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HomeMy Public PortalAbout8.A. Second Reading and Adoption of Ordinance No. 13-979 Establish Low Impact Development Standards and a Green Streets PolicyAGENDA ITEM 8.A. COMMUNITY DEVELOPMENT DEPARTMENT MEMORANDUM DATE: November 19,2013 TO: The Honorable City Council FROM: Jose E. Pulido, City ManageN Via: Mark Persico, AICP, Cbflt'munity Development Director By: Hesty Liu, AICP, Associate Planner SUBJECT: SECOND READING AND ADOPTION OF ORDINANCE NO. 13-979, AMENDING ARTICLE E ("SITE PLAN REVIEW AND CONGESTION MANAGEMENT") OF CHAPTER 1 ("ZONING CODE") OF TITLE 9 ("ZONING REGULATIONS") OF THE TEMPLE CITY MUNICIPAL CODE TO ESTABLISH LOW IMPACT DEVELOPMENT (LID) STANDARDS AND A GREEN STREETS POLICY RECOMMENDATION: The City Council is requested to waive further reading and adopt Ordinance No. 13-979 (Attachment "A"), amending Article E ("Site Plan Review and Congestion Management") of Chapter 1 ("Zoning Code") of T itle 9 ("Zoning Regulations") of the Temple City Municipal Code to establish Low Impact Development (LID) standards and a Green Streets Policy. BACKGROUND: 1. On November 8, 2012, under the authority of the Clean Water Act, the Los Angeles Regional Water Quality Control Board adopted the Municipal Separate Storm Sewer System Permit (known as MS4 Permit), which requires that all local jurisdictions in Los Angeles County (i.e., Permittees) electing to participate in a Watershed Management Program or an Enhanced Watershed Management Program have LID ordinances in place. MS4 Permit also requires Permittees to have a Green Streets Policy in place and/or commence development of a policy that specifies the use of green street strategies for transportation corridors. The deadline for compliance is December 15, 2013. 2. On June 28, 2013, Temple City submitted a Notice of Intent to the Los Angeles City Council November 19, 2013 Page 2 of 3 Regional Water Quality Control Board, indicating the intention of participating in the Enhanced Watershed Management Program (EWMP) of the Upper Los Angeles River Watershed Group. 3. From July to September 2013, staff worked on developing LID standards and a Green Streets Policy for the City, in order to comply with the deadline of MS4 Permit issued by the California Regional Water Quality Control Board, Los Angeles Region. 4. On October 17, 2013, the Planning Commission reviewed the Draft Ordinance No. 13-979, the proposed Temple City LID Manual (Attachment "B"), and the proposed Temple City Green Streets Manual (Attachment "C"). The Planning Commission made the recommendation to the City Council to adopt the proposed code amendment, the proposed LID Manual, and Green Streets Manual. 5. On November 5, 2013, the City Council introduced Ordinance No. 13-979 for first reading, and scheduled the second reading of the ordinance for November 19, 2013. ANALYSIS: As provided in the staff report at the November 5, 2013 City Council meeting (Attachment "D"), the proposed ordinance will enable the City to establish LID standards and a Green Street Policy, in order to comply with the mandates and deadline (i.e., December 15, 2013) of the Municipal Separate Storm Sewer System Permit (MS4) issued by Los Angeles Water Quality Control Board. Ultimately, the LID standards and Green Streets Policy will benefit the community by reducing impermeable surfaces for developments, improving water quality in the local aquifer, and enhancing landscape and streetscape within the City. CONCLUSION: The City Council is requested to adopt the proposed code amendment, the Temple City LID Manual, and the Temple City Green Streets Manual. FISCAL IMPACT: It is anticipated that the adoption of proposed Ordinance No. 13-979 will not have a fiscal impact on the Fiscal Year (FY) 2013-14 City Budget. The City will generate revenue to cover the cost of processing development applications. Staff cannot estimate City Council November 19, 2013 Page 3 of 3 at this time how many development applications will be approved, however, if the increase in revenues is significant, staff will revise the revenue estimates accordingly. ATTACHMENTS: A. Ordinance No. 13-979 B. Temple City LID Development Manual C. Temple City Green Streets Manual D. Staff Report for November 5, 2013 City Council Meeting CITY OF TEMPLE CITY ORDINANCE NO. 13-979 Attachment A AN ORDINANCE OF THE CITY COUNCIL OF THE CITY OF TEMPLE CITY AMENDING ARTICLE E (SITE PLAN REVIEW AND CONGESTION MANAGEMENT) OF CHAPTER 1 (ZONING CODE) OF TITLE 9 (ZONING REGULATIONS) OF THE TEMPLE CITY MUNICIPAL CODE TO ESTABLISH LOW IMPACT DEVELOPMENT STANDARDS AND A GREEN STREETS POLICY WHEREAS, the City is authorized by Article XI, Section 5 and Section 7 of the State Constitution to exercise the police power of the State by adopting regulations to promote public health, public safety and general prosperity; and WHEREAS, the federal Clean Water Act establishes Regional Water Quality Control Boards in order to prohibit the discharge of pollutants in stormwater runoff to waters of the United States; and WHEREAS, the City is a permittee under the California Regional Water Quality Control Board, Los Angeles Region Order No. R4-2012-0175, issued on November 08, 2012 which establishes Waste Discharge Requirements for Municipal Separate Storm Sewer Systems (MS4) Discharges within the Coastal Watersheds of Los Angeles County, Except those Discharges Originating from the City of Long Beach MS4; and WHEREAS, Order No. R4-2012-0175 contains requirements for municipalities to establish an LID Ordinance and Green Streets Policies in order to participate in a Watershed Management Program and/or Enhanced Watershed Management Program; and WHEREAS, the Regional Board has adopted Total Maximum Daily Loads (TMDLs) for pollutants which are numerical limits that must be achieved effectively through LID implementation; and WHEREAS, the City has the authority under the California Water Code to adopt and enforce ordinances imposing conditions, restrictions and limitations with respect to any activity that might degrade waters of the State; and WHEREAS, the City is committed to a stormwater management program that protects water quality and water supply by employing watershed-based approaches that balance environmental and economic considerations; and WHEREAS, urbanization has led to increased impervious surface areas resulting in increased water runoff and less percolation to groundwater aquifers causing the transport of pollutants to downstream receiving waters; and WHEREAS, it is the intent of the City to expand the applicability of the existing LID and Green Streets requirements by providing stormwater and rainwater LID strategies and Green Streets Policy for Development and Redevelopment projects as defined under "Applicability." THE CITY COUNCIL OF THE CITY OF TEMPLE CITY HEREBY ORDAINS AS FOLLOWS: SECTION 1. Based upon information presented in the Planning Commission Staff Report dated October 17, 2013; and based upon public input which was received at the noticed public hearing before the Planning Commission on October 17, 2013 to consider amending Article E (Site Plan Review and Congestion Management) of Chapter 1 (Zoning Code) of Title 9 (Zoning Regulations) of the Temple City Municipal Code to establish Low Impact Development standards and Green Streets Policies; SECTION 2. This project is not anticipated to result in any significant effects upon the environment and is exempt from environmental review in accordance with Sections 15061(b)(3) and 15308 of the CEQA Guidelines. The Preliminary Assessment indicates that there is no potential for adverse impact to the environment as it relates to all wild animals, birds, plants, fish, amphibians and Ordinance 13-979 Low Impact Development and Green Streets Policy Page 2 of 11 related ecological communities, including the habitat upon which the wildlife depends for its continued viability. SECTION 3. The Municipal Code shall be amended by adding Part 3 under Article E of Chapter 1 of Title 9, which shall read as follows: Part 3. Low Impact Development (LID) Standards and Green Streets Policy 9194: DEFINITIONS: (If the definition of any term contained in this chapter conflicts with the definition of the same term in Order No. R4-2012-0175, then the definition contained in Order No. R4-2012-0175 shall govern) AUTOMOTIVE SERVICE FACILITY BASIN PLAN BEST MANAGEMENT PRACTICE (BMP) BIOFIL TRATION BIORETENTION means a facility that is categorized in any one of the following Standard Industrial Classification (SIC) and North American Industry Classification System (NAICS) codes. For inspection purposes, Permittees need not inspect facilities with SIC codes 5013, 5014, 5511, 5541, 7532-7534, and 7536-7539 provided that these facilities have no outside activities or materials that may be exposed to stormwater (Order No. R4-2012-0175). means the Water Quality Control Plan, Los Angeles Region, Basin Plan for the Coastal Watersheds of Los Angeles and Ventura Counties, adopted by the Regional Water Board on June 13, 1994 and subsequent amendments (Order No. R4-2012-0175). means practices or physical devices or systems designed to prevent or reduce pollutant loading from stormwater or non-stormwater discharges to receiving waters, or designed to reduce the volume of stormwater or non-stormwater discharged to the receiving water (Order No. R4-2012- 0175). means a LID BMP that reduces stormwater pollutant discharges by intercepting rainfall on vegetative canopy, and through incidental infiltration and/or evapotranspiration, and filtration. Incidental infiltration is an important factor in achieving the required pollutant load reduction. Therefore, the term "biofiltration" as used in this Ordinance is defined to include only systems designed to facilitate incidental infiltration or achieve the equivalent pollutant reduction as biofiltration BMPs with an underdrain (subject to approval by the Regional Board's Executive Officer). Biofiltration BMPs include bioretention systems with an underdrain and bioswales (Order No. R4-2012-0175). means a LID BMP that reduces stormwater runoff by intercepting rainfall on vegetative canopy, and through evapotranspiration and infiltration. The bioretention system typically includes a minimum 2-foot top layer of a specified soil and compost mixture underlain by a gravel-filled temporary storage pit dug into the in-situ soil. As defined in this Ordinance, a bioretention BMP may be designed with an overflow drain, but may not include an underdrain. When a bioretention BMP is designed or constructed with an underdrain it is regulated by Order No. R4-2012-0175 as biofiltration (Order No. R4-2012-0175). Ordinance 13-979 Low Impact Development and Green Streets Policy Page 3 of 11 BIOSWALE means a LID BMP consisting of a shallow channel lined with grass or other dense, low-growing vegetation. Bioswales are designed to collect stormwater runoff and to achieve a uniform sheet flow through the dense vegetation for a period of several minutes (Order No. R4-2012-0175). CLEAN WATER ACT (CWA) means the Federal Water Pollution Control Act enacted in 1972, by Public Law 92-500, and amended by the Water Quality Act of 1987. The Clean Water Act prohibits the discharge of pollutants to Waters of the United States unless the discharge is in accordance with an NPDES permit. COMMERCIAL DEVELOPMENT COMMERCIAL MALLS CONSTRUCTION ACTIVITY CONTROL DEVELOPMENT means any development on private land that is not heavy industrial or residential. The category includes, but is not limited to: hospitals, laboratories and other medical facilities, educational institutions, recreational facilities, plant nurseries, car wash facilities; mini-malls and other business complexes, shopping malls, hotels, office buildings, public warehouses and other light industrial complexes (Order No. R4-2012- 0175). means any development on private land comprised of one or more buildings forming a complex of stores which sells various merchandise, with interconnecting walkways enabling visitors to easily walk from store to store, along with parking area(s). A commercial mall includes, but is not limited to: mini-malls, strip malls, other retail complexes, and enclosed shopping malls or shopping centers (Order No. R4-2012-0175). means any construction or demolition activity, clearing, grading, grubbing, or excavation or any other activity that result in land disturbance. Construction does not include emergency construction activities required to immediately protect public health and safety or routine maintenance activities required to maintain the integrity of structures by performing minor repair and restoration work, maintain the original line and grade, hydraulic capacity, or original purposes of the facility. See "Routine Maintenance" definition for further explanation. Where clearing, grading or excavating of underlying soil takes place during a repaving operation, State General Construction Permit coverage by the State of California General Permit for Storm Water Discharges Associated with Industrial Activities or for Stormwater Discharges Associated with Construction Activities is required if more than one acre is disturbed or the activities are part of a larger plan (Order No. R4-2012- 0175). means to minimize, reduce or eliminate by technological, legal, contractual, or other means, the discharge of pollutants from an activity or activities (Order No. R4-2012-0175). means construction, rehabilitation, redevelopment or reconstruction of any public or private residential project (whether single-family, multi-unit or planned unit development); industrial, commercial, retail, and