The URL can be used to link to this page

2013-507614 DOC ## 201 3-0507614 111111111111111111111111111111111111111111111111111111111 IN AUG 13, 2013 3:51 PM OFFICIAL RECORDS Recording Requested By: SAN DIEGO COUNTY RECORDER'S OFFICE Ernest J. Dronenburg,Jr.,COUNTY RECORDER City Engineer FEES: 76.00 PAGES: 21 When Recorded Mail to: 1 ��)��I��11111 IN IN City Clerk City of Encinitas 505 South Vulcan Avenue Encinitas, CA 92024 SPACE ABOVE FOR RECORDER'S USE MAINTENANCE AGREEMENT FOR PRIVATE STORMWATER TREATMENT AND STORMWATER POLLUTION CONTROL AND HYDROMODIFICATION g, MANAGEMENT FACILITIES BY HOMEOWNER'S ASSOCIATION ✓ ti/ APNs:254-400-14 & 254-400-19 Project No.: 11-189 TM Plan No.: 11528-G/I/FM THIS AGREEMENT is between the City of Encinitas, a municipal corporation, hereinafter referred to as the "City", and LENNAR HOMES OF CALIFORNIA, INC., A CALIFORNIA CORPORATION, its heirs, successors, and assigns, collectively hereinafter referred to as "Developer", owner(s) of that certain real property hereinafter referred to as "Property" that is described in Exhibit "A", which is attached hereto and made a part hereof. This Agreement is for the periodic Maintenance of certain private stormwater treatment, pollution control, and hydromodification management facilities, hereinafter referred to collectively as "Stormwater Facilities". Stormwater Facilities include but are not limited to Best Management Practices (BMPs), Integrated Management Practices (IMPs), Low Impact Development (LID) features, Hydromodification Management Plan (HMP) facilities, structural stormwater treatment devices, and drainage facilities. The description and plat of Stormwater Facilities is set forth in Exhibit "B" which is, attached hereto and made a part hereof. The term Maintenance is defined in Paragraph 1 below. WHEREAS, this Agreement is required by the City as condition of approval of a City permit pursuant to City of Encinitas Municipal Code Chapter 20.08 and Chapter 23.24 as well as the City of Encinitas Stormwater Manual; and WHEREAS, the Stormwater Facilities described in Exhibit "B" benefit said Property, the developer, and the future owners of the lots/parcels created per Map Case No. 11-189 TM, their heirs, successors, and assigns, collectively hereinafter referred to as "Owners"; and WHEREAS, City requires that Developer establish a homeowners association in conformance with the California Civil Code Sections 1350 through 1376, hereinafter referred to as "HOA", to be responsible for the Maintenance of Stormwater Facilities into perpetuity; and WHEREAS, it is the desire of the City, the responsibility of the Owners, HOA, and Developer, herein after collectively referred to as "Parties", and to the benefit of the Public that Maintenance of said Stormwater Facilities occur on a regular and periodic basis as necessary to preserve the Storm Water Facilities in good-working order by the Parties in accordance with the minimum Maintenance requirements set forth in Exhibit "C", which is attached hereto and made a part hereof, and in accordance with the City of Encinitas Municipal Code, the Encinitas Stormwater Manual, and other related City policies and requirements; and WHEREAS, it is responsibility of the Developer and HOA to manage and oversee Maintenance of Stormwater Facilities and to assign a single point of contact between the City of Encinitas and HOA or Developer; and WHEREAS, Developer's responsibility of Maintenance of Stormwater Facilities will be transferred to HOA after the sale of all lots/parcels, the completion of development, and the approval of the City; and WHEREAS, following Developer's completion of the development and acceptance by the City, the Owners are responsible to continuously have an HOA for purposes of Maintenance of the Stormwater Facilities; and WHEREAS, for the purpose of this agreement, Maintenance responsibilities mentioned on this agreement equally and collectively apply to Owners and the HOA; WHEREAS, it is requirement of development that this Agreement constitute a covenant running with the land, binding upon each successive owner of all or any portion of the Property into perpetuity; NOW THEREFORE, IT IS HEREBY AGREED FOR VALUABLE CONSIDERATION AS FOLLOWS: 1. This agreement establishes the Parties' Maintenance requirements for the Stormwater Facilities. The term "Maintenance" wherever capitalized in this agreement shall include, but shall not be limited to: inspection for purposes of identifying operational deficiencies in the Stormwater Facilities, routine upkeep and repair of the Stormwater Facilities in proper working order as determined by the City, and preparation and submittal of the annual inspection report to the City, all as set forth in subparagraph 1.i) through 1.iii). The Parties' requirements for providing Stormwater Facilities Maintenance as stated in this agreement shall mean Maintenance managed and paid for by the Parties, and performed by a qualified contractor hired by the Parties. i) The Parties shall inspect the Stormwater Facilities after all major storms. In addition, the Parties shall inspect the Stormwater Facilities at the minimum frequency specified in Exhibit "C", but not less than twice per year. ii) The Parties shall provide upkeep and repair to keep the Stormwater Facilities in good working order and shall repair all deficiencies identified in the Parties' inspections no later than 30 days following the inspection or prior to the next anticipated rain event. Interim water quality control measures shall be utilized to protect damaged or deficient Stormwater Facilities until such time as the Facilities are repaired. The minimum upkeep and repair frequency shall be consistent with the Exhibit "C" but not less than once per year. To the satisfaction of the Director of Engineering Services, the Parties shall ensure that the Stormwater Facilities are in proper working order for the rainy season, which starts on October 1. iii) The Parties shall obtain the City of Encinitas Stormwater Inspection Report form from the City website or the City of Encinitas Civic Center, complete the inspection report form, and submit the inspection report to the City of Encinitas Department of Engineering Services. Prior to the submittal of the inspection report to the City, the Parties shall perform an inspection of the Stormwater Facilities, identify deficiencies, and repair and correct all deficiencies. The inspection report shall be submitted to the City once a year between August 1 and September 30. 