Storm Water Management Facilities Maintenance Agmt 2019-0354743RECORDING REQUESTED BY:
CITY OF POWAY
AND WHEN RECORDED MAIL TO:
CITY CLERK
CITY OF POWAY
P O BOX 789
POWAY, CA 92074
APN: 314-840-18
DOC# 2019-0354743
IIIII IIIII IIIII IIIII IIII 111111 IIIII IIIII IIIII IIIII IIIII IIIII IIII IIII
Aug 21, 2019 10:47 AM
OFFICIAL RECORDS
Ernest J. Dronenburg, Jr.,
SAN DIEGO COUNTY RECORDER
FEES: $0.00 (SB2 Atkins: $0.00)
PAGES: 44
(THIS SPACE FOR RECORDER'S USE)
STORM WATER MANAGEMENT FACILITIES
MAINTENANCE AGREEMENT
13391 Del Poniente Road
The undersigned grantor(s) declares:
Documentary Transfer Tax is $ -0- pursuant to R & T Code 11922 (conveyance to a Government Agency)
This AGREEMENT for the maintenance and repair of certain Storm Water Management Facilities is
entered into between the Property Owner Thomas Sparrvik, trustee of the Sparrvik Thomas Trust 01-
25-07, (hereinafter referred to collectively as "OWNER") and the City of Poway (hereinafter referred to
as "CITY") for the benefit of the CITY, the OWNER, the successors in interest to the CITY or the
OWNER, and the public generally.
WHEREAS, OWNER is the owner of certain real property located in the City of Poway, California,
more particularly described in Attachment "A", hereto (hereinafter referred to as the "PROPERTY"),
which is being developed into a single family residence, in accordance with applications for a Minor
Development Review Application 16-011, which is on file with the CITY. This Agreement is required
as a condition of approval for such development.
WHEREAS, in accordance with the City of Poway's Stormwater Management and Discharge Control
Ordinance, Poway Municipal Code, Chapter 13 and 16 (the "Stormwater Ordinance"), the City of
Poway Subdivision Ordinance, the City of Poway Zoning Ordinance, the City of Poway Grading
Ordinance and/or other ordinances or regulations of CITY which regulate land development and urban
runoff, OWNER has proposed that storm water runoff from the PROPERTY be managed by the use of
the following Storm Water Management Facilities which are identified as "Best Management
Practices" or "BMPs":
Three biofiltration basins located throughout the proposed residence, a Filterra Bioretention
System and self -mitigating areas as shown on Attachment "B".
The precise location(s) and extent of the BMPs are indicated in the approved Water Quality Technical
Report, dated February 27, 2017, on file with CITY's Development Services Department as MDRA16-
011. The manner and standards by which the BMPs must be repaired and maintained in order to
retain their effectiveness are as set forth in the Operation and Maintenance Plan (hereinafter "O&M
PLAN"), which is attached hereto and incorporated herein as Attachment "C".
Because additional impervious area may require the addition of or alteration of storm water
management areas and strategies, no impervious area may be added to the project site without prior
approval from the City Engineer. Additional impervious area includes, but is not limited to, patio
covers, hardscape improvements, and building additions.
WHEREAS, OWNER's representations that the BMPs will be maintained have been relied upon by
CITY in approving OWNER's development applications. It is the purpose of this Agreement to assure
that the BMPs are maintained, by creating obligations that are enforceable against the OWNER and
the OWNER's successors in interest in the PROPERTY. It is intended that these obligations be
enforceable notwithstanding other provisions related to BMP maintenance that are provided by law.
NOW, THEREFORE, for consideration of (a) CITY's approval of the above development applications
and (b) the mutual covenants set forth herein, IT IS HEREBY AGREED AS FOLLOWS:
Maintenance of Storm Water Management Facilities. OWNER agrees, for itself and its
successors in interest, to all or any portion of the PROPERTY, to comply in all respects with
the requirements of the Stormwater Ordinance with regards to the maintenance of BMPs, and
in particular agrees to perform, at its sole cost, expense and liability, the following
"MAINTENANCE ACTIVITIES` all inspections, cleaning, repairs, servicing, maintenance and
other actions specified in the O&M PLAN, with respect to all of the BMPs listed above. at the
times and in the manner specified in the O&M PLAN. OWNER shall keep records of this
maintenance and provide copies of such records and annual certification of maintenance as
requested by CITY. OWNER shall initiate, perform and complete all MAINTENANCE
ACTIVITIES at the required time, without request or demand from CITY or any other agency.
OWNER further agrees that "MAINTENANCE ACTIVITIES" shall include replacement or
modification of the BMPs in the event of failure. Replacement shall be with an identical type,
size and model of BMP, except that:
(a) The City Engineer may authorize substitution of an alternative BMP if he or she
determines that it will be as effective as the failed BMP; and
(b) If the failure of the BMP, in the judgment of the City Engineer, indicates that the BMP in
use is inappropriate or inadequate to the circumstances, the BMP must be modified or
replaced with a more effective BMP to prevent future failure in the same or similar
circumstances.
2. Notices. OWNER further agrees that it shall, prior to transferring ownership of any land on
which any of the above BMPs are located, or any lot or portion of the PROPERTY which is
served by the above BMPs, and also prior to transferring ownership of any such BMP, provide
clear written notice of the above described maintenance obligations to the transferee.
3. CITY's Right to Perform Maintenance. It is agreed that CITY shall have the right, but not the
obligation, to elect to perform any or all of the MAINTENANCE ACTIVITIES if, in the CITY's
sole judgment, OWNER has failed to perform the same. Such maintenance by the CITY shall
be conducted in accordance with the nuisance abatement procedures set forth in Poway
Municipal Code Chapter 8.72. In the case of maintenance performed by the CITY, it may be
performed by CITY forces, or a contractor hired by the CITY, at the CITY's sole election. It is
recognized and understood that the CITY makes no representation that it intends to or will
perform any of the MAINTENANCE ACTIVITIES. and any election by CITY to perform any of
the MAINTENANCE ACTIVITIES shall in no way relieve OWNER of its continuing
maintenance obligations under this agreement. If CITY elects to perform any of the
MAINTENANCE ACTIVITIES, it is understood that CITY shall be deemed to be acting as the
agent of the OWNER and said work shall be without warranty or representation by CITY as to
safety or effectiveness, shall be deemed to be accepted by OWNER "as is", and shall be
covered by OWNER's indemnity provisions below.
SWMFMA Sparrvik (MDRA1 6-011) Page 2
If CITY performs any of the MAINTENANCE ACTIVITIES, after CITY has demanded that
OWNER perform the same and OWNER has failed to do so within a reasonable time stated in
the CITY's demand, then OWNER shall pay all of CITY's costs incurred in performing the
MAINTENANCE ACTIVITIES, plus an administrative fee. OWNER's obligation to pay CITY's
costs of performing MAINTENANCE ACTIVITIES is a continuing obligation. If OWNER fails to
pay CITY's costs for performing MAINTENANCE ACTIVITIES, CITY may assess a lien on the
property or properties of the responsible parties pursuant to the procedures set forth in Poway
Municipal Code Chapter 8.72.
4. Grant of Easement to CITY. OWNER hereby grants to CITY a perpetual easement over,
under and across all of the PROPERTY, for purposes of accessing the BMPs, inspecting the
BMPs, and performing any of the MAINTENANCE ACTIVITIES specified in Paragraph 1
above. CITY shall have the right, at any time and without prior notice to OWNER, to enter
upon any part of said area as may be necessary or convenient for such purposes. OWNER
shall at all times maintain the PROPERTY so as to make CITY's access clear and
unobstructed.
