13.30.100 Stormwater pollution prevention plan or erosion and sediment control plan.
(a) SWPPP Required. A SWPPP shall be required for any project which will have land disturbance activity of one acre or more. Applicant for a permit shall provide Utilities Director with a copy of NOI issued by KDHE and a copy of SWPPP submitted as part of the NOI application.
(b) Erosion Control Plan Required. An erosion and sediment control plan shall be required for any project which will have removal or increase of 101 or more cubic yards of soils or other material subject to erosion by wind or water or land disturbance activity of 3,000 or more square feet but less than one acre.
(c) The erosion control plan or SWPPP shall meet the following criteria:
(1) Minimize, in area and duration, exposed soil and unstable soil conditions.
(2) Minimize disturbance of natural soil cover and vegetation.
(3) Protect receiving water bodies, wetlands and storm sewer inlets.
(4) Protect adjacent properties from sediment deposition.
(5) Minimize off-site sediment transport on trucks and equipment.
(6) Minimize work in and adjacent to water bodies and wetlands.
(7) Maintain stable slopes.
(8) Avoid steep slopes and the need for high cuts and fills.
(9) Minimize disturbance to the surrounding soils, root systems and trunks of trees adjacent to site activity that are intended to be left standing.
(10) Minimize the compaction of site soils.
(d) Erosion and Sediment Control Plan or SWPPP Requirements. The erosion and sediment control plan or SWPPP shall include the following on all relevant plans and drawings:
(1) Site Plans for Existing and Proposed Conditions. A complete site plan and specifications, signed by the person who designed the plan, shall be drawn to an easily legible scale, shall be clearly labeled with a north arrow and a date of preparation, and shall include, at a minimum, the following information:
(i) Project Map. A map at least eight and one-half by 11 inches indicating site boundaries, property lines and lot dimensions in relation to surrounding roads, buildings and other structures, and other significant geographic features.
(ii) Identification of all natural and artificial water features (including drain tiles) on or adjacent to the site including, but not limited to, lakes, ponds, streams (including intermittent streams), wetlands, natural or artificial water diversion or detention areas, subsurface drainage facility, stormwater conveyance, and storm sewer catch basins.
(iii) Identification of 100-year flood elevations and stream buffers.
(iv) Existing and proposed grades showing drainage on and adjacent to the site.
(v) Existing and proposed impervious surfaces.
(vi) Steep slopes where areas of 12 percent or more exist over a distance of 50 feet or more.
(vii) Location of all areas not to be disturbed during construction including trees, vegetation, and appropriate areas for infiltration.
(viii) Proposed grading or other land-disturbing activity including areas of grubbing, clearing, tree removal, grading, excavation, fill and other disturbance; areas of soil or earth material storage; quantities of soil or earth material to be removed, placed, stored or otherwise moved on site, and delineated limits of disturbance.
(ix) Locations of proposed runoff control, erosion prevention, sediment control, and temporary and permanent soil stabilization measures.
(2) Erosion and Sediment Control Plan or SWPPP Specifications. The erosion and sediment control plan or SWPPP shall include a specifications section that addresses and includes the following requirements that are applicable to the project:
(i) Stockpiles of soil or other materials subject to erosion by wind or water shall be covered, vegetated, enclosed, fenced on the down gradient side or otherwise effectively protected from erosion if the soil or material is stockpiled for more than seven calendar days. No stockpiling is allowed in the street.
(ii) To reduce soil compaction and enhance vegetation establishment, all compacted soil shall be tilled to a depth of at least six inches before revegetation.
(iii) Provide that all silt fences used for erosion and sedimentation control and all other temporary controls shall not be removed until 70 percent of the permanent ground cover has been established and all temporary erosion control shall be removed within 30 days thereafter.
(iv) Methods to prevent sediment damage to adjacent properties and sensitive environmental areas such as water bodies, plant communities, rare, threatened and/or endangered species habitat, wildlife corridors, greenways, etc.
(v) Design and construction methods to stabilize steep slopes.
(vi) Stabilization of all waterways and outlets.
(vii) Protection of storm sewer infrastructure from sediment loading or plugging.
(viii) Stabilization of disturbed areas, including utility construction areas, as soon as possible.
(ix) Protection of roads from sediment and mud from construction site activities.
(x) Disposal of collected sediment and floating debris.
(xi) Any mitigation measures required as a result of any review conducted for the project (e.g., stream buffer mitigation, etc.).
(3) Schedule of Events. A detailed schedule indicating dates and sequence of land alteration activities; implementation, maintenance and removal of erosion and sedimentation control measures; and permanent site stabilization measures shall be provided.
(4) Designation of Responsible Person. The erosion and sediment control plan or SWPPP must identify the person who will oversee the implementation of the erosion and sediment control plan and the installation, inspection and maintenance of the temporary and permanent erosion control measures.
(5) Monitoring, Reporting and Inspection. A detailed description of how erosion control, sediment control and soil stabilization measures implemented pursuant to the erosion and sediment control plan or SWPPP will be monitored, reported, maintained and removed. At a minimum, the erosion and sediment control plan or SWPPP shall provide for the following:
(i) During the construction season, the responsible party shall inspect the erosion and pollution control devices and complete the inspection and maintenance reports every seven days and within 24 hours of a precipitation event of one-half inch or more.
(ii) During inactive seasons, such as winter shutdowns, inspection of the site condition shall be made at least once a month. The devices shall be monitored at least daily during prolonged rainfall. Corrective action must begin within 48 hours of any deficiencies being found and must be completed within seven calendar days.