2. The Property is benefited by this Agreement, and it is the purpose of the signatories hereto that this instrument be recorded to the end and intent that the obligation hereby created shall be and constitute a covenant running with the land. Any heirs, executors, administrators, assignees, and/or successors in interest to all or any portion of the Property, by acceptance of delivery of a deed and/or conveyance regardless of form, shall be deemed to have consented to and become expressly bound by these presents, including without limitation, the right of any person entitled to enforce the terms of this Agreement to institute legal action as provided in Paragraph 12 hereof, such remedy to be cumulative and in addition to other remedies provided in this Agreement and to all other remedies at law or in equity. 3. The Stormwater Facilities shall be constructed by and have Maintenance performed by the Parties in accordance with the term and conditions of this agreement and the plans and specifications identified in approved Grading Plan Number 11528-G which is on file as a permanent public record in the City of Encinitas. 4. The cost and expense of the Maintenance of the Stormwater Facilities shall be paid by the Parties. The Parties' share of Stormwater Facilities Maintenance costs is proportional to number of lots/parcels that Owners and Developer own as a fraction of the total number of lots/parcels in the Property using and benefiting from the Stormwater Facilities but excluding common ownership lots/parcels. 5. In the event the Property is subdivided in future, the owners, heirs, assigns, and successors in interest of each such newly created parcel(s) shall be included in the existing HOA and be liable under this Agreement and with the HOA for their then pro rata share of expenses reflecting such newly created parcels. 6. The Maintenance to be performed under this Agreement shall include upkeep, repair, and improvements to adequately ensure the Stormwater Facilities are in proper working order as determined by the City. Upkeep, repair, and improvements under this Agreement shall include, but are not limited to, repairing access roadbeds; repairing, preserving, and providing improvement for the upkeep of drainage structures; removing debris, sediment, oil, grease, and other pollutants as determined by the City; perpetually preserving adequate groundcover and/or other erosion control measures within the Property in order to prevent erosion; and the management of materials, pollutants, and hazardous waste to prevent pollution of the stormwater system or Municipal Separate Stormwater Sewer System (MS4) as referenced in local and State codes. Upkeep, repair, and improvement shall also include other work necessary to repair and preserve the Stormwater Facilities for their intended purposes as well as the restoration of the Stormwater Facilities following any non-permitted modification. The restoration shall be as required to restore the Stormwater Facilities to the condition existing prior to damage or alteration. 7. Developer, Owners, and HOA are collectively responsible to the City for Maintenance of Stormwater Facilities so long as either Developer or Owners own any lots/parcels. Developer remains responsible for Maintenance of Stormwater Facilities until such Facilities have been approved by the City, even if Developer no longer owns any lots/parcels of the Property. 8. Upon establishment of an HOA and a management company to manage the maintenance of the stormwater facilities, the Developer must notify the City of the contact information for the HOA and management company within thirty (30) days. At a minimum, contact information for HOA and management company shall include: organization name, mailing address, email address, phone number, contract person, contact person's phone number, and email address. The above information must be provided to the City prior to occupancy of the first unit (model home occupancy may be exempt from this requirement). If the Developer is the acting HOA manager at the time of occupancy, the Developer's current contact information shall be provided in lieu of the management company information. Any future changes in HOA or management company contact information shall be provided to the City within thirty (30) days of the change being made. Contact information shall be provided in writing to the following address (or current City of Encinitas, Civic Center address): City of Encinitas Stormwater Division 505 S Vulcan Ave Encinitas, CA 92024 9. Any liability of the Parties for personal injury to any worker employed to provide Maintenance under this Agreement, or to third persons, as well as any liability of the Parties for damage to the property of any third persons, as a result of or arising out of Maintenance under this Agreement, shall be borne by the Parties. 