(A) The P-SWPPP shall include provisions for stormwater quality BMPs that are designed to achieve the following design/performance objectives:
(1) Remove 80% of the average annual post development total suspended solids (TSS) from the first flush as defined by land use characteristics and contributing area; or capture and treatment of at least 0.6 inch precipitation applied over the contributing area. The formula for water quality volume is:
WQv = (A * d) / (43560ft^2 * 12in)
Where: WQv = Ac-ft
A = proposed impervious area (ft^2)
d = 0.6 (in)
(2) Reduce or buffer increases in stormwater runoff temperatures caused by contact with impervious surfaces;
(3) Reduce or buffer increases in stormwater runoff volume and flow rate caused by increases in directly connected impervious area and overall impervious area;
(4) Stormwater quantity facilities (detention/retention) 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 determined by the National Oceanic and Atmospheric Administration for Campbellsville, Kentucky at the time of the development. The outlet structure shall be designed capable of controlling the discharge rates for the first flush, two-, ten-, and 25-year design storm events;
(5) When redevelopment rather than new development occurs, reduce the discharge rate by a flat rate of 20%;
(6) Stormwater detention/retention facilities shall be designed with a minimum of one foot of freeboard above the calculated high water elevation for the 25-year storm;
(7) Stormwater detention/retention facilities shall be designed with an emergency spillway to effectively pass the 100-year design storm event in such a manner downstream properties are not adversely affected. The 100-year design storm event may also be conveyed by overflow device and pipe without the design of the emergency spillway.
(B) Soil bioengineering, "green" and other "soft" slope and stream bank stabilization methods shall receive preference over rip rap, concrete and other hard armoring techniques. Examples are rain gardens and permeable materials.
(C) Supportive data must be submitted to justify the type of facility selected. The facility may be designed to infiltrate runoff to groundwater rather than transmit it downstream under conditions up to a ten-year storm event. It must be able to bypass all other storms including 100-year events with a discharge rate equivalent to or less than pre-development conditions without negatively impacting the 100-year floodplain above or below the site. If data indicates that the facility cannot retain a significant portion (95%) of the runoff, then the facility must be designed to detain runoff.
(D) The city reserves the right to require superseding or additional treatment criteria or objectives for specific pollutants as necessary to meet overall stormwater quality management program objectives or directives under a watershed improvement or Total Maximum Daily Load (TMDL) program as administered by the USEPA or KYDOW.
(E) The design shall include and/or address the following elements:
(1) Area vicinity map showing current zoning, adjoining property owners, and street lines within 100 feet of the project boundaries all drawn at a scale not greater than one inch = 2,000 feet;
(2) North arrow and its basis;
(3) Legend explaining symbols and abbreviations used on the plan;
(4) "Do Not Disturb Limits" for construction activity indicated by a heavy dashed line and labeled as such;
(5) Boundary of site defined by bearings and distances and indicated by a heavy solid line;
(6) Drawing(s) at a scale not greater than one inch = 100 feet. In the case of an unusually large development, a scale of one inch = 200 feet may be acceptable;
(7) Acreage of the total site and acreage of the project site (if different);
(8) Soil classifications;
(9) Existing and proposed runoff coefficients;
(10) Impervious areas as measured in square feet;
(11) Benchmark location(s), description(s) and elevation(s) at sea level;
(12) Basis of elevation datum;
(13) Name, address, and telephone number of the owner, developer, permittee, and project qualified professional;
(14) Existing and proposed topography at two-foot contour intervals;
(15) Mapping accuracy shall conform to National Standards of Mapping;
(16) Location of conservation zones, sinkholes, streams, steep slopes, known springs and watercourses;
(17) Location of any existing buildings or structures;
(18) Location of any pertinent utilities, sanitary sewers, water and stormwater facilities on the property within 50 feet of the site;
(19) Elevations, dimensions, locations, and the extent of all planned grading indicated with proposed contours;
(20) A grading plan for borrow pits, quarries and material-processing facilities based on the findings of soil site investigations;
(21) Design details of temporary and permanent structural controls;
(22) Approximate location of the 100-year floodplain or a statement by a professional engineer or professional land surveyor that the site is not located in an area subject to flooding. The basis for this determination shall be shown;
(23) A detailed cost estimate for installation and maintenance of all stormwater management control measures;
(24) Identification of perimeter controls at outfalls and areas where construction site drainage leaves the property boundary or disturbed area(s);
(25) Arrows indicating drainage flow patterns;
(26) Location, dimensions, detailed specifications, and construction details of all temporary and permanent stormwater quality measures;
(27) Temporary stabilization plans and sequence of implementation including seeding mixture, method of seedbed preparation and kind and quality of mulching;
(28) Permanent stabilization plans and sequence of implementation including seeding mixtures and rates, types of sod, method of seedbed preparation, expected seeding dates, type and rate of lime and fertilizer application, and kind and quantity of mulching;
(29) A sequence of construction of the development site, including stripping and clearing, rough grading, construction of utilities, infrastructure, and construction of buildings, final grading and landscaping. Sequencing shall identify the expected date each activity will occur and the expected duration of each. A description should be given describing the relationship between implementation of stormwater quality measures and phases of construction activities. Phasing of construction should be performed to limit disturbed areas to 20 acres;
(31) Anticipated inspection and maintenance requirements for permanent and temporary measures. This shall include the expected frequency of routine inspections and maintenance activities such as removal of sediment and waste concrete;
(32) Name of receiving waters;
(33) Management practices or other controls to address the following:
(a) Waste concrete management;
(b) Material delivery, handling and storage;
(c) Sanitary/septic waste management;
(d) Solid waste/trash and debris management;
(e) Vehicle and equipment cleaning, fueling, and maintenance;
(f) Sensitive and vegetated area preservation;
(g) Pit and channel de-watering operations;
(h) Contaminated soil management as defined and approved by the Kentucky Divisions of Water and Waste Management;
(i) Pesticides, herbicides, and fertilizer use;
(j) Long-term stormwater quality treatment;
(k) Blowing of dust or sediment from the site.
(34) Plan for stabilizing the entire site at the end of the construction season. If vegetation cannot be established, the site shall have a heavy mulch layer (straw or wood chips) applied to control erosion.
(F) The permittee shall notify the city in writing of any substantial field changes made to the approved Stormwater Quality Management Plan. Changes made to the plan must be approved by the MS4 coordinator or their designee.
(G) The city shall review the P-SWPPP within a reasonable time frame, typically 30 calendar days from the date of submission and issue or deny the requested permit. Failure to do so will allow the Person to proceed with land-disturbing activities in accordance with BMPs and the submitted P-SWPPP. However, the city reserves the right to review and require changes it determines appropriate.
(Ord. 14-08, passed 9-3-2014; Am. Ord. 19-02, passed 5-6-2019; Am. Ord. 20-05, passed 7-20-2020) Penalty, see § 54.999