(A) Storm water quality management. The permittee shall complete a permit application that includes a post-construction storm water pollution prevention plan (P-SWPPP) to be completed, sealed and signed by a licensed professional engineer and submitted to the city representative.
(B) Post-construction storm water pollution prevention plan. The P-SWPPP shall include the following information:
(1) A description of the proposed land use including amount of impervious area, directly connected impervious area and nature of the development;
(2) Location, dimensions, detailed specifications and construction details of all post- construction storm water quality best management practices (BMPs), as defined in the city guidance documents;
(3) A sequence describing when each post-construction storm water quality BMP will be installed;
(4) A long-term operation and maintenance agreement containing maintenance guidelines for all post-construction storm water quality measures to facilitate their proper long-term function. This agreement shall be made available to future parties, including property owners, who will assume responsibility for the operation and maintenance of the post-construction storm water quality measures;
(5) The P-SWPPP shall include provisions for waterway buffers:
(a) The waterway buffer will be used to define areas where land disturbance activities shall be permitted, but construction of any building or structure shall not be permitted;
(b) A waterway buffer shall be applied to all waterways serving more than 25 acres of tributary area or presented on a United States Geological Survey map as a blue line stream;
(c) The waterway buffer shall be defined as the greater of:
1. Area contained within a boundary established by the floodplain boundary as defined by FEMA or city master planning: or
2. The buffer will be 25-feet on each side from the top of waterway bank as defined by geomorphic shape (not by the current water surface elevation).
(d) The waterway buffer and floodplain may be used for application of storm water quality devices. This may only be permitted if erosion prevention and sediment control, water quality and floodplain cut fill policies are adequately addressed as determined by the city;
(e) Exemptions may be granted at the discretion of the city for:
1. Roads and utilities crossing waterways;
2. Pedestrian trails and walkways proximate to waterways; and
3. Other exemptions.
(6) A licensed professional engineer in the commonwealth shall stamp all construction plans and long-term maintenance documentation. This shall include all proposed improvements or modifications to existing or new storm-water infrastructure and other related improvements or modifications; and
(7) The city may require the posting of a maintenance bond to secure the structural integrity of said facilities as well as the functioning of said facilities in accordance with the approved post-construction SWPPP for a term of 24 months from the date of acceptance of dedication. An irrevocable letter of credit can be used as the financial assurance in lieu of a maintenance bond although the contribution shall be equivalent to the amount that would be estimated for the maintenance bond. The maintenance bond shall be calculated as 20% of the estimated construction cost and may be reduced to 10% after 12 months if there are no concerns by the city representative.
(C) BMP design requirements and criteria.
(1) The city reserves the right to develop or adopt other guidance documents to serve as design and implementation standards. Other guidance documents distributed by the city should be reviewed and considered when preparing the post-construction SWPPP. These documents may be applied as standards by which designs are to be prepared and controls implemented.
(2) The city shall have authority to implement this chapter by appropriate regulations, guidance or other related materials. In this regard, technical, administrative or procedural matters may be modified as needed to meet the objectives defined herein, so long as such modifications as to technical, administrative or procedural matters are not contrary or beyond the intent of the objectives defined above.
(a) Regulations, guidance or other related materials that may be given authority by this chapter may include, but are not limited to: best management practice (BMP) manuals, design regulations and requirements, submittal checklists, review checklists, inspection checklists, certifications, storm water management manuals, in lieu fee schedule, and operation and maintenance manuals.
(b) Materials may include information deemed appropriate by the city including and specifications for the preparation of grading plans, guidance selecting environmentally sound practices for managing storm water, minimum specifications and requirements, more complete definitions and performance standards.
(c) The above referenced documents may restrict or prevent the use of specific products, techniques or management practices (that are to be accepted by the public or are deemed to have a negative impact on public infrastructure or the MS4) that have been identified as unacceptable for performance, maintenance or other technically based reasons.
(d) Documents referenced above may be updated periodically to reflect the most current and effective practices and shall be made available to the public. However, the failure to update the manual shall not relieve any applicant from the obligation to comply with this chapter, and shall not prevent the city from imposing the most current and effective practices.
