natural sheetflow
or street flooding is also considered remote. The site is in close proximity to the
Aqua Hedionda Lagoon. However, as shown on a Tsunami Inundation Map
included as Plate 12, the site is sufficiently removed from the lagoon, making a
Tsunami or Seiche impacting the site remote.
4. Liquefaction and Seismically Induced Settlements: Soil liquefaction or
related ground failures can adversely impact manmade structures and
improvements at the site where subsoils consist of loose sandy alluvial deposits
inundated with groundwater. Liquefaction is the sudden loss of soil strength in
response to ground shaking during an earthquake event.
The project site is underlain at relatively shallow depths by competent and
medium dense to dense sandstone deposits. In addition, static groundwater
conditions were not encountered to the explored depths. Under these
circumstances, the possibility of liquefaction within the underlying natural
deposits is considered extremely remote to none. Secondary phenomena such
as seismically induced ground settlements, surface manifestation, flow slides
and lateral spread potential are also not indicated.
5. Slope Stability: As detailed in a preceding section, significant slopes are not
present and large new graded embankments are not planned. Consequently,
slope stability is not considered to be a major geotechnical factor in the planned
residential development, as currently proposed.
6. Static Settlement: Static or at-rest settlement of foundation bearing soils is an
important factor in the future performance of the planned new structures. At the
project site underlying dense Old Paralic Deposits are stable and competent
deposits.
Post construction settlement is expected to be within the acceptable tolerances
and are anticipated to be less than approximately 1-inch occurring below the
heaviest loaded footing(s).The magnitude of post construction differential
settlement of site fill deposits, as expressed in terms of angular distortion, is not
anticipated to exceed ½-inch in a distance between similarly loaded adjacent
structural elements, or a maximum distance of 20 feet.
V1NJE & 1v1mD!LlON ENG!NLEIUNC, INC.• 2450 Aut.o P;1rk \\/ar • Escund1do, Californi.1 92029~1229 • Phone (760) 743-1214
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PAGE9
7. Collapsible Soils: Buildings and improvements founded on collapsible soils
may be damaged by sudden and often large induced settlement when these
soils are saturated after construction. Collapsible soils are typified by low values
of dry unit weight and natural water content. The amount of settlement depends
on the applied vertical stresses and the extent of the wetting and availability of
water.
Surficial soils and weathered friable sandstone deposits indicate a potential for
collapsible. However, these deposits are recommended for removal and
recompaction. Consequently, soil collapse is not considered a major
geotechnical concern in the project development.
8. Expansive Soils: Based upon our field observations and laboratory testing,
onsite soils are chiefly sandy deposits with very low expansion potential (per ·
ASTM D4829). However, some low expansive sandstone deposits are locally
present, but expected to be in minor quantities overall. Consequently, expansive
soils are not considered a major geotechnical concern provided our grading and
import recommendations are followed.
I. Field and Laboratory Tests and Test Results
Earth deposits encountered in our exploratory test excavations were closely
examined and sampled for laboratory testing. Based upon our test pit and field
exposures site soils have been grouped into the following soil type:
TABLE 2
Soil Type Description
1 Brown/red brown fine sand-sandstone: T opsoil/01 · ~ . ~ . ,--
The following tests were conducted in support of this investigation:
1. Maximum Dry Density and Optimum Moisture Content: The maximum dry density
and optimum moisture content of Soil Type 1 was determined in accordance with ASTM
D-1557. The results are presented in Table 3.
TABLE3
Soil Maximum Ory Optimum Moisture
Location TvDe Oensitv (Ym-Dcfl Content lwopt-%)
TP-1@ 2' 4 117.5 9.0
VJNJE &. M lDDLElON EM~INEERING, INC.• 2-150 At110 !);nk W1y • Escondido, Cal,fomia 92029-1229 • Phone (760) 7-i3-121+
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GEOTECHNICAL INVESTIGATION AUGUST 18, 2020
PAGE 10 HILLSIDE DRIVE & PARK DRIVE. CARLSBAD, CALIFORNIA
2. Moisture-Density Tests (Undisturbed Chunk Samples): In-place dry density and
moisture content of representative soil deposits beneath the site were determined from
relatively undisturbed chunk samples using the water displacement test method.
Results are presented in Table 4 and tabulated on the attached Test Pit Logs.
TABLE 4
Field Degree
Moisture Field Dry Max. Ory In-Place of
Sample Soil Content Density Density Relative Saturation
Location Type {w-%) (Yd-pcf) {Ym-pcf) Compaction s {%)
TP-1 @ 2' 1 3 101 .0 117.5 86 15
TP-1 @ 4' 1 3 96.6 117.5 82 12
TP-1 @ 5' 1 7 106.9 117.5 91 40
TP-2@ 2' 1 4 95.4 117.5 81 16
TP-2@ 4' 1 8 99.1 117.5 84 36
TP-2@ 5' 1 8 101.5 117.5 86 38
TP-3 @ 3' 1 10 94.3 117.5 80 39
TP-3 @ 5' 1 14 103.3 117.5 88 71
TP-3 @ 7' 1 12 102.0 117.5 87 59
TP-3@ 9' 1 8 111 .9 117.5 95 53
TP-4@ 3' 1 9 101.2 117.5 86 44
TP-4 @ 5' 1 8 103.1 117.5 88 40
TP-5 @ 3' 1 4 108.6 117.5 92 24
TP-5@ 5' 1 11 102.6 117.5 87 55
TP-5@ 8' 1 14 104.4 117.5 89 73
Note 1: Sample may be somewhat disturbed.
Assumptions And relationships:
In-place Relative Compaction = (Yd + Ym) X100
Gs= 2.70
e = (Gs Yw + Yd) -
1
S = (w Gs)+ e
3. Expansion Index Test: One expansion index (El) test was performed on a
representative sample of Soil Type 1 in accordance with the ASTM D-4829. The test
results are presented in Table 5.
\!JNJE & iv1mDLl::ToN ENCiiNLEiUNG, INC.• 2-4-50 Auto P,uk \Vay • Escond ido. Califl,rnia 92029~1.229 • Phone (760) 743•12!-!
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GEOTECHNICAL INVESTIGATION
HILLSIDE DRIVE & PARK DRIVE, CARLSBAD, CALIFORNIA
TABLE 5
Molded Degree of Final Initial Dry
Sample Soil w Saturation w Density
Location Type (%) (%) (%) (PCF)
TP-3@ 5' 1 9.6 44.5 19.6 106.5
(w) = moisture content in percent.
AUGUST 18, 2020
PAGE 11
El
Measured 50%
El Saturation
27 24
EISO = Elmeas · (50 • Smeas) ((65 + Elmeas) -;-(220 -Smeas))
Expansion Index (El) Expansion Potential
0-20 Very Low
21 -50 Low
51 -90 Medium
91 -130 High
) 130 Very High
4. Direct Shear Test: One direct shear test was performed on a representative sample
of Soil Type 1. The prepared specimen was soaked overnight, loaded with normal
loads of 1, 2, and 4 kips per square foot respectively, and sheared to failure in an
undrained condition. The test result is presented in Table 6.
TABLE 6
Wet Angle of Apparent
Sample Soil Sample Density Int. Frie. Cohesion
Location Type Condition {Yw-(Cl>-Deg.) (c-psf)
pct)
TP-1 @ 2' 1 Rernolded to 90% of YM @ % WOP! 115.8 30 35
5. pH and Resistivity Test: pH and resistivity of a representative sample of Soil Type 1
was determined using "Method for Estimating the Service Life of Steel Culverts," in
accordance with California Test Method (CTM) 643. The test result is tabulated in
Table 7.
TABLE 7 I Sample Location Soil Type ! Minimum Resistivity (OHM-CM) pH I TP-3@ 5' I 2240 6.8
6. Sulfate Test: A sulfate test was performed on a representative sample of Soil Type
1 in accordance with California Test Method (CTM) 417. The test result is presented
in Table 8.
V1NJE & IVltrlD!.J:TON ENCi!NEERINC, INC.• 2•-t-50 Auro Park \V;1y • Esumdido, CalifrH"nia 91029~1229 • Phone {760~'., i43-l2l•l
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GEOTECHNICAL INVESTIGATION
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AUGUST 18, 2020
PAGE12
TABLES
Amount of Water Soluble Sulfate
Sample Location SoilTvPe In Soil (% bv Weiaht)
TP-3 @ 5' 1 0.003
7. Chloride Test: A chloride test was performed on a representative sample of Soil Type
1 in accordance with the California Test Method (CTM) 422. The test result is
presented in Table 9.
TABLE 9
Sample Location I SoilType I
TP-3@ 5' I I
VI. SITE CORROSION ASSESSMENT
Amount of Water Soluble Chloride
In Soil (% by Weight}
0.006
A site is considered to be corrosive to foundation elements, walls and drainage structures
if one or more of the following conditions exist:
• Sulfate concentration is greater than or equal to 2000 ppm (0.2% by weight).
• Chloride concentration is greater than or equal to 500 ppm (0.05 % by weight).
• pH is less than 5.5.
For structural elements, the minimum resistivity of soil (or water) indicates the relative
quantity of soluble salts present in the soil (or water). In general, a minimum resistivity
value for soil ( or water) less than 1000 ohm-cm indicates a potential for presence of high
quantities of soluble salts and a higher propensity for corrosion. Appropriate corrosion
mitigation measures for corrosive conditions should be selected depending on the service
environment, amount of aggressive ion salts (chloride or sulfate), pH levels and the desired
service life of the structure.
Results of limited laboratory tests performed on selected representative of site soil samples
indicated that the minimum resistivity is more than 1000 ohm-cm suggesting presence of
low quantities of soluble salts. Test results further indicate that pH levels are greater than
5.5, sulfate concentrations less than 2000ppm and chloride concentration levels less than
500ppm. Based on the results of the available limited corrosion analyses performed on
selected samples, the project site is considered non-corrosive. The project site is not
located within 1000 feet of salt or brackish water, however, the Aqua Hedionda Lagoon lies
approximately 2000 feet to the south.