10. Parties shall jointly and severally defend, indemnify, and hold harmless City, City's engineer, its consultants, and each of its officials, directors, officers, agents, and employees from and against all liability, claims, damages, losses, expenses, personal injury, and other costs, including costs of defense and attorney's fees, to any contractor, any subcontractor, any user of the Stormwater Facilities, or to any other third persons arising out of or in any way related to the use, Maintenance, or the failure to provide Maintenance of the Stormwater Facilities. This Agreement imposes no liability of any kind whatsoever on the City and the Parties agree to hold the City harmless from any liability in the event the Stormwater Facilities fail to operate properly. 11. Nothing in this Agreement, the specifications, other contract documents, the City's approval of the plans and specifications, or the City's inspection of the work constitutes an acknowledgement of any City responsibility for any such item or the material contained therein, and the City, City's engineer, its consultants, and each of its officials, directors, officers, employees and agents, shall have no responsibility or liability therefore. 12. The Parties shall provide access to the Stormwater Facilities within the Property to the City's inspectors, employees, agents, and contractors within 48 hours of receipt of a written notification by the City. The access shall be provided unconditionally and without any obstruction, interference, or hazard. Any animals kept on the Property shall be secured outside of the area subject to the City's inspection. 13. The Parties hereby grant permission to the City, its authorized agents, and its employees, to enter upon the Property and to inspect the Stormwater Facilities following a 48-hour notice whenever the City deems necessary. The purpose of inspection is to evaluate the condition and performance of the Stormwater Facilities, to follow-up on reported deficiencies, to respond to citizen complaints, and/or to comply with State and City requirements for City inspection of such facilities. The City shall provide the Owner, with copies of the inspection findings and a directive to commence with any repairs deemed necessary. 14. In the event the Parties fail to preserve the Stormwater Facilities in good working condition as determined by the City Engineer, the City, its agents, employees, or its contractors, may enter upon the Property and take the steps deemed necessary to correct deficiencies and shall charge the costs of such repairs to the Parties. In the event the City pursuant to this Agreement, performs work of any nature, or expends any funds for attorney's fees, administrative costs, contractors, employees, consultants, materials, or other costs in the performance of said work, the Owner shall reimburse the City. Such reimbursement shall be due within thirty (30) days of receipt of a notification for all costs incurred by the City, including any administrative costs and attorney's fees. If said funds are not paid by the Parties within (30) days, City reserves the right to take legal action for cost recovery and to file with the County Recorder of San Diego County an assessment lien on the Property. It is expressly understood and agreed that the City is under no obligation to perform Maintenance of said Stormwater Facilities, and in no event shall this Agreement be construed to impose any such obligation on the City. 15. The terms of this Agreement may be amended in writing following the Parties request and upon written approval by the City Engineer. 16. This Agreement shall be governed by the laws of the State of California. 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 HEREOF, the Parties have executed this Agreement. LENNAR HOMES OF CALIFO A, INC., A CALIFORNIA CORPORATION By: Name: 6k Pia d1A h Title:—Vim d Date: /U k13 (Notarization of DEVELOPERs signature is attached). CITY OF ENCINITAS: ' 913 1, ,-Glenn Prui rw Date Director of Engineering and Public Works City of Encinitas CALIFORNIA ALL-PURPOSE ACKNOWLEDGMENT CIVIL CODE§ 1189 � a State of California County of,:�&d ,A/Qy) On before me,, G�'A/L �G ViCr,&dZ e PU&G/L Date Here Insert Name and Title of the Officer personally appeared 4&6 j111eLD5 Name(s)of Signer(s) who proved to me on the basis of satisfactory evidence to be the person(s) whose name( is re subscribed to thpWithin instrument and acknowledged e that he/ he/they executed the same in s/ er/their orized capacity(ies), and that by RANDA GAIL MILLJOUR his her/their signature(s) on the instrument the v Commission#1916144 < rson(s), or the entity upon behalf of which the Notary Public - California ;u Sari Diego County person(s) acted, executed the instrument. My Commission Exp, Jan. 6, 2015 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: Place Notary Seal Above Signature of Notary Pub' OPTIONAL Though the information below is not required by law, it may prove valuable to persons relying on the document and could prevent fraudulent removal and reattachment of this form to another document. Description of Attached Document Title or Type of Document: Document Date: Number of Pages: Signer(s) Other Than Named Above: Capacity(ies) Claimed by Signer(s) Signer's Name: Signer's Name: ❑ Corporate Officer — Title(s): ❑Corporate Officer — Title(s): i ❑ Individual ❑ Individual ❑ Partner — ❑Limited ❑General Top of thumb here ❑ Partner — ❑ Limited ❑General Top of thumb here < ❑ Attorney in Fact ❑Attorney in Fact ❑ Trustee ❑Trustee ❑ Guardian or Conservator ❑Guardian or Conservator ❑ Other: ❑Other: i Signer Is Representing: Signer Is Representing: I i L©2010 National Notary Association•National Notary.org•1-800-US NOTARY(1-800-876-6827) Item#5907 ACKNOWLEDGMENT State of California County of Orange ) On August 6, 2013 before me, Kelly J. Willis, a Notary Public, (insert name and title of the officer) personally appeared John Baayoun who proved to me on the basis of satisfactory evidence to be the personN whose name( is/CIT subscribed to the within instrument and acknowledged to me that he/she/the�(executed the same in his/f sdth'e r authorized capacity(l), and that by his/ftedth%ir signatureN on the instrument the person(a)—or the entity upon behalf of which the person(N acted, executed the instrument. 