other non-residential projects, including public agency projects; or mass grading for future construction. It does not include routine maintenance to maintain original line and grade, hydraulic capacity, or original purpose of facility, nor does it include emergency construction activities required to immediately protect public health and safety (Order No. R4-2012- 0175). Ordinance 13-979 Low Impact Development and Green Streets Policy Page 4 of 11 Dl RECTL Y ADJACENT DISCHARGE DISTURBED AREA FLOW-THROUGH TREATMENT BMPS FULL CAPTURE SYSTEM GENERAL CONSTRUCTION ACTIVITIES STORM WATER PERMIT (GCASP) GENERAL INDUSTRIAL ACTIVITIES STORM WATER PERMIT (GIASP) GREEN ROOF HILLSIDE INDUSTRIAL/ COMMERCIAL FACILITY means situated within 200 feet of the contiguous zone required for the continued maintenance, function, and structural stability of the environmentally sensitive area (Order No. R4-2012-0175). means any release, spill, leak, pump, flow, escape, dumping, or disposal of any liquid, semi-solid, or solid substance. means an area that is altered as a result of clearing, grading, and/or excavation (Order No. R4-2012-0175). means a modular, vault type "high flow biotreatment" devices contained within an impervious vault with an underdrain or designed with an impervious liner and an underdrain (Order No. R4-2012-0175). means any single device or series of devices, certified by the Executive Officer, that traps all particles retained by a 5 mm mesh screen and has a design treatment capacity of not less than the peak flow rate Q resulting from a one-year, one-hour storm in the sub-drainage area (Order No. R4-2012-0175). means the general NPDES permit adopted by the State Board which authorizes the discharge of stormwater from construction activities under certain conditions (Order No. R4-2012-0175). means the general NPDES permit adopted by the State Board which authorizes the discharge of stormwater from certain industrial activities under certain conditions (Order No. R4-2012-0175). means a LID BMP using planter boxes and vegetation to intercept rainfall on the roof surface. Rainfall is intercepted by vegetation leaves and through evapotranspiration. Green roofs may be designed as either a bioretention BMP or as a biofiltration BMP. To receive credit as a bioretention BMP, the green roof system planting medium shall be of sufficient depth to provide capacity within the pore space volume to contain the design storm depth and may not be designed or constructed with an underdrain (Order No. R4-2012-0175). means a property located in an area with known erosive soil conditions, where the development contemplates grading on any natural slope that is 25% or greater and where grading contemplates cut or fill slopes (Order No. R4-2012-0175). means any facility involved and/or used in the production, manufacture, storage, transportation, distribution, exchange or sale of goods and/or commodities, and any facility involved and/or used in providing professional and non-professional services. This category of facilities includes, but is not limited to, any facility defined by either the Standard Industrial Classifications (SIC) or the North American Industry Classification System (NAICS). Facility ownership (federal, state, municipal, private) and profit motive of the facility are not factors in this definition (Order No. R4-2012-0175). Ordinance 13-979 Low Impact Development and Green Streets Policy Page 5 of 11 INDUSTRIAL PARK INFILTRATION BMP LOW IMPACT DEVELOPMENT (LID) MUNICIPAL SEPARATE STORM SEWER SYSTEM (MS4)" (i) (ii) (iii) (iv) NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES)" NATURAL DRAINAGE SYSTEM NEW DEVELOPMENT means land development that is set aside for industrial development. Industrial parks are usually located close to transport facilities, especially where more than one transport modalities coincide: highways, railroads, airports, and navigable rivers. It includes office parks, which have offices and light industry (Order No. R4-2012-0175). means a LID BMP that reduces stormwater runoff by capturing and infiltrating the runoff into in-situ soils or amended onsite soils. Examples of infiltration BMPs include infiltration basins, dry wells, and pervious pavement (Order No. R4-2012-0175). consists of building and landscape features designed to retain or filter stormwater runoff (Order No. R4-2012-0175). means a conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade channels, or storm drains): Owned or operated by a State, city, town, borough, county, parish, district, association, or other public body (created by or pursuant to State law) having jurisdiction over disposal of sewage, industrial wastes, stormwater, or other wastes, including special districts under State law such as a sewer district, flood control district or drainage district, or similar entity, or an Indian tribe or an authorized Indian tribal organization, or a designated and approved management agency under section 208 of the CWA that discharges to waters of the United States; Designed or used for collecting or conveying stormwater; Which is not a combined sewer; and Which is not part of a Publicly Owned Treatment Works (POTW) as defined at 40 CFR Section 122.2. (40 CFR Section 122.26(b)(8)) (Order No. R4-2012-0175) means the national program for issuing, modifying, revoking and reissuing, terminating, monitoring and enforcing permits, and imposing and enforcing pretreatment requirements, under CWA Section 307, 402, 318, and 405. The term includes an "approved program" (Order No. R4- 2012-0175). means a drainage system that has not been improved (e.g., channelized or armored). The clearing or dredging of a natural drainage system does not cause the system to be classified as an improved drainage system (Order No. R4-2012-0175). means land disturbing activities; structural development, including construction or installation of a building or structure, creation of impervious surfaces; and land subdivision (Order No. R4-2012-0175). Ordinance 13-979 Low Impact Development and Green Streets Policy Page 6 of 11 NON-STORMWATER DISCHARGE OUTFALL PARKING LOT POLLUTANT PROJECT RAINFALL HARVEST AND USE RECEIVING WATER REDEVELOPMENT REGIONAL BOARD RESTAURANT means any discharge to a municipal storm drain system that is not composed entirely of stormwater (Order No. R4-2012-0175). means a point source as defined by 40 CFR 122.2 at the point where a municipal separate storm sewer discharges to waters of the United States and does not include open conveyances connecting two municipal separate storm sewers, or pipes, tunnels or other conveyances with connect segments of the same stream or other waters of the United Sates and are used to convey waters of the United States. (40 CFR Section 122.26(b)(9)) (Order No. R4-2012-0175). means land area or facility for the parking or storage of motor vehicles used for businesses, commerce, industry, or personal use, with a lot size of 5,000 square feet or more of surface area, or with 25 or more parking spaces (Order No. R4-2012-0175). means any "pollutant" defined in Section 502(6) of the Federal Clean Water Act or incorporated into the California Water Code Section 13373 (Order No. R4-2012-0175). means all development, redevelopment, and land disturbing activities. The term is not limited to "Project" as defined under CEQA (Pub. Resources Code Section 21065) (Order No. R4-2012-0175). means a LID BMP system designed to capture runoff, typically from a roof but can also include runoff capture from elsewhere within the site, and to provide for temporary storage until the harvested water can be used for irrigation or non-potable uses. The harvested water may also be used for potable water uses if the system includes disinfection treatment and is approved for such use by the local building department (Order No. R4-2012-0175). means "water of the United States" into which waste and/or pollutants are or may be discharged (Order No. R4-2012-0175). means land-disturbing activity that results in the creation, addition, or replacement of 5,000 square feet or more of impervious surface area on an already developed site. Redevelopment includes, but is not limited to: the expansion of a building footprint; addition or replacement of a structure; replacement of impervious surface area that is not part of routine maintenance activity; and land disturbing activity related to structural or impervious surfaces. It does not include routine maintenance to maintain original line and grade, hydraulic capacity, or original purpose of facility, nor does it include emergency construction activities required to immediately protect public health and safety (Order No. R4-2012-0175). means the California Regional Water Quality Control Board, Los Angeles Region. means a facility that sells prepared foods and drinks for consumption, including stationary lunch counters and refreshment stands selling prepared foods and drinks for immediate consumption (SIC Code 5812) (Order No. R4-2012-0175). Ordinance 13-979 Low Impact Development and Green Streets Policy Page 7 of 11 RETAIL GASOLINE OUTLET means any facility engaged in selling gasoline and lubricating oils (Order No. R4-2012-0175). ROUTINE MAINTENANCE includes, but is not limited to projects conducted to: 1. Maintain the original line and grade, hydraulic capacity, or original purpose of the facility. 2. Perform as needed restoration work to preserve the original design grade, integrity and hydraulic capacity of flood control facilities. 3. Includes road shoulder work, regrading dirt or gravel roadways and shoulders and performing ditch cleanouts. 4. Update existing lines* and facilities to comply with applicable codes, standards, and regulations regardless if such projects result in increased capacity. 5. Repair leaks Routine maintenance does not include construction of new** lines or facilities resulting from compliance with applicable codes, standards and regulations. * Update existing lines includes replacing existing lines with new materials or pipes. ** New lines are those that are not associated with existing facilities and are not part of a project to update or replace existing lines (Order No. R4-2012-0175). SIGNIFICANT ECOLOGICAL AREAS (SEAS) means an area that is determined to possess an example of biotic resources that cumulatively represent biological diversity, for the purposes of protecting biotic diversity, as part of the Los Angeles County General Plan. Areas are designated as SEAs, if they possess one or more of the following criteria: 1. The habitat of rare, endangered, and threatened plant and animal species. 2. Biotic communities, vegetative associations, and habitat of plant and animal species that are either one of a kind, or are restricted in distribution on a regional basis. 3. Biotic communities, vegetative associations, and habitat of plant and animal species that are either one of a kind or are restricted in distribution in Los Angeles County. 4. Habitat that at some point in the life cycle of a species or group of species, serves as a concentrated breeding, feeding, resting, migrating grounds and is limited in availability either regionally or within Los Angeles County. 5. Biotic resources that are of scientific interest because they are either an extreme in physical/geographical limitations, or represent an unusual variation in a population or community. 6. Areas important as game species habitat or as fisheries. 7. Areas that would provide for the preservation of relatively undisturbed examples of natural biotic communities in Los Angeles County. 8. Special areas (Order No. R4-2012-0175). Ordinance 13-979 Low Impact Development and Green Streets Policy Page 8 of 11 SITE means land or water area where any "facility or activity" is physically located or conducted, including adjacent land used in connection with the facility or activity (Order No. R4-2012-0175). STORM DRAIN SYSTEM means any facility or any parts of the facility, including streets, gutters, conduits, natural or artificial drains, channels and watercourse that are used for the purpose of collecting, storing, transporting or disposing of stormwater and are located within the City. STORM WATER OR STORMWATER URBAN RUNOFF means runoff and drainage related to precipitation events (pursuant to 40 CFR Section 122.26(b)(13); 55 Fed. Reg. 47990, 47995 (Nov. 16, 1990)). means surface water flow produced by storm and non-storm events. Non-storm events include flow from residential, commercial or industrial activities involving the use of potable and non-potable water. 