V n,..:1E & Jv1mDLETOr-: ENGJNI.J:R!NC, INC. • 2450 Auto P,1rk \V;1y • Escondido, C;1ltform.1 92029-1229 •·Phom' \_7600) 74.J-121-1
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GEOTECHNICAL INVESTIGATION
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PAGE13
Vinje & Middleton Engineering, Inc. does not consult in the field of corrosion engineering
and the client, project architect, or structural engineer should agree on the required level
of corrosion protection, or consult a corrosion engineer as warranted. Based on the result
of the tested soil sample, the amount of water soluble sulfate (SO4) was found to be 0.003
percent by weight which is considered negligible according to ACI 318 (SO Exposure Class
with Not Applicable severity). Water soluble chloride (CL) was found to be 0.006 percent
by weight and concrete is expected to be dry or protected from moisture. Consequently,
exposures to chloride are also considered negligible (CO Exposure Class with Not
Applicable severity). As a minimum, concrete consisting of Portland cement Type II with
minimum 28 days compressive strength (f'c) of 2500 psi and maximum 0.50 water-cement
ratio is typically considered adequate for SO and CO Class exposures, unless otherwise
specified, or noted on the project plans.
Table 10 below is appropriate based on the pH-Resistivity test results. Adequate
protective measures against corrosion should be considered for all buried metal pipes,
connections, elbows, conduits, improvements and structures, as necessary and
appropriate. Buried metal pipes and conduits should be wrapped and provided with
appropriate protective cover wherever applicable.
TABLE10
Gage 18 16 14 12 10 8
Years to Perforation of Steel Culverts 19 24 30 41 53 64
VII. HYDRO MODIFICATIONS
Project stormwater quality treatment control Best Management Practices (BMP), if
appropriate and as applicable, should be designed and constructed considering the site
indicated geotechnical conditions. The implemented management practice(s) and water
treatment control BMPs shall have no short and long term impacts on the site new building
pads, graded embankments and natural surfaces, fills and backfills, structures, and onsite
and nearby offsite improvements.
Bio-retention and filtration systems consisting of vegetated buffers or strips and self-
contained retention/detention areas with impermeable liners on sides and bottom, special
engineered sand filter media and perforated pipe(s) which discharge into an approved
storm drain facility are typical methods consistent with the project geotechnical conditions
for stormwater quality treatment control BMPs, if applicable. The bio-retention/detention
areas should be sited adequately away from the site structures, improvements, retaining
walls, foundations and top and toe of graded embankments, unless otherwise specifically
approved.
ViNlF &. ivtl!)J".H.f.:TON ENGINEEH.JNC. l.Nc. • 2-150 Auto Park \Vay • Escondido. California 92029-1229 • Phom·. {_760) 743-1214
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GEOTECHNICAL INVESTIGATION
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AUGUST 18, 2020
PAGE14
The bio-retention/detention basins should be properly sized for adequate storage capacity
with filtrations completed not more than 72 hours and vegetation carefully managed to
prevent creating mosquito and other vector habitats. Additional and more specific
recommendations should be provided by the project geotechnical consultant at the final
plans review phase, if necessary.
VIII. CONCLUSIONS
Based on the foregoing investigation, the planned single-family residential development,
substantially as proposed, is feasible from a geotechnical viewpoint. The project property
planned for the support of new structures and improvements is underlain by Old Paralic
Deposits at shallow depths overlain by a mantle of loose surficial soils. The following
factors are unique to the property and will most impact project construction procedures and
associated costs from a geotechnical viewpoint:
•. Landslides, faults or significant shear zones are not present at the project property
and are not considered a geotechnical factor in planned development. The study
site is not located near or within the Alquist -Priolo earthquake fault zones
established by the State of California. However, moderate to locally high levels of
ground shaking are expected at the site during occasional periods of seismic activity
along distant active faults.
• The study property is generally characterized by relatively level to gentle surfaces,
and large natural or graded slopes are not present at the project site. Minor road fill
embankments mark the north and east site margins. Finish grades are planned at
78.0 (MSL), which is near adjacent street elevations, requiring imported fill to
achieve design pad grades. The creation of new large graded embankments is not
planned. Consequently, slope stability is not considered a geotechnical concern in
the project development.
• Project earth operations will consist of remedial grading of upper site soils and the
importing of fill soils to achieve finish grades. All excavations, earthwork, remedial
and grading efforts should be completed in accordance with requirements of the
following sections.
• The site surficial soil mantle and upper exposures of the underlying Old Paralic
Deposits are loose and compressible deposits not suitable for structural support.
These deposits should be stripped (removed) to the underlying more dense Old
Paralic Deposits, as approved in the field, and placed back as properly compacted
fills in accordance with the recommendations of this report. Dense Old Paralic
Deposits are those with in-place densities of 86% or better. Approximate stripping
depths are provided in the following sections.
Vn,qr: & lv1mDLETON Er,.a.;1N1:ER!NCi, lNc. • 2-450 Auto Park\VJ)' • Escondido, Califorrna 92029--1.129 • Phone (760) 743.]214
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PAGE 15
• Stripping and recompaction remedial grading work will be required under all
proposed new structures and site improvements in order to construct uniform
bearing and subgrade soil conditions throughout, as specified in the following
sections. There should be at least 24 inches of well-compacted fills below bottom
of the deepest footing(s), and site improvements, unless otherwise approved. Cut-
fill daylight transition is not expected to be factor in the planned residential
development provided our remedial grading recommendations are followed.
• Added care will be required to avoid any damages to the existing nearby offsite
structures and improvements due to site excavations, remedial earthwork grading
and construction work. Adjacent public and private properties and right-of-ways
should also be properly protected as necessary and appropriate. For this purpose,
completing excavations and remedial grading adjacent to improvements in limited
section may become necessary based on actual field conditions. Permission to
grade offsite, or near property lines, should be obtained from neighboring property
owners and public agencies as necessary and appropriate. Added care should be
taken when grading near the offset limits for the protected Torrey pine tree.
• Earth deposits generated from the site excavations will predominantly consist of
sandy deposits which are considered suitable for reuse as new fills and backfills,
provided they are prepared and manufactured into a uniform mixture in accordance
with requirements of this report.
• Project new fills and backfills should be clean deposits free of trash, roots, stumps,
organic matter and deleterious materials, properly processed, throughly mixed,
placed in thin lifts horizontal lifts and compacted as specified in the following
sections.
• Final bearing and subgrade soils at the project property will be largely based on the
imported soil needed to achieve proposed grades. Import soils should meet the
requirements outlined in a following section, and be approved by the project
geotechnical engineer prior to delivery to the site.
• Groundwater conditions were not encountered to the depths explored and is not
expected to be a factor in the planned new residential construction or impact future
performance of the new building and site improvements. As with all graded sites,
the proper control of surface drainage and storm water is a critical component to
overall site and building performance. Runoff water should not be allowed to flow
onto the property from the adjacent roadways or pond upon graded surfaces
Irrigation water should not be excessive. Over-watering of site vegetation may also
create perched water and the creation of excessively moist areas at finished
surfaces and should be avoided.
V!NJE & ?vt!UDLFlON ENUNEEIUN(i, INC • 2450 Amo P;1rk \.V,1y • Escondido, C;11ifr,rnia 92029-1229 • Phone {760) 743-I 21-!
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GEOTECHNICAL INVESTIGATION
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PAGE16
Storm water and drainage control facilities should be designed and installed for
proper control and disposal of surface water as shown on the approved grading or
drainage improvement plans.
• Settlement of foundation bearing soils is not expected to be a major geotechnical
factor in the construction of the planned structures and improvements provided our
recommendations are followed. Post construction foundation bearing soil
settlements are expected to be less than approximately 1-inch and should occur
below the heaviest loaded footing(s). The magnitude of post construction differential
settlements, as expressed in terms of angular distortion, is not anticipated to exceed
½-inch in a distance between similarly loaded adjacent structural elements, or a
maximum distance of 20 feet.
• Soil collapse, liquefaction and seismically induced settlements will not be a factor
in the development of the project property provided our remedial grading
recommendations are followed.
IX. RECOMMENDATIONS
The following recommendations are consistent with the indicated geotechnical conditions
at the project property and should be reflected in the final plans and implemented during
the grading and construction phase. Added or modified recommendations may also be
appropriate and should be provided in a plan review report when final grading and
redevelopment plans are available:
A. Grading and Earthwork:
Modest remedial grading efforts and importing fill soils will be required in order to
achieve final design pad grades and construct safe and stable level surfaces for the
support of planned new structures and site improvements.
Importing fill soils and raising surface grades should only be carried out after
completion remedial grading of existing upper loose to soft surficial fill exposures.
All excavations, grading, earthwork, construction and bearing soil preparation should
be completed in accordance with Chapter 18 (Soils and Foundations) and Appendix
"J" (Grading) of the 2019 California Building Code (CBC), ASCE 7-16, the Standard
Specifications for Public Works Construction, City of Carlsbad Ordinances, the
requirements of the governing agencies and following sections, wherever
appropriate and as applicable:
V1r--:11::: & i'v1JDDLETON ENGlt--:1':TlU~G. lr--T. • 1450 Auto Park \Vay• Escondido, California 92029-1229 • Phonc (.760) 7-±3-1214-
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PAGE 17
1. Existing Underground Utilities and Buried Structures: All existing
underground waterlines, sewer lines, pipes, storm drains, utilities, tanks,
structures and improvements at or nearby the project site should be thoroughly
potholed, identified and marked prior to the initiation of the actual grading and
earthwork. Specific geotechnical engineering recommendations may be required
based on the actual field locations and invert elevations, backfill conditions and
proposed grades in the event of a grading conflict.
Utility lines may need to be temporarily redirected, if necessary, prior to
earthwork operations and reinstalled upon completion of earthwork operations.
Alternatively, permanent relocations may be appropriate as shown on the
approved plans.
Abandoned irrigation lines, pipes and conduits should be properly removed,
capped or sealed off to prevent any potential for future water infiltrations into the
foundation bearing and subgrade soils. Voids created by the removals of the
abandoned underground pipes, tanks and structures should be properly
backfilled with compacted fills in accordance with the requirements of this report.
2. Clearing and Grubbing: Remove all existing surface and subsurface
structures, tanks, vaults, pipes, vegetation, tree roots, stumps, and all other
unsuitable materials and deleterious matter from all areas proposed for new fills,
improvements, and structures plus a minimum of 5 horizontal feet outside the
perimeter, where possible and as approved in the field.
All debris generated from the site clearing and vegetation removals should be
properly disposed from the site. Trash, vegetation and debris generated from the
site clearing and grubbing should not be allowed to occur or contaminate new
site fills and backfills.
The prepared ground should be observed and approved by the project
geotechnical consultant or his designated field representative prior to grading
and earthwork.