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. Co mission*988732 Notary Public-California Z to Orange County My Comm.Expires Jul 30,2016 Signature (Seal) EXHIBIT'A' Legal Description of Property Real property in the City of Encinitas, County of San Diego, State of California, described as follows: PARCEL A: (APN:254-400-19-00) THAT PORTION OF LOT 1 IN BLOCK "G" OF SOUTH COAST PARK ANNEX, IN THE CITY OF ENCINITAS, COUNTY OF SAN DIEGO, STATE OF CALIFORNIA, ACCORDING TO THE MAP THEREOF NO. 1788, FILED IN THE OFFICE OF THE COUNTY RECORDER OF SAN DIEGO COUNTY, MARCH 29, 1924, LYING EASTERLY OF A LINE DESCRIBED AS FOLLOWS: BEGINNING AT A POINT ON THE SOUTH LINE OF SAID LOT 1, DISTANT THEREON 413 FEET WESTERLY FROM THE SOUTHEASTERLY CORNER OF SAID LOT 1;THENCE NORTH 0° 04' 50" EAST IN A STRAIGHT LINE TO A POINT IN THE NORTHERLY LINE OF SAID LOT 1. EXCEPTING THEREFROM THAT PORTION THEREOF CONVEYED TO THE STATE OF CALIFORNIA, BY DEED RECORDED APRIL 20, 1962 AS INSTRUMENT NO. 67749 OF OFFICIAL RECORDS, BEING MORE PARTICULARLY DESCRIBED AS FOLLOWS: ALL THAT PART OF THE PORTION OF LOT 1 IN BLOCK"G" OF SOUTH COAST PARK ANNEX,ACCORDING TO MAP THEREOF NO. 1788, FILED IN THE OFFICE OF THE COUNTY RECORDER OF SAN DIEGO COUNTY, MARCH 29, 1924 AS CONVEYED TO PHILLIP L. B. SCOTT, ET UX, BY DEED RECORDED JUNE 30, 1959 IN BOOK 7744, PAGE 20 OF OFFICIAL RECORDS, FILED IN THE OFFICE OF SAID COUNTY RECORDER, DESCRIBED AS FOLLOWS: BEGINNING AT THE SOUTHEASTERLY CORNER OF THAT PARCEL OF LAND AS CONVEYED TO EUGENE C. CORNETT, ET, UX, BY DEED RECORDED IN OCTOBER 27, 1955 IN BOOK 5847, PAGE 43 OF SAID OFFICIAL RECORDS; THENCE ALONG THE SOUTHEASTERLY LINE OF SAID LOT 1 SOUTH 89° 00' 31" EAST 147.41 FEET; THENCE LEAVING SAID SOUTHEASTERLY LINE NORTH 68° 07' 00" WEST, 80.00 FEET; THENCE NORTH 13° 39' 00" WEST, 291.71 FEET TO THE EASTERLY LINE OF SAID PARCEL OF LAND AS CONVEYED TO SAID CORNETT; THENCE SOUTHERLY ALONG SAID EASTERLY LINE, SOUTH 0° 47' 43"WEST, 310.77 FEET TO THE POINT OF BEGINNING. ALSO THE UNDERLYING FEE INTEREST APPURTENANT TO THE ABOVE DESCRIBED PARCEL IN THE ADJOINING PUBLIC WAY. PARCEL B: (APN: 254-400-14-00) LOT 5, BLOCK G OF SOUTH COAST PARK ANNEX, IN THE CITY OF ENCINITAS, COUNTY OF SAN DIEGO, STATE OF CALIFORNIA, ACCORDING TO THE MAP THEREOF NO. 1788, FILED IN THE OFFICE OF THE RECORDER OF SAID SAN DIEGO COUNTY, MARCH 29, 1924. EXHIBITS' Description and Plat of Stormwater Facilities The stormwater runoff will surface flow in the streets to several catch basins. The underground storm drain systems will divert the runoff to the water quality bioretention basin located near the southwest corner of the site. Refer to the Plat as park of Exhibit B for location. The bioretention basin is approximately 11,908 sqaure feet and has been sized per the City of Encinitas BMP calculator. Refer to separately prepared Storm Water Management Plan for additional information. Catch basins should be inspected and cleaned at least 3 times per year. Remove of any trash and debris that has accumulated and replace of trash screens as needed. Inspect storm drain signage and replace as needed. v� W ui -�q �I I I/Y Y QI I_— E. LL N x � N I U) WoW ' I I ♦_ �I I Z co W o �p N 9 < c CIO O I N 1 U ■ O I , , W -_� --�-- I -Mj w z 0z I 1 I I I W a O z J I , 1 I I Q Z Q m U T� I d F-w m H a J m U Z I ilk ---�----- C� NN � 00 O N i i wm a Q ° 1O�o LLJ I C�.� O _ I I o< C�, �LLJ � Q �� dd U 0 OU� U N H I Z V) co ' I I I o �I� w\ ��ui [if Ij p Z V) ' oO Q O Z •— �__ I Dew O D J� o ~ Z Q J Q cn V)11! 1 I N w W II Jwi mxo-w p m a J��O N Qn- 2 U F.r7 O } awof F / � I - a- w N J I J .� C.W.) S 1 � d !Y V)r a w w U U) W Q Cl 00 LLJ =�Q "V) V) W Z I O f U W=U H W ]J_W Z S LLJ Of Q� O.O O p O O U m W Z W Z O LLJ (if LLJ UU U W(b �O Q a_ LLJ Z Q U Z Q U O m W ~O p r �iUV) !Z EXHIBIT `C' Minimum Maintenance Requirements for Stormwater Facilities Refer to the attached CASQA BMP Fact Sheet TC-32 — Bioretention and SD-13 — Storm Drain Signature for minimum maintenance requirements. Bioretention TC-32 Design Considerations w4• Soil for Infiltration • Tributary Area • Slope • Aesthetics • Environmental Side-effects Description The bioretention best management practice(BMP)functions as a Targeted Constituents soil and plant-based filtration device that removes pollutants through a variety of physical,biological,and chemical treatment Q Sediment a processes. These facilities normally consist of a grass buffer Q Nutrients A strip,sand bed,ponding area,organic layer or mulch layer, 0 Trash a planting soil,and plants. The runoffs velocity is reduced by 0 Metals a passing over or through buffer strip and subsequently distributed Q Bacteria a evenly along a ponding area. Exfiltration of the stored water in p Oil and Grease a the bioretention area planting soil into the underlying soils Q Organics a occurs over a period of days. Legend(Removal Effectiveness) California Experience , Low a High None documented_Bioretention has been used as a stormwater ♦ Medium BMP since 1992. In addition to Prince George's County,MD and Alexandria,VA,bioretention has been used successfully at urban and suburban areas in Montgomery County,MD;Baltimore County,MD;Chesterfield County,VA;Prince William County, VA.Smith Mountain Lake State Park,VA; and Cary,NC. Advantages ■ Bioretention provides stormwater treatment that enhances the quality of downstream water bodies by temporarily storing runoff in the BMP and releasing it over a period of four days to the receiving water(EPA, 1999). ■ The vegetation provides shade and wind breaks,absorbs noise,and improves an area's landscape. Limitations ■ The bioretention BMP is not recommended for areas