9195: LOW IMPACT DEVELOPMENT AND GREEN STREETS POLICY A. Objective. The provisions of this Section establish requirements for construction activities and facility operations of Development and Redevelopment projects to comply with the current "Order No. R4-2012-0175," lessen the water quality impacts of development by using smart growth practices, and integrate LID practices and standards for stormwater pollution mitigation through means of infiltration, evapotranspiration, biofiltration, and rainfall harvest and use. LID shall be inclusive of new development and/or redevelopment requirements. B. Scope. This Section contains requirements for stormwater pollution control measures in Development and Redevelopment projects and authorizes the City to further define and adopt stormwater pollution control measures, and to develop LID principles and requirements, including but not limited to the objectives and specifications for integration of LID strategies, grant waivers from the LID requirements, and collect funds for projects that are granted waivers. Except as otherwise provided herein, the City shall administer, implement and enforce the provisions of this Section. C. Applicability. Development projects subject to Permittee conditioning and approval for the design and implementation of post-construction controls to mitigate storm water pollution, prior to completion of the project(s), are: (1) All development projects equal to 1 acre or greater of disturbed area that adds more than 10,000 square feet of impervious surface area. (2) Industrial parks 10,000 square feet or more of surface area. (3) Commercial malls 10,000 square feet or more of surface area. (4) Retail gasoline outlets with 5,000 square feet or more of surface area. (5) Restaurants (Standard Industrial Classification (SIC) of 5812) with 5,000 square feet or more of surface area. (6) Parking lots with 5,000 square feet or more of impervious surface area, or with 25 or more parking spaces. (7) Streets and roads construction of 10,000 square feet or more of impervious surface area. Street and road construction applies to standalone streets, roads, highways, and freeway projects, and also applies to streets within larger projects. (8) Automotive service facilities (Standard Industrial Classification (SIC) of 5013, 5014, 5511, 5541, 7532-7534 and 7536-7539) 5,000 square feet or more of surface area. Ordinance 13-979 Low Impact Development and Green Streets Policy Page 9 of 11 (9) Projects located in or directly adjacent to, or discharging directly to an Environmentally Sensitive Area (ESA), where the development will: a. Discharge stormwater runoff that is likely to impact a sensitive biological species or habitat; and b. Create 2,500 square feet or more of impervious surface area (1 0) Single-family hillside homes. ( 11) Redevelopment Projects a. Land disturbing activity that results in the creation or addition or replacement of 5,000 square feet or more of impervious surface area on an already developed site on Planning Priority Project categories. b. Where Redevelopment results in an alteration to more than fifty percent of impervious surfaces of a previously existing development, and the existing development was not subject to post-construction stormwater quality control requirements, the entire project must be mitigated. c. Where Redevelopment results in an alteration of less than fifty percent of impervious surfaces of a previously existing development, and the existing development was not subject to post-construction stormwater quality control requirements, only the alteration must be mitigated, and not the entire development. d. Redevelopment does not include routine maintenance activities that are conducted to maintain original line and grade, hydraulic capacity, original purpose of facility or emergency redevelopment activity required to protect public health and safety. Impervious surface replacement, such as the reconstruction of parking lots and roadways which does not disturb additional area and maintains the original grade and alignment, is considered a routine maintenance activity. Redevelopment does not include the repaving of existing roads to maintain original line and grade. e. Existing single-family dwelling and accessory structures are exempt from the Redevelopment requirements unless such projects create, add, or replace 10,000 square feet of impervious surface area. D. Specific Requirements. The Site for every Planning Priority Project shall be designed to control pollutants, pollutant loads, and runoff volume to the maximum extent feasible by minimizing impervious surface area and controlling runoff from impervious surfaces through infiltration, evapotranspiration, bioretention and/or rainfall harvest and use. (1) A new single-family hillside home development shall include mitigation measures to: a. Conserve natural areas; b. Protect slopes and channels; c. Provide storm drain system stenciling and signage; d. Divert roof runoff to vegetated areas before discharge unless the diversion would result in slope instability; and e. Direct surface flow to vegetated areas before discharge, unless the diversion would result in slope instability. (2) Street and road construction of 10,000 square feet or more of impervious surface shall follow USEPA guidance regarding Managing Wet Weather with Green Infrastructure: Green Streets (December 2008 EPA-833-F-08-009) to the maximum extent practicable. (3) The remainder of Planning Priority Projects shall prepare a LID Plan to comply with the following: Ordinance 13-979 Low Impact Development and Green Streets Policy Page 10 of 11 a. Retain stormwater runoff onsite for the Stormwater Quality Design Volume (SWQDv) defined as the runoff from: i. The 85th percentile 24-hour runoff event as determined from the Los Angeles County 85th percentile precipitation isohyetal map; or ii. The volume of runoff produced from a 0. 75 inch, 24-hour rain event, whichever is greater. b. Minimize hydromodification impacts to natural drainage systems as defined in Order No. R4-2012-0175. c. To demonstrate technical infeasibility, the project applicant must demonstrate that the project cannot reliably retain 100 percent of the SWQDv on-site, even with the maximum application of green roofs and rainwater harvest and use, and that compliance with the applicable post-construction requirements would be technically infeasible by submitting a site-specific hydrologic and/or design analysis conducted and endorsed by a registered professional engineer, geologist, architect, and/or landscape architect. Technical infeasibility may result from conditions including the following: i. The infiltration rate of saturated in-situ soils is less than 0.3 inch per hour and it is not technically feasible to amend the in-situ soils to attain an infiltration rate necessary to achieve reliable performance of infiltration or bioretention BMPs in retaining the SWQDv onsite. ii. Locations where seasonal high groundwater is within five to ten feet of surface grade; iii. Locations within 100 feet of a groundwater well used for drinking water; iv. Brownfield development sites or other locations where pollutant mobilization is a documented concern; v. Locations with potential geotechnical hazards; vi. Smart grow1h and infill or redevelopment locations where the density and/ or nature of the project would create significant difficulty for compliance with the ensile volume retention requirement. d. If partial or complete onsite retention is technically infeasible, the project Site may biofiltrate 1.5 times the portion of the remaining SWQDv that is not reliably retained onsite. Biofiltration BMPs must adhere to the design specifications provided in Order No. R4- 2012-0175. i. Additional alternative compliance options such as offsite infiltration and groundwater replenishment projects may be available to the project Site. The project Site should contact the City of Temple City to determine eligibility. e. The remaining SWQDv that cannot be retained or biofiltered ensile must be treated ensile to reduce pollutant loading. BMPs must be selected and designed to meet pollutant- specific benchmarks as required per Order No. R4-2012-0175. Flow-through BMPs may be used to treat the remaining SWQDv and must be sized based on a rainfall intensity of: i. 0.2 inches per hour, or ii. The one year, one-hour rainfall intensity as determined from the most recent Los Angeles County isohyetal map, whichever is greater. E. Additional Requirements. The site for projects not classified with general applicability listed in Section C of this Ordinance, but resulting in the creation or addition or replacement of 500 square feet or more of impervious surface area shall be designed to control pollutants, pollutant loads, and runoff volume per the Temple City Low Impact Development Manual. Ordinance 13-979 Low Impact Development and Green Streets Policy Page 11 of 11 9196: VALIDITY: If any provision of this Ordinance is found to be unconstitutional or otherwise invalid by any court of competent jurisdiction, such invalidity shall not affect remaining provisions of this Ordinance are declared to be severable. SECTION 4. This Ordinance shall be effective on the 31st day after adoption. SECTION 5. The City Clerk shall certify to the passage and adoption of this ordinance and to its approval by the Mayor and shall cause the same to be published according to law. APPROVED AND ADOPTED THIS 19TH DAY OF NOVEMBER 2013. MAYOR ATIEST: APPROVED AS TO FORM: CITY CLERK CITY ATIORNEY I, City Clerk of the City of Temple City, hereby certify that the foregoing Ordinance 13-979 was introduced at the regular meeting of the City Council of the City of Temple City held on the 51 " day of November, 2013 and was duly passed, approved and adopted by said Council, a~proved and signed by the Mayor and attested to by the City Clerk at the regular meeting held on the 191 day of November, 2013 by the following vote: AYES: NOES: ABSENT: ATTEST: CITY CLERK Councilmember- Councilmember- Councilmember- Attachment B City of emp, e City Low Impact Development For Small Sites Technical Guidance Manual LID Technical Guidance Manual TABLE OF CONTENTS Section 1-Introduction ............................................................................................................................... 3 1.1 What Is LID? .................................................................................................................................. 3 1.2 Why Is LID being required? ........................................................................................................... 3 1.3 Project Applicability ...................................................................................................................... 4 1.4 LID Exemptions ............................................................................................................................. 6 Section 2-Commonly Asked Questions ...................................................................................................... 7 Section 3-Design Guidelines and Specifications ........................................................................................ 8 3.1 Design Capture Volume ................................................................................................................ 8 3.2 Flow-Through Planter Box ............................................................................................................ 9 3.3 Vegetated Swale ......................................................................................................................... 11 3.4 Rain Garden ................................................................................................................................ 13 3.5 "Hollywood" Driveway ............................................................................................................... 15 3.6 Bottomless Trench ...................................................................................................................... 17 Section 4-References ............................................................................................................................... 19 City of Temple City 2013 LID Technical Guidance Manual SECTION 1 -INTRODUCTION 1.1 WHAT IS LID? LID Stands for: Low Impact Development, it is a stormwater management strategy that emphasizes conservation and the use of existing natural site features integrated with distributed, small-scale stormwater controls to more closely mimic natural hydrologic patterns in residential, commercial, and industrial settings. 1.2 WHY IS LID BEING REQUIRED? The urbanization of Southern California has disrupted the natural flow of stormwater runoff. Rain falling on roofs now flows into metal or plastic downspouts, then to concrete curbs and gutters along asphalt roads, then to concrete storm drains, then to concrete river channels, and then finally into estuaries and the Pacific Ocean. You can see the problem; rainwater no longer comes into contact with dirt and vegetation. Any pollutants (heavy metals, bacteria, nutrients, pesticides) that would have previously been naturally degraded, are now flowing straight out to environmentally sensitive areas. LID is a new design strategy that corrects this problem. There are many highly technical manuals for designing LID systems, some of which are listed in Section 4 herein. The purpose of this guidance manual is to simplify your design. Typical LID systems include: • Flow-Through Planter Boxes • Vegetative Swales • Rain Gardens • "Hollywood" Driveways • Bottomless Trenches In addition to the LID systems listed above, there are many other acceptable systems such as capture and re-use (cisterns/ rain barrels), green roofs, pervious pavement/pavers, turf block, etc. However, the design, installation, and subsequent operation and maintenance of these systems can be complex and should be carefully evaluated prior to being proposed. When using these other systems, a published design standard shall be followed. City of {Temple City] Page 3 of 19 2013 LID Small Site Technical Guidance Manual 1.3 PROJECT APPLICABILITY Step 1: Categories. There are four LID categories. The first step in LID design is to determine which category the project fits into. Category 1. Category2. Category 3. Category4. The project will disturb less than 500 square feet of soil The project is exempt from LID requirements. The project is residential, will involve 4 or less dwelling units and will disturb more than 500 square feet of soil The project falls under the Residential LID Categorv. The project will involve 5 or more dwelling units or is at a commercial or industrial site. It will disturb more than 500 square feet of soil The project falls under the Commercial/Industrial LID Categorv. The project is subject to the provision of the Municipal Separate Storm Sewer System permit (MS4) issued by the California Regional Water Quality Control Board. These projects typically include (but are not limited to): new industrial parks 10,000 square feet or more; new commercial malls 10,000 square feet or more; Retail gasoline outlets 5,000 square feet or more; new restaurants 5,000 square feet or more; new parking lots 5,000 square feet or more; or the creation or addition or replacement of 5,000 square feet or more of impervious surfaces of existing projects meeting the Regional Board's applicability criteria. The project is beyond the scope of this manual and is subject to the requirements as outlined in the MS4 Permit. Step 2: LID Design Requirements. For Residential LID Projects (Category 2) • A Residential LID Project must incorporate two or more of the following LID systems in the project design (The systems must be shown on the plans submitted to the City): 1. Porous pavement: Install porous pavement that allows rainwater to infiltrate through it. Porous pavement includes, but is not limited to, porous asphalt, porous concrete, ungrouted paving blocks, and gravel. At least 50 percent of the pavement on the lot shall be porous. For an example of a driveway that allows rainwater infiltration, see section 3.5, "Hollywood driveway." 