(a) All Erosion and Sediment Kept on Site. Erosion and sedimentation caused by accelerated wind or storm water runoff over the site due to earth disturbing activities shall be stabilized and confined to within the boundaries of the development site.
(b) Discharge of Untreated Storm Water. To the maximum extent practicable the site shall not discharge untreated storm water directly into a receiving body of water.
(c) Structural and Nonstructural Best Management Practices.
(1) Nonstructural storm water management practices shall be used to the maximum extent practicable. Such practices may include, but not be limited to, preserving riparian areas, preserving existing vegetation and vegetative buffer strips, phasing of construction, and designation of tree preservation areas.
(2) Nonstructural and structural storm water management practices shall be designed in accordance with requirements and standards specified in this chapter and/or by the authorized agent.
(3) Structural and nonstructural storm water management practices shall be placed in easements and recorded on the property deeds on which they are located and shall remain unaltered unless first approved by the City authorized agent.
(4) In designing storm water detention and retention facilities, water quality benefits shall be considered to the maximum extent practicable.
(d) Stream and Wetland Riparian Buffers. The site owner and/or applicant shall leave an undisturbed riparian buffer on both sides of and/or surrounding water resources, except for crossings and other riparian area and wetland impacts approved by the City authorized agent. Buffer width will be determined on a case by case basis using criteria such as floodplain, topography, vegetative cover, canopy cover, and soil types, etc.
(e) Channel Protection. To protect stream channels from degradation a specific channel protection criteria shall be provided as prescribed in the latest edition of Rainwater and Land Development.
(f) Temporary Stabilization of Disturbed Areas and Soil Stockpiles. A temporary vegetative cover shall be established on disturbed areas as specified in Table 1 below.
Table 1: Temporary Stabilization
Area requiring temporary stabilization | Time frame to apply erosion controls |
Any disturbed areas within 50 feet of a stream and not at final grade. | Within 2 days of the most recent disturbance if that area will remain idle for more than 21 days. |
For all construction activities, any disturbed area, including soil stockpiles, that will be dormant for more than 21 days but less than one year. | Within 7 days of the most recent disturbance within the area. |
Disturbed areas that will be idle over winter. | Prior to onset of winter weather. |
(1) Application practices include vegetative establishment, mulching, and the early application of gravel base on areas to be paved. Soil stabilization measures should be appropriate for the time of year, site conditions and estimated time of use.
(2) Topsoil removed shall be stored on site and shall be stabilized with quick growing plants or other means, so that it is protected from wind and water erosion. Topsoil shall be maintained in a usable condition for sustaining vegetation and reused on the site.
(g) Permanent Stabilization.
(1) A permanent vegetative cover shall be established on disturbed areas as specified in Table 2 below.
Table 2: Permanent Stabilization
Area requiring permanent stabilization | Time frame to apply erosion controls |
Any area that will lie dormant for 6 months or more. | Within 7 days of the most recent disturbance. |
Any area at final grade. | Within 7 days of reaching final grade within that area. |
(2) The following criteria shall apply to revegetation efforts:
A. Reseeding must be done with an annual or perennial cover crop accompanied by placement of straw mulch or its equivalent of sufficient coverage to control erosion until such time as the cover crop is established over 90 percent of the seeded area.
B. Replanting with native woody and herbaceous vegetation must be accompanied by placement of straw mulch or its equivalent of sufficient coverage to control erosion until the plantings are established and are capable of controlling erosion.
C. Any area of revegetation must exhibit survival of a minimum of 75 percent of the cover crop throughout the year immediately following revegetation. Revegetation must be repeated in successive years until the minimum 75 percent survival for one year is achieved.
D. Permanent vegetation shall not be considered established until a ground cover is achieved which is mature enough to control soil erosion and will survive severe weather conditions.
(h) Cut and Fill Slopes. Cut and fill slopes shall be designed, constructed and stabilized in a manner which will minimize erosion. Consideration should be given to the length and steepness of the slope, the soil type, upslope drainage area, groundwater conditions and other applicable factors. If after final grading excessive erosion takes place, additional slope stabilizing measures by the owner, developer or builder will be required until the problem is corrected. The following guidelines are provided to aid in developing an adequate design.