3. Over-Excavations and Removals: Uniform and stable bearing soils conditions
shall be constructed under all planned site structures and improvements. For this
purpose, over-excavation (removal) and recompaction of the site surficial soil
mantle and upper weathered exposures of underlying Old Paralic Deposits will
be required. Over-excavations and remedial grading should extend a minimum
of 5 horizontal feet outside the perimeter of the proposed new building and
improvement envelop where possible, unless otherwise approved in the field.
VJNjE &'. !V1JDDLET01' ENC!N!:TRING, INC. • 2't50 Auro Park \Vay • Escondidn, C;i!if<.)rr11a 92029-1229 • Phone {760) 743-12 I 4
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PAGE 18
Over-excavation depths shall encompass the entire building and improvement
envelop and extend to the underlying dense and competent Old Paralic Deposits
suitable for receiving new fills and backfills (in-place densities of 86% or better),
as approved in the field. Actual over-excavation depths should be established
in the field by the project geotechnical consultant or his designated field
representative. However, based on available exploratory test pits, over-
excavation depths are anticipated to be on the order of 4 to 5 feet below the
existing ground surfaces (BGS). Locally, deeper over-excavations may be
necessary and should be anticipated.
Bottom of all removals should be additionally prepared, ripped and recompacted
to a minimum depth of 6 inches, as a part of initial fill lift placement, and as
directed in the field. The exposed bottom of over-excavation should be observed
and expose dense and competent sandstone deposits, below the weathered
zone, as approved by the project geotechnical consultant or his designated field
representative prior to fill or backfill placement.
4. Temporary Excavation Slopes and Trenching: Over-excavation and
trenching deeper than 5 feet maximum are not expected in connection with the
project development. In general, undermining existing nearby underground
utilities and improvements, structures and adjacent public and private properties
by the site excavations, removal and trenching operations shall not be allowed.
For this purpose, adequate excavation set backs shall be maintained and
excavation slopes laid back at safe gradients, where necessary and as
appropriate.
Temporary excavations and trenching less than 3 feet in maximum height, may
be constructed at near vertical gradients, unless otherwise approved or directed
in the field. Temporary excavations and trenching greater than 3 feet may be
constructed at near vertical gradients in the lower 3 feet and laid back at 1 :1
gradients within the upper portion. The remaining wedge exposed at the laid
back temporary slopes should then be properly benched out and new
fills/backfills tightly keyed-in as the backfilling progresses. All temporary
construction slopes will require geotechnical observation during the excavation
operations.
Additional and site specific recommendations should be given in the field by the
project geotechnical consultant based on actual exposures. Revised temporary
construction slope and trenching recommendations including flatter slope
gradients, larger setbacks and the need for temporary shoring/trench shield
support may be necessary and should be anticipated.
\'iNJL & J'V1ll)DLETO~ E~~GlNEERlNG, INc. • 2450 ;\uro Park \Vay • Escondido. California 92029-1229 • Phone :_/60) 7-t3~I21 4
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AUGUST 18, 2020
PAGE19
The project contractor shall also obtain appropriate permits, as needed, and
conform to Cal-OSHA and local governing agencies' requirements for
trenching/open excavations and safety of the workmen during construction.
Appropriate permits for offsite grading or excavation encroachments into the
adjacent neighboring private properties, utility easement(s) and public right-of-
ways shall be obtained from respective owners and agencies, as required and
necessary.
5. Imported Soil: Import soils, required to complete grading and achieve final
design pad grades, should be good quality sandy granular non-corrosive
deposits (SM/SW) with very low expansion potential (100% passing 1-inch sieve,
more than 50% passing #4 sieve and less than 18% passing #200 sieve with
expansion index less than 20). Import soils should be observed, tested as
necessary, and approved by the project geotechnical engineer prior to delivery
to the site. Import soils should also meet or exceed engineering characteristic
and soil design parameters as specified in the following sections.
6. Fill/Backfill Placement, Spreading and Compaction: Uniform bearing and
subgrade soil conditions should be constructed throughout the building and
improvement surfaces by the project pad and remedial grading earthwork
operations. Site soils should be adequately processed, thoroughly mixed,
moisture conditioned to slightly (2%) above the optimum moisture levels, as
directed in the field in thin (8 inches maximum) uniform horizontal lifts and
mechanically compacted to a minimum of 90% of the corresponding laboratory
maximum dry density per ASTM 01557, unless otherwise approved or directed
in the field.
7. Surface Drainage and Erosion Control: A critical element to the continued
stability of graded building pad and improvement surfaces is an adequate
stormwater and surface drainage control.
Surface water should not be allowed to flow toward or pond near the building
foundations or impact the graded construction and improvement sites. For this
purpose establishing positive drainage (minimum 5%) during fine grading efforts
away from the building and site improvements onto a suitable drainage collection
and disposal facility will be necessary. Roof gutters and area drains should be
installed. Over-watering of the site landscaping should also not be allowed. Only
the amount of water to sustain vegetation should be provided.
Temporary erosion control facilities and silt fences should be installed during the
construction phase periods and until landscaping is fully established. Site
drainage improvements should be completed as shown on the project approved
grading/erosion control plans.
\,.INJE & I\11lDDLETON ENG!NELfUNC, fNC. • 2-450 Aw.o Park \Vay • Escondido, C,t!d(1rn i:1 92029-1229 • Phone {_760\ 74-3-1 214
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GEOTECHNICAL INVESTIGATION
HILLSIDE DRIVE & PARK DRIVE, CARLSBAD, CALIFORNIA
AUGUST 18, 2020
PAGE 20
8. Engineering Observations and Testing: All earthwork operations including
excavations, removals (stripping), suitability of earth deposits used as
compacted fills and backfills, and compaction procedures should be continuously
observed and tested by the project geotechnical consultant and presented in a
final report. The nature of finished bearing and subgrade soils should be
confirmed in the final report at the completion of project earthworks construction.
Geotechnical engineering observations and testing should include but are not
limited to the following:
• Initial observation -After clearing and grading limits have been staked, but
before brushing and over-excavations start.
• Stripping, removals and bottom of over-excavation observation -After dense
and firm Old Paralic Deposits are exposed, but before new fill or backfill is
placed.
• Temporary trenching and excavation observations -After the excavation is
started but before the vertical depth of excavation is more than 4 feet. Local
and Cal-OSHA safety requirements for open excavations apply.
• Fill/backfill observation -After the fill/backfill placement is started but before
the vertical height of fill/backfill exceeds 2 feet. A minimum of one test shall
be required for each 100 lineal feet maximum in every 2 feet vertical gain,
with the exception of wall backfills where a minimum of one test shall be
required for each 30 lineal feet maximum. Finish rough and final pad grade
tests shall be required regardless of fill thickness.
• Foundation trench and subgrade soil observation -After the foundation
trench excavations but prior to the placement of steel reinforcing for proper
moisture and specified compaction levels.
• Geotechnical foundation/slab steel observation -After the steel placement is
completed but before the scheduled concrete pour.
• Underground utility, plumbing and storm drain trench observation -After the
trench excavations but before placement of pipe bedding or installation of the
underground facilities. Local and Cal-OSHA safety requirements for open
excavations apply. Observations and testing of pipe bedding may also be
required by the project geotechnical engineer.
V1N_IE & fv1IDDLETO!'--' EN(ilN[J:RJJ',.;G, INC.• 2450 :\urn P,1rk \Vay • Escondido, C;ilit(Jrnia 92029-1229 • Phone (_760) 7-43-1214
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GEOTECHNICAL INVESTIGATION
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AUGUST 18, 2020
PAGE 21
• Underground utility, plumbing and storm drain trench backfill observation -
After the backfill placement is started above the pipe zone but before the
vertical height of backfill exceeds 2 feet. Testing of the backfill within the pipe
zone may also be required by the governing agencies. Pipe bedding and
backfill materials shall conform to the governing agencies' requirements and
project soils report if applicable. Plumbing trenches more than 12 inches
deep maximum under the floor slabs should also be mechanically compacted
and tested for a minimum of 90% compaction levels. Flooding or jetting
techniques as a means of compaction method should not be allowed.
• Pavement/improvements base and subgrade observation -Prior to the
placement of concrete or asphalt for proper moisture and specified
compaction levels.
8. Footings and Slab-on-Grade Floor Foundations
The following recommendations are consistent with the recommended sandy
(SM/SW) imported bearing soils with very low expansion potential ( expansion index
less than 20), and site indicated geotechnical conditions. All design
recommendations should be further confirmed and/or revised as necessary at
completion of site grading work based on actual testing of final bearing and
subgrade soils:
1. Shallow stiff concrete footings and slab-on-grade floor type foundations may be
considered for support of the new dwelling and ADU structure. All foundations
should be supported on minimum 90% compacted fills, placed in accordance
with the requirements of this report. There should be at least 24 inches of
compacted fills below bottom of the deepest footing(s) throughout (or at least 4
feet of compacted fill below rough finish pad grades), unless otherwise
approved.
2. Perimeter and interior continuous strip footings should be sized at least 15
inches wide and 18 inches deep for one and two-story building loading
conditions. Isolated spread pad footings, if any, should be at least 24 inches
square and 18 inches deep and structurally interconnected with the continuous
strip footings with grade beams. Interconnecting grade beams should be a
minimum of 12 inches wide by 18 inches deep. Footing depths are measured
from the lowest adjacent ground surface, not including the sand/gravel layer
underneath floor slabs.
Exterior continuous footings should enclose the entire building perimeter.
Flagpole footings also need to be tied together if the footing depth is less than
4 feet below rough finish grade.
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AUGUST 18, 2020
PAGE 22
Continuous interior and exterior footings should be reinforced by at least 2-#5
reinforcing bars placed near the top and 2-#5 reinforcing bars placed near the
bottom. Interconnecting grade beams (if any are required) should be reinforced
with minimum 2-#4 bars top and bottom and #3 ties at 30 inches center to center
maximum. Reinforcement details for spread pad footings should be provided by
the project architect/structural engineer.
3. All interior slabs should be a minimum 5 inches in thickness, reinforced with #4
reinforcing bars spaced 16 inches on center each way, placed mid-height in the
slab. Slabs should be underlain by 4 inches of clean sand (SE 30 or greater)
which is provided with a well performing moisture barrier/vapor retardant
(minimum 10-mil Stego) placed mid-height in the sand. Alternatively, a 4-inch
thick base of compacted ½-inch clean aggregate provided with the vapor barrier
(minimum 15-mil Stego) in direct contact with (beneath) the concrete may also
be considered provided a concrete mix which can address bleeding, shrinkage
and curling is used
Provide "softcut" contraction/control joints consisting of sawcuts spaced 1 0 feet
on centers each way for all interior slabs. Cut as soon as the slab will support the
weight of the saw and operate without disturbing the final finish which is normally
within 2 hours after final finish at each control joint location or 150 psi to 800 psi.