5. Administration of Agreement for CITY. CITY hereby designates the City Engineer as the
officer charged with responsibility and authority to administer this Agreement on behalf of
CITY. Any notice or communication to the City related to the implementation of this
Agreement shall be addressed to:
City Engineer
City of Poway
13325 Civic Center Drive
Poway, CA 92064
6. Defense and Indemnity. CITY shall not be liable for, and OWNER and its successors in
interest shall defend and indemnify CITY and the employees and agents of CITY (collectively
"CITY PARTIES"), against any and all claims, demands, liability, judgments, awards, fines,
mechanic's liens or other liens, labor disputes, losses, damages, expenses, charges or costs
of any kind or character, including attorneys' fees and court costs (hereinafter collectively
referred to as "CLAIMS"), related to this Agreement and arising either directly or indirectly from
any act, error, omission or negligence of OWNER, OWNER's successors, or their contractors,
licensees, agents, servants or employees, including, without limitation, claims caused by the
concurrent negligent act, error or omission, whether active or passive, of CITY PARTIES.
OWNER shall have no obligation, however, to defend or indemnify CITY PARTIES from a
claim if it is determined by a court of competent jurisdiction that such claim was caused by the
sole negligence or willful misconduct of CITY PARTIES. Nothing in this Agreement, CITY's
approval of the development application or plans and specifications, or inspection of the work
is intended to acknowledge responsibility for any such matter, and CITY PARTIES shall have
absolutely no responsibility or liability therefore unless otherwise provided by applicable law.
7. Allocation of Costs. Following the sale or transfer of any of the individual residential lots by
OWNER, the cost of the MAINTENANCE ACTIVITIES required by this Agreement shall be
divided equally by all lot owners, and paid by each lot owner or his or her heirs, assigns and
successors in interest. This requirement shall be binding on all lot owners in the subdivision,
and each shall be responsible for his or her equal share of the cost associated with the
maintenance.
8. Agreement Binds Successors and Runs With the PROPERTY. It is understood and
agreed that the terms, covenants and conditions herein contained shall constitute covenants
running with the land and shall be binding upon the heirs, executors, administrators,
SWMFMA Sparrvik (MDRA16-011) Page 3
successors and assigns of OWNER and CITY, shall be deemed to be for the benefit of all
persons owning any interest in the PROPERTY (including the interest of CITY or its
successors in the easement granted herein). It is the intent of the parties hereto that this
Agreement shall be recorded and shall be binding upon all persons purchasing or otherwise
acquiring all or any lot, unit or other portion of the PROPERTY, who shall be deemed to have
consented to and become bound by all the provisions hereof.
9. OWNER's Continuing Responsibilities Where Work Commenced or Permit Obtained.
Notwithstanding any other provision of this Agreement, no transfer or conveyance of the
PROPERTY or any portion thereof shall in any way relieve OWNER of or otherwise affect
OWNER's responsibilities for installation or maintenance of BMPs which may have arisen
under the ordinances or regulations of CITY referred to in this Agreement, or other federal,
state or CITY laws, on account of OWNER having obtained a permit which creates such
obligations or having commenced grading, construction or other land disturbance work.
10. Amendment and Release. The terms of this Agreement may be modified only by a written
amendment approved and signed by the Director of Development Services acting on behalf of
CITY and by OWNER or OWNER's successor(s) in interest. This Agreement may be
terminated and OWNER and the PROPERTY released from the covenants set forth herein, by
a release, which CITY may execute if it determines that another mechanism will assure the
ongoing maintenance of the BMPs or that it is no longer necessary to assure such
maintenance.
11. Governing Law and Severability. This Agreement shall be governed by the laws of the
State of California. Venue in any action related to this Agreement shall be in the Superior
Court of the State of California, County of San Diego. OWNER hereby waives any right to
remove any such action from San Diego County as is otherwise permitted by California Code
of Civil Procedure Section 394. In the event that any of the provisions of this Agreement are
held to be unenforceable or invalid by any court of competent jurisdiction, the validity, and
enforceability of the remaining provisions shall not be affected thereby.
IN WITNESS WHEREOF, the parties have executed this Agreement on the dates set forth
hereinafter.
OWNER: SPARRVI OMAS TRUST 0 1 -25-07
\s
By:
Thomas Sparrvik, Truste
Daae
SWMFMA Sparrvik (MDRA16-011) Page 4
CALIFORNIA ALL-PURPOSE ACKNOWLEDGMENT
CIVIL CODE § 1189
M -7 ITINn<.�
A notary public or other officer completing this certificate verifies only the identity of the individual who signed the
document to which this certificate is attached, and not the truthfulness, accuracy, or validity of that document.
State of California
County of San Diego
On -tel /1 1 before me,
Date Here Insert Name and Title of the Officer
I ho►�yt,e�s S ac, rr � � k
Name(s) of Signer(s)
Ana Marie Alarcon, Notary Public
personally appeared
who proved to me on the basis of satisfactory evidence to be the person(s) whose name(s) is/are
subscribed to the within instrument and acknowledged to me that he/she/they executed the same in
his/her/their authorized capacity(ies), and that by his/her/their signature(s) on the instrument the person(s),
or the entity upon behalf of which the person(s) acted, executed the instrument.
ANA MARIE ALARCON
l Commission No. 2120463
NOTARY PUBLIC -CALIFORNIA On
+'� _ ; SAN DIEGO COUNTY
MY Comm Expires JULY 23 2019
Place Notary Seal Above
I certify under PENALTY OF PERJURY under the laws
of the State of California that the foregoing paragraph
is true and correct.
WITNESS my hand and official seal.
Signature /)l
Signature of Notary Public
OPTIONAL
Though this section is optional, completing this information can deter alteration of the document or
fraudulent reattachment of this form to an unintended document.
Description of Attached Document
Title or Type of Document:
Number of Pages:
Document Date:
Signer(s) Other Than Named Above:
Capacity(ies) Claimed by Signer(s)
Signer's Name:
❑ Corporate Officer — Title(s):
❑ Partner — i- i Limited i I General
❑ Individual ❑ Attorney in Fact
❑ Trustee ❑ Guardian or Conservator
❑ Other:
Signer Is Representing:
Signer's Name:
❑ Corporate Officer — Title(s):
❑ Partner — Limited 1 General
❑ Individual Attorney in Fact
❑ Trustee Guardian or Conservator
__1 Other:
Signer Is Representing:
02014 National Notary Association • www.NationalNotary.org • 1 -800 -US NOTARY (1-800-876-6827) Item #5907
CITY OF POWAY:
Rob rt J. Manis
I
Director of Development Se Ices
APPROVED AS TO FORM:
Office of the City Attorney
Alan enstermacher, City Attorney
Attachment
A. Parcel Legal Description
B. Parcel Site Plan
C. Operations and Maintenance Plan
D. Certificate of Acceptance
Date: gl'?11 �
APPROVED AS TO CONTENT:
Engineering Division
Thomas Frank, P.E.
City Engineer
MAengserv\Land Development Projects120161SWFMA Projects Without Grading\MDRA16-011 Sparrvik SWFMA.docx
SWMFMA Sparrvik (MDRA16-011) Page 5
CALIFORNIA• • •GMENT CIVIL CODE . 1189
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A notary public or other officer completing this certificate verifies only the identity of the individual who signed the
document to which this certificate is attached, and not the truthfulness, accuracy, or validity of that document.
State of California
County of San Diego
On before me, _
Date
Yvonne Mannion Notary Public
Here Insert Name and Title of the Officer
personally appeared
Name(s) of Signer(s)
who proved to me on the basis of satisfactory evidence to be the person(s) whose name(s) is/are
subscribed to the within instrument and acknowledged to me that he/she/they executed the same in
his/her/their authorized capacity(ies), and that by his/her/their signature(s) on the instrument the person(s),
or the entity upon behalf of which the person(s) acted, executed the instrument.