with slopes greater than 20%or where mature tree removal would January 2003 California Stormwater BMP Handbook 1 of 8 New Development and Redevelopment www.cabmphandbooks.com 7C-32 Bioretention be required since clogging may result,particularly if the BMP receives nuioff with high sediment loads(EPA,1999)• • Bioretention is not a suitable BMP at locations where the water table is within 6 feet of the ground surface and where the surrounding soil stratum is unstable. • By design,bioretention BMPs have the potential to create very attractive habitats for mosquitoes and other vectors because of highly organic,often heavily vegetated areas mixed with shallow water. • In cold climates the soil may freeze,preventing runoff from infiltrating into the planting soil. Design and Sizing Guidelines • The bioretention area should be sized to capture the design storm runoff. • In areas where the native soil permeability is less than o.5 in/hr ail underdrain should be provided. • Recommended minimum dimensions are 15 feet by 40 feet,although the preferred width is 25 feet.Excavated depth should be 4 feet. • Area should drain completely within 72 hours. • Approximately 1 tree or shrub per 5o ft'of bioretention area should be included. • Cover area N�ith about 3 inches of mulch. Construetionjlnspection Considerations Bioretention area should not he established until contributing watershed is stabilized. Performance Bioretention removes stornwater pollutants through physical and biological processes, including adsorption,filtration,plant uptake,microbial activity,decomposition,sedimentation and volatilization(EPA,1999). Adsorption is the process whereby particulate pollutants attach to soil(e.g.,clay)or vegetation surfaces. Adequate contact time between the surface and pollutant must be provided for in the design of the system for this removal process to occur. Thus,the infiltration rate of the soils must not exceed those specified in the design criteria or pollutant removal may decrease. Pollutants removed by adsorption include metals,phosphorus, and hydrocarbons. Filtration occurs as runoff passes through the bioretention area media,such as the sand bed,ground cover,and planting soil. Common particulates removed from stornlwater include particulate organic.matter, phosphorus,and suspended solids. Biological processes that occur in wetlands result in pollutant uptake by plants and microorganisms in the soil. Plant growth is sustained by the uptake of nutrients from the soils,with woody plants locking up these nutrients through the seasons_ Microbial activity within the soil also contributes to the removal of nitrogen and organic matter. Nitrogen is removed by nitrifying and denitrifying bacteria,while aerobic bacteria are responsible for the decomposition of the organic matter. Microbial processes require oxygen and can result in depleted oxygen levels if the bioretention area is not adequately 2 of 8 California 5tormwater BMP Handbook )anuary 2003 New Development and Redevelopment www.cabmphandbooks.com Bioretention TC-32 aerated.Sedimentation occurs in the swale or ponding area as the velocity slows and solids fall out of suspension. The removal effectiveness of bioretention has been studied during field and laboratory studies conducted by the University of Maryland(Davis et al, 1998). During these experiments, synthetic stormwater runoff was pumped through several laboratory and field bioretention areas to simulate typical storm events in Prince George's County,MD. Removal rates for heavy metals and nutrients are shor=n in Table 1. Table 1 Laboratory and Estimated Bioretention Davis et al, (1998); PGDER (1993) Politrtant Removal Rate Total Phosphors —0-83% Metals(Cu,Zn,Pb) 93-98% TKN 68-80% Total Suspended Solids 90% Organics 90% Bacteria 90% Results for both the laboratory and field experiments were similar for each of the pollutants analyzed. Doubling or halving the influent pollutant levels had little effect on the effluent pollutants concentrations(Davis et al,1998). The microbial activity and plant uptake occurring in the bioretention area«rill likely result in higher removal rates than those determined for infiltration BMPs. Siting Criteria Bioretention BMPs are generally used to treat stormwater from impervious surfaces at commercial,residential,and industrial areas(EPA,1999). Implementation of bioretention for stormwater management is ideal for median strips,parking lot islands,and swales. Moreover, the runoff in these areas can be designed to either divert directly into the bioretention area or convey into the bioretention area by a curb and gutter collection system. The best location for bioretention areas is upland from inlets that receive sheet flow from graded areas and at areas that will be excavated(EPA,1999). In order to maximize treatment effectiveness,the site must be graded in such a way that minimizes erosive conditions as sheet flow is conveyed to the treatment area. Locations where a bioretention area can be readily incorporated into the site plan tivithout further environmental damage are preferred. Furthermore,to effectively minimize sediment loading in the treatment area,bioretention only should be used in stabilized drainage areas. January 2003 California Stormwater 8MP Handbook 3 of 8 New Development and Redevelopment www.cabmphandbooks.com TC-32 Bioretention Additional Design Guidelines The layout of the bioretention area is determined after site constraints such as location of utilities,underlying soils,existing vegetation,and drainage are considered(EPA,1999).Sites with loamy sand soils are especially appropriate for bioretention because the excavated soil can be bac101ed and used as the planting soil,thus eliminating the cost of importing planting soil. The use of bioretention may not be feasible given an unstable surrounding