The sawcuts should be minimum 1-inch in depth but should not exceed 1 ¼-
inches deep maximum. Anti-ravel skid plates should be used and replaced with
each blade to avoid spalling and raveling. Avoid wheeled equipments across
cuts for at least 24 hours.
Provide re-entrant corner reinforcement for all interior slabs. Re-entrant corners
will depend on slab geometry and/or interior column locations. The enclosed
Plate 13 may be used as a general guideline.
4. Foundation trenches and slab subgrade soils should be observed and tested for
exposing suitable bearing strata, proper moisture and specified compaction
levels and approved by the project geotechnical consultant prior to steel
placement or pouring concrete.
C. Soil Design Parameters
The following soil design parameters are based on the available strength tests
completed by this office on representative samples of onsite earth deposits and are
appropriate for the proposed retaining wall designs:
1. Design soil unit weight = 116 pcf.
2. Design angle of internal friction of soil = 30 degrees.
\'n<fE &·. ]Vt HlDLETClt< ENGi NEE!UNC. l NC. • 2450 Aurn P:lrk \Vay • Escondido, Califorrn,1 91029~ i 229 • Phone (7600) 7 43~ 12 1-1-
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GEOTECHNICAL INVESTIGATION AUGUST 18, 2020
PAGE 23 HILLSIDE DRIVE & PARK DRIVE. CARLSBAD, CALIFORNIA
3. Design active soil pressure for retaining structures= 39 pcf (EFP), level backfill,
cantilever, unrestrained walls.
4. Design at-rest soil pressure for retaining structures= 58 pcf (EFP), non-yielding,
restrained walls.
5. Design soil passive resistance for retaining structures = 347 pcf (EFP), level
surface at the toe (soil mass on the toe side extends a minimum of 10 feet or 3
times the height of the surface generating passive resistance).
6. Design coefficient of friction for concrete on soils = 0.38.
7. Net allowable foundation pressure = 1500 psf.
8. Allowable lateral bearing pressure = 150 psf/ft.
Notes:
-An additional seismic force due to seismic increments of earth pressure should
also be considered in the project designs, if appropriate and where applicable. A
seismic lateral inverted triangular earth pressure of 17 pcf (EFP), acting at 0.6H
(H is the retained height) above the base of the wall should be considered.
Alternatively, seismic loading based on Mononobe-Okake (M-0) coefficients may
be considered for seismic force due to seismic increments of earth pressure. The
following relationships and design values are appropriate:
Wall Total Seismic Lateral Ka Ko Kh KAE KoE Ysoil
Condition Lateral Pressure
Pressure
Unrestrain PAE=PA + PAE llPAE=3/eKhYH2 0.33 0.15 0.48 116
ed
Restrained POE=PO + POE llPOE=Kh YH2 0.50 0.15 -0.65 116
-Use a minimum safety factor of 1.5 for wall over-turning and sliding stability.
However, because large movements must take place before maximum passive
resistance can be developed, a safety factor of 2 may be considered for sliding
stability where sensitive structures and improvements are planned near or on top
of retaining walls.
-When combining passive pressure and frictional resistance the passive
component should be reduced by one-third. The upper 6 inches of ground
surfaces should not be included in the design for passive soil resistance, unless
otherwise noted or specified.
\.'iNJE & !v1iDDLLH.'!r-: ENC!NfTHING, INC.• 2450 Auro P,1rk \Vay • Escondido, Califrn:nia 92029-1229 • Phone (760) 7-:l,J ~l.214-
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GEOTECHNICAL INVESTIGATION
HILLSIDE DRIVE & PARK DRIVE, CARLSBAD, CALIFORNIA
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PAGE 24
-The net allowable foundation pressure provided herein were determined based
on minimum 12 inches wide by 12 inches deep footings. The indicated value may
be increased by 20% for each additional foot of depth and 20% for each additional
foot of width to a maximum of 4500 psf, if needed. The allowable foundation
pressures provided herein also applies to dead plus live loads and may be
increased by one-third for wind and seismic loading.
-The allowable lateral bearing earth pressures may be increased by the amount of
the designated value for each additional foot of depth to a maximum of 1500
pounds per square foot.
D. Swimming Pool/ Spa Construction
A swimming pool/ spa is proposed on the southeast pad margin, as shown on the
enclosed Plate 2.
The pool excavations are expected to expose low expansive, fills soils (based on our
import recommendations). The pool should be entirely supported on compacted fills
or undisturbed bedrock. In the case of fill support, there should be at least 12-inches
of well-compacted fill beneath the pool.
The pool may be designed and constructed for very low expansive soils (expansion
index less than 20) and based on lateral earth pressures provided in this report. The
pool should also be provided with a minimum 15 inch wide by 18 inch deep perimeter
grade beam reinforced with minimum 2-#4 bars top and bottom around the top of the
concrete shell. Pool shell reinforcements and thickness per structural details.
E. Exterior Concrete Slabs and Flatwork
1. All exterior slabs (walkways, patios, pool flatwork) supported on very low
expansive subgrade soils should be a minimum of 4 inches in thickness,
reinforced with #3 bars at 18 inches on center in both directions placed mid-
height in the slab. The subgrade soils should be recompacted to minimum 90%
compaction levels at the time of fine grading and before placing the slab
reinforcement.
Reinforcements lying on subgrade will be ineffective and shortly corrode due to
lack of adequate concrete cover. Reinforcing bars should be correctly placed
extending through the construction joints tying the slab panels. In construction
practices where the reinforcements are discontinued or cut at the construction
joints, slab panels should be tied together with minimum 18 inches long #3
dowels at 18 inches on centers placed mid-height in the slab (9 inches on either
side of the joint).
\'INJE &. iv1tDDLETON ENGINEERJNCi, lNc. • 2450 Aut.o P,1rk \V:1y • Escondido, Cali!Orni:1 92029-1229 • Phone (_760) 74-3~121-t
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GEOTECHNICAL INVESTIGATION
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AUGUST 18, 2020
PAGE 25
2. Provide "tool joint" or "softcut" contraction/control joints spaced 10 feet on center
(not to exceed 12 feet maximum) each way. The larger dimension of any panel
shall not exceed 125% of the smaller dimension. Tool or cut as soon as slab will
support weight, and can be operated without disturbing the final finish which is
normally within 2 hours after final finish at each control joint location or 150 psi
to 800 psi. Tool or softcuts should be a minimum of 1-inch but should not
exceed 1 ¼-inch deep maximum. In case of softcut joints, anti-ravel skid plates
should be used and replaced with each blade to avoid spalling and raveling.
Avoid wheeled equipments across cuts for at least 24 hours.
Joints shall intersect free-edges at a 90° angle and shall extend straight for a
minimum of 1½ feet from the edge. The minimum angle between any two
intersecting joints shall be 80°. Align joints of adjacent panels. Also, align joints
in attached curbs with joints in slab panels. Provide adequate curing using
approved methods (curing compound maximum coverage rate = 200 sq.
ft./gal.).
3. As a minimum, use Green Book 560-C-3250 concrete for sidewalks, flatwork
and exterior slabs. All exterior slab designs should be confirmed in the final as-
graded compaction report.
4. Subgrade soils should be tested for proper moisture and specified compaction
levels and approved by the project geotechnical consultant prior to the
placement of concrete.
F. Pavement Design
1. Asphalt Concrete (HMA) Paving: Specific HMA pavement designs can best
be provided at the completion of rough grading based on A-value tests of the
actual finish subgrade soils; however, the following structural sections may be
considered for initial planning phase and cost estimating purposes only (not for
construction):
• A minimum section of 4 inches HMA (AC) on 6 inches Caltrans Class 2
aggregate base (AB) or the minimum structural section required by City of
Carlsbad, whichever is more, may be considered for the onsite asphalt
paving surfaces outside the private and public right-of-way. Actual designs
will depend on final subgrade A-value and design Tl, and the approval of the
City of Carlsbad.
\IJNj£ & MlL>nL t:TON ENGINEERING, INL • 2450 Auto Park \Va)'•. Escund,do, California 91019-1129 • Phone ( 760) 7-13-J 2i 4
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GEOTECHNICAL INVESTIGATION
HILLSIDE DRIVE & PARK DRIVE, CARLSBAD, CALIFORNIA
AUGUST 18, 2020
PAGE 26
• Maximum lift for asphalt concrete shall not exceed 3 inches, unless
otherwise approved. The asphalt concrete layer (4-inch total section) may
consist of 2.5 inches of a binder/base course (¾-inch aggregate) and 1.5
inches of finish top course (½-inch aggregate) topcoat, placed in accordance
with the applicable local and regional codes and standards. The Class 2
aggregate or recycled base (AB) materials shall meet or exceed the
requirements set forth in the current California Standard Specification
(Caltrans Section 26-1.02). Aggregate base (AB) materials should be
compacted to a minimum 95% of the corresponding maximum dry density
(ASTM 0-1557). Subgrade soils beneath the asphalt paving surfaces should
also be compacted to a minimum 95% of the corresponding maximum dry
density within the upper 12 inches.
2. PCC Paving: Residential PCC driveways and parking supported on very low
expansive (expansion index less than 20) granular subgrade soils should be a
minimum of 5½ inches in thickness, reinforced with #3 reinforcing bars at 16
inches on center each way placed at mid-height in the slab. Subgrade soils
beneath the PCC driveways and parking should be compacted to a minimum
95% of the corresponding maximum dry density, unless otherwise specified. As
a minimum, use Green Book 560-C-3250 concrete for PCC pavings.
Reinforcing bars should be correctly placed extending through the construction
(cold) joints tying the slab panels. In construction practices where the
reinforcements are discontinued or cut at the construction joints, slab panels
should be tied together with minimum 18 inch long (9 inches on either side of the
joint) #3 dowels at 16 inches on centers placed mid-height in the slab.
Provide "tool joint" or "soft cut" contraction/control joints spaced 1 0 feet on center
(not to exceed 15 feet maximum) each way. The larger dimension of any panel
shall not exceed 125% of the smaller dimension. Tool or cut as soon as the slab
will support the weight and can be operated without disturbing the final finish
which is normally within 2 hours after final finish at each control joint location or
150 psi to 800 psi. Tool or softcuts should be a minimum of 1-inch in depth but
should not exceed 1 ¼-inches deep maximum. In case of softcut joints, anti-
ravel skid plates should be used and replaced with each blade to avoid spalling
and raveling. Avoid wheeled equipments across cuts for at least 24 hours.