YVONNE MANNION I certify under PENALTY OF PERJURY under the laws
NotaryPublic- California of the State of California that the foregoing paragraph
San Diego County R_ is true and correct.
Commission a 2201766 WITNESS my hand and official seal.
My Comm. Expires Jun 18, 2021
SignatureA LAt Aj &AA i0 1DSignature of Notary Public
Place Notary Seal Above
OPTIONAL
Though this section is optional, completing this information can deter alteration of the document or
fraudulent reattachment of this form to an unintended document.
Description of Attached Document
Title or Type of Document:
Document Date: +t
Signer(s) Other Than Named Above:
Capacity(ies) Claimed by Signer(s)
Signer's Name:
❑ Corporate Officer — Title(s):
❑ Partner — ❑ Limited ❑ General
❑ Individual ❑ Attorney in Fact
❑ Trustee ❑ Guardian or Conservator
❑ Other:
Signer Is Representing:
A
::I;tj,ei dna i(itl
Number of Pages:
Signer's Name:
❑ Corporate Officer — Title(s):
❑ Partner — ❑ Limited ❑ General
❑ Individual ❑ Attorney in Fact
❑ Trustee ❑ Guardian or Conservator
❑ Other:
Signer Is Representing:
02016 National Notary Association - www.NationalNotary.org - 1 -800 -US NOTARY (1-800-876-6827) Item #5907
ATTACHMENT A
Legal Description
PARCEL AAS SHOWN ON CERTIFICATE OF COMPLIANCE NO. 08-01 AS EVIDENCED BY
DOCUMENT RECORDED SEPTEMBER 22, 2009 AS INSTRUMENT NO. 2009-0527124 OF
OFFICIAL RECORDS, BEING MORE
PARTICULARLY DESCRIBED AS FOLLOWS:
LOT 8 OF CITY OF POWAY TRACT MAP NO. 89-09, IN THE CITY OF POWAY, COUNTY OF
SAN DIEGO, STATE OF CALIFORNIA, ACCORDING TO MAP THEREOF NO. 14091, FILED IN
THE OFFICE OF THE COUNTY RECORDER OF SAN DIEGO COUNTY, DECEMBER 5, 2000.
EXCEPTING THEREFROM THAT PORTION OF SAID LOT 8, DESCRIBED AS FOLLOWS:
BEGINNING AT THE MOST NORTHEAST CORNER OF SAID LOT 8; THENCE ALONG THE
EASTERLY LINE THEREOF, SOUTH 16044'00" WEST, 297.71 FEET; THENCE LEAVING SAID
EASTERLY LINE NORTH 28016'00" WEST, 7.07 FEET; THENCE NORTH 16°44'00" EAST,
292.84 FEET TO A POINT ON THE NORTHERLY LINE OF SAID LOT 8, SAID NORTHERLY
LINE BEING A 280 FOOT CURVE CONCAVE SOUTHERLY; THE CENTER OF SAID CURVE
BEARS NORTH 17042'40" EAST TO SAID POINT; THENCE EASTERLY ALONG SAID
NORTHERLY LINE THROUGH A CENTRAL ANGLE OF O1°01'24", A DISTANCE OF 5.00 FEET
TO THE POINT OF BEGINNING.
TOGETHER WITH A PORTION OF LOT 7 OF CITY OF POWAY TRACT MAP 89-09, IN THE
CITY OF POWAY, COUNTY OF SAN DIEGO, STATE OF CALIFORNIA, ACCORDING TO MAP
NO. 14091, FILED IN THE OFFICE OF THE COUNTY RECORDER OF SAN DIEGO COUNTY,
DECEMBER 5, 2000 OF OFFICIAL RECORDS, DESCRIBED AS FOLLOWS:
BEGINNING AT THE SOUTHWEST CORNER OF SAID LOT 7; THENCE ALONG THE
WESTERLY LINE THEREOF, NORTH 16044'00" WEST, 152.13 FEET; THENCE LEAVING SAID
WESTERLY LINE SOUTH 28016'00" EAST, 14.14 FEET; THENCE SOUTH 16°44'00" WEST,
143.16 FEET TO A POINT ON THE SOUTHERLY LINE OF SAID LOT 7; THENCE ALONG SAID
SOUTHERLY LINE NORTH 67024'00" WEST 10.05 FEET TO THE POINT OF
BEGINNING.
THE FOLLOWING RECITAL CONTAINED IN PATENT DEED RECORDED OCTOBER 26, 1938,
IN BOOK 835, PAGE 404 OF OFFICIAL RECORDS, WHICH RECITES IN PART AS FOLLOWS:
SUBJECT TO ANY VESTED AND ACCRUED WATER RIGHTS FOR MINING AGRICULTURAL
MANUFACTURING OR OTHER PURPOSES AND RIGHTS TO DITCHES AND RESERVOIRS
USED IN CONNECTION WITH SUCH WATER RIGHTS.
`Ots..1
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y
1 INCH = 80 FEET
BMP 2
BMP3
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It I
i
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U�ST�oos EXISTING
CURB
OUTLETS
/ BMP 1 `
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OR
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CONCRETE
DITCH
LEGEND
2,10 FILTRATION FACILITY
DRAINAGE MANAGEMENT AREA (DMA)
FLOW DIRECTION
ATTACHMENT 8
08cM EXHIBIT
SPARRVIK RESIDENCE
:SHEET 1 0F 1
A77A G11MF N T L
Sparrvik Residence
Operation and Maintenance plan for Treatment BMPs
MDRA-16-011
City of Poway, Ca.
December 4, 2018
Prepared For:
Thomas Sparrvik
15597 Paseo Del Arroyo
Poway CA, 92064
858-405-3030
Prepared By
Florez Engineering
10732 Charbono Terrace
San Diego CA, 92131
(858) 229-2493
TABLE OF CONTENTS
1.0 INTRODUCTION
2.0 SELF MITIGATING AREAS
2.1 OPERATION AND MAINTENANCE
2.2 GENERAL MAINTENANCE
2.3 INSPECTION FREQUENCY AND REQUIREMENTS
2.4 MAINTENANCE FREQUENCY AND REQUIREMENTS
3.0 BIOFILTRATION FACILITIES
3.1 OPERATION AND MAINTENANCE
3.2 GENERAL MAINTENANCE
3.3 INSPECTION FREQUENCY AND REQUIREMENTS
3.4 MAINTENANCE FREQUENCY AND REQUIREMENTS
4.0 FILTERRA UNIT
5.0 FISCAL RESOURCES - POST BMP MAINTENANCE AND MAINTENANCE
ASSURANCE
5.1 MAINTENANCE MECHANISM TO BE IN PLACE BEFORE ACCEPTANCE
5.2 VERIFICATION MECHANISMS
5.3 RESPONSIBLE PARTY
ATTACHMENT
A. POST -CONSTRUCTION BMP PLAN
B. BIOFILTRATION HANDOUT (BF -1)
VICINITY MAP
1.0 INTRODUCTION
This operation and maintenance plan is provided to establish mechanisms and guidelines for
maintaining post -construction BMPs listed in the Storm Water Quality Management Plan for the
Sparrvik Residence. This plan categorizes the maintenance activities to assure post -construction
BMP's will be adhered to. This plan also will address maintenance funding methods in
accordance with the City of Poway.
2.0 Self -mitigating areas (on-site).
• The project proposes Self -mitigating areas; these areas consists of natural vegetation that
do not require regular application of fertilizer and pesticides.
• These areas area separate from drainage areas that contain permanent storm water
pollutant control BMPs.
2.1 Operation and Maintenance
The proper functioning of the proposed self -mitigating areas depends on its long-term
maintenance. Maintenance is relatively minimal and similar to regular landscaped areas.