soil stratum,soils with clay content greater than 25 percent,a site with slopes greater than 20 percent,and/or a site with mature trees that would be removed during construction of the BMP. Bioretention can be designed to be off-line or on-line of the existing drainage system(EPA, 1999).The drainage area for a bioretention area should be between o.1 and 0.4 hectares(0.25 and i.o acres). Larger drainage areas may require multiple bioretention areas. Furthermore, the maximum drainage area fora bioretention area is determined by the expected rainfall intensity and runoff rate. Stabilized areas may erode when velocities are greater than 5 feet per second(1.5 meter per second). The designer should determine the potential for erosive conditions at the site. The size of the bioretention area,which is a function of the drainage area and the runoff generated from the area is sized to capture the water quality volume. The recommended minimum dimensions of the bioretention area are 15 feet 46 meters)wide by 40 feet(12.2 meters)long,where the minimum width allows enough space for a dense, randomly-distributed area of trees and shrubs to become established. Thus replicating a natural forest and creating a microclimate,thereby enabling the bioretention area to tolerate the effects of heat stress,acid rain,runoff pollutants,and insect and disease infestations which landscaped areas in urban settings typically are unable to tolerate. The preferred Nvidtll is 25 feet(7.6 meters),with a length of twice the width. Essentially,any facilities wider than 20 feet(6.1 meters)should be Mice as long as they are wide,which promotes the distribution of flow and decreases the chances of concentrated flow. In order to provide adequate storage and prevent water from standing for excessive periods of time the ponding depth of the bioretention area should not exceed 6 inches(15 centimeters). Water should not be left to stand for more than 72 hours. A restriction on the type of plants that can be used may be necessary due to some plants'water intolerance. Furthermore,if water is left standing for longer than 72 hours mosquitoes and other insects may start to breed. The appropriate planting soil should be backfilled into the excavated bioretention area. Planting soils should be sandy loam,loamy sand,or loam texture with a clay content ranging from io to 25 percent. Generally the soil should have infiltration rates greater than 0.5 inches(1.25 centimeters)per hour,vvbich is typical of sandy loams,loamy sands,or loams. The pH of the soil should range between J.5 and 6.5,where pollutants such as organic nitrogen and phosphorus can be adsorbed by the soil and microbial activity can flourish. Additional requirements for the planting soil include a 1.5 to 3 percent organic content and a maximum 500 ppm concentration of soluble salts. 4 of 8 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabrnphandbooks.com Bioretention TC-32 Soil tests should be performed for every boo cubic yards(382 cubic meters)of planting soil, NN the exception of pH and organic content tests,which are required only once per bioretention area(EPA,1999). Planting soil should be 4 inches(10.1 centimeters)deeper than the bottom of the largest root ball and 4 feet(1.2 meters)altogether. This depth will provide adequate soil for the plants'root systems to become established,prevent plant damage due to severe wind,and provide adequate moisture capacity. Most sites will require excavation in order to obtain the recommended depth. Planting soil depths of greater than 4 feet(1.2 meters)may require additional construction practices such as shoring measures(EPA,1999). Planting soil should be placed in 18 inches or greater lifts and lightly compacted until the desired depth is reached. Since high canopy trees may be destroyed during maintenance the bioretention area should be vegetated to resemble a terrestrial forest community ecosystem that is dominated by understory trees. Three species each of both trees and shrubs are recommended to be planted at a rate of 2500 trees and shrubs per hectare(l000 per acre). For instance,a 15 foot 46 meter)by 40 foot(12.2 meter) bioretention area(60o square feet or 55.75 square meters)would require 14 trees and shrubs. The shrub-to-tree ratio should be 2:1 to 3:1. Trees and shrubs should be planted when conditions are favorable. Vegetation should be watered at the end of each day for fourteen days following its planting. Plant species tolerant of pollutant loads and varying wet and dry conditions should be.used in the bioretention area. The designer should assess aesthetics,site layout,and maintenance requirements when selecting plant species. Adjacent non-native invasive species should be identified and the designer should take measures,such as providing a soil breach to eliminate the threat of these species invading the bioretention area. Regional landscaping manuals should be consulted to ensure that the planting of the bioretention area meets the landscaping requirements established by the local authorities. The designers should evaluate the best placement of vegetation within the bioretention area. Plants should be placed at irregular intervals to replicate a natural forest. Trees should be placed on the perimeter of the area to provide shade and shelter from the wind. Trees and shrubs can be sheltered from damaging flows if they are placed away from the path of the incoming runoff. In cold climates,species that are more tolerant to cold winds,such as evergreens,should be placed in windier areas of the site. Follou inng placement of the trees and slit ubs,the ground cover and/or mulch should be established. Ground cover such as grasses or legumes can be planted at the beginning of the growing season. Mulch should be placed immediately after trees and shrubs are planted. Two to 3 inches(5 