Joints shall intersect free-edges at a 90° angle and shall extend straight for a
minimum of 1 ½ feet from the edge. The minimum angle between any two
intersecting joints shall be 80°. Align joints of adjacent panels. Also, align joints
in attached curbs with joints in slab panels. Provide adequate curing using
approved methods (curing compound maximum coverage rate= 200 sq. ft./gal.).
\/JNJE & ~1iDDLETON ENCINEL.RlNC. INC.• 2450 Auto Park \Vay • Escondido, California 92029-1229 • Phone (760") 743.1214
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GEOTECHNICAL INVESTIGATION
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PAGE 27
3. General Paving: Base section and subgrade preparation per structural section
design, will be required for all surfaces subject to traffic including roadways,
travelways, drive lanes, driveway approaches and ribbon (cross) gutters.
Driveway approaches within the public right-of-way should have 12 inches
subgrade compacted to a minimum of 95% compaction levels and provided with
a 95% compacted Class 2 base section per the structural section design.
Base layer under curb and gutters should be compacted to a minimum of 95%,
while subgrade soils under curb and gutters, and base and subgrade under
sidewalks should be compacted to a minimum of 90% compaction levels, unless
otherwise specified. Base section may not be required under curb and gutters,
and sidewalks, in the case of very low to non-expansive subgrade soils
(expansion index less than 20). More specific recommendations should be
given in the final as-graded compaction report.
G. General Recommendations
1. The minimum foundation design and steel reinforcement provided herein are
based on soil characteristics and are not intended to be in lieu of reinforcement
necessary for structural considerations.
2. Adequate staking and grading control is a critical factor in properly completing
the recommended remedial and site grading operations. Grading control and
staking should be provided by the project grading contractor or surveyor/civil
engineer, and is beyond the geotechnical engineering services. Staking should
apply the required setbacks shown on the approved plans and conform to
setback requirements established by the governing agencies and applicable
codes for the protected Torrey Pine, offsite private/public properties and property
lines, utility easements, right-of-ways, nearby structures and improvements,
leach fields and septic systems, and graded embankments. Inadequate staking
and/or lack of grading control may result in illegal encroachments or
unnecessary additional grading which will increase construction costs.
3. Open or backfilled trenches parallel with a footing shall not be below a projected
plane having a downward slope of 1-unit vertical to 2 units horizontal (50%) from
a line 9 inches above the bottom edge of the footing, and not closer than 18
inches from the face of such footing.
4. Where pipes cross under-footings, the footings shall be specially designed.
Pipe sleeves shall be provided where pipes cross through footings or footing
walls, and sleeve clearances shall provide for possible footing settlement, but
not less than 1-inch all around the pipe.
V!NJF & JvlJDDLETON ENGINU:::IUNG. 1r--:c. • 2450 Amo Park \Vay • Escondido. (:;1Jiforni:i 92029-1129 • Phone (760) 7..J-3-]11-1-
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GEOTECHNICAL INVESTIGATION
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AUGUST 18, 2020
PAGE 28
5. Expansive clayey soils should not be used for backfilling of any retaining
structure. All retaining walls should be provided with a 1 :1 wedge of granular,
compacted backfill measured from the base of the wall footing to the finished
surface and a well-constructed back drain system as shown on the enclosed
Typical retaining Wall Backdrain, Plate 14. Planting large trees behind site
retaining walls should be avoided.
6. All underground utility and plumbing trenches should be mechanically
compacted to a minimum of 90% (95% in public right-of-way) of the maximum
dry density of the soil unless otherwise specified or required by the governing
agencies. Care should be taken not to crush the utilities or pipes during the
compaction of the soil. Very low expansive, granular import backfill soils should
be used. Trench backfill materials and compaction beneath pavements within
the public right-of-way shall conform to the requirements of governing agencies.
7. Finish ground surfaces immediately adjacent to the building foundations shall be
sloped away from the building at a minimum 5% for a minimum horizontal
distance of 10 feet measured perpendicular to face of the building wall (CBC
1804.4 Site Grading). If physical obstructions or property lines prohibit 1 0 feet
of horizontal distance, a 5% slope shall be provided with an alternative method
for diverting water away from the foundation. Swales used for this purpose shall
be sloped not less than 2% where located within 10 feet of the building
foundation. Impervious surfaces (concrete sidewalks) within 10 feet of the
building foundation shall also be sloped at minimum 2% away from the building.
8. Care should be taken during the construction, improvements, and fine grading
phases not to disrupt the designed drainage patterns. Roof lines of the buildings
should be provided with root gutters. Roof water should be collected and
directed away from the buildings and structures to a suitable location.
9. All foundation trenches should be observed to ensure adequate footing
embedment and confirm competent bearing soils. Foundation and slab
reinforcements should also be inspected and approved by the project
geotechnical consultant.
10. The amount of shrinkage and related cracks that occur in the concrete slab-on-
grades, flatwork and driveways depend on many factors, the most important of
which is the amount of water in the concrete mix. The purpose of the slab
reinforcement is to keep normal concrete shrinkage cracks closed tightly. The
amount of concrete shrinkage can be minimized by reducing the amount of
water in the mix. To keep shrinkage to a minimum the following should be
considered:
\/iNJf: & JViJDLJLETON ENGJNLERlNG. Jr,..;t:. • 2450 Aurn (\trk\Vay • E.scondido, C;iliforma 92029~1229 • Phone (_760'! 7--13~1214
90
GEOTECHNICAL INVESTIGATION
HILLSIDE DRIVE & PARK DRIVE, CARLSBAD, CALIFORNIA
AUGUST 18, 2020
PAGE 29
• Use the stiffest mix that can be handled and consolidated satisfactorily.
• Use the largest maximum size of aggregate that is practical. For example,
concrete made with %-inch maximum size aggregate usually requires about
40-lbs. more (nearly 5-gal.) water per cubic yard than concrete with 1-inch
aggregate.
• Cure the concrete as long as practical.
The amount of slab reinforcement provided for conventional slab-on-grade
construction considers that good quality concrete materials, proportioning,
craftsmanship, and control tests where appropriate and applicable are
provided.
11. A preconstruction meeting between representatives of this office, the
property owner or planner, city inspector as well as the grading
contractor/builder is recommended in order to discuss grading and
construction details associated with site development.
X. GEOTECHNICAL ENGINEER OF RECORD (GER)
Vinje & Middleton Engineering, Inc. will be the geotechnical engineer of record (GER) for
providing a specific scope of work or professional service under a contractual agreement
unless it is terminated or canceled by either the client or our firm. In the event a new
geotechnical consultant or soils engineering firm is hired to provide added engineering
services, professional consultations, engineering observations and compaction testing,
Vinje & Middleton Engineering, Inc. will no longer be the geotechnical engineer of the
record. Project transfer should be completed in accordance with the California
Geotechnical Engineering Association (CGEA) Recommended Practice for Transfer of
Jobs Between Consultants.
The new geotechnical consultant or soils engineering firm should review all previous
geotechnical documents, conduct an independent study, and provide appropriate
confirmations, revisions or design modifications to his own satisfaction. The new
geotechnical consultant or soils engineering firm should also notify in writing Vinje &
Middleton Engineering, Inc. and submit proper notification to the City of Carlsbad for the
assumption of responsibility in accordance with the applicable codes and standards (1997
UBC Section 3317.8).
VINJE & MIDDLETON ENGIN£TIUNC, ]NC.• 2-150 Auto Park \V,1y • Escondido. C11iforma 92029-1229 • Phone (760: 743-121"1
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GEOTECHNICAL INVESTIGATION
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XI. LIMITATIONS
AUGUST 18, 2020
PAGE 30
The conclusions and recommendations provided herein have been based on available
data obtained from the review of pertinent reports and plans, subsurface exploratory
excavations as well as our experience with the soils and formational materials located in
the general area. The materials encountered on the project site and utilized in our
laboratory testing are believed representative of the total area; however, earth materials
may vary in characteristics between excavations.
Of necessity, we must assume a certain degree of continuity between exploratory
excavations and/or natural exposures. It is necessary, therefore, that all observations,
conclusions, and recommendations be verified during the grading operation. In the event
discrepancies are noted, we should be contacted immediately so that an inspection can
be made and additional recommendations issued if required.
The recommendations made in this report are applicable to the site at the time this report
was prepared. It is the responsibility of the owner/developer to ensure that these
recommendations are carried out in the field.
It is almost impossible to predict with certainty the future performance of a property. The
future behavior of the site is also dependent on numerous unpredictable variables, such
as earthquakes, rainfall, and on-site drainage patterns.
The firm of VINJE & MIDDLETON ENGINEERING, INC., shall not be held responsible for
changes to the physical conditions of the property such as addition of fill soils, added cut
slopes, or changing drainage patterns which occur without our inspection or control.
This report should be considered valid for a period of one year and is subject to review by
our firm following that time. If significant modifications are made to your tentative
reconstruction plan, especially with respect to the height and location of cut and fill slopes,
this report must be presented to us for review and possible revision.
This report is issued with the understanding that the owner or his representative is
responsible lo ensure that the information and recommendations are provided to the
project architect/structural engineer so that they can be incorporated into the plans.
Necessary steps shall be taken to ensure that the project general contractor and
subcontractors carry out such recommendations during construction.
The project geotechnical engineer should be provided the opportunity for a general review
of the project final design plans and specifications in order to ensure that the
recommendations provided in this report are properly interpreted and implemented. If the
project geotechnical engineer is not provided the opportunity of making these reviews, he
can assume no responsibility for misinterpretation of his recommendations.
V 1NJE & ivIIDDLtTON ENGlNl:[iUNC, INC.• 2450 Auto P,u:k \Vay • Escondido, California 92029-1229 • Phone (760) 7-!J-12J-!
92
GEOTECHNICAL INVESTIGATION
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AUGUST 18, 2020
PAGE 31
Vinje & Middleton Engineering, Inc., warrants that this report has been prepared within the
limits prescribed by our client with the usual thoroughness and competence of the
engineering profession. No other warranty or representation, either expressed or implied,
is included or intended.
Should any questions arise concerning this report, please do not hesitate to contact this
office. Reference to our Job #20-178-P will help to expedite our response to your
inquiries.
We appreciate this opportunity to be of service to you.