2.2 General Maintenance
• Trash and Debris. During each inspection and maintenance visit to the site, trash
removal will be conducted to reduce the potential for clogging of existing offsite
downstream storm drain structures.
2.3 Inspection Frequency and Requirements
Frequency
• Once a month at a minimum.
Requirements (Visual Observation)
• Inspect for trash accumulation.
2.4 Maintenance Frequency and Requirements
Frequency
• Once a month at a minimum
Requirements
• Collect trash and dispose properly.
0 See Attachment "A" for limits of self -mitigating areas.
3.0 Bio -filtration facility
Most of the newly created impervious surfaces will drain to the three proposed Biofiltration
facilities. The proposed facilities will detain the runoff in a surface reservoir, filter it through
plant roots and a biologically active soil mix and through a gravel layer. The site soils are not
that permeable, an under drain will convey treated runoff to the proposed storm drain.
3.1 Operation and Maintenance
The proper functioning of the biofiltration BMPs cells depends on their long-term
maintenance. While maintenance is relatively minimal and similar to regular landscaped
areas, extra care must be taken to maintain the area's pollutant removal and infiltration
capacity. This is accomplished by maintaining soil structure, caring for soil invertebrates,
mulching as needed, and periodic removal of debris.
Biofiltration BMPs typically require routine landscape maintenance using the same
equipment that is used for general landscape maintenance. At times these BMPs may
require excavation of clogged media (e.g. bioretention soil media, or sand for the sand
filter), and should be accessible to appropriate equipment for excavation and
removal/replacement of media.
3.2 General Maintenance
• Trash and Debris. During each inspection and maintenance visit to the site, debris
and trash removal will be conducted to reduce the potential for outlet pipes and other
components from becoming clogged and inoperable during storm events.
• Accumulation of sediment, litter, or debris. Sediment accumulation, as part of the
operation and maintenance program at a bioretention cell will be monitored once a
month during the dry season and after every large storm (0.50 inch). Specifically, if
sediment reaches a level at or near plant height, or could interfere with flow or
operation, the sediment will be removed. If accumulation of debris or sediment is
determined to be the cause of decline in design performance, prompt action (i.e.,
within ten working days) will be taken to restore the facility to design performance
standards. Actions will include using additional fill and vegetation and/or removing
accumulated sediment to correct channeling or ponding. Characterization and
Appropriate disposal of sediment will comply with applicable with City of Poway
requirements.
• Removal of Standing Water. Make appropriate corrective measures such as adjusting
irrigation system, removing obstructions of debris or invasive vegetation, clearing
underdrains (where applicable), or repairing/replacing clogged or compacted soils.
0 Obstructed inlet or outlet structure. Clear obstructions.
• Damage to structural components .such as weirs, inlet or outlet structures. Repair or
replace as applicable.
3.3 Inspection Frequency and Requirements
Frequency
• Once a month at a minimum.
• 72 hours (for drawdown time) after every large storm (after every storm monitored or
those storms with more than 0.50 inch of precipitation.)
• On a weekly basis during extended periods of wet weather.
Requirements (Visual Observation)
• Inspect the bioretention area for proper drawdown or evidence of clogging
• Inspect for debris accumulation.
• Inspect for accumulated sediment around yard drains.
• Inspect low flow outlet orifice for clogging.
3.4 Maintenance Frequency anti Requirements
Frequency
• Once a month at a minimum during peak growing season (late spring and early fall).
Requirements
• Removal of debris and sediment accumulation.
• Check condition of soil mix and replace as necessary
• Check condition of the outlet pipe and replace if cracked or damaged.
• Remove debris and sediment around and inside the low flow outlet orifice.
NOTE: TOP OF GRADE ELEVATIONS INTENTIONALLY
SET AT 9" ABOVE BIORETENTION AREA SURFACE
1� t)r-
HARWOOD
CAPPEC
CLEANOUT PORT
18" THICK SOIL MEDIA
SEE SPECIFICATION
DETAIL
4" SOIL VIEDIA BARRIER
(2" 'HASHED SAND OVER
2" OF NO. 8 CHOKINC
STONE) J
IMPERMEABLE LINER SIDES AND BOTTOI`,
15MIL MIRAFI NT 100 OR EQUIVALENT
WITH ALL SEEMS HEAT WELDED
ren.mn.iur, nFPTN in"
LAYER (WASHED #57 STONE)
RISER STRUCTURE
3:1 SLOPE
)RO—MODIFICATION
NTROL ORIFICE AT
SUBGRADE
ELEVATION
OUTLET TO
DRAINAGE
NETWORK
„ .ATED a"" SCH 40 PVC
COLLECTOR PIPE WITH SLOTS/HOLES
SPACED EVERY 6 IN. MAY USE
PERFORATED 4" SCH 40 PVC FOR
LATERAL DRAINAGE PIPE
BIO -FILTRATION FACILITY PROFILE
HO s
81O14E7r-NT7aq ENGINEERED SOIL LAYER
SHALL RE .VIN)MDAM 18" LEEP "SANDY
LOAM' SOIL MIX inTH No uoRE rr4AN 5Z
CLAY CONTENT. PERCcO+LAi70N .RATE
5-10roA.R MINIMUM SUSTAINED
24", 24" & 9" DRAINAGE
LAYER (WASHED"57 STONE)
TO PER PLAN
FG PER PLAN
12" X 12"
CATCH BASIN
_ —
- '
FLOW CONTROL
ORIFICE PLA TE
SEE DETAIL NS
SNEET
IMPERMEABLE UNER SIDES-/ UNDERDRAIN
AND BOTTOM 15MIL MIRAFI CONNECTION
NT 100 OR EQUIVALENT PIPE
WITH ALL SEEMS HEAT
WELDED
ORIFICE PLATE MIN. SQUARE
DIMENSIONS 1.0 FT GREATER
THAN PIPE DIA. HOT—CIP
GALVANIZED PLATE AFTER
HOLES HAVE BEEN DRILLED
U
U�
1/2" AMAX
OUTFLOW
DUP ORIFICE SIZE
PIPE
o ORIFICE
1 0.3?DIAMETER
2 0.44"
3/8" DIA.
.3 0.45"
HOLE
OUTFAL PPE
j FLOiWv
M
FL PER PLAN
BIO -FILTRATION SECTION DETAILS
N0710 SCAM
Operation & Maintenance
(OM) Manual v01
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Bioretention Systems
Ci-4`i'1�i--FNTECH"
ENGINEERED SOLUTIONS
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BiaTstentiun Systems
Fable of Contents
Overview
• Fifterra General Description
• hfterra Schemofic
• Basic Operations
• Design
Maintenance
• Maintenance Overview
* Why Maintain?
a When to Maintain?
• Exclusion of Services
• Maintenance Visit Summary
• Maintenance Tools, Safety Equipment and Supplies
Maintenance `sit Procedure
• Maintenance Checklist
Resources
• Example Fifterra Project Maintenance Report Sheet
ExampJe Fifterra Structure Maintenance Report Sheet
• Filters Warranty
- Dravring FIST -2: Fitterra Standard Configurafion Detail
• Dravl'ng FTNL-3: Fifterra Narrow Length Configuration Detail
• Drawing FTNW- 3: FiHerra Narrow Width ConEgurotion Defail
C'\\�NTECH`
ENGINEERED SOLUTIONS
w.wr.ContcrhES.com/filterra 800-338-1122
General Description
The fallowing general specifications describe the general opemtions and mointenanae requirements for the Contech Engineered
Solutions LLC storrriNvater bioretenfion filtration systimr the Fi cerci- The system uirli:es physical, chemical and biological
mechanisms of a soil, plant and microbe oomplcc to remove polluinnts typically found in urban sformwcrter runoff. The
treatment system is a fully "uippcd, pre -constructed drop-in place unit designed for applications in the urban landscape to treat
contaminated runoff
Slorm-,s ter flows through a sptcially designed filter media mixture contained in a landscaped concrete container_ The mixture
immobilises pollvtants which are then dreamposed, volatilized and incorporated into the biomass of the Filterru system's micro/
macro fauna and flora_ Storm%uter runoff flows through the media an -d into an underdrain system at the bottom of the container,
where the treated-e-uter is discharged. Highcr flours bypass the Fiftcr- to a downstream inlet or outfall. Maintenance is a simple,
inexpensive and safe operation that does not require confined space access, pumping or vacuum equipment or specialised tools.