2. Downspout routing Each roof downspout shall be directed to one oft he following BMPs. The sum of the capacity of the downspout BMPs shall total at least 200 gallons. City of Temple City 2013 LID Small Site Technical Guidance Manual a. Cistern/rain barrel Direct roof downspouts to rain barrels or cisterns. The stored stormwater can then be used for irrigation or other nonpotable uses as permitted under the Los Angeles County Building/Plumbing Code. b. Rain garden/planter box Direct roof downspouts to rain gardens or planter boxes that provide retention and treatment of stormwater (see Section 3.4 for details). 3. Disconnect impervious surfaces Slope driveways and other impervious surfaces to drain toward pervious surfaces. If possible, runoff should be directed toward vegetated areas or water quality BMPs. The ratio of impervious to pervious area shall be no less than 2:1. Limit the total area not directed toward vegetated areas or water quality BMPs to 10 percent or less of the impervious surfaces. 4. Drywell Install a dry well to infiltrate stormwater. The dry well shall be sized to contain and infiltrate at least 200 gallons of stormwater in a 36 hour period. 5. Bottomless trench Install a bottomless trench across the end driveway to catch rainfall as it washes down the driveway towards the street (see Section 3.6 for details). 5. Landscaping and landscape irrigation Plant trees near impervious surfaces to intercept rainfall in their leaves. Trees planted adjacent to impervious surfaces can intercept water that otherwise would have become runoff. A minimum of two 15 gallon trees shall be planted a maximum of 10 feet from impervious surfaces. Install irrigation systems that minimize water usage and eliminate dry-weather urban runoff. • Before a project can be approved, the following must be verified through the plan check process: o The following statement must be included on the plans: As the engineer/architect of record for this project, I have designed the LID system in accordance with the design criteria of the City of Temple City's LID Guidance Manual. o The project engineer/architect must make sure the safety and soil stability of the LID system is carefully evaluated prior to its inclusion in the design. o Language describing maintenance activities and indicating the responsible party for such activities (including signature) must be located on the document(s) submitted to the City. o The entire project area must drain to the LID system(s). If water is flowing to the LID system from areas outside the project area, the LID system must be designed accordingly to treat all tributary areas. In instances where a project cannot treat the runoff from the development area, an equivalent area may be treated as an alternative. City of Temple City 2013 LID Small Site Technical Guidance Manual For Commercial/Industrial LID Projects (Category 3 above) • A Commercial/Industrial LID Project must incorporate one or more LID system(s), as found in Section 3 of this manual, in the project design. The system(s) must be shown on the plans submitted to the City. • Include the following statement: As the engineer/architect of record for this project, I have designed the LID system in accordance with the design criteria of the City of Temple City's LID Guidance Manual. • The project engineer/architect must make sure the safety and soil stability of the LID system is carefully evaluated prior to its inclusion in the design. • Language describing maintenance activities and indicating the responsible party for such activities (including signature) must be located on the document(s) submitted to the City. • The entire project area must drain to the LID system(s). If water is flowing to the LID system from areas outside the project area, the LID system must be designed accordingly to treat all tributary areas. In instances where a project cannot treat the runoff from the development area, an equivalent area may be treated as an alternative. • Calculations must be included on the plans showing the LID system is adequately sized. A calculation template is shown in Section 3.1. For Commercial/Industrial LID Projects, the BMP(s) must be sized to treat the entire design capture volume (DCV). Step 3: Plan development and submittal. The LID system(s) design and location must be shown on the plans and submitted to the City. The Standard Plans are available (yet not required) for guidance. 1.4 LID EXEMPTIONS Exemptions from LID Requirements. LID requirements do not apply to any of the following: 1. A Development that only creates, adds or replaces less than 500 square feet of impervious area; 2. A Development involving only emergency construction activity required to immediately protect public health and safety; 3. Infrastructure projects within the public right-of-way; 4. A Development or Redevelopment involving only activity related to gas, water, cable, or electricity services on private property; 5. A Development involving only resurfacing and/or re-striping of permitted parking lots, where the original line and grade, hydraulic capacity, and original purpose of the facility is maintained; 6. A project involving only exterior movie or television production sets, or facades on an existing developed site; 7. A project not requiring a City building, grading, demolition or other permit for construction activity. City of Temple City 2013 LID Small Site Technical Guidance Manual SECTION 2 -COMMONLY ASKED QUESTIONS 1. I am adding a second story to my house. The existing footprint will remain unchanged, does LID apply? No, LID is required only where 500 square feet of soil is being disturbed. 2. I will be adding a new 500 square foot room that will replace some of my backyard. Does LID apply? Yes, you've crossed the 500 square foot threshold. 3. I will be building a new addition that will be over 500 square feet, but I can't fit an LID system into the new addition. Can I create an LID system for an equivalent area of the existing building? Yes, you can create an LID system for an equivalent area af the existing building. 4. I own a business. It is concrete and asphalt all around. Will LID be required if infeasible? A waiver for technical infeasibility may be issued by the Director; however in this situation it is unlikely to be granted. Generally there is always a way to implement LID requirements. 5. How big do I have to design the LID systems? On the following pages are design criteria. Generally you have ta make the systems big enough to treat runoff from a %inch storm. 6. I am removing a 500 square foot concrete pad that is in need of repair and replacing it with an identical new concrete pad. Does LID apply? if the construction would not result in soil disturbance, this would be considered routine maintenance. However, if the construction did result in soil disturbance an LID system would be required. 7. I am installing new interior electrical and new plumbing and will have more than 500 square feet of disturbed soil. When the project is finished, the trenches will be patched to match the existing surrounding surfaces. The existing building will be unchanged. Will LID apply? No, utility projects are exempt from LID requirements. See Section 1.4 of this document. 8. My project does not require any permits from the City, does LID apply? No, only projects requiring city permits need to comply with LID. 9. If at some time in the future I want to change the design of the LID system, can I? Only with Community Development Department approval. City of Temple City 2013 LID Small Site Technical Guidance Manual SECTION 3 -DESIGN GUIDELINES AND SPECIFICATIONS 3.1 DESIGN CAPTURE VOLUME The Design Capture Volume (DCV) is requ ired to design the flow t hrough planter box, vegetated swale, rain garden, and any other volume-based LID system . DCV Equation : 1 DC V (ft3) = c X d. X A X 43560 X -2 1 With: C = (0.75 x impervious A·r ea) + 0 .15 d = De s ion.S torm Depth (assum e 0 .75 iJ1ch Im l ess otherwi se known) A = Trt.but ary A rea The in formation provided below are guidelines that must be followed when designing LID for your project. Standard drawings for each LID are included for reference. City of Temple City 2013 LID Small Site Technical Guidance Manual 3.2 FLOW-THROUGH PLANTER BOX Figure 1: Flow-through planter box (http://lateameffort.blogspot.com). Design criteria for a flow-through planter box include the following: • Design drawdown time= 48 hours (surface); 72 hours (total) • Factor of safety= 2 • Max ponding depth= 18 inches • Soil depth = 2 feet (3 preferred) • Slotted PVC pipe (2 inches Minimum) within 6 inches of bottom of facility • The area (width * length) must equal 4% of the tributary area • Flows my outlet to a curb drain, rain garden, or equivalent • Cover must be dense, wet, and dry tolerant vegetation City of Temple City 2013 SPLASH BLOCK 2' MIN. AMENDED SOIL LID Small Site Technical Guidance Manual DEPTH .----3" MULCH -:q FILTER FABRIC (OPTIONAL, NOTE 5) 1' MIN. GRAVEL SLOTTED PVC PIPE (2" MIN, 6" MAX) 6" THICK IMPERVIOUS MATERIAL BOTTOM GENERAL NOTES: 1. DENSE, WET AND DRY TOLERANT VEGETATION. 2. PONDED WATER MUST DRAIN WITHIN 72 HOURS TO PREVENT VECTOR BREEDING. 3. IF NEEDED, MULTIPLE PIPES MAY BE USED. 4. THE PLANTER BOX AREA (WIDTH * LENGTH) MUST EQUAL 4% OF THE TRIBUTARY AREA. 5. FILTER FABRIC AVAILABLE AT LOCAL HARDWARE STORES. 6. FLOWS MAY OUTLET TO A CURB DRAIN, RAIN GARDEN, OR EQUIVALENT. DRAFT REVISIONS CITY OF TEMPLE CITY PUBLIC WORKS DEPT. f------ILID-FLOW THROUGH PLANTER BOX City of Temple City 2013 LID Small Site Technical Guidance Manual 3.3 VEGETATED SWALE Figure 2: Vegetated Swale (Signal Hill, CA). Design criteria for a vegetated swale include the following: • Design flow velocity~ 1ft/sec. • Side slopes shall not exceed 3:1 (H:V). • Slope in flow direction 1% (min) to 6% (ma x). • Minimum bottom width= 1 foot • Minimum swale length = 15 feet • Max ponding depth= 5 Inches • Soil depth= 2 feet min • Design draw down time= 48 hours (su rface); 72 hours (total) • The area (width * length) must equal4% of the tributary area • Cover must be dense, wet, and dry tolerant vegetation City of Temple City 2013 LID Small Site Technical Guidance Manual ,-----------------------------------~ FILTER FABRIC (OPTIONAL, NOTE 4) 1' MIN GRAVEL GENERAL NOTES: SEE NOTE 1 1. DENSE, WET AND DRY TOLERANT VEGETATION. IMPERMEABLE LAYER (CONDITIONAL, NOTE 5) 2. PONDED WATER MUST DRAIN WITHIN 72 HOURS TO PREVENT VECTOR BREEDING. 3. THE BOTTOM AREA (WIDTH * LENGTH) MUST EQUAL 4% OF THE TRIBUTARY AREA. 4. FILTER FABRIC AVAILABLE AT LOCAL HARDWARE STORES. 5. AN IMPERMEABLE LAYER MUST BE USED IF GROUNDWATER IS LESS THAN 10 FEET FROM THE BOTTOM OF THE GRAVEL LAYER. DRAFT CITY OF TEMPLE CITY PUBLIC WORKS DEPT. I------1LID-VEGETATED SWALE City of Temple City 2013 LID Small Site Technical Guidance Manual 3.4 RAIN GARDEN Figure 3: Rain Garden (http://www.prairiefirenewspaper.com/2009/04/rain-gardens). Design criteria for a rain garden include the following: • Design drawdown time= 48 hours (surface); 72 hours (total) • Factor of safety = 2 • Maximum pending depth= 18 inches • Minimum pending depth = 8 inches • Soil depth= 2 feet minimum {3 preferred) • If downspout is directed to rain garden, slope must be 2% minimum • Cover must be dense, wet, and dry tolerant vegetation • The bottom of the rain garden should be no less than 10 feet from the groundwater table City of Temple City 2013 BUILDING LID Small Site Technical Guidance Manual DOWN SPOUT FOR AESTHETIC PURPOSES SLOPE CAN v SPLASH BLOCK SEE NOTE 1 FOUNDATION ~II ~Iir~~~____,""-'i'n'J. I I MIN 5' OR AS DETERMINED BY GEOTECHNICAL ENGINEER PONDING 8" MIN. 18" MAX. MULCH NOTE 3 GENERAL NOTES: 1. DENSE, WET AND DRY TOLERANT VEGETATION. 2. PONDED WATER MUST DRAIN WITHIN 72 HOURS TO PREVENT VECTOR BREEDING. 3. BIORETENTION SOIL DEPTH 2' MINIMUM (3' PREFERRED). 