VINJE & MIDDLETON ENGINEERING, INC.
\/ft-,;!E & i'v1JDDLETON [),Ki!NFUUNG. INC:.• 2-150 Auro Park \\:1y • Escondido, C.:ilifrnni;1 92029-1229 • Phone {760) 7-13-1 214
93
REFERENCES
Annual Book of ASTM Standards, Section 4 -Construction, Volume 04.08: Soil and Rock (I); D420 -
D5876, 2016.
Annual Book of ASTM Standards, Section 4 -Construction, Volume 04.09: Soil and Rock (II); D5877 -
Latest, 2016.
Corrosion Guidelines, Caltrans, Version 1.0, September 2003.
California Building Code (CBC), California Code of Regulations Title 24, Part 2, Volumes 1 & 2, 2016,
International Code Council.
"The Green Book" Standard Specifications For Public Works Construction, Public Works Standards,
Inc., BNi Building News, 2015 Edition.
California Geological Survey, 2008 (Revised), Guidelines for Evaluating and Mitigating Seismic
Hazards in California, Special Publication 117 A, 108p.
California Department of Conservation, Division of Mines and Geology (California Geological Survey),
1986 (revised), Guidelines for Preparing Engineering Geology Reports: DMG Note 44.
California Department of Conservation, Division of Mines and Geology (California Geological Survey),
1986 (revised), Guidelines to Geologic and Seismic Reports: DMG Note 42.
"Proceeding of The NCEER Workshop on Evaluation of Liquefaction Resistance Soils," Edited by T.
Leslie Youd and lzzat M. Idriss, Technical Report NCEER-97-0022, Dated December 31, 1997.
"Recommended Procedures For Implementation of DMG Special Publication 117 Guidelines For
Analyzing and Mitigation Liquefaction In California," Southern California Earthquake center; USC,
March 1999.
"Foundations & Earth Structures," Naval Facilities Engineering Command, OM 7.02.
"Introduction to Geotechnical Engineering, Robert D. Holtz, William D. Kovacs.
"Introductory Soil Mechanics and Foundations: Geotechnical Engineering," George F. Sowers, Fourth
Edition.
"Foundation Analysis and Design," Joseph E. Bowels.
Caterpillar Performance Handbook, Edition 29, 1998.
"An Engineering Manual For Slope Stability Studies," J.M. Duncan, A.L. Buchignani and Marius De
Wet, Virginia Polytechnic Institute and State University, March 1987.
"Minimum Design Loads For Buildings and Other Structures," ASCE 7-10, American Society of Civil
Engineers (ASCE).
USGS Maps http://ngmdb.usgs.gov/maps/mapview/, 2016b.
SEAOC/OSHPD (Structural Engineers Association of America I California's Office of Statewide Health
Planning and Development) ground motion calculator https://seismicmaps.org/
94
VICINITY MAP
SW Comer of Hillside Drive & Park Drive
Carlsbad
J,ffersan \
Elementary~\
VI ► z:
C ...
0
0
"' ~ ...
USGS The NmlNI lribo: NallNI 8cumria Om2f. lOEP ~
___ .. ___ _
~~LMSCIMfOlttlllm,NdlNISnlcb'eSOllmd.llffd
~ T~ 0Calet USGS GbtlCI ~ U.S. C:cn=
Carlsbad
Seaside
Acade11ty ~· Chestnut I>
Ma9ru,liii
Elemmtary
Va/1,y M,ddl,
k
C
"'r
Approximate Scale 1 :20,000 North ~
.. Q
l.a._qlll'.a Ri\•,ra
Park
PLATE 1
V &M JOB #20-178-P
95 ,,. >~, \,~~, ·--~~:~~--~~ "-~~[ GEOTECHNICAL MAP] 1 J 2 "'~-,/'--,,, "<:'<'• ,;" . .._~,.:-,,-:.:--_ !0~ . a------= -------------. -1 I . '--.. '\ "'-.. ..... r... ·-. ~ I '-,. '• '0• '• ', <-:,--,, -D~./,,,,_ , ,.,,.,.. -,-------~ ~ 1 , g "-,. "-,,, '\, '-'.•-..,-,-..::;~~---, '-<:!' . . \\ -. ~ -~>r' E I ' ' , 0-.--...____ ""~•---. , , --------✓ I " ~ ,~J ''-.......
..._ ...... t"fo .........
-,'!1-c-, ,, i---:--', ---~~--~;,~-......... _ -~ -:-r-,-,"l~~-.: ---~-t,AH ____ 3 I / .... -~:--~------' \\ "C•i-,.,-,.,_,~ ~ -I < \ \ ----=-(_, _,., -1 --~-li=~~'<i;!;;-::::.---------. -,--,.-,.-,._,._,._ i ,'-i-----~I (SO}--.. _ <-i-o,, l "'11111-(lll -r~r.a· ---'"t~.l"'l ...... ~l~---------r-~-M-..._ ---..,__,;,,.'"-I ? -----~ ----=---~::-~-.i.: ..... _,..,_,.,_ I ---.. .:::::::-;::..~ ----::::~-IIIJ.:::-. ..... <J 1\1)-(W)-~-,.,_ 7 , a' --e----.... 1.1;a)--...... 1-1---,m., --(1111-:;-~1«r .... -~--.!';--.. ~ --~,!ltt;~--s,-,,,-=:,' .... ,,~J--.. ,.., ----g "•---..,~ ~ ) . I~ ' ~-----01-,"-',,'.:''~'"-•> "''oH ~(,~(si-m-~ I I ', I r--= . --D, ~ "'-,,~ ·---...::,,.,,-,. r ~--~ ~ I -· ----~r:'!f--__---<~--:•-,,,f--f,-IT I ' -----I ---f :'-.>, J I. / -r---. ..., ~ ', ;) I I I /,,: I ' -·--', '-', -o ' ~ f 1 / Qop2-4 ',,, --~~, '•<"'l-f j ! /I/ 1/ C!i:ICJ 8 0 .---------~ ~ ~ ... r,", J ,//~," -'j 0® ---.....
...
,: I "/"""-.' e: 1 I / / r:;::-:--) TP-4 ' ' - _ --~· E ;--.,.~~--/ ~ I ~ I I t,~'-, :/, f:5), I ,.:/:!, .· , 'tt:::':51"~[1Jr_ -;;;._;:.:1:~~~~~b~ ---. , , 1 -<:--.~--,,, -\ I I / / i ',<~ \ I '7!!!i~hr""'ff~~=-1~ E i/ rt I I ' £ : E a/ / / f / !: Ji i, , 1 ! r 1 fJ~r r g /E/ I/... I !lJ ~ g Y,' t{ L/!J! -~,-) · \ J\ \l\l 111 ~{ If lj I!: I . • , I , I' r/, \. I I .-', 11 . I ~PRO'l'ECTED TORREY PINE I/ / ! i ! i 'I -l.::'.J ---I ' ~ / f /: rJI. I ______ , -J ___ , ' I ·. i i \ . -· \;' -I \ I PLATE 2 l ~&M JOB #20-178-P RE\1SION DESCRIPTION GEOTECHNICAL LEGEND -I====' Raf Qop2-4 Approx. Location of Test Pit Geologic Cross-Section Road Fill Old Paralic Deposit ~ 10' 5' o' '~ 1Q'_ SCALE:: l'":. 20' 'AS BUILT' "''--°'"·--om R£V1£'ol(b IY• lNSPCCttJI: ~ ~lj CITY OF CARI..SBAD l'~a L_j!_J EHG!NEERING DCPMtHDIT ~ .. ~ I APf>R()',£0: JASON s. GEl.ODI
an'EHGNIJIP£63012p:Plg9/Jll/2D QA?[ l=~-~11 PSo.ECf ,o II"'=~
96
PRIMARY DIVISIONS GROUP SECONDARY DIVISIONS SYMBOL
GRAVELS CLEAN GRAVELS GW Well Jr.u.led gr.ncl1, gra\·cl-sand mixtures, little orno fines. (LESS THAN
MORE THAN HALF OF 5% FINES) GP Poorly grt1dcd yra"c!s or gra\'Cl-snnd mixrures, linlc orno fines COARSE GRAINED COARSE FRACTTJON IS SOILS GRAVELS GM Silty 81'3\·els, i:;ra,·cl-sm,d mixtures. non•plastic fines LARGER THAN NO. 4 WITH
MORE THAN llALF OF SIEVE FINES GC Clayq gravels, gr.n·cl,sanJ•clny mixtures, plnsric fines
MATERIAL JS LARGER SANDS CLEAN SANDS SW Well i:;radcd sands, gran::lly S.111ds. littlc or no fines. TIIAN NO 200 SIEVE (LESS THAN SIZE MORE THAN HALF OF S~HINES) SP Poorly w-aded sands, grun:lly sands, little or no fines.