Properly trained landscape personnel can effc6vrly maintain Filler— Stormvvater systems by fallowing instructions in this manual.
vnvw_ContcchES.com/fiHerra 800-338-1122
Basic Operations
Filters is a bioretrntior. system in a concrete box.
Contaminated stormwater runoff enters the filter box through
the curb inlet spreading over the 3 -inch layer of mulch on the
surface of the filter media. As the water passes through the
mulch layer, most of the larger sediment particles and heavy
metals arc removed through sedimentation and chemical
reactions with the organic material in the mulch. Water passes
through the soil media where the finer particles are removed
and other chemical reactions take place to immobilize and
capture pollutants in the soil media. The cleansed water
passes into an undcrdrain and flows to a pipe system or other
appropriate discharge point. Once the pollutants are in the soil,
the bacteria begin to break down and metabolize the materials
and the plants begin to uptake and metabolize the pollutorrts.
Some pollutants such as heavy metals, which are chemically
bound to organic particles in the mulch, are released over
time as the organic matter decomposes to release the metals
to the feeder roots of the plants and the cells of the bacteria in
the soil where they remain and are recycled. Other pollutants
such as phosphorus are chemically bound to the soil particles
and released slowly back to the plants and bacteria and used
in their metabolic processes. Nitrogen goes through a very
comp!ex variety of biochemical processes where it can ultimately
end up in the plant/bacteria biomass, turned to nitrogen gas
or dissolves back into the water column as nitrates depending
on soil temperature, pH and the availability of oxygen. The
pollutants ultimately are retained in the mulch, soil and biomass
with some passing out of the system into the air or bock into the
water.
Design and Installation
Each project presents different scopes for the use of Filterra
systems_ To ensure the safe and specified function of the
stormwater BMP, Contech review each application before
supply. Information and help may be provided to the design
engineer during the planning process. Correct Filterra box
sizing (by rainfall region) is essential to predict pollutant
removal rates for a given area. The engineer shall submit
calculations for approval by the local jurisdiction. The contractor
I s responsible for the correct installation of FiHcrra units as
shown in approved plans. A comprehensive installation manual
is available at www-conteches.com.
Maintenance
Why Maintain?
All siormwater treatment systems require maintenance for
effective operation. This necessity is often incorporated in
your property's permitting process as a legally binding BMP
maintenance agreement.
• Avoid legal challenges from your jurisdiction's
maintenance enforcement program.
• Prolong the expected lifespan of your Filterra media.
• Avoid more costly media replacement.
• Help reduce pollutant loads leaving your property.
Simple maintenance of the Filterra is required to continue
effective pollutant removal from stormwater runoff before
discharge into downstream waters. This procedure will also
extend the longevity of the living biofilter system_ The unit will
recycle and accumulate pollutants within the biomass, but
is also subjected to other materials entering the throat. This
may include trash, silt and (eaves etc_ -which will be contained
within the void below the top grate and above the mulch
layer. Too much silt may inhibit the Filterra'sOR flow rate, which
is the reason for site stabilisation before activation. Regular
replacement of the mulch stops accumulation of such sediment_
When to Maintain?
Contech includes a 1 -year maintenance plan with each system
purchase- Annual included maintenance consists of a maximum
of two t2) scheduled visits. Additional maintenance may be
necessary depending on sediment and trash loading (by Owner
or at additional cost). The start of the maintenance plan begins
when the system is activated for full operation. Full operation
is defined as the unit installed, curb and gutter and transitions
in place and activation (by Supplier) when. mulch and plant are
added and temporary throat protection removed.
Activation cannot be tamed out until the site is fully stabilized
(full landscaping, grass cover, final paving and street sweeping
completed). Maintenance visits are scheduled seasonally, the
spring visit aims to dean up atter winter loads including salts
and sands while the fall visit helps the system by removing
excessive leaf litter_
It has been found that in regions which retrive between 30-50
inches of annual rainfall, (2) two visits arc generally required,-
regions
equired;regions with less rainfall often only require (1) one visit per
annum.. Varying land uses can affect maintenance frequency;
c_g. some fast food restaurants require more frequent trash
removal. Contributing drainage arcus which are subject to neer
development wherein the recommended erosion and sediment
control measures have not been implemented may require
additional maintenance visits_
Some sites may be subjected to extreme sediment or trash
loads, requiring more frequent maintenance visits. This is the
reason for detailed notes of maintenance actions per unit,
helping the Supplier and Owner predict future maintenance
frequencies, reflecting indr'ridual site conditions.
Owners must promptly notify the (maintenance) Supplier of any
damage to the plantts), which constituie(s) an integral part of
the bioretention technology. Owners should olso advise other
landscape or maintenance contractors to leave all maintenance
to the Supplier (i -c- no pruning or fertilizing).
www.CortechES.com1fiFtcrra 800-336-1122
Exclusion of Services
It is the responsibility of the owner to provide adequate irrigation when necessary to the plant of the Fificrra system_
Clean up due to major contamination such as oils, chemicals, toxic spills, etc. Will result in additional costs and are not covered
under tfie Supplier maintena ice contract. Should a major contamination event occur the Owner must block off the outlet pipe of
the Filterra (where the cleaned runoff drains to, such as drop inlet( and block off the ihroai of the Filterra_ The Supplier should be
informed irnmediatelyr
Maintenance Visit Summary
Each maintenance visit cors) sts of the follov.ing simple tasks (detailed instructions below) -
1 _ Inspection of Filierr3 and surrounding area
2_ Removal of tree grate and erosion control stones
3_ Removal of debris, trash and mulch
4_ Mulch replacement
5_ Plant health evaluation and pruning or replacement as necessary
6. Clean arca around Filferra
?_ Complete paperwork
Maintenance Tools, Safety Equipment and Supplies
Ideal tools include_ camera, bucket, shovel, broom, pruners, hotfrake, and tape measure_ Appropriate Personal Protective
Equipment {PPE) should be used in accordance with local or compary procedures. This may include impervious gloves where the
type of trash is unknown, high visibility clothing and barricades when working in close proximity to traffic and o!so safety hats and
shoes. A T -Bar or crowbar should be used for mining the tree grates (up to 170 lbs ea.). Most visits require minor trash removal
and a full replacement of mulch. See below for actual number of bagged mulch that is required in each unit size. Mulch should be
a double shredded, hardwood,.unety; do not use colored or dyed mulch. Some visits mmy require odditional Filterra engineered
soil media available from +e Supplier.
Box Lrngth
Box Width
Filter Surface
Area (F)
Volume at 3' [ft3}
n of 2 ft3 Mulch
Bogs
'
II
I
www.ContechES.cornAilterra I 800-338-1122
Maintenance Visit Procedure
Keep sufficient documentation of mclintenance actions to pscclict location specific
maintenance frequencies and needs_ An example Maintencnce Report is included
in this manual_
1. Inspection of Filterra and surrounding area
• Record individual unit before maintenance with photograph (numbered).