(3) The P-SWPPP shall include provisions for storm water quality BMPs functioning independently or in combination. Acceptable storm water quality BMPs shall be defined by policy and guidance documents as approved by the city.
(4) The P-SWPPP shall include provisions for storm water quality BMPs that are designed to achieve the following design/performance objectives:
(a) Development shall be designed with management measures that are built and maintained to treat, filter, flocculate, infiltrate, screen, evapo-transpire, harvest and reuse storm water runoff, or otherwise manage the storm water quality produced from an eightieth percentile precipitation event (0.75-inch rainfall). At least 80% of the average annual post-construction total suspended solids (TSS) load shall be removed.
(b) Reduce or buffer increases in storm water runoff temperature caused by contact with impervious surfaces.
(c) Reduce or buffer increases in storm water runoff volume and flow rate caused by increases in impervious area.
(d) Storm water detention/retention facilities shall be designed to address the rate at which flow is released over the entire runoff discharge period and the volume of discharge over the critical design-storm period as defined by city storm water master plans. The outlet structure shall be designed as a v-notch weir or other multiple stage configurations capable of controlling (limiting) the discharge rates for the two-, ten-, 25- and 100-year, 24-hour, SCS Type II distribution, design storm events to pre-developed levels for all new developments. The approved P-SWPPP may require the first flush (0.75-inch rainfall) to be retained in the basin without discharge. Redevelopment shall reduce the discharge from their site to meet this same standard. This may require the redesign and reconstruction of existing basins at the site to meet the current standard.
(e) Culvert and storm sewer improvements shall be designed to minimize scour. The FHWA HDS No. 5 design methodology (latest edition) considering inlet and outlet control shall be used. For major culverts and storm sewers, as designated by the city, a 100-year, SCS Type II, 24-hour design flow shall be used with a HW/d less than or equal to one. For minor, subdivision level culverts and storm sewers, a 25-year SCS Type II 24-hour storm and a HW/d less than or equal to one shall be used. In this instance, a check of the 100-year SCS Type II 24-hour flow with a HW/d less than or equal to 1.2 shall also be performed. Pipe outlets shall be protected with channel lining or permanent turf reinforcement mat, as supported by sound civil engineering design.
(f) Storm water hotspots are areas that often produce higher concentration of certain pollutants, such as hydrocarbons or heavy metals, than are normally found in urban runoff. These sites shall be required to provide effective removal of the particular pollutant(s) which they discharge. Effective removal shall be deemed as that which existed prior to development of the site or in the case of redevelopment that which existed prior to any development to the site. Review and approval is required prior to commencement of construction.
1. Examples of storm water hotspots include:
a. Gas/fueling stations;
b. Restaurants;
c. Vehicle repair facilities;
d. Vehicle washing/steam cleaning facilities (including mobile operations);
e. Auto and metal recycling facilities;
f. Outdoor material storage areas;
g. Loading and transfer areas;
h. Landfills;
i. Industrial sites; and
j. Industrial rooftops.
2. Storm water hotspots shall have treatment on site and cannot rely on regional solutions offered by the city or the larger development to meet their individual treatment requirement.
(g) Soil bioengineering, “green” and other “soft” slope and stream bank stabilization methods shall receive preference over rip rap, concrete and other hard armoring techniques, except where necessitated by sound civil engineering design.
(h) Retention-supportive data must be submitted to justify the type of facility selected. If the facility is designed to retain (volume control) all or a significant portion of runoff (as opposed to temporarily detain), then appropriate soils analyses findings shall be submitted to the city. This submission shall also discuss the impacts the facility will have on karst topography if found through inspection or a geotechnical investigation of the site. The facility may be designed to infiltrate runoff to groundwater rather than transmit it downstream under conditions up to a 100-year storm event. Injection wells shall not generally be permitted due to the relationship between subterranean and surface flows.