COARSE FRACTTION IS SANDS SM Silly sands, wid-sih mixtures. non-pla.sric fines SMALLER THAN NO. 4 WITH SIEVE FINES SC Clayc W1ds, wid-cfoy mixtures, plastic fines
SIL TS & CLA VS ML lnorgnnic sills nnd \'cry line sa.ndJ, rock Hour. sdty or clayey line $!111d$ or
clavcv silu wid1 sliwhl olosticitv
FINE GRAINED CL (nory1111ic clays orlow to medium plo.sc:iciiy. gr:i\·clly clays. sandy clay.t.,
SOILS LIQUID LIMIT IS slltv cl:ivs. lc&1 clavs
LESS TIIAN Sm'. OL Ofiarm: s.il1S ond or~nnic silty cl11ys oflow plnsridty MORE THAN l·IALF OF lnorynnic sills, miaiccous ord1111om.1ca,us fine sand) or silty soils, MATERIAL IS SMALLER SIL TS & CLA VS MH clostic soils THAN NO. 200 SIEVE CH lnor}!llfllc clays ofhigb r,lasticily. fat clays SIZE LIQUID LIMIT IS
MORE THAN 50¾ 011 Orynnic cloys. ofmeJium to hish plasticiry, oryimic: sills
HIGHLY ORGANIC SOILS PT Pc:;it or other highly OIJ;Mic soils
GRAIN SIZES S STANO.\RD SERIES SIEVE CLEAR SQAURE SIEVE OPENINGS
200 40 10 4 ½" J" 12"
SAND GRAVEL
SIL TS & CLA VS I COARSE
COBBLES BOULDERS
FINE MEDIUM COARSE FINE
RELATIVE DENSITY CONSISTENCY
SANDS. GRAVELS & BLOWS/ FOOT CLAYS& STRENGTl·I BLOWS /FOOT NON-PLASTIC SIL TS PLASTIC SILTS
VERY LOOSE 0 -4 VERY SOFT o-Y. 0-2
SOFT Y.-½ 2~4 LOOSE 4-10
FIRM Y,. I 4-8
MEDIUM DENSE 10-30
STIFF 1-2 8 • 16
DENSE 30-so
VERY STIFF 2 -4 16 -32
VERY DENSE OVER SO HARD OVER4 OVER32
I. BLOW COUNT: 140 POUND HAMMER FALLING 30-INCIIES ON A 2-INCl·I DIAMETER O.D. SPLIT SPOON SAMPLER (ASTM D-1586)
2. UNCONFINED COMPRESSIVE STRENGTH PER SOIL TEST POCKET PENETROMETER CL-700
~ Nuclear Densometer/
Sa11dco11e Test ■ Bulk Sample B \Standnrd Penetration Tesl (SPT) -(ASTM D-1586) Blow Counts Per 6-lnches
□ Chu11k Sample Q Drive11 Rings 1%1\ California Sampler With Blow Counls Per 6-lnches
VINJE & MIDDLETON ENGINEERING, INC. KEY TO BORING / TEST PITS LOGS
2-t50 Aulo Park Wa\' UNIFIED SOIL CLASSIFICATION SYSTEM Escomlitlu. Cnlirumia 91029
760-743-121-t ,, injc.m idd lcton'!!' hcglohal. net (ASTM D-2-487)
December, 2013
97
~ VINJE & MIDDLETON ENGINEERING, INC. TEST PIT: TP-1
PROJECT: Pro11osed Residential Develo11ment CLIENT: Curt Gibson
PROJECT NO.: 20-178-P PROJECT LOCATION: SW Corner of Hillside Drive and Park Drive Carlsbad
Date Excavated: 7/24/20 Bucket Size: 24" Logged By: SJM
Equipment: John Deere 35G Mini-Excavator Contractor: Colonello
Remarks: No cavin". No 11roundwater.
u "" ii;. !:c ~i': !;~ ~8 "' .... ?i~ DEPTH ~ MATERIAL DESCRIPTION i~ ~~l ~il (ft) ~_, "' So-~~ 0 ::i ;EU l:lc ~<
.:":_:·:::::-:
::.:\ .. t Topsoil:
;:.:· '.i:j}
Silty fine sand. Brown color. Dry to damp. Loose. Roots.
I-1 -ST-I
SM '· 't.
I-2 -i-i \fi DI '•:'./1.: Loose to medium dense at 2 feet. Dry. 3 101.0 86 15
1:::1'-:-(
I-3 ,.·.-r..:·1-..·
:.·:-:·. \\ Old Paralic Deposit (0op2-4}:
I-4 -
~\'.'.:.: ... }}
Sandstone. Fine grained. Red brown color. Weathered.
Friable. Massive. Modertely cemented. Loose to medium r, 3 96.6 82 12 SP dense. ST-I
, ........
I-5 -:-:-:·ii-)} Tight at 5 feet. Blocky. Dense. I 7 106.9 91 40
I:: .. ::::::
Bottom of test pit at 5.5 feet.
■ BULK □ CHUNK T DENSITY ,SZ GRO ND PLATE 3 SAMPLE SAMPLE TEST -WATER
98
~ VINJE & MIDDLETON ENGINEERING, INC. TEST PIT: TP-2
PROJECT: Proposed Residential Development CLIENT: Curt Gibson
PROJECT NO.: 20-178-P PROJECT LOCATION: SW Corner of Hillside Drive and Park Drive Carlsbad
Date Excavated: _ _.7""'/2'"'4;..::/2""0_ Bucket Size: ----=24~"----Logged By: --~S=J=M~--t
Equipment: John Deere 35G Mini-Excavator
Remarks: No cavinl!. No l!roundwater.
Contractor: _C=o=lo=n=e=ll=o ____________ _,
u
DEPTH ~8
(fl) ;;;; ....
0
<Ii u
"' ::i
■ BULK
SAMPLE
MATERIAL DESCRIPTION
Topsoil:
Silty fine sand. Brown color. Dry to damp. Very loose. Roots.
ST-I
Continues dry and very loose at 2 feet. I ,-.'---,---+--+--il-----1 4 95.4 81 16
Old Paralic Deposit {Oopl-4):
Sandstone. Fine grained. Brown to red brown color. Moist.
Weathered. Friable. Massive. Loose to medium dense. ST-I
Blocky at 5 feet.
dense.
□ CHUNK
SAMPLE
Moderately cemented. Medium dense to
Bottom oftest pit at 5.5 feet.
DENSITY
TEST 'SJ. GROUND • WATER
rr= 8 99.1 84 36
rr= 8 IOl.5 86 38
PLATE 4
99
~ VINJE & MIDDLETON ENGINEERING, INC. TEST PIT: TP-3
PROJECT: Prol!osed Residential Develol!ment CLIENT: Curt Gibson
PROJECT NO.: 20-178-P PROJECT LOCATION: SW Corner of Hillside Drive and Park Drive Carlsbad
Date Excavated: 7/24/20 Bucket Size: 24" Logged By: SJM
Equipment: John Deere 350 Mini-Excavator Contractor: Colonello
Remarks: No cavinl!:. No l!:roundwater.
I u w wi t:c:-!:; ~ ~~ :i:c, .,; ~ ~ DEPTH <.i MATERIAL DESCRIPTION -'W ?i~ i=--~r c..o ....
(ft) ;;;..J "' ~~ !!! -~~ :s~t o c ::i 00 ::to ~< " ;;v
:: .-.::.?
Topsoil: . •:-· '.::. .: <:
·,, Silty fine sand. Brown color. Dry. Very loose. ST-I -1 -•: __ ·:\
::, ', _.,::
·:, :_-. ·".-SM ,-..
·::-: : ·?
-2-·:.' ,'·, ·-: ,, ·,. -..
::::':-:,/ ·-· _.._. /
-3 ·:, :::·:.-.·
1·::::·:·'.·:·-'-'· I 10 94.3 80 39
::::::·:::· Old Paralic Deposit (0op2-4): -:-:-:·::.::.,
::: .. Sandstone. Fine grained. Brown/red brown color. Moist. -4-...
,:::::;:::::::_:_::: Weathered friable. Massive. Loose. ST-I
1:: ...... .'." ....
-5-:-~-:-:•:·:·:::::{
DI .... ·: .. ,:-:-Somewhat blocky and moderately cemented at 5 feet. Continues 14 103,3 88 71 ...
""" moist. Medium dense to dense . ... ..... , .:
...... ""
,_5_ ......
""" .. : .. -:::-SC !
"
:::::•:•:•:•:·:·:·?
-7-;::---:-:-Medium dense to dense at 7 feet. I 12 102.0 87 59
::::-: :::::·
.,:,:----
-8-.-.-.
::t .... _.
·:: .........
-9-::::::-·-----:.:.:.::
·:::::::: .. : Consistent characteristics at 9 feet: Moist. Massive. Dense. I 8 111.9 95 53
::::::.'""
Bottom of test pit at 9 .5 feet.
■ BULK □ CHUNK T DENSITY Sl GROUND SAMPLE SAMPLE TEST -WATER PLATE 5
100
~ VINJE & MIDDLETON ENGINEERING, INC. TEST PIT: TP-4
PROJECT: Pro(!osed Residential Develo(!ment CLIENT: Curt Gibson
PROJECT NO.: 20-178-P PROJECT LOCATION: SW Corner of Hillside Drive and Park Drive. Carlsbad
Date Excavated: 7/24/20 Bucket Size: 24" Logged By: SJM
Equipment: John Deere 350 Mini-Excavator Contractor: Colonello
Remarks: No cavine. No eroundwater.
!,! .,; gti ,::, ~~-~~ !DEPTH i!:8 '-! MATERIAL DESCRIPTION if ~ -~ ~~ .. cm ~...I "l ~ l!! t ~ :s~e lili:!-;:, 00 gto C, :,u Q<
\·,. ·.·. ·. --·. ~ .. . . .... Topsoil:
· .. -;, .....
·.• •. ·=·· Silty fine sand. Brown/red brown color. dry to damp. Very
t-1 -:\•~ .. -.~:. _.._.
·•·. loose. ST-I
r,::: \
:,-: SM
.. ·
t-2 -)} .: ·.-.-.·.-,.,• :-_._,: ·-.
·.: · . .... .....
,_3 . _.,,-:: .:-:
I·••··••·••• LL 9 101.2 86 44
·-:: Old Paralic De(!osit {Qopl-4}:
-4-
--~·'.:·:·i::::}: Sandstone. Fine grained. Brown/red brown color. Moist.
1j:::·::\:::
Weathered friable. Moderately cemented. Medium dense to
SP dense. ST-I
t-5 -1:-:--·•-:/?: rr= Blocky at 5 feet. Dense. 8 103.1 88 40 ... ····•·
Bottom of test pit at 5.5 feet.
■ BULK □ CHUNK T DENSITY SZ GROUND SAMPLE SAMPLE TEST -WATl!R PLATE 6
101
~ VINJE & MIDDLETON ENGINEERING, INC. TEST PIT: TP-5
PROJECT: ProRosed Residential DeveloRment CLIENT: Curt Gibson
PROJECT NO.: 20-178-P PROJECT LOCATION: SW Corner of Hillside Drive and Park Drive Carlsbad
Date Excavated: 7/24/20 Bucket Size: 24" Logged By: SJM
Equipment: John Deere 35G Mini-Excavator Contractor: Colonello
Remarks: No cavini,. Nn i,roundwater.
u <lj Hl !:,;;-~c ~~ ic DEPTH "-o u MATERIAL DESCRIPTION ii! s!-~r (ft) >-::s~e ~.., "' ... ~~ s .._
t:> ::i ~8 ~i!l c<
{, -1? . -:It: .-:::,;\. Topsoil:
-1 -
·' ·1c:=.:
.::-. ·/ Silty fine sand. Brown color. Dry. Very loose. ST-I
.:· :':: ·.::: {r I·· SM
l•'f l'•'
-2-\. ,.I'> 1:,:f .1,:: ·..,: .}·•:
,:.-:·1::: · .. :_ :1-.,·.
-3 :::1·,;.
..... : ... : I 4 108.6 92 24
::::':::}\ Old Paralic Deposti (0op2-4):
1-4-:::_:::,:_:•::\ Sandstone. Fine grained. Brown/red brown color. Dry.