Record on Mcintenance Report (see example in this document) the
fol lavang:
www.Contc&E&com/fiiterra 1800-333-1122
4. Mulch replacement
- Please see mulch specifications_
- Add double shredded mulch evenly across the entire unit to a depth of 3"_
- Ensure coned repositioning of erosion control stones by the Filterra inlet to
allow for en" of trash during a storm e.�ent_
- Replace Filterra grates correctly using appropriate lifting or moving tools,
taking care not to damage the plant_
i. C[ean area around Filterra
• Clean area around unit and remove all refuse to be disposed of
appropncztebj_
7. Complete paperwork
• Deliver Maintenance Report and photographs to appropriate location
(normally Contech during maintenance oontract period).
• Some 1-urisdi6on5 may require submission of maintenance reports in
accordance with approvals. It is the responsibility of the Owner to comply
witn local regulations_
w N,_ContemES.corrkffiltrrra 1 800-338-1122
Maintenance Checklist
Drainage
Failure
Froblem
Conditions to Check
Condition thoat Should B6st
Actions
Inlet should be free of
Excessive
Accumulated sediments or
obstructions aliov+ing free
Sediments and/or trash
Inlet
sediment or trash
trash impair free flaw of
distributed flow of water
should be removed.
accumulation.
water into Filterra_
into Filterra.
Trash and debris should
Trash and
be removed and mulch
Excessive trash and/or
Minimal crash or other
Mulch Cover
flo�otable debris
cover raked level. Ensure
debris accumulation.
debris on mulch cover.
accumulation.
bark nugget mulch is not
used.
"Ponding' in unit could be
"Ponding" of water
indicative of clogging due
Stormwater should drain
Recommend contact
Mulch Cover
to excessive fine sediment
freely and cvcnly through
manufacturer and replace
an mulch cover.
accumulation or spill of
mulch cover_
mulch as a minimum,
pefrolcum oils.
Soil!m;.11ch too wet,
Plants not growing
evidence of spill. Incorrect
Vegetation
or in poor
plant selection. Pest
Plants should be healthy
Contact manufacturer for
and pest free_
advice.
condition.
infestation_ Vandalism to
pionts.
Trim/prune plants in
Plant growth
Plants should be
vetch typical
Vegetation
appropriate to the species
excessive_
landscaping and safety
and location of 1=ilfcrra_
needs.
Cracks wider than 1/2
Structure has
inch or evidence of soil
Structure
partides mtenng the
Vault should be repaired.
visible cracks.
structure through the
cracks_
Pubainfenance is ideafly to
be perfonmed fwice annuzr)F _
C, ,\\ �L-
,%,,,NTECH`
ENGINEERED SOLUTIONS
0 See Attachment "A" Filterra facility for location
5.0 Fiscal Resources for BMP Maintenance and Maintenance
Assurance
5.1 Maintenance mechanism to be in place before acceptance. (Section 16.104.010 of
MC)
Structural BMPs shall not be considered "effective," and shall not be accepted as meeting
the MEP standard, unless a mechanism is in place that will ensure ongoing long-term
maintenance of all structural BMPs. As part of project review, if a project proponent is
required to include interim or permanent structural BMPs in project plans, and if the
Director of Development Services does not provide a mechanism for BMP maintenance,
the project proponent shall provide verification of maintenance requirements through
such means as may be appropriate, at the discretion of the Director of Development
Services, including, but not limited to covenants, legal agreements, maintenance
agreements, and/or conditional use permits. (Ord. 702 § 12, 2010; Ord. 569 § 2, 2002.
Formerly 16.108.010)
5.a Verification mechanisms. (Section 16.104.030 of MC)
In all instances, the project proponent shall provide proof of execution of an approved
method of maintenance repair and replacement before the issuance of construction
approvals.
The party responsible for the structural BMP maintenance shall provide to the City
annual written verification of effective operation and maintenance of each approved
treatment control BMP. (Ord. 702 § 12, 2010; Ord. 671 § 67, 2008; Ord. 569 § 2, 2002.
Formerly 16.108.030)
5.3 Responsible Party.
• The property owner is responsible to ensure inspection, O&M of permanent structural
BMPs on their property. When property ownership changes (i.e. the property is sold or
otherwise transferred to a new owner), maintenance responsibility also transfers to the
new owner, typically by transfer of a maintenance agreement recorded against the
property by the County Assessor.
ATTACHMENT A
8.5'X I I" POST -CONSTRUCTION BMP PLAN
i
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1 INCH = 80 FEET
BMP2
` BMP3
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allo
GuFST� �s 1
o�EXISTING
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\ OUTLETS
BMP1
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EXISTIN _ OUf V�FM
CONCRETE
DITCH
LEGEND
BIO FILTRATION FACILITY
DRAINAGE MANAGEMENT AREA (DMA)
-- FLOW DIRECTION
ATTACHMENT A
O&M EXHIBIT
SPARRVIK RESIDENCE
SHEET 1 OF 1
ATTACHMENT B
BIOFILTRATION HANDOUT (BF -1)
BF -1 Biofiltration
MS4 Permit Category
Biofiltration
Manual Category
Biofiltration
Applicable Performance
Standard
Pollutant Control
Flow Control
Primary Benefits
Treatment
Volume Reduction (Incidental)
Peak Flow Attenuation (Optional)
Description
Biofiltration (Bioretention with underdrain) 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. Bioretention with underdrain facilities are commonly
incorporated into the site within parking lot landscaping, along roadsides, and in open spaces. Because
these types of 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 chain system.
Treatment is achieved through filtration, sedimentation, sorption, biochemical processes and plant
uptake.
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 expected 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
www.sandiegocounty.gov/stormwater E-150 Effective January 1, 2019
CUR
CUR
12"
BF -1 Biofiltration
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PLAN
NOT TO SCALE
A SURFAC A A
46" DROP FROM CURB CUT TO APRON
APRON FOR ENERGY DISSIPATION 2" MIN FREEBOARD
r 3" SHREDDED HARDWOOD
6" MIN. TO 12" MAX. / MULCH
SURFACE PONDING MAINTENANCE
CURB CUT � ACCESS CLEANOUT -i
EXCAVATED SLOPE
(SHOWN AT 1 H 1 V1 ,
MIN. 18" MEDIA WITH
MIN 51NJHR
FILTRATION RATE
SATURATED STORAGE
(OPTIONAL)
FILTER COURSE
AGGREGATE STORAGE LAYER
(AS NEEDED)
II_
OVERFLOW
_ STRUCTURE
IMPERMEABLE LINER (OPTIONAL)
MIN 3" AGGREGATE BELOW UNDERDRAIN
MIN. 6" DIAMETER UNDERDRAIN
EXISTING UNCOMPACTED SOILS
Typical plan and Section view of a Biofiltration BMP
Design Adaptations for Project Goals
Biofiltration Treatment BMP for storm water pollutant control. The system is lined or un -lined
to provide incidental infiltration, and an underdrain is provided at the bottom to carry away filtered
www.sandiegocount}'.gov/stormwater E-151 Effective January 1, 2019
BF -1 Biofiltration
runoff. This configuration is considered to provide biofiltration treatment via flow through the media
layer. Storage provided above the underdrain within surface ponding, media, and aggregate storage is
considered included in the biofiltration treatment volume. Saturated storage within the aggregate
storage layer can be added to this design by raising the underdrain above the bottom of the aggregate
storage layer or via an internal weir structure designed to maintain a specific water level elevation.
Integrated storm water flow control and pollutant control configuration. The system can be
designed to provide flow rate and duration control by primarily providing increased surface ponding
and/or having a deeper aggregate storage layer above the underdrain. This will allow for significant
detention storage, which can be controlled via inclusion of an outlet structure at the downstream end
of the underdrain.