(i) Each P-SWPPP shall be evaluated for consistency with the storm water master plan or watershed study for the major watershed or watersheds within which the project site is located. The individual project evaluation will determine if storm water quantity and quality management practices can adequately serve the property and limit impacts to downstream public and private properties. The presence of a regional facility(s) will be considered in determining the extent to which storm water quantity and/or quality controls will be necessary.
(j) The city reserves the right to require superseding or additional treatment criteria or objectives for specific pollutant(s) as necessary to meet overall storm water quality management program objectives or directives under a watershed improvement or total maximum daily load (TDML) program as administered by the USEPA or commonwealth.
(k) On-site BMP coordination with regional BMPs:
1. All properties are expected to implement on-site storm water quality control measures, but the extent of application may be reduced given the availability, proximity and nature of regional storm water quality BMPs; and
2. The extent and type of on-site storm water quality management practices implemented shall be proportionate to the land use and proximity to regional storm water quality management practices.
(D) BMP ownership and easement.
(1) Any storm water management facility or BMP which services individual property owners shall be privately owned. General routine maintenance (controlling vegetative growth, seeding, regrading and removing debris) shall be provided by the owner(s).The owner shall establish a public utilities and drainage easement over the locality for access for inspection and emergency maintenance by the city. The city, or its designee, has the right, but not the duty, to enter premises for emergency repairs.
(2) Any storm water management facility or BMP which services an individual residential subdivision in which the facility or BMP is within designated open areas or serves as an amenity with an established homeowners association shall be privately owned and maintained consistent with provisions of this chapter. The owner shall maintain a public utilities and drainage easement which allows access for inspection and emergency maintenance by the city. The city, or its designee, has the right, but not the duty, to enter premises for emergency repairs.
(3) Any storm water management facility or BMP which services commercial and industrial development shall be privately owned and maintained. The owner shall maintain a public utilities and drainage easement which allows access for inspection and emergency maintenance by the city. The city, or its designee, has the right, but not the duty, to enter premises for emergency repairs.
(4) All regional storm water management control facilities proposed by the owners, if approved and accepted by the city for dedication as a public regional facility, shall be publicly owned and/or maintained. All other storm water management control facilities and BMPs shall be privately owned and/or maintained unless accepted for maintenance by the city.
(5) The city may require public dedication of privately-owned storm water facilities which discharge to the city storm water system. This shall be at the approval of the City Council.
(E) Regional facilities management.
(1) The objective of a regional storm water management facility, pond, lake or other device, is to address the storm water management concerns in a given watershed with greater economy and efficiency than possible through individual facilities. The intended result is fewer storm water management facilities to maintain in the affected watershed while sustaining efficiency.
(2) The city encourages regional storm water quantity and/or quality management practices, which may be consistently and efficiently managed and maintained. These types of practices will be encouraged in order to replace or reduce the implementation of on-site storm water quantity and/or quality management practices, as determined to be appropriate by the city.
(3) Where a regional storm water management facility has been established by the city, or by an authority operating on behalf of the city, a development or subdivision, unless excepted by the city, may participate in said regional program in lieu of constructing site runoff control required by this chapter. This may be permitted; provided that:
(a) Runoff from the development or subdivision is benefited by an approved existing or proposed public regional storm water management facility that is currently operational or will be operational within one year;
(b) Participation in the form of contribution of funds, contribution of land, contribution of storm water management facility construction work, or a combination of these, the total value of which shall be in accordance with a fee schedule adopted by the city;
(c) The city finds that the storm water quality management plans are in compliance with all other applicable requirements and ordinances;
(d) Fiscal or other contribution shall be used for acquisition, design, construction or maintenance of one or more regional storm water management facilities with the Valley Creek Watershed; and
(e) Detention facilities may, and are encouraged to, be designed to serve multiple purposes. For example, runoff may be detained under wet-weather conditions, but also serve as common or recreational areas during dry weather conditions. Where multi-purpose facilities are provided, or where flat grades or poorly draining soils are encountered, provisions for adequate low-flow storm water management system may be required. Where the retention/detention facility is planned to be used as a lake, pond or storm water quality management practice with a permanent pool, calculations shall be performed and submitted to demonstrate that an adequate permanent pool depth is expected during dry summer months without vegetative growth issues.