4. THE RAIN GARDEN AREA (WIDTH * LENGTH) MUST EQUAL 4% OF THE TRIBUTARY AREA. 5. THE BOTTOM OF THE RAIN GARDEN SHOULD BE NO LESS THAN 10' FROM THE GROUNDWATER TABLE. DRAFT REVISIONS CITY OF TEMPLE CITY PUBLIC WORKS DEPT. 1-----ILID-RAIN GARDEN City of Temple City 2013 LID Small Site Technical Guidance Manual 3.5 "HOLLYWOOD" DRIVEWAY Figure 4: "Hollywood Driveway" (Temple City, CA}. Design criteria for a "Hollywood" Driveway include the following: • Recommended spacing between ribbons is 5 to 7 feet (may vary depending on expected traffic) • Ribbon width= 2 feet minimum • Ribbon thickness= 6 inches minimum (with mesh or rebar) • Ribbons should drain outward from the center of crown • Center strip should include an irrigation line City of Temple City 2013 LID Small Site Technical Guidance Manual DRAIN FROM MIN. 5' O.C. CENTER OUTWARD)~ ~" IN 1' CROWN) \ MAX. 7' O.C (NOTE 1) MAX. 3' ~<:>):' :.· . ~, •· ~ -I 2' MIN. I - I 4' MAX. I (NOTE 1) GENERAL NOTES: 1. MAXIMUM WIDTH AND SPACING ARE RECOMMENDED AND MAY VARY DEPENDING ON EXPECTED TRAFFIC. 2. DRIVEWAY RIBBONS SHOULD BE AT LEAST 2 FEET IN WIDTH. 3. DRIVEWAY RIBBONS SHOULD BE AT LEAST 6 INCHES THICK WITH MESH OR REBAR. 4. PERVIOUS SURFACE INCLUDES; VEGETATION (GRASS), WIDELY SPACED INTERLOCKING PAVERS, AND GRAVEL. 5. DRIVEWAY RIBBONS SHALL BE CONCRETE, TRAFFIC RATED PAVERS, BRICK, OR EQUIVALENT MATERIAL. DRAFT REVISIONS CITY OF TEMPLE CITY PUBLIC WORKS DEPT. r-------1LID-SEMI-PERVIOUS DRIVEWAY City of Temple City 2013 LID Small Site Technical Guidance Manual 3.6 BOTTOMLESS TRENCH Figure 5: Bottomless trench (http :/ /www.cob.org/services/environment/water-quality/). Design criteria for a Bottomless Trench include the following: • Trench width = 24 inches (across driveway) • Trench depth= 18 inches • Bottom 8 inches of the trench must be filled with crushed rock • Trench must be at least 12 inches from back of sidewalk (or edge of pavement in the case of no sidewalk) • Longitudinal width= 6 inche s (along driveway) • Frame and grate must be pedestrian safe City of Temple City 2013 LID Small Site Technical Guidance Manual PEDESTRIAN SAFE------. FRAME & GRATE (SEE NOTE 9) CRUSHED ROCK W/FILTER CLOTH GENERAL NOTES: SECTION A PLAN VIEW .r--DIMENSIONS VARY (NOTE 7) o+-1---=---#4 REBAR TOP & BOTTOM CRUSHED ROCK OPTIONAL PERFORATED PIPE TO ADJACENT LAWN NOTE 7 1. TRENCH SHOULD BE 24" WIDE (ACROSS DRIVEWAY) X 18" DEEP. 2. PRECAST MAY BE USED. 3. FILTER CLOTH MUST BE PLACED IN THE TRENCH EXTENDING 12" VERTICAL. 4. BOTTOM 8" OF THE TRENCH MUST BE FILLED WITH CRUSHED ROCK. 5. DIMENSIONS DETERMINED BY GRATE FRAME DIMENSION. USE FRAME AS A FORM. 6. MUST BE APPLIED AT LEAST 12" FROM BACK OF SIDEWALK OR EDGE OF PAVEMENT IN THE CASE OF NO SIDEWALK. 7. MINIMUM LONGITUDINAL WIDTH (MEASURED ALONG DRIVEWAY) OF FRAME & GRATE IS EQUAL TO 6" WITH %" SLOT OPENINGS. EAST JORDAN IRON OR EQUAL. City of Temple City 2013 LID Small Site Technical Guidance Manual SECTION 4-REFERENCES The Los Angeles County Low Impact Development Standards Manual at: http://dpw.lacounty.gov/wmd/dsp_LowlmpactDevelopment.cfm The City of Los Angeles Low Impact Development Best Management Practices Handbook at: http:/ /lacitysa n. org/wpd/Siteorgjprog ram/LI D/lidi ntro. htm Please note that the City of Temple City's LID ordinance takes precedent in the event of any inconsistencies with any outside references. City of Temple City 2013 Attachment C fTe Green Streets Manual October 2013 Green Streets Manual TABLE OF CONTENTS Section 1-Introduction ............................................................................................................................... 1 1.1 What are Green Streets? .............................................................................................................. 1 1.2 Why are Green Streets being required? ....................................................................................... 1 1.3 Planning and Development .......................................................................................................... 2 Site Considerations Design Considerations 1.3.1 1.3.2 1.3.3 BMP Sizing for Applicable Green Streets 1.3.4 Alternative Compliance Options for 1.3.5 Infiltration Cor1siclerartions ....... Section 2 -Infiltration 2.1 2.2 2.3 Infiltration Trenches and Dry Rain Gardens Permeable Pavement Section 3-R;ntcP"trnP,,t 3.1 3.2 3.3 3.4 5.1 Section 6- Section 7- City of TEMPLE CI'TY; Table af Contents 2 3 4 4 8 9 ............ 10 ............ 11 ............ 13 ........... 13 ........... 14 ........... 15 ........... 16 16 16 18 18 19 20 October 2013 Green Streets Manual SECTION 1 -INTRODUCTION 1.1 WHAT ARE GREEN STREETS? Roads present many opportunities for green infrastructure application. One principle of green infrastructure involves reducing and treating stormwater close to its source. Urban transportation right- of-ways integrated with green techniques are often called "green streets." Green streets provide source controls for stormwater runoff and pollutant loads. In addition, green infrastructure approaches complement street facility upgrades, street aesthetic improvements, and urban tree canopy efforts that also make use of the right-of-way and allow it to achieve multipleg~~,ls, and benefits. Using the right-of- way for treatment of stormwater runoff links green with ~c~yq)ptrastructure by making use of the engineered conveyance of roads and providing connections toicis"~Veyance systems when needed. <> '>/;;-jy<>i>+>-\, Green streets are beneficial for new road COI1Struc:tio:n:~~H51;e~~flflt::0, They can provide substantial economic benefits when used in transportation . c6if~?Anating green infrastructure installation with broader transportation im reduce the cd~t!<?t,~tormwater management by including it within larger infrastructure A large munici~a.Ji,t;~:~cern regarding green infrastructure use is maintenance and '·a~··_:}ocations for green infrastructure not only addresses but also 'imllviates access and maintenance concerns by using installations ali"~\liffor easy public maintenance. Green streets can incorporate pavements, bioretention, the functional goals are . conveyance to the practicable, and will encourage soil and 1.2 This G 0175) Including street trees, permeable . nee of green streets will vary, its transport and pollutant (~~~pi~-2~~~''h~d;~logy to the maximum extent ucce~:;ful application of green techniques and retention of stormwater. with the MS4 Permit (Order Number R4-2012- Angeles County reduce contaminants in runoff to improve •'•ai4't;;·~,. stem from the National Pollutant Discharge Elimination r Act (CWA). strategies to be implemented for transportation corridors. Transportation 1 large percentage of the impervious area within Los Angeles and therefore generate a of runoff from storm events. The altered flow regime from traditional roadways, runoff volume, and high runoff peak flows, are damaging to the environment and a risk to property downstream. Traditionally, street design has focused on removing water from the street as quickly as possible and transferring it to storm drains, channels, and water bodies. Stormwater runoff can contain bacteria and other pollutants, and is thereby regulated at the state and local level (refer to Table 1 for a list of pollutants typical of roads). Green Streets will help to transform the design of streets from the conventional method of moving water off-site as quickly as possible to a method of storing and treating water on-site for a cleaner discharge into the waters of the U.S. -=----;c:::--:--=------------=----:------------=--:----:::::-:-:--·--- City of Temple City Page 1 October 2013 Street and road construction applies to major arterials, state routes, highways, or rail lines used for the movement of people or goods by means of bus services, trucks, and vehicles, and transportation corridors within larger projects. Projects which are required to follow this Green Streets Guidance Manual include the following: 1. Street and road construction of 10,000 square feet or more of impervious surface area. 2. Street and road redevelopment resulting in the creation or addition or replacement of 5,000 square feet or more of impervious surface area on an already developed site. Redevelopment does not include routine maintenance activities that are conducted to maintain original line and grade, hydraulic capacity, original purpose of facility or emergency redevelopment activity required to protect public health and safety. Impervious surface replacement, such as the reconstruction of parking lots and roadways which does not disturb additional area and maintains the original grade and alignment, is considered a routine maintenance activity. Redevelopment does not include the repaving of existing roads to maintain original line and grade. 3. Street and road improvement with a cost of $500,000 or more. Table 1: Examples of Stormwater Pollutants Typical of Roads (Managing Wet Weather With Green Infrastructure Municipal Handbook: Green StreetsJ 2008). Pollutant Source Effects Trash Littering Physical damage to aquatic animals and fish, release of poisonous substances Increased turbidity, increased transport of soil Sediment/solids Construction, unpaved areas bound pollutants, negative effects on aquatic organisms reproduction and function Metals {Copper, Zinc, Lead, Vehicle brake pads, vehicle tires, motor oil, vehicle Toxic to aquatic organisms and can accumulate in emissions and engines, vehicle emissions, brake Arsenic) linings, automotive fluids sediments and fish tissues Organics associated with Vehicle emissions, automotive fluids, gas stations Toxic to aquatic organisms petroleum {e.g., PAHs) Nutrients Vehicle emissions, atmospheric deposition Promotes eutrophication and depleted dissolved oxygen concentrations 1.3 PLANNING AND DEVELOPMENT Ideally, a site would be designed to capture and use or infiltrate the entire runoff volume of a storm, however site and design constraints make it difficult to achieve that goal. This Green Streets Manual is designed to provide guidance with BMP selection based on site constraints typical to street design. Streetscape geometry, topography, and climate determine the types of controls that can be implemented. The initial step in selecting a stormwater tool is determining the available open space and constraints. Stormwater controls should be selected using the hierarchy represented in Figure 1, the site guidelines represented in Table 2, and the location opportunities listed in Table 3. 1.3.1 Site Considerations Specific elements which should be given special consideration in the site assessment process for applicable Green Streets include: • Ownership of land adjacent to right of ways. The opportunity to provide stormwater treatment may depend on the ownership of land adjacent to the right-of-way. Acquisition of City of Temple City Page2 October 2013 additional right-of-way and/or access easements may be more feasible if land bordering the project is owned by relatively few land owners. • Location of existing utilities. The location of existing storm drainage utilities can influence the opportunities for Green Streets infrastructure. For example, stormwater planters can be designed to overflow along the curb-line to an existing storm drain inlet, thereby avoiding the infrastructure costs associated with an additional inlet. The location of other utilities may limit the allowable placement of BMPs to only those areas where a clear pathway to the storm drain exists. • Grade differential between road surface and storm drain system. Some BMPs require more head from inlet to outlet than others; therefore, allowable head drop may be an important consideration in BMP selection. Storm drain elevations may be constrained by a variety of factors in a roadway project (utility crossings, outfall elevations, etc.) that cannot be overcome and may override stormwater management considerations. • Longitudinal slope. The suite of BMPs which may be installed on steeper road sections is more limited. Specifically, permeable pavement and swales are more suitable for gentle grades. Other BMPs may be more readily terraced to be used on steeper slopes. • Soil suitability. Infiltration BM Ps require specific types of soil. The site assessment should determine the type of soils on the site and the infiltration rate of the soils if infiltration BMPs are proposed. • Potential access opportunities. A significant concern with installation of BMPs in major right of ways is the ability to safely access the BMPs for maintenance considering traffic hazards. Vehicle travel lanes and specific areas potentially hazardous for maintenance crews should be identified during the site assessment. The Green Streets WQMP should provide subsequent steps to avoid placing BMPs in the identified hazardous areas. 1.3.2 Design Considerations The drainage patterns of the project should be developed so that drainage can be routed to areas with BMP opportunities before entering storm drains. For example, if a median strip is present, a reverse crown should be considered, where allowed, so that stormwater can drain to a median swale. Likewise, standard peak-flow curb inlets should be located downstream of areas with potential for stormwater planters so that water can first flow into the planter, and then overflow to the downstream inlet if capacity of the planter is exceeded. It is more difficult to apply green infrastructure after water has entered the storm drain. Green Streets projects are not required to treat off-site runoff; however treatment of co mingled off-site runoff may be used to off-set the inability to treat areas within the project for which significant constraints prevent the ability to provide treatment. Applicable Green Streets projects should apply the following site design measures to the maximum extent practicable and as specified in the local permitting agency's codes: • Minimize street width where feasible while maintaining traffic flow and public safety. • Add tree canopy by planting or preserving trees/shrubs. • Use porous pavement or pavers for low traffic roadways, on-street parking, shoulders or sidewalks. • Integrate traffic calming measures in the form of bioretention curb extensions. City of Temple City Page3 October 2013 1.3.3 BMP Sizing for Applicable Green Streets Projects An 85th percentile standard design storm should be used to determine the appropriate size, slope, and materials of each facility. After identifying the appropriate stormwater facilities for a site, an integrated approach using several BMPs is encouraged. To increase water quality and functional hydrologic benefits, several stormwater management BMPs can be used in succession. This is called a treatment train approach. The control measures should be designed using available topography to take advantage of gravity for conveyance to and through each facility. All Green Streets designs must be based off of a published design standard. The following steps should be used to size BMPs for applicable Green Streets projects: 1. Delineate drainage areas tributary to BMP locations and compute imperviousness. 