Weathered friable. Massive. Blocky. Medium dense to dense.
... ... ST-I ···;, ...
-:-:-:···:.:.:,:-:
-5--:•:-:-.::: .. :·:·::::. Moist at 5 feet. Dense. I II 102.6 87 55 ···;;·;;:·:: . .... ... ....
:·:::·::-::::::::::: SP
-6-...... ... .... ... ...... ............ ·.•.·:::::::::.
:·:-:::::::::::. Running sand from ±6-7 .5 feet. Moist. Local horizonatal r-7-......... .......... bedding along dark-colored seams. Tight. Generally
:/_:,.:-:-;\ cohesionless.
·::~::::·:·:•:•::.:.:.:
-8-.......... ........... Moderately cemented and blocky at 8 feet. Moist. Dense . I 14 104.4 89 73 ......
····:::.:::·
Bottom oftest pit at 8.5 feet.
■ BULK □ CHUNK T DENSITY S[ GROUND SAMPLE SAMPLE TEST -WATER PLATE 7
102
Pertinent Geologic Deposits
GEOLOGIC MAP
SW Comer of Hillside Drive and Park Drive
Carlsbad
North~ Scale 1 :50,000
Old Paralic Deposits Units 2-4 (Late to Middle Pleistocene): Brown/red brown sandstone (site specific)
Santiago Fonnation (Middle Eocene)
Excerpt From the Geologic Map of the San Diego 30' x 60' Quadrangle, California, Michael P. Kennedy and Siang S. Tan, 2008.
Plate 8
V &M Job #20-178-P
103 80 60 & f?. I / / -::_::_-____ _ [ GEOLOGIC CROSS-SECTIONS] SCALE:= 20' ---=:-:.:::::::=-.. I PROPOSED I DWELLING ~ & [) I I I ROAD ""-KltLSIDE OR. PROPOSED Ft.ATWORK I PROPOSED GRADE(APP~80 .-•r ,,,,-•~• "~? -~~ OLD PARALIC DEPOSIT [Qop2-4] 60 I83 fP so~ I 60 40 -----= PROPOSED DWELLING II> _ I ROAD ,a, I83 [) ---(Ran PARK DR, --~_:_ 1 ~,-~~ 60 OLD PARALIC DEPOSIT {Qop2-4] 40 I PLATE 9 ] V&M JOB #20-178-P
104
FAULT-EPICENTER MAP
SAN DIEGO COUNTY REGION
Indicated Events Through a 200 Year Period
N
i
Approx. Scale: 1" = 50 Miles
EPICENTER MAP LEGEND
1800 -1669 -1932
1l:88 1931 199g
~,.o •••
~ 1 6560 •••
J 60-64 e e e
5.5-59 • • • •
HIS1Dnal Faulting -
Hofocano Fau!ling ---
Hljlhwsya fJ.Co1,:,1) ---
ttighways {MKlOf) ---
l.llkCS T'
Ai Lmn two 11:gtts ol M > 6 5 W' eant.qua.ke year
•
Map is reproduced from California Division of Mines
and Geology, "Epicenters of/ and Areas Damaged by
M 2:: 5 California Earthquakes, 1800-1993.
Plate 10
V &M Job #20-178-P
105
National Flood Hazard Layer FIRMette
SW Corner of Hillside Drive & Park Drive, Carlsbad
Legend .--------,--_... ________ -:-__ -==-e=----,-- -
=='
UlliERAR£ASOf FIDIXIHAZAIID
----Flada.....(IR) ............
WD.-EWDeplb,._A&..M.ll&.1111 --D.aAlna,IQua,a Aoolll M&mnl."'-r1 u, ...... chanc::9lklod wlll, ....
di!r,ithlaal!Wllonafllllll•_.llldnltlll,O
... o11euUunono..-,effllo,._•
Futuret::Mdlllona1,.""""-1 DMw'ICll Flood HaDtd ,_,.,
Aft■ wllfl Rcduad Aoad Rbk Illa ..
""'"-.S.ONlilel.Z.. ..
........ ,....fflllldulltD~i-• ................... ...__,
Ufslt11e LO--.
atHDI AREAS MJ• DI U~fba:tttatMI -•
GENERAL Cllmlnd.Cuhcrt.mStannS-.:,.
S1JftletVRES ..._,m.,arFIDatwd
!Oeu-.Swl0,~1'Am .. 1Chonco
wamr 5urfaco EkMltlon
-Cont.al-
-Baa Fmd --IJne 18Ft) =um11ofSClldy -----Cont.al-Baelne
OTHER ----IDTtJRES __ Hyd,ofl'IIOl,c r..turo
' +
Tha pin ~don Um map Is an -,p0almate
polntHloctcd a.,, tho ncr and dow not rcpntta1l
ml allflodtlldw ~locatJDn.
·-f FEMA
Plate 11
V &M Job #20-178-P
106
TSUNAW INUNDATION MAP
Map Legend
-../"\J---Tsunami Inundation Line
Scale: 1 :12,000
Tsunami Inundation Area
Excerpt from the Tsunami Inundation Map for Emergency Planning,
Oceanside Quadrangle/San Luis Rey Quadrangle, June 1, 2009.
Plate 12
V &M Job #20-178-P
107
ISOLATION JOINTS & RE-ENTRANT CORNER REINFORCEMENT
(A)
RE-ENTRANT CORNER REINFORCEMENT---....._
No. 4 BARS PLACED AT l.S"
BELOW TOP OF SLAB
NOTES:
Typical -No Scale
(B)
ISOLATION JOlNTS
(C)
RE-ENTRANT CORNER CRACK
1. Isolation joints around the columns should be either circular as shown in (A) or diamond shaped as shown in (B).
If no isolation joints are used around comlumns, or if comers of the isolation joints do no meet the contraction
joints, radial cracking as shown in (C) may occur (Reference ACI).
2. In order to control cracking at the re-entrant comers (~270° comers), provide reinforcement as shown in (C).
3. Re-entrant caner reinforcement shown is provided as a general guideline only and is subject to verification and
changes by the project architect or structural engineer based upon slab geometry, location, and other engineering
and construction factors.
VINJE & MIDDLETON ENGINEERING, INC.
2450 Auto Parle Way
Escondido, California 92029
760-743-1214 vinjc.middlcton@sbcglobal.net
PLATE 13
V &M Job #20-178-P
July 2018
108
RETAINING WALL DRAIN DETAIL
Typical -No Scale
Waterproofing
Drain e
Approved Compacted Soil or Competent Natural Material
CONSTRUCTION SPECIFICATIONS:
Filter material. Crushed rock (wrapped in
filter fabric) or Class 2 Permeable.
(See specifications below)
SPECIFICATIONS FOR CAL TRANS
CLASS 2 PERMEABLE MATERIAL
(68-1.025)
SIEVE SIZE % PASSING
I" .............................. 100
¾" ............................. 90-100
¾" ............................. 40-100
No. 4 ··········· ................. 25-40
No. 8 •······· .................... 18-33
No. 30 ........................... 5-15
No. 50 ············ ............... 0-7
No. 200 .... , .................... 0-3
Sand Equivalent > 75
I. Provide granular, non-expansive backfill in a I: I gradient wedge behind the wall. Compact backfill to minimum
90% of laboratory standard.
2. Provide back drainage for wall to prevent build-up of hydrostatic pressures. Use drainage openings along base of
wall or back drain system as outlined below.
3. Backdrain should consist of 4" diameter PVC pipe (Sch. 40 or equivalent) with perforations down. Drain to suitable
outlet at a minimum 1% fall. Provide¾" to½" crushed rock filter wrapped in filter fabric (Mirafi 140N or
equivalent). Delete filter fabric ifCaltrans Class 2 Permeable material is used. Compact Permeable Class 2 to
minimum 90% of laboratory standard.
4. Seal back of wall with waterproofing in accordance with the architects specifications.
5. Provide positive drainage to disallow ponding of water above wall. A lined drainage ditch with a minimum 2%
flow away from wall is recommended.
• Use 1 ½ cubic foot per foot crushed rock with granular soil and 4 cubic foot per foot if expansive soil is present.
VINJE & MIDDLETON ENGINEERING, INC.
2450 Auto Park Woy
Escondido, Culifomiu 92029
760-743-1214 vinje.middleton@sbcglobul.net
PLATE14
V &M Job #20-178-P
Setember 2018
109
Attachment A
110
7/27/2020 U.S. Seismic Design Maps
OS HPD
20-178-P SW Corner of Hillside Drive & Park Drive, Carlsbad
Latitude, Longitude: 33.1501, -117.3264
9 California WaterSports
Go gle
Date
De1lgn Code Referenca Document
Risk Category
Site Class
Type Value
Ss 1.043
s, 0.378
SMs 1.129
s,.., null -See Secllon 11.4.8
Sos 0,753
So1 null -See Secllon 11.4.8
Pacifica House 9
Description
7127/2020, 2:59:44 PM
ASCE7-16
II
0-Stiff Soll
MCER ground motion. (for 0.2 second period)
MCER ground motion. (for 1.0s period)
Site-modified speclrel acceleration value
Site-modified speclral accaleratlon value
Numeric seismic design value at 0.2 second SA
Numeric seismic design value at 1.0 second SA
Type Value Description
soc null -See Section 11.4.8
Fa 1.083
Fv null -See Section 11.4.8
PGA 0.459
FPGA 1.141
PGAM 0.523
TL 8
SsRT 1.043
SsUH 1.165
SsO 1.5
S1RT 0.378
S1UH 0.417
S1D 0.6
PGAd 0.534
CRs 0.895
CR1 0.907
https://selsmlcmaps.org
Seismic design category
Sile amplification faclor al 0.2 second
SIie amplification faclor at 1.0 second
MCEG peak ground acceleration
SIie amplification factor at PGA
Sile modified peak ground acceleration
Long-period transition period in seconds
Probabilistic risk-taryeted ground motion. (0.2 second)
Factored uniform-hazard (2% probability of exceedance In 50 years) speclrel acceleration
Factored deterministic acceleration value. (0.2 second)
Probabilistic risk-taryeted ground motion. (1.0 second)
Faclored uniform-hazard (2% probability of exceedance In 50 years) spectral acceleration.
Factored deterministic accelerallon value. (1.0 second)
Factored datermlnlstic acceleration value. (Peak Ground Acceleration)
Mappad value of lhe risk coefficient at short periods
Mapped value of lhe risk coefficient al a period of 1 s
1/2