(iii) Each inspection report shall contain, at a minimum, the name of the responsible party, date of inspection, observations relative to the effectiveness of the erosion and pollution control measures, actions taken or necessary to correct deficiencies and areas where activities have been completed. Site inspection reports shall be maintained on site with the SWPPP or erosion control plans.
(6) Changes or Modification. The Utilities Director will require additional or modified information when there is a change in design, operation, maintenance, weather or seasonal conditions that have a significant effect on discharge, and/or inspections indicate that the erosion and sediment control plan is not effective and existing BMPs are not controlling pollutants and discharges from the site.
(e) SWPPP or Erosion and Sediment Control Plan Performance Standards and Design Criteria. All SWPPPs and erosion and sediment control plans shall be reviewed by the Utilities Director for effectiveness of erosion and sediment control measures in the context of the site topography and drainage. Proposed design, suggested location and phased implementation of effective, practicable stormwater pollution prevention measures for SWPPPs and erosion and sediment control plans shall be designed, engineered and implemented using the following performance standards and design criteria:
(1) Runoff Easements. If a stormwater management plan involves directing some or all runoff from the site, the responsible person shall obtain from adjacent property owners any necessary easements or other property interests concerning flowage of water.
(2) Scheduling Site Activities. The responsible person shall schedule site activities to lessen their impact on erosion and sediment creation.
(3) Minimize Exposed Soil. The responsible person shall minimize the amount of exposed soil. Mass grading should be avoided and sequencing promoted. At no time shall more than 20 acres be exposed.
(4) Perimeter Sediment Controls. Perimeter sediment control measures shall be properly installed by the builder before construction activity begins. Such structures may be adjusted during dry weather to accommodate short-term activities, such as those that require very large vehicles. As soon as this activity is finished or before rainfall, the erosion and sediment control structures must be returned to the configuration specified by the Utilities Director.
(5) Channel Protection. Channel protection measures will be required as set forth in the erosion control plan, SWPPP or as set forth in the applicable State or Federal regulation.
(6) Outlet Protection. Pipe outlets must have energy dissipation installed within 24 hours of connection to a surface water.
(7) Erosion and Sediment Control Methods.
(i) All disturbed areas shall be stabilized if it has not been worked for 14 days with temporary erosion protection or permanent cover.
(ii) If more than 10 acres are disturbed and drained to a single point of discharge, temporary sediment basins must be installed. When site restrictions do not allow for a temporary sediment basin, equivalent measures such as smaller basins, check dams, and vegetated buffer strips can be included.
(iii) For disturbed areas less than 10 acres, sedimentation basins are encouraged, but not required. The responsible person shall install erosion and sediment controls at locations directed by the Utilities Director. Minimum requirements include silt fences, rock check dams, or other equivalent control measures along slopes. Silt fences, rock check dams, etc., must be regularly inspected and maintained.
(8) Sediment Basins Related to Impervious Surface Area. Where a project’s ultimate development replaces surface vegetation with one or more cumulative acres of impervious surface, and all runoff has not been accounted for in the City of Topeka’s existing stormwater management plan or practice, runoff from the one-half-inch 24-hour storm event shall be treated unless discharge is to a special water where runoff from the one-inch 24-hour storm event shall be treated.
(9) Silt Fence. Silt fence shall be properly installed by being trenched and buried at least six inches into the soil. Generally, sufficient silt fence will be required to contain sheet flow runoff generated at an individual site.
(10) Stockpile Protections. For soil stockpiles greater than 10 cubic yards the toe of the pile must be more than 25 feet from a road, drainage channel or stormwater inlet. If left for more than seven days, erosion from stockpiles must be controlled with perimeter control devices such as silt fence. If the physical features on the site prevent stockpiling at least 25 feet from a road drainage channel or stormwater inlet, the Utilities Director may allow stockpiling within 25 feet, provided the stockpile must be controlled with perimeter control devices immediately.
(11) Vehicle Entrances. Temporary rock construction entrances must be installed and maintained wherever vehicles enter and exit a site. The design of this entrance shall take into consideration the amount of traffic that will be entering and exiting the site. Construction entrances shall be stabilized with at least two-inch clear aggregate or an approved equal as determined by the Utilities Director. On sites with high traffic, the Utilities Director may require wash racks, wash ponds or other means of minimizing sediment leaving the site.
(12) Street Cleaning. Streets shall be cleaned and swept within 24 hours whenever tracking of sediments occurs and before sites are left idle for weekends and holidays.
(13) Dewatering Treatment Required. Sediment-laden water that is being removed from the site by pumping or trenching shall be treated to remove a minimum of 80 percent of suspended solids before discharge. Water may not be discharged in a manner that causes erosion to receiving channels or flooding of the discharge site.
(14) Storm Drain Protection. All storm drain inlets shall be protected during construction with control measures as approved by the Utilities Director. These devices shall remain in place until final stabilization of the site. A regular inspection and maintenance plan shall be developed and implemented to assure these devices are operational at all times. Storm drain protection shall be removed and area inlet shall be cleaned of debris following site stabilization.
(f) Modification of Plan. The responsible person must amend the erosion control plan or SWPPP as necessary to include additional requirements such as additional or modified BMPs designed to correct problems identified or address situations whenever:
(1) A change in design, construction, operation, maintenance, weather, or seasonal conditions has a significant effect on the discharge of pollutants to surface waters or underground waters.
(2) Inspections indicate that the erosion control plan or SWPPP is not effective in eliminating or significantly minimizing the discharge of pollutants to surface waters or underground waters or that the discharges are causing water quality standard exceedances.
(3) The SWPPP is not achieving the general objectives of controlling pollutants or is not consistent with the terms and conditions of this permit. (Ord. 20089 § 106, 10-17-17.)
Cross References:Utilities Department, TMC 2.20.110.