2. Look up the recommended sizing method for the BMP selected in each drainage area and calculate target sizing criteria. 3. Design BMPs per a published design standard. 4. Attempt to provide the calculated sizing criteria for the selected BMPs. 5. If sizing criteria cannot be achieved, document the constraints that override the application of BMPs and provide the largest portion of the sizing criteria that can be reasonably provided given constraints. If BMPs cannot be sized to provide the calculated volume for the tributary area, it is still essential to design the BMP inlet, energy dissipation, and overflow capacity for the full tributary area to ensure that flooding and scour is avoided. It is strongly recommended that BMPs which are designed to less than their target design volume be designed to bypass peak flows. 1.3.4 Alternative Compliance Options for Applicable Green Streets Projects Alternative compliance programs should be considered for applicable Green Streets projects if on-site green infrastructure approaches cannot practicably treat the design volume. The primary alternative compliance option for applicable Green Streets projects is the completion of off-site mitigation projects. The proponent would implement a project to reduce stormwater pollution for other portions of roadway or similar land uses when being reconstructed to the project in the same hydrologic unit, ideally as close to the project as possible and discharging to the same outfall. 1.3.5 Infiltration Considerations Appropriate soils, infiltration media, and infiltration rates should be used for infiltration BMPs. If infiltration is proposed, a complete geotechnical or soils report should be undertaken to determine infiltration rates, groundwater depth, soil toxicity and stability, and other factors that will affect the ability and the desirability of infiltration. At a minimum, the infiltration capacity of the underlying soils shall be deemed suitable for infiltration {0.3 inches per hour or greater), appropriate media should be used in the BMP itself, the groundwater shall be located at a depth of ten feet or greater. City of Temple City Poge4 October 2013 Figure 1: BMP Selection Flow Chart . Dr:.•rr!rm:'ne ij(i!'r:.'t'n S~rc~r~ i-; Applfrnble D otJs th~ Proj~(t lm·o !\'t! o Trrmsportr.tion Corrido6' Do•'> one oft he Foilowi"g /lpp (v: 1. Cos :r.c L<e1 st S500 .000? 2. Ne1v Dc ,·eiopm,.•ntofl.O.OOO sjor ?·lore.'. 3. Rc~dt'Veiopmt'1~t of5.000 sjor ~'·/o rr:? l"es tin~f'H Strr~r$ Dc"'\'elov mer:r Proj(•ct · Dt?tr:.•rmfn e Sit r! Co:!dit :'OI!'S (j J!d Co nstJ'r.iJtr> Dere rmh !~ Jnj Urratio:: Fe nsibi!ity No No !njiit n,rion Fer:s.ibftt !::jiinmio:1 !t:jeosibie City of Temple City Assess S.uoce lll•ai!ob!e fo r Biotre.•r.tmenr 8:1~!?$ I Bfotrr:.•ntment F easi ble imp:'c•m r.1 nt Biotrtacment B:'-'/Ps PageS Biorre(ltmenr !nfeo$i!Jle ~ lmplement Tri'at nut:tBl-JPs (Se,' Section -l) October 2013 Table 2: BMP Selection by Street Context (Model for Living Streets Design Manual, 2011). BIORETENTJON DETENTION PAVING INLET PROTECTIONS STREET Vegetated Infiltration Trenches Permeable Storm Drain Storm Drain ' Pipe Filter Swales Planters Rain Gardens i CONTEXT Buffer Strips & Dry Wells Pavement Inlet Screens Filter Inserts Inserts Downtown " " " " " " Commercial Commercial " " " " " " " Commercial Throughway Neighborhood " " " " " " " " Commercial Downtown " " " " " " " " Residential Residential " " " " " " " " Residential Throughway Neighborhood " " " " " " " " Residential Industrial Industrial " " " " " " " " And Mixed-Use " " " " " " " " Mixed-Use Sidewalk " " " " " " " " Furniture Zone Park Edg€ " " ! " " " " " " Special Boulevard " " " " " " " I " Ceremonial " " " " (Civic) Alley " " " " " " Shared Public " " " " " " Small Way Walk Street " " " " " " " ' City of Temple City Page 6 of22 September 2013 Table 3 : BMP Location Opportunity Summary. BMP Bioretention Infiltration Trench/Dry Well Rain Gardens Permeable Pavement Flow-Through Planters Vegetated Swales City of Temple City Location Opportunity Summary • Adjacent to t raveled way and in frontage or furniture sidewalk zones • Can be loca ted in curb extensions, medians, traffic circles, roundabouts, and any othe r land scaped area • Suitable for constrained locations • Can be located under sidewalks and in sidewa lk planting strips, curb extensions, roundabouts, and medians • Can be integrated medians, islands, ci r cles, street ends, chicanes, and curb extensions • Can be located at the termin us of swales in the landscape • Suitable for parking or emergency access lanes • Can be located i n furniture zones of sidewalks especially adjacent to tree wells • Cannot be placed in areas w ith large t raffic volume or heavy load lanes • Avoid steep streets • Cannot be placed within 20 feet of sub-sidewalk basements • Cannot be within 50 feet of domestic water wells • Above-grade planters should be structurally separate from adjacent sidewalks • At-grade planter systems can be installed adjacent to curbs within the frontage and/or furniture zones • Can be loca ted adjacent to roadways, sidewalks, or parking areas • Can be integrated into traffic calming devices such as chicanes an d curb extensions • Can be placed in medians where the street drains to the median • Can be placed alongs id e streets and pathways Page 7 of 22 September 2013 " Should be designed to work in conjunction with the street slope " Can be located in multi-way boulevards, park edge streets, or Vegetated Buffer Strips sidewalk furniture zones " Can serve as pre-treatment " Can be located in a catch basin, manhole, or vault " Can be installed on an existing outlet pipe or at the bottom of an existing catch basin with an overflow Treatment BMPs " Can be placed on existing curbside catch basins and flush grate openings " Can be installed on the existing wall of a catch basin and on the curb side wall of a catch basin " Minimum set-backs from foundations and slopes should be observed if the BMP is not lined " Can be placed on sidewalks, in furniture zones, and on medians Street Trees " Adequate spacing must be provided between trees and street lights, pedestrian lights, accessible parking spaces, bus shelters, awnings, canopies, balconies, and signs SECTION 2-INFILTRATION Infiltration systems utilize rock, gravel, and other highly permeable materials for on-site infiltration. In these systems, stormwater runoff is directed to the system and allowed to infiltrate into the soils for on- site retention and groundwater recharge. During small storm events, infiltration systems can result in significant or even complete volume reduction of stormwater runoff. Infiltration should be used to the maximum extent practicable. Biotreatment BMPs should be considered if infiltration is found to be infeasible due to low infiltration rates, soil instability, high groundwater, or soil contamination. Infiltration BMPs may become damaged by stormwater carrying high levels of sediment, therefore pre- treatment features should be designed to treat street runoff prior to discharging to infiltration features. Media filters, filter inserts, vortex type units, bioretention devices, sumps, and sedimentation basins are several pre-treatment tools effective at removing sediment. City of Temple City PageS October 2013 2.1 INFILTRATION TRENCHES AND DRY WELLS ~\ ,, Drain Rock Optional Filter Fabric Native Soil Perforated Pipe Figu re 2: Infiltration Trench (Mode/for Living Streets Design Manual, 2011}. Description Infiltratio n trenches are linear, rock-filled features that promote in f iltration by providing a high ratio of sub-surface void space in permeable soils. They provide on-site stormwater retention and may contribute to groundwater recharge. Infiltration trenches may accept stormwater from sheet flow, concentrated flow from a swale or other surface feature, or piped flow from a catch basin. Because they are not flow-through BMPs, infiltration trenches do not have outlets but may have overflow outlets for large storm events. Dry wells are typically distinguishe d from infiltration t renches by being deepe r than they are wide. They are usually circular, resembling a well, and are backfilled with the same materials as infiltration trenches. Dry wells typically accept concentrated flow from surface features or from pipes and do not have outlets. In f iltration trenches and dry wells are typically designed to infiltrate all flow they receive. In large storm events, partial infiltration of runoff can be achieved by providing an overflow outlet. In these systems, significant or even complete volume reduction is possible in smaller storm events . During large storm events, these systems may function as detention facilities and provide a limited amount of retention and infiltration. Location and placement guidelines Infiltration trenches and dry wells typically have small surface footprints so they are potentially some of the most f lexible elements of landscape design. However, because they involve sub-surface excavation, t hese feature s may interfere with surround ing structures. Care needs to be taken to ensure that surrounding building foundations, pavement bases, and util ities are not damaged by infiltration features. Once structural soundness is ensured, infiltration features may be located under sidewalks and in sidewalk planting strips, curb extensions, roundabouts, and medians. When located in medians, they are most effective when the street is graded to drain to the median. Dry wells r equire les s surface area than trenches and may be more feasible in densely developed areas. Infiltration features should be sited on uncompacted soils with acceptable infiltration capacity. They are best used where soil and topography allow for moderat e to good infi ltration rates (0.3 inch es per hour or better) and the depth to groundwater is at least 10 feet . Prior to design of any retention or infiltration system, proper soil invest igatio n and percolation testing shall be conducted to determine appropriate infiltrat ion design rates, depth to groundwa t er, and if soil will exh ibit instability as a result of infiltration. Any site with potential for previous underground contamination shall be investigated. Infiltration trenches and dry wells ca n be designed as stand-alone systems when water qualit y is not a concern or may be combi ned in series with other stormwater tools . City of Temple City Page9 October 2013 Perforated pipes and piped inlets and outlets may be included in the design of infiltration trenches. Cleanouts shou ld be installed at both ends of any piping and at regular inte r vals in long sections of piping, to allow access to the system . Access ports are recommended for both trenches and wells and can be combined with clean-outs. If included, the overflow inlet from the infiltration trench should be properly designed for ant icipated flows. 2 .2 RA IN GARDENS Figure 3: Ra i n garden (Mode/for Living Streets Design Manual, 2011}. Description Rain gardens are vegetated depressions in the landscape . They have flat bottoms and gently sloping sides. Rain gardens can be similar in appearance to swales, but their footprints may be any shape. Rain gardens hold water on the surface, like a pond, and have overflow outlets. The detained water is infiltrated through the topsoil and subsurface drain rock unless the volume of water is so large that some must overflow. Rain gardens can reduce or eliminate off-site stormwater discharge while increasing on-site recharge. Location and Placement Guidelines Rain gardens may be placed where there is sufficient area in the landscape and where soils are suitable for infiltration. Rain gardens can be integrated with traffic calming measures installed along streets, such as medians, islands, circles, street ends, chicanes, and curb extensions. Rain gardens are often used at the terminus of swales in the landscape . City of Temple City Page 10 October 2013 2.3 PERMEABLE PAVEMENT Figure 4: Permeable pavement during a storm event (Model for Living Streets Design Manual, 2011}. Description Permeable pavement is a system with the primary purpose of slowing or eliminating direct runoff by absorbing rainfall and allowing it to infiltrate into the soil. Permeable pavement also filters and cleans pollutants such as petroleum deposits on streets, reduces water volumes for existing overtaxed pipe systems, and decreases the cost of offsite or onsite downstream infrastructure. This BMP is impaired by sediment-laden run-on which diminishes its porosity. Care should be taken to avoid flows from landscaped areas reaching permeable pavement. Permeable pavement is, in certain situations, an alternative to standard pavement. Conventional pavement is designed to move stormwater off-site quickly. Permeable pavement, alternatively, accepts the water where it falls, minimizing the need for management facilities downstream . Location and Placement Guidelines r-1 -.._.,) I ) -------Varies -------'1-- Sidewalk I Pervious l Sidewalk pavement 1 ~ ~ ~~~~~~~~~-.