to 7.6 cnnn)of commercially-available fine shredded hardwood mulch or shredded hardwood chips should be applied to the bioretention area to protect from erosion. Maintenance The primary maintenance requirement for bioretention areas is that of inspection and repair or replacement of the treatment area's components. Generally,this involves nothing more than the routine periodic maintenance that is required of any landscaped area. Plants that are appropriate for the site,clnnatic,and watering conditions should be selected for use in the bioretention cell. Appropriately selected plants will aide in reducing fertilizer,pesticide,water, and overall maintenance requirements. Bioretention system components should blend over time through plant and root growth,organic decomposition,and the development of a natural January 2003 California Stormwater BMP Handbook 5 of 8 New Development and Redevelopment www.cabmphandbooks.com c TC-32 Bioretention soil horizon. These biologic and physical processes over time will lengthen the facility's life span and reduce the need for extensive maintenance. Routine maintenance should include a biannual health evaluation of the trees and shrubs and subsequent removal of any dead or diseased vegetation(EPA,1999). Diseased vegetation should be treated as needed using preventative and low-toxic measures to the extent possible. BMPs have the potential to create very attractive habitats for mosquitoes and other vectors because of highly organic,often heavily vegetated areas mixed with shallow water. Routine inspections for areas of standing water within the BMP and corrective measures to restore proper infiltration rates are necessary to prevent creating mosquito and other vector habitat. In addition,bioretention BMPs are susceptible to invasion by aggressive plant species such as cattails,which increase the chances of water standing and subsequent vector production if not routinely maintained. In order to maintain the treatment area's appearance it may be necessary to prune and weed. Furthermore,mulch replacement is suggested when erosion is evident or when the site begins to look unattractive. Specifically,the entire area may require mulch replacement every two to three years,although spot mulching may be sufficient when there are random void areas. Mulch replacement should be done prior to the start of the wet season. New Jersey's Department of Environmental Protection states in their bioretention systems standards that accumulated sediment and debris removal(especially at the inflow point)will normally be the primary maintenance function. Other potential tasks include replacement of dead vegetation,soil pH regulation,erosion repair at inflow points,mulch replenishment, unclogging the underdrain,and repairing overflow structures. There is also the possibility that the cation exchange capacity of the soils in the cell will be significantly reduced over time. Depending on pollutant loads,soils may need to be replaced nvithin 5-10 years of construction (LID,2000). Cost Construction Cost Construction cost estimates for a bioretention area are slightly greater than those for the required landscaping for a new development(EPA,1999). A general rule of thumb(Coffinan, 1999)is that residential bioretention areas average about$3 to$4 per square foot,depending on soil conditions and the density and types of plants used. Commercial,industrial and institutional site costs can range between$10 to$40 per square foot,based on the need for control structures,curbing,storm drains and underdrains. Retrofitting a site typically costs more,averaging$6,500 per bioretention area. The higher costs are attributed to the demolition of existing concrete,asphalt,and existing structures and the replacement of fill material with planting soil. The costs of retrofitting a commercial site in Maryland, Kettering Development,with 15 bioretention areas were estimated at$111,600. In any bioretention area design,the cost of plants varies substantially and can account for a significant portion of the expenditures. While these cost estimates are slightly greater than those of typical landscaping treatment(due to the increased number of plantings,additional soil excavation,backfill material,use of underdrains etc.),those landscaping expenses that would be required regardless of the bioretention installation should be subtracted when determining the net cost. 6 of 8 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com Bioretention TC-32 Perhaps of most importance,however,the cost savings compared to the use of traditional structural stormwater conveyance systems makes bioretention areas quite attractive financially. For example,the use of bioretention can decrease the cost required for constructing stormwater conveyance systems at a site. A medical office building in Maryland was able to reduce the amount of storm.drain pipe that was needed from Boo to 230 feet-a cost savings of$24,000 (PGDER,3993). And a new residential development spent a total of approximately$100,000 using bioretention cells on each lot instead of nearly$400,000 for the traditional stormwater ponds that were originally planned(Rappahanock,). Also,in residential areas,stormwater management controls become a part of each property owner's landscape,reducing the public burden to maintain large centralized facilities. Maintenance Cost The operation and maintenance costs for a bioretention facility will be comparable to those of typical landscaping required for a site. Costs beyond the normal landscaping fees will include the cost for testing the soils and may include costs for a sand bed and planting soil. References and Sources of Additional Information Coffman,L.S.,R.Goo and R.Frederick,1999: Low impact development: an innovative alternative approach to stormwater management.Proceedings of the 26th Annual Water Resources Planning and Management Conference ASCE,June 6-9,Tempe,Arizona. Davis,A.P.,Shokouhian,M.,Sharma,H.and Minami, C.,"Laboratory Study of Biological Retention(Bioretention)for Urban Stormwater Management," Water Environ.Res.,73(1),5-14 (2001). Davis,A.P.,Shokouhian,M.,Sharma, H.,Alinanii,C.,and Winogradoff,D. "Water Quality Improvement through Bioretention: Lead,Copper,and Zinc," Water Environ.Res.,accepted for publication,August 2002. Kim,H.,Seagren,E.A.,and Davis,A.P.,"Engineered Bioretention for Removal of Nitrate from Stormwater Runoff," IVEPTEC 2000 Conference Proceedings on CDROM Research. Symposium,Nitrogen Removal,Session 19,Anaheim CA,October 2000. Hsieh,C.