(1) Roughened soil surfaces are generally preferred to smooth surfaces on slopes.
(2) Diversions should be constructed at the top of long steep slopes which have significant drainage areas above the slope. Diversions or terraces may also be used to reduce slope length.
(3) Concentrated storm water should not be allowed to flow down cut or fill slopes unless contained within an adequate channel, flume or slope drain structure.
(4) Wherever a slope face crosses a water seepage plane which endangers the stability of the slope, adequate drainage or other protection should be provided.
(i) Protection of Adjacent Properties/Public Right-of-Ways. Properties, public right-of- ways, and thoroughfares adjacent to the site of an earth disturbing activity shall be protected from sediment deposition. This may be accomplished by preserving a well-vegetated buffer at the perimeter of the site, by installing perimeter controls such as sediment barriers, filters, dikes, sediment basins, or by a combination of such measures.
(j) Sediment Control Structures.
(1) Sediment control structures shall be used to control erosion and trap sediment on a site remaining disturbed for more than 14 days. Such structures may include, but are not limited to, silt fences, storm drain inlet protection, sediment basins and diversions or channels which direct runoff to a sediment basin. All sediment control practices must be capable of ponding runoff in order to be considered functional.
(2) Sediment control structures shall be constructed as a first step in grading and be made functional before upslope earth disturbing activities take place. Earthen structures such as dams, dikes, and diversions shall be seeded and mulched as soon as the installation is complete. Sediment control structures shall be functional throughout the course of earth disturbing activity and until the site is stabilized with permanent vegetation.
(3) Sheet flow runoff from the site shall be intercepted by silt fence or diversions. Silt fence shall be placed on a level contour and shall be capable of temporarily ponding runoff. The relationship between the maximum drainage area to silt fence for a particular slope range is shown in Table 3 below.
Table 3: Maximum Drainage Area to Silt Fence
Maximum drainage area (in acres) to 100 linear feet of silt fence | Range of slope for a particular drainage area (percent) |
0.5 | <2% |
0.25 | 2% but < 20% |
0.125 | 20% but < 50% |
(4) Storm water diversion practices shall be used to keep runoff away from disturbed areas and steep slopes. Such devices, which include swales, dikes or berms, may receive storm water runoff from areas up to ten acres.
(5) Whenever storm water detention is required the storm water runoff from the site shall pass through a sediment basin or other suitable sediment trapping facility before discharge to a receiving water body. The authorized agent(s) may require sediment basins or traps for smaller disturbed areas where deemed necessary.
(k) Stabilization of Waterways and Outlets. All on-site storm water conveyance channels shall be designed and constructed to withstand the expected velocity of flow without erosion. Methods adequate to prevent erosion shall also be provided at the outlets of all pipes and paved channels.
(l) Storm Sewer Inlet Protection. All storm sewer inlets shall be protected so that sediment-laden water will not enter the conveyance system without first being filtered or otherwise treated to remove sediment.
(m) Working in or Crossing Waters of the State.
(1) All activities shall be kept out of waters of the State to the extent possible. Where in-channel work is necessary, precautions shall be taken to stabilize the work area during construction to minimize erosion. The channel (including bed and banks) shall be restored to its original cross-section and all disturbed area stabilized immediately after in-channel work is completed.
(2) Where a water of the State will be crossed regularly during construction, a temporary stream crossing shall be provided, used for the shortest period practical, removed following site construction, and restored as described above.
(n) Maintenance and Removal of Temporary Measures.
(1) All temporary erosion and sediment control practices shall be maintained and repaired to assure continued performance.
(2) All temporary erosion and sediment control measures shall be removed within 30 days after final site stabilization is achieved or after the temporary measures are no longer needed. Trapped sediment and other disturbed soil areas resulting from the removal of temporary measures shall have the final grade re-established and be permanently stabilized to prevent further erosion and sedimentation.
(o) Control of Construction Site Debris and Wastes. All owners, applicants, contractors and developers shall control wastes such as discarded building materials, concrete truck washout, chemicals, litter, and sanitary waste on