Recommended Siting Criteria
Si ng Cuter a
Intent,IRa tlonale
Placement observes geotechnical
recommendations regarding potential hazards
(e.g., slope stability, landslides, liquefaction
Must not negatively impact existing site
zones) and setbacks (e.g., slopes, foundations,
geotechnical concerns.
utilities).
Lining prevents storm water from
An impermeable liner or other hydraulic
impacting groundwater and/or sensitive
E3
restriction layer is included if site constraints
environmental or geotechnical features.
indicate that infiltration or lateral flows should
Incidental infiltration, when allowable,
not be allowed.
can aid in pollutant removal and
groundwater recharge.
Bigger BMPs require additional design
features for proper performance.
Contributing tributary area greater than 5
acres may be allowed at the discretion of
Contributing tributary area must be <_ 5 acres
County staff if the following conditions
(< 1 acre preferred).
are met: 1) incorporate design features
(e.g. flow spreaders) to minimize short
circuiting of flows in the BMP and 2)
incorporate additional design features
requested by County staff for proper
performance of the regional BMP.
[�
Finish grade of the facility is <_ 2%.
Flatter surfaces reduce erosion and
channelization within the facility.
www.sandiegocount-,-.gov/stormwater E-152 Effective January 1, 2019
BF -1 Biofiltration
Design Criteria and Considerations
Biofiltration must meet the following design criteria. Deviations from the below criteria may be
approved at the discretion of County staff if it is determined to be appropriate:
Siting and Design
Sutfa cc Pon ding
Surface ponding is limited to a 24-hour
drawdown time.
Surface ponding depth is > 6 and :5 12
inches.
A minimum of 2 inches of freeboard is
provided.
Side slopes are stabilized with vegetation and
are = 3H:1 V or shallower.
Vegetation
In tent/Rationale
Surface ponding limited to 24 hour for
plant health. Surface ponding
drawdown time greater than 24 -hours
but less than 96 hours may be allowed
at the discretion of County staff if
certified by a landscape architect or
agronomist.
Surface ponding capacity lowers
subsurface storage requirements. Deep
surface ponding raises safety concerns.
Surface ponding depth greater than 12
inches (for additional pollutant control
or surface outlet structures or flow -
control orifices) may be allowed at the
discretion of County staff if the
following conditions are met: 1) surface
ponding depth drawdown time is less
than 24 hours; and 2) safety issues and
fencing requirements are considered
(typically ponding greater than 18" will
require a fence and/or flatter side
slopes) and 3) potential for elevated
clogging risk is considered.
Freeboard provides room for head
over overflow structures and minimizes
risk of uncontrolled surface discharge.
Gentler side slopes are safer, less prone
to erosion, able to establish vegetation
more quickly and easier to maintain.
w,w-w.sandiegocounit)-.gov/stormwater E-153 Effective January 1, 2019
BF -1 Biofiltration
Siting and Design Intent/Rationale
Plantings are suitable for the climate and Plants suited to the climate and
❑ expected ponding depth. A plant list to aid in ponding depth are more likely to
selection can be found in Appendix F. survive.
An irrigation system with a connection to Seasonal irrigation might be needed to
water supply should be provided as needed. keep plants healthy.
Mulch (Man da tori)
EI 3 inches of well -aged, shredded hardwood Mulch will suppress weeds and
mulch. maintain moisture for plant growth.
Media Layer
n
0
Media maintains a minimum filtration rate
of 5 in/hr over lifetime of facility. An initial
filtration rate of 8 to 12 in/hr is
recommended to allow for clogging over
time; the initial filtration rate should not
exceed 12 inches per hour.
Media is a minimum 18 inches deep,
meeting either of these two media
specifications: Appendix F.2 Biofiltration
Soil Media (BSM) or County of San Diego
Low Impact Development Handbook:
Appendix G -Bioretention Soil Specification
Qune 2014, unless superseded by more
recent edition).
Alternatively, for proprietary designs and
custom media mixes not meeting the media
specifications, the media meets the pollutant
treatment performance criteria in Section
F.1.1.
A filtration rate of at least 5 inches per
hour allows soil to drain between
events. The initial rate should be higher
than long term target rate to account
for clogging over time. However an
excessively high initial rate can have a
negative impact on treatment
performance, therefore an upper limit
is needed.
A deep media layer provides additional
filtration and supports plants with
deeper roots.
Standard specifications must be
followed.
For non-standard or proprietary
designs, compliance with F.1.1 ensures
that adequate treatment performance
will be provided.
www. sandiegocounty.gov/stormwater E-154 Effective January 1, 2019
BF -1 Biofiltration
Siting and Design
Intent/Rationale
Greater surface area to tributary area
ratios: a) maximizes volume retention
as required by the MS4 Permit and b)
decrease loading rates per square foot
and therefore increase longevity.
Media surface area is 3% of contributing
Adjusted runoff factor is to account for
area times adjusted runoff factor or greater.
❑
site design BMPs implemented
Unless demonstrated that the BMP surface
upstream of the BMP (such as rain
area can be smaller than 3%.
barrels, impervious area dispersion,
etc.). Refer to Appendix B guidance.
If media surface area is under 3% of
contributing area, refer to Sediment
Loading calculations in Appendix B.
Potential for pollutant export is partly a
Where receiving waters are impaired or have
function of media composition; media
❑ a TMDL for nutrients, the system is
design must minimize potential for
designed with nutrient sensitive media
export of nutrients, particularly where
design (see fact sheet BF -2).
receiving waters are impaired for
nutrients.
Filtet Course Layer
A filter course is used to prevent migration
Migration of media can cause clogging
❑ of fines through layers of the facility. Filter
of the aggregate storage layer void
fabric is not used.
spaces or subgrade. Filter fabric is
more likely to clog.
------------
Washing aggregate will help eliminate
❑ Filter course is washed and free of fines.
fines that could clog the facility and
impede infiltration.
Gradation relationship between layers
Filter course calculations assessing suitability
can evaluate factors (e.g., bridging,
❑ for particle migration prevention have been
permeability, and uniformity) to
completed.
determine if particle sizing is
appropriate or if an intermediate layer
is needed.
Aggrega to Storage Layer
- - ----------------------------
www.sandiegocounty.gov/stormwater E-155 Effective January 1, 2019
Siting and Design
Class 2 Permeable per Caltrans specification
68-1.025 is recommended for the storage
layer. Washed, open -graded crushed rock
may be used, however a 4-6 inch washed pea
gravel filter course layer at the top of the
crushed rock is required.
The depth of aggregate provided (12 -inch
❑ typical) and storage layer configuration is
adequate for providing conveyance for
underdrain flows to the outlet structure.
BF -1 Biofiltration
Intent/Rationale
Washing aggregate will help eliminate
fines that could clog the aggregate
storage layer void spaces or subgrade.
Proper storage layer configuration and
underdrain placement will minimize
facility drawdown time.
Inflow, Underdrain, and Outflow Structures
Inflow, underdrains and outflow structures Maintenance will prevent clogging and
are accessible for inspection and ensure proper operation of the flow
maintenance. control structures.
- ----------
Inflow velocities are limited to 3 ft/s or less
or use energy dissipation methods. (e.g., High inflow velocities can cause
❑ riprap, level spreader) for concentrated erosion, scour and/or channeling.
inflows.
Curb cut inlets are at least 12 inches wide,
[] have a 4-6 inch reveal (drop) and an apron
and energy dissipation as needed.
Underdrain outlet elevation should be a
❑ minimum of 3 inches above the bottom
elevation of the aggregate storage layer.
❑ Minimum underdrain diameter is 6 inches.
Inflow, Underdrain, and Outflow Structures
Inlets must not restrict flow and apron
prevents blockage from vegetation as it
grows in. Energy dissipation prevents
erosion.