(F) Long-term operation and maintenance agreements.
(1) General. Long-term operation and maintenance agreements shall include a maintenance plan for all storm water quality BMPs in new development or redevelopment that require more than general maintenance (e.g., periodic mowing).
(a) The plan will be developed to ensure that the storm water quality BMP(s) is (are) kept functional. The maintenance agreement will specify minimum operation and maintenance requirements and intervals to be performed by the property owner.
(b) The plan shall address schedules for inspections and techniques for operation and maintenance, including vegetation clearing or mowing and removing accumulated trash, debris, sediment pollutants and other forms of pollution.
(c) The agreement shall be noted on the final plat with the appropriate notation on the particular lot(s).
(d) The agreement shall be included with property ownership title documents and shall be binding on the owner, its administrators, executors, assigns, heirs and any other successors in interest.
(e) The format for the long-term operational and maintenance agreement shall be provided through example by the city, or through guidance documents.
(f) Care must be taken to ensure that any required facilities do not become nuisances or health hazards. Detention and retention facilities should be designed to require minimal maintenance, and maintenance expectations must be clearly stated in the long-term operation and maintenance agreement.
(g) When a storm water quality BMP serves more than one parcel, a binding contract for the purpose of operation and maintenance is required. A property or home owners association shall be responsible for operation and maintenance of the BMP(s) as directed by this chapter.
(2) Single entity ownership. Where the permanent storm runoff control facilities are designed to manage runoff from property in a single entity ownership, the maintenance responsibility for the storm water control facilities shall be with the single entity owner.
(a) A single entity shall be defined as an association, public or private corporation, partnership firm, trust, estate or any other legal entity allowed to own real estate exclusive of an individual lot owner.
(b) The stated responsibilities of the entity shall be documented in the long-term operation and maintenance agreement. Terms including owning, operating and maintaining the facilities shall be submitted with plans in application for a SWQMP Permit for an adequacy determination. Approval of a SWQMP shall be conditioned upon the approval of these terms. These terms shall be in writing, shall be in recordable form, and shall, in addition to any other terms deemed necessary by the city, contain a provision permitting inspection at any reasonable time by the city of all facilities deemed critical in the public welfare.
(c) Upon approval of the storm water quality BMPs by the city, the facility owner(s) shall demonstrate the ability to guarantee and apply the financial resources necessary for long-term maintenance requirements. The funding mechanism shall be in a form approved by the city. The city will only approve funding mechanism(s) for long-term maintenance responsibilities that can be demonstrated to be permanent or transferable to another entity with equivalent longevity.
(d) In the event that proposed funding is through an owners association, then it must be demonstrated that the association may not dissolve unless long-term operation and maintenance activities are accepted by another entity with equivalent longevity and adequate funding. Furthermore, the owners association’s responsibility must be stated in the association’s declaration, covenants or by-laws, as appropriate.
(e) Unless made specifically clear in the preliminary stages of the site design and construction plan review procedure, it will be assumed that all storm water detention, retention, treatment or storage facilities and/or devices shall be owned, operated and maintained by a single entity, as defined above.
(3) City ownership. Where the city has accepted an offer of public dedication of the permanent storm water quality BMPs, the city shall be responsible for operation and maintenance.
(G) Special watersheds.
(1) Special watersheds may be designated by the city with unique goals and requirements. The minimum measures outlined in this chapter shall be met at all times. Additional requirements, unique to the specific watershed, shall be required to meet the specific needs of the watershed.
(2) Special watersheds designated:
(a) Hawkins Drive; flow quantity limitation. The post-developed flow rate and quantity from the development cannot exceed the pre-developed flow rate and quantity in this unique watershed. The karst feature that receives the flow from this watershed has no predictable capacity. Therefore site storage, reuse and other innovative methods to abate both rate and volume increases due to development shall be required; and
(b) Current and future listings by KDOW.
(Ord. 07-2012, passed 4-2-2012)