-h.and Davis,A.P."Engineering Bioretention for Treatment of Urban Stormwater Runoff," IVatersheds 2002,Proceedings on CDROMResearch Symposium,Session 15,Ft. Lauderdale,FL,Feb.2002. Prince George's County Department of Environmental Resources(PGDER),1993.Design Manual for Use of Bioretention in Stormwa ter Management.Division of Environmental Management,Watershed Protection Branch. Landover,MD. U.S.EPA Office of Water,1999.Stormwater Technology Fact Sheet: Bioretention.EPA 832-17- 99-012. Weinstein,N.Davis,A.P.and Veerarmachaneni,R. "Low Impact Development(LID)Stormwater Management Approach for the Control of Diffuse Pollution from Urban Roadways,"5th International Conference Diffuse/Nonpoint Pollution and Watershed Management Proceedings,C.S.Melching and Emre Alp,Eds.2001 International Water Association January 2003 California Stormwater BMP Handbook 7 of 8 New Development and Redevelopment www.cabmphandbooks.com Storm Drain Signago SD-13 Design Objectives Maximize Infiltration Provide Retention Slow Runoff Minimize Impervious Land Coverage m Prohibit Dumping of Improper Materials Contain Pollutants Collect and Convey Description_ Waste materials dumped into storm drain inlets can have severe impacts on receiving and ground waters. Posting notices regarding discharge prohibitions at storm drain inlets can prevent waste dumping. Storm drain signs and stencils are highly visible source controls that are typically placed directly adjacent to storm drain inlets. Approach The stencil or affixed sign contains a brief statement that prohibits dumping of improper materials into the urban runoff conveyance system. Storm drain messages have become a popular method of alerting the public about the effects of and the prohibitions against waste disposal. Suitable Applications Stencils and signs alert the public to the destination of pollutants discharged to the storm drain. Signs are appropriate in residential, commercial, and industrial areas,as well as any other area where contributions or dumping to storm drains is likely. Design Considerations Storm drain message markers or placards are recommended at all storm drain inlets within the boundary of a development project. The marker should be placed in clear sight facing toward anyone approaching the inlet from either side. All storm drain inlet locations should be identified on the development site map. Designing New Installations The following methods should be considered for inclusion in the project design and show on project plans: ■ Provide stenciling or labeling of all storm drain inlets and catch basins,constructed or modified,within the project area with prohibitive language. Examples include"NCO DUMPING January 2003 California Stormwater BMP Handbook 1 of 2 New Development and Redevelopment www.cabmphandbooks.com SD-13 Storm Drain Signage —DRAINS TO OCEAN" and/or other graphical icons to discourage illegal dumping. ■ Post signs with prohibitive language and/or graphical icons,which prohibit illegal dumping at public access points along channels and creeks within the project area. Note-Some local agencies have approved specific signage and/or storm drain message placards for use. Consult local agency stormwater staff to determine specific requirements for placard types and methods of application. Redeveloping Eristing Installations Various jurisdictional stormwater management and mitigation plans(SUSMP, WQMP, etc.) define"redevelopment" in terms of amounts of additional impervious area,increases in gross floor area and/or exterior construction, and land disturbing activities with structural or impervious surfaces. If the project meets the definition of"redevelopment",then the requirements stated under" designing new installations" above should be included in all project design plans. Additional Information Maintenance Considerations • Legibility of markers and signs should be maintained. If required by the agency with jurisdiction over the project,the owner/operator or homeowner's association should enter into a maintenance agreement with the agency or record a deed restriction upon the property title to maintain the legibility of placards or signs. Placement • Signage on top of curbs tends to weather and fade. • Signage on face of curbs tends to be worn by contact with vehicle tires and sweeper brooms. Supplemental Information Examples ■ Most MS4 programs have storm drain signage programs. Some MS4 programs will provide stencils, or arrange for volunteers to stencil storm drains as part of their outreach program. Other Resources A Manual for the Standard Urban Stormwater Mitigation Plan(SUSMP), Los Angeles County Department of Public Works,May 2002. Model Standard Urban Storm Water Mitigation Plan(SUSMP)for San Diego County,Port of San Diego, and Cities in San Diego County,February 14, 2002. Model Water Quality Management Plan(WQMP)for County of Orange, Orange County Flood Control District,and the Incorporated Cities of Orange County, Draft February 2003. Ventura Countywide Technical Guidance Manual for Stormwater Quality Control Measures, July 2002. 2 of 2 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com