A minimal separation from subgrade or
the liner lessens the risk of fines
entering the underdrain and can
improve hydraulic performance by
allowing perforations to remain
unblocked.
Smaller diameter underdrains are prone
to clogging.
Underdrains are made of slotted, PVC pipe
Slotted underdrains provide greater
conforming to ASTM D 3034 or equivalent intake capacity, clog resistant drainage,
and reduced entrance velocity into the
or corrugated, HDPE pipe conforming to pipe, thereby reducing the chances of
A-ASHTO 252M or equivalent. solids migration.
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Siting and Design
An underdrain cleanout with a minimum 6 -
inch diameter and lockable cap is placed
every 250 to 300 feet as required based on
underdrain length.
Overflow is safely conveyed to a
downstream storm drain system or discharge
point Size overflow structure to pass 100 -
year peak flow for on-line infiltration basins
and water quality peak flow for off-line
basins.
BF -1 Biofiltration
Intent/Rationale
Properly spaced cleanouts will facilitate
underdrain maintenance.
Planning for overflow lessens the risk
of property damage due to flooding.
Conceptual Design and Sizing Approach for Storm Water Pollutant Control Only
To design biofiltration for storm water pollutant control only (no flow control required), the following
steps should be taken:
1. Verify that siting and design criteria have been met, including placement requirements,
contributing tributary area, maximum side and finish grade slopes, and the recommended
media surface area tributary ratio.
2. Calculate the DCV per Appendix B based on expected site design runoff for tributary areas.
3. Use the sizing worksheet presented in Appendix B.5 to size biofiltration BMPs-
Conceptual Design and Sizing Approach when Storm Water Flow Control is Applicable
Control of flow rates and/or durations will typically require significant surface ponding and/or
aggregate storage volumes, and therefore the following steps should be taken prior to determination
of storm water pollutant control design. Pre -development and allowable post -project flow rates and
durations should be determined as discussed in Chapter 6 of the manual.
1. Verify that siting and design criteria have been met, including placement requirements,
contributing tributary area, maximum side and finish grade slopes, and the recommended
media surface area tributary ratio.
2. Iteratively determine the facility footprint area, surface ponding and/or aggregate storage layer
depth required to provide detention storage to reduce flow rates and durations to allowable
limits. Flow rates and durations can be controlled from detention storage by altering outlet
structure orifice size(s) and/or water control levels. Multi-level orifices can be used within an
outlet structure to control the full range of flows.
3. If bioretention with underdrain cannot fully provide the flow rate and duration control
required by this manual, an upstream or downstream structure with significant storage volume
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BF -1 Biofiltration
such as an underground vault can be used to provide remaining controls.
4. After bioretention with underdrain has been designed to meet flow control requirements,
calculations must be completed to verify if storm water pollutant control requirements to treat
the DCV have been met.
Maintenance Overview
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 to 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
BMP 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. I£ the issue is not corrected by restoring the
BMP to the original plan and grade, the County reviewer shall be contacted prior to any
additional repairs or reconstruction.
Other Special Considerations. 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
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BF -1 Biofiltration
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.
Sediment Loading. Consider the effects of BMP design and tributary area land uses on the clogging
potential of the BMP. Complete the sediment loading analysis included in Appendix F.
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BF -1 Biofiltration
Summary of Standard Inspection and Maintenance
The property owner is responsible to ensure inspection, operation and maintenance of permanent BMPs 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 to 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/ 11 1r nance Action Inspection { 1 Maintenance1 1
Accumulation of sediment, litter, or debris Remove and properly dispose of • Inspect monthly. If the BMP is 25% full* or
accumulated materials, without damage to more in one month, increase inspection
the vegetation or compaction of the media frequency to monthly plus after every 0.1 -
layer. 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 materials found
at each inspection.
Damage to structural components such as Repair or replace as applicable • Inspect annually.
weirs, inlet or outlet structures • Maintain when needed.
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BF -1 Biofiltration
reshold/ Indicator
Maintenance Action
Inspection and Maintenance Freqi,797"
• Inspect monthly.
Poor vegetation establishment
Re -seed, re -plant, or re-establish vegetation
per original plans.
• Maintain when needed.
Dead or diseased vegetation
Remove dead or diseased vegetation, re -seed,
• Inspect monthly.
re -plant, or re-establish vegetation per
• Maintain when needed.
original plans.
Overgrown vegetation
Mow or trim as appropriate.
• Inspect monthly.
• Maintain when needed.
2/3 of mulch has decomposed, or mulch has
Remove decomposed fraction and top off
.Inspect monthly.
been removed
with fresh mulch to a total depth of 3 inches.
• Replenish mulch annually, or more
frequently when needed based on
inspection.
Erosion due to concentrated irrigation flow
Repair/re-seed/re-plant eroded areas and
• Inspect monthly.
adjust the irrigation system.
• Maintain when needed.
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BF -1 Biofiltration
IThreshold/Indicator
Maintenance Action
Inspection and Maintenance Frequency
Erosion due to concentrated storm water
Repair/re-seed/re-plant eroded areas, and
• Inspect after every 0.5 -inch or larger storm
runoff flow
make appropriate corrective measures such
event. If erosion due to storm water flow
as adding erosion control blankets, adding
has been observed, increase inspection
stone at flow entry points, or minor re-
frequency to after every 0.1 -inch or larger
grading to restore proper drainage according
storm event.
to the original plan. If the issue is not
*Maintain when needed. If the issue is not
corrected by restoring the BMP to the
corrected by restoring the BMP to the
original plan and grade, the County reviewer
original plan and grade, the County
shall be contacted prior to any additional
reviewer shall be contacted prior to any
repairs or reconstruction.
additional repairs or reconstruction.
Standing water in BMP for longer than 24
Make appropriate corrective measures such
• Inspect monthly and after every 0.5 -inch or
hours following a storm event
as adjusting irrigation system, removing
larger storm event. If standing water is
Surface ponding longer than approximately
obstructions of debris or invasive vegetation,
observed, increase inspection frequency to
24 hours following a storm event may be
clearing underdrains, or repairing/replacing
after every 0.1 -inch or larger storm event.
detrimental to vegetation health
clogged or compacted soils.
• Maintain when needed.
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BF -1 Biofiltration
Threshold/Indicator
1 1 1 Action
InspectOPORTINAWNWnce1 1
• Inspect monthly and after every 0.5 -inch or
Presence of mosquitos/larvae
If mosquitos/larvae are observed: first,
immediately remove any standing water by
larger storm event. If mosquitos are
I � ( )r images of egg rafts, larva, pupa, and adult
dispersing to nearby landscaping; second,
observed, increase inspection frequency to
mosquitos, see
make corrective measures as applicable to
after every 0.1 -inch or larger storm event.
/b'-�
restore BMP drainage to prevent standing
,Maintain when needed.
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 County reviewer 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.
Underdrain clogged
Clear blockage.
Inspect if standing water is observed for
longer than 24-96 hours following a storm
event.
Maintain when needed.
"25% full" is defined as V44 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).
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ATTACHMENT D
CERTIFICATE OF ACCEPTANCE
(Storm Water Management
Facilities Maintenance Agreement)
OF
PO
4.
LQ
60
IN: THE C 1 0
This is to certify that the interest in real property located in the City of Poway conveyed by the
Grant of Easement described in Item 4 of the attached document dated h- i l k Jac, J -7 , from
Thomas Sparrvik, to the City of Poway, a political corporation and/or governmental agency, is hereby
accepted by the undersigned officer or agent on behalf of the City Council pursuant to authority
conferred by Resolution No. 17-007 adopted on April 18, 2017.
Dated: �W/ �Ilq
CITY OF POWAY
By:
bert J. Man
Director of Development Se ices
SWMFMA Sparrvik (MDRA16-011) Page 6