-~.---------------------------------.. ~-.:.: ... :.:.:,.-.. ·.:,~.-.~:··~ .. :·7·~.~.~.:.~.·-.~-~~-~r .. :~7~:.:.~_.~:i_·:~f-~7~~~~m~*~~~~ .••. : ·• ':.~ ~: . ':.:~:·,· •. :. ·,: :} U tility a nd Infrastructure .... _ -• Zone Figure 5: Possible pervious pavement design layout (Model for Living Streets Design Manual-2011}. Conditions where permeab le pavement should be encouraged include: • Sites where the re is limited space in the right-of-way for other BMPs; • Parking or emergency access lanes; and • Furniture zones of sidewalks especially adjacent to tree wells City of Tem ple City Page 11 October 2013 Conditions where permeable pavement should be avoided include: • Large traffic volume or heavy load lanes; • Where runoff is already being harvested from an impervious surface for direct use, such as irrigation of bioretention landscape areas; • Steep streets; • Gas stations, car washes, auto repair, and other sites/sources of possible chemical contamination; • Areas with shallow groundwater; • Within 20 feet of sub-sidewalk basements; and • Within 50 feet of domestic water wells. Material and Design Guidelines A soil or geotechnical report should be conducted to provide information about the permeability rate of the soil, load-bearing capacity of the soil, the depth to groundwater (10 feet or more required), and if soil will exhibit instability as a result of implementation. Infiltration rate and load capacity are key factors in the functionality of this BMP. Permeable pavement generally does not have the same load- bearing capacity as conventional pavement, so this BMP may have limited applications depending on the underlying soil strength and pavement use. Permeable pavement should not be used in general traffic lanes due to the possible variety of vehicles weights and heavy volumes of traffic. When used as a road paving, permeable pavement that carries light traffic loads typically has a thick drain rock base material. Pavers should be concrete as opposed to brick or other light-duty materials. Other possible permeable paving materials include porous concrete and porous asphalt. These surfaces also have specific base materials that detain infiltrated water and provide structure for the road surface. Base material depths should be specified based on design load and the soils report. Plazas, emergency roads, and other areas of limited vehicular access can also be paved with permeable pavement. Paving materials for these areas may include open cell paver blocks filled with stones or grass and plastic cell systems. Base material specifications may vary depending on the product used, design load, and underlying soils. When used for pedestrian paths, sidewalks, and shared-use paths, appropriate materials include those listed above as well as rubber pavers and decomposed granite or something similar (washed or pore- clogging fine material). Pedestrian paths may also use broken concrete pavers as long as ADA requirements are met. Paths should drain into adjoining landscapes and should be higher than adjoining landscapes to prevent run-on. Pavement used for sidewalks and pedestrian paths should be ADA compliant, especially smooth, and not exceed a 2 percent slope or have gaps wider than 0.25 inches. In general, tripping hazards should be avoided. Design considerations for permeable pavement include: • The location, slope and load-bearing capacity of the street, and the infiltration rate of the soil; • The amount of storage capacity of the base course; • The traffic volume and load from heavy vehicles; • The design storm volume calculations and the quality of water; and • Drain rock, filter fabrics, and other subsurface materials. City of Temple City Page 12 October 2013 Maintenance Guidelines Maintenance of permeable pavement systems is essential to their continued functionality. Regular vacuuming and street sweeping should be performed to remove sediment from the pavement surface. The bedding and base material should be selected for long li f e and sufficient infiltration rates. SECTION 3-BIOTREATMENT Biotreatment BMPs are landscaped, shallow depressions that capture and filter stormwater runoff. These types of BMPs are an increasingly common type of stormwater treatment device that are insta lled at curb leve l and filled with a bioretention type soil. They are designed as soil and plant-based f iltration devices that remove pollutants through a variety of physical, bio logica l, and chemical treatment processes. They typically consist of a pending area, mulch layer, planting soils, and plants. Stormwater is directed to t he system and pollutants are treated as the stormwater drains through the planting soil and either infiltrated or collected by an underdrain and directed to a collection system. Biotreatment should only be used in cases where infiltration has been proven infeasible due to low infiltration rates, soil in stability, hig h groundwater, or soil contamination. 3 .1 BIORETENTION Figure 6: Bioretention system (Model for Living Streets Design Manual, 2011). Description Bioretention is a stormwater management process that cleans stormwater by mimicking natural soi l filtration processes as water flows through a bioretention BMP. It incorporates mulch, soi l pores, microbes, and vegetation to reduce and remove sediment and pollutants from stormwater. Bioretention is designed to slow, spread, and, to some extent, infiltrate water. Each component of the bioretention BMP i s designed t o ass ist in retaining water, evapotranspiration, and adsorption of pollutants into the soil matrix. As runoff passes t hrough the vegetation and soil, the combined effects of filtration, absorption, adsorption, and biological uptake of plants remove pollutants. City of Temple City Page 13 October 2013 For areas with low permeability or other soil constraints, bioretention can be designed as a flow-through system with a barrier protecting stormwater from native soils. Bioretention areas can be designed with an underdrain system that directs the treated runoff to infiltration areas, cisterns, or the storm drain system, or may treat the water exclusively through surface flow. Examples of bioretention BMPs include swales, planters, and vegetated buffer strips. Location and Placement Guidelines Bioretention facilities can be included in the design of all street components; adjacent to the t raveled way and in the frontage or furniture sidewalk zones. They can be designed into curb extensions, medians, traffic circles, roundabouts, and any other landscaped area. Depending on the feature, maintenance and access should always be cons ide red in locating the device. Bioretention systems are also appropriate in constrained locations where other stormwater facilities requiring more extensive subsu rface materials are not feasible . If bioretention devices are designed to include in filtration, native soil should have a minimum permeability rate of 0.3 inches per hour and at least 10 feet to the groundwater table. Sites that have more than a 5 percent slope may require other stormwater management approaches or special engineering. 3.2 FLOW-THROUGH PLANTERS Figure 7: Flow-through planter (Model for Living Streets Design Manua~ 2011}. Description Flow-through planters are typically above-grade or at-grade with solid walls and a flow-through bottom. They are contained within an impermeable liner and use an underdrain to direct treated runoff back to the collection system. Where space permits, buildings can direct roof drains first to building-adjacent planters. Both underdrains and surface overflow drains are typically installed with building-adjacent p lan ters . At-grade street-adjacent planter boxes are systems designed to take street runoff and/or sidewalk runoff and incorporate bioretention processes to treat stormwater. These systems may or may not include underdrains . Location and Placement Guidelines City of Temple City Page 14 October 2013 Above-grade planters should be structurally separate from adjacent sidewalks to allow for future maintenance and structural stability per local department of public works' standards. At-grade planter systems can be installed adjacent to curbs within the frontage and/or furniture zones . All planters should be designed to pond water for less than 48 hours after each storm. Flow-through planters designed to detain roof runoff can be integrated into a building's foundation walls, and may be either raised or at grade. For at-grade planters, small localized depressions may be included in the curb opening to encourage flow into the planter. Following the inlet, a sump (depression) to capture sediment and debris may be integrated into the design to reduce sediment loadings. 3.3 VEGETATED SWALES Figure 8 : Vegetated swale (Signal Hill, CA). Description Swales are linear, vegetated depressions that capture rainfall and runoff from adjacent surfaces. The swale bottom should have a gradual slope to convey water along its length . Swales can reduce off-site stormwater discharge and remove pollutants along the way. In a swale, water is slowed by traveling through vegetation on a relatively flat grade. This gives particulates time to settle out of the water while contaminants are removed by the vegetation. Location and Placement Guidelines Swales can easily be located adjacent to roadways, sidewalks, or parking areas. Roadway runoff can be directed into swales via flush curbs or small evenly-spaced curb cuts into a raised curb. Swale systems can be integrated into traffic calming devices such as curb extensions. Swales can be placed in medians where the street drains to the median. Placed alongside streets and pathways, vegetated swales can be landscaped with native plants which filter sediment and pollutants and provide habitat for wildlife. Swales should be designed to work in conjunction with the street slope to maximize filtration and slowing of stormwater. Swales are designed to allow water to slowly flow through the system. Depending on the landscape and design storm, an overflow or bypass for larger storm events may be needed. Curb openings should be City of Temple City Page 15 October 2013 designed to direct flow into the swale. Following the inlet, a sump may be built to capture sediment and debris. 3.4 VEGETATED BUFFER STRIPS Figure 9 : Vegetated buffer strip detail (Model for Living Streets Design Manual, 2011). Description Vegetated buffer strips are sloping planted areas designed to treat and absorb sheet flow from adjacent impervious surfaces. These strips are not intended to detain or retain water, only to treat it as a flow- through feature. They should not receive concentrated flow from swales or other surface features, or concentrated flow from pipes. Location and Placement Guidelines Vegetated buffer strips are well-suited to treating runoff from roads and highways, small parking lots, and pervious surfaces . They may be commonly used on multi-way boulevards, park edge streets, or sidewalk furniture zones with sufficient space. When selecting potential placement the need for supplemental irrigation should be considered. Vegetated buffers can also be situated so they serve as pre-treatment for another stormwater management feature, such as an infiltration BMP. SECTION 4-TREATMENT BMPS 4.1 SAND FILTERS & STORM DRAIN INLET PROTECTIONS As described in Section 1 of this Green Streets Manual, it may be infeasible for specific projects to apply infiltration or biotreatment BMPs. In these cases, sand filters or filter inserts as treatment BMPs can be considered as an alternative. Sand filters and filter inserts can be designed to prevent particulates, debris, metals, and petroleum-based materials conveyed by stormwater from entering the storm drain system. All treatment BMP units should have an overflow system that allows the storm drain to remain functional if the filtration system becomes clogged during rainstorms. All storm drain inlet protections must be of a style and configuration approved by the agency with ownership of the inlet. Typical maintenance of catch basins includes scheduled trash removal if a screen or other debris capturing device is used. Street sweeping should be performed by vacuum sweepers with occasional City of Temple City Page 16 October 2013 weed and large debris removal. Maintenance should include keeping a log of the amount of sediment collected and the data of removal. The following are examples of acceptable treatment BMPs: • Sand Filters: Sand filters are designed to filter stormwater through a constructed media bed and to an underdrain system. As stormwater flows through the media pollutants are filtered out of the water. The filtered water is conveyed through the underdrain to a collection system. Pretreatment is necessary to eliminate significant sediment load or other large particles which would clog the system. Minimum set-backs from foundations and slopes should be observed if the facility is not lined. Filters should be designed and maintained such that ponded water should not persist for longer than 48 hours following a storm event. • Cartridge Media Filters: Cartridge media filters contain multiple modular filters which contain engineered media. The filters can be located in a catch basin, manhole, or vault. The manhole or vault may be divided into multiple chambers so that the first chamber may act as a pre- settling basin for removal of coarse sediment while the next chamber may act as the filter chamber. Cartridge media filters are recommended for drainage areas with limited available surface area or where surface BMPs would restrict uses. Depending on the number of cartridges, maintenance events can have long durations. Locations should be chosen so that maintenance events will not significantly disrupt businesses or traffic. Inlet inserts should be sized to capture all debris and should therefore be selected to match the specific size and shape of each catch basin and inlet. Filter media should be selected to target pollutants of concern. A combination of media may be used to remove a variety of pollutants. Systems with lower maintenance requirements are preferred. • Storm Drain Inlet Screens: Inlet screens are designed to prevent large litter and trash from entering the storm drain system while allowing smaller particles to pass through. The screens function as the first preventive measure in removing pollutants from the storm water system. The city's street sweeping department should be consulted to ensure compliance with local specifications and to schedule regular maintenance. Annual inspection of the screen is recommended to ensure functionality. Note that most LA River drainage areas are already protected using connector pipe screens through collective systems. Storm Drain Pipe Filter Insert: The storm drain outlet pipe filter is designed to be installed on an existing outlet pipe or at the bottom of an existing catch basin with an overflow. This filter removes debris, particulates, and other pollutants from stormwater as it leaves the storm drain system. This BMP is less desirable than a protection system that prevents debris from entering the storm drain system because the system may become clogged with debris. Outlet pipe filters can be placed on existing curbside catch basins and flush grate openings. Regular maintenance is required and inspection should be performed rigorously. Because this filter is located at the outlet of a storm drain system, clogging with debris is not as apparent as with filters at street level. This BMP may be used as a supplemental filter with an inlet screen or inlet insert unit. City of Temple City Page 17 October 2013 SECTION 5 -STREET TREES 5.1 STREET TREES Figure 10: Street trees (Temple City, CA}. Description Healthy urban trees are powerful stormwater management tools. Leaves and branches catch and slow rain as it falls, helping it to soak into the ground. The plants themselves take up and store large quantities of water that would otherwise contribute to surface runoff. Part of this moisture is the n returned to the air through evaporation to further cool the city. As an important element along sidewalks, street trees must be provided with conditions that allow them to thrive, including adequate uncompacted soil, water, and air. The goal of adding street trees is to i ncrease the canopy cover of the street, the percentage of its surface either covered by or shaded by vegetation. The selection, placement, and management of all elements in the street should enhance the longevity of a city's street trees and healthy, mature plantings should be retained and protected whenever possible. Benefits to adding street trees include: • Creation of shade to lower temperatures in a city, reduces energy use, and makes the street a more pleasant place in which to walk and spend time • Slowing and capture of rai nwater, he lping it soak into the ground to restore local hydrologic functions and aquifers • Imp roving air quality by cooling air, produci ng oxygen , and absorbi ng and storing carbon i n woody plant tissues City of Temple City Page 18 Octobe r 2013 SECTION 6-DEFINITIONS Best Management Practice (BMP) Operating methods and/or structural devices used to reduce stormwater volume, peak flows, and/or pollutant concentrations of stormwater runoff through evapotranspiration, infiltration, detention, filtration, and/or biological and chemical treatment. Bioretention Soil and plant-based retention practice that captures and biologically degrades pollutants as water infiltrates through sub-surface layers containing microbes that treat pollutants. Treated runoff is then slowly infiltrated and recharges the groundwater. Conveyance The process of water moving from one place to another. Design Storm A storm whose magnitude, rate, and intensity do not exceed the design load for a storm drainage system or flood protection project. Detention Stormwater runoff that is collected at one rate and then released at a controlled rate. The volume difference is held in temporary storage. Filtration A treatment process that allows for removal of solid (particulate) matter from water by means of porous media such as sand, soil, vegetation, or a man-made filter. Filtration is used to remove contaminants. Furniture Zone The furniture zone is the area which lies between the curb and pedestrian zones and is intended to house utilities and pedestrian amenities. Hardscape Impermeable surfaces, such as concrete or stone, used in the landscape environment along sidewalks or in other areas used as public space. Infiltration The process by which water penetrates into soil from the ground surface. Permeability/Impermeability The quality of a soil or material that enables water to move through it, determining its suitability for infiltration. Retention The reduction in total runoff that results when stormwater is diverted and allowed to infiltrate into the ground through existing or engineered soil systems. Runoff Water from rainfall that flows over the land surface that is not absorbed into the ground. City of Temple City Page 19 October 2013 Sedimentation The deposition and/or settling of particles suspended in water as a result of the slowing of the water. Storm water Water runoff from rain or snow resulting from a storm. Transportation Corridor A major arterial, state route, highway, or rail line used for the movement of people or goods by means of bus services, trucks, and vehicles. SECTION 7-REFERENCES 1. los Angeles County. Model for Living Streets Design Manual. 2011. 2. U.S. Environmental Protection Agency (EPA). Managing Wet Weather With Green Infrastructure Municipal Handbook: Green Streets. December 2008. 3. Orange County. Technical Guidance Document. May 2011. -----·~~~~----------------~~------------------~~~~-City of Temple City Page 20 October 2013 Attachment D COMMUNITY DEVELOPMENT DEPARTMENT MEMORANDUM DATE: November 5, 2013 TO: The Honorable City Council FROM: Jose E. Pulido, City Manager Via: Mark Persico, AICP, Community Development Director By: Hesty Liu, AICP, Associate Planner SUBJECT: INTRODUCTION AND FIRST READING OF ORDINANCE NO. 13-979, AMENDING ARTICLE E ("SITE PLAN REVIEW AND CONGESTION MANAGEMENT") OF CHAPTER 1 ("ZONING CODE") OF TITLE 9 ("ZONING REGULATIONS") OF THE TEMPLE CITY MUNICIPAL CODE TO ESTABLISH LOW IMPACT DEVELOPMENT (LID) STANDARDS AND A GREEN STREETS POLICY RECOMMENDATION: The City Council is requested to: a) Introduce Ordinance No. 13-979 (Attachment "A") for first reading by title only, amending Article E ("Site Plan Review and Congestion Management") of Chapter 1 ("Zoning Code") of Title 9 ("Zoning Regulations") of the Temple City Municipal Code to establish Low Impact Development (LID) standards and a Green Streets Policy; b) Waive further reading of Ordinance No. 13-979; and c) Schedule the second reading of Ordinance No. 13-979 for November 19, 2013. BACKGROUND: 1. On November 8, 2012, under the authority of the Clean Water Act, the Los Angeles Regional Water Quality Control Board adopted the Municipal Separate Storm Sewer System Permit (known as MS4 Permit), which requires that all local jurisdictions in Los Angeles County (i.e., Permittees) electing to participate in a Watershed Management Program or an Enhanced Watershed Management Program have LID ordinances in place. MS4 Permit also requires Permittees to City Council November 5, 2013 Page 2 of 4 have a Green Streets Policy in place and/or commence development of a policy that specifies the use of green street strategies for transportation corridors. The deadline for compliance is December 15, 2013. 2. On June 28, 2013, Temple City submitted a Notice of Intent to the Los Angeles Regional Water Quality Control Board, indicating the intention of participating in the Enhanced Watershed Management Program (EWMP) of the Upper Los Angeles River Watershed Group. 3. From July to September 2013, staff worked on developing LID standards and a Green Streets Policy for the City, in order to comply with the deadline of MS4 Permit issued by the California Regional Water Quality Control Board, Los Angeles Region. 4. On October 17, 2013, the Planning Commission reviewed the Draft Ordinance No. 13-979, the proposed Temple City LID Manual, and the proposed Temple City Green Streets Manual. The Planning Commission made the recommendation to the City Council to adopt the proposed code amendment, the proposed LID Manual, and Green Streets Manual (See "Attachment D" for Planning Commission staff report). ANALYSIS: As a participant of the Enhanced Watershed Management Program of the Upper Los Angeles River Watershed Group, Temple City must adopt a LID ordinance and a streets policy to comply with the MS4 Permit requirement before the deadline. Noncompliance will subject the City to a fine of potentially up to $10,000 per day. The goals of requiring the implementation of Low Impact Development Standards and Green Streets policy are to provide source control of stormwater as well as to reduce the amounts of pollutants in stormwater and urban runoff. In light of the MS4 Permit mandate and the goals of the regional water board, staff proposes four categories for the implementation of LID in Temple City: Category 1. Category 2. Category3. Exemption: The project will disturb less than 500 square feet of soil. Residential LID Category: The project is a residential development, involves 4 or less dwelling units and will disturb more than 500 square feet of soil. Commercialllndustrial LID Category: The project is a residential development involving 5 or more dwelling units, or is at a commercial or City Council November 5, 2013 Page 3 of 4 Category4. industrial site. The project will also disturb more than 500 square feet of soil. Projects covered bv MS4 Permit applicability list: The project is subject to the provision of the Municipal Separate Storm Sewer System permit (MS4) issued by the California Regional Water Quality Control Board. Under the MS4 permit, implementing LID Standards for projects not covered by MS4 applicability list but will "result in the creation or addition or replacement of 500 square feet or more of impervious surface area" is not mandatory. However, considering that the majority of the projects in Temple City are smaller projects, and implementing LID would benefit the community, staff proposes creating two additional categories ( Category 2 and 3), for inclusion in the LID implementation. Requirements developed for Category 2 and 3 are based on the goals of not creating an unnecessary burden on the property owners and limiting the need for the City's enforcement. Most projects under the two categories do not need to prepare a separate LID plan, and reviews can be conducted by City staff. Also, many treatment systems recommended in the LID Manual are low-maintenance systems, some of which can be easily integrated into the landscape design of the projects. The proposed code amendment did not separate applicable criteria for LID and the Green Streets Policy because they are both covered under the MS4 Permit Applicability List. Temple City Green Streets Manual is created to provide a technical guidance for the City's implementation of the Green Streets Policy. The proposed code amendment is exempt from CEQA, per Section 15061 (b)(3) and Section 15308 of the CEQA Guidelines. Adopting the proposed code amendment will enable the City to comply with MS4 Permit mandates and deadline. It is also a necessary move for the City to participate in the regional effort of water quality control. By requiring projects to address post-construction stormwater runoff issues, the City will eventually benefit from a reduction in impermeable surfaces, improved water quality in the local aquifers, and enhanced landscape and streetscape within the City. CONCLUSION: The City Council is requested to adopt the proposed code amendment, the Temple City LID Manual, and the Temple City Green Streets Manual. The proposed code amendment is tailored to the development types of the City, with the LID Manual and Green Streets Manual serving as a technical guide for implementation. City Council November 5, 2013 Page 4 of 4 FISCAL IMPACT: It is anticipated that the adoption of proposed Ordinance No. 13-979 will not have a fiscal impact on the Fiscal Year (FY) 2013-14 City Budget. The City will generate revenue to cover the cost of processing development applications. Staff cannot estimate at this time how many applications will be approved, however, if the increase in revenues is significant, staff will return at FY 2013-14 Mid-Year Budget Review with a revised revenue estimate. ATTACHMENTS: A. Ordinance No. 13-979 B. Temple City LID Development Manual C. Temple City Green Streets Manual D. Planning Commission Staff Report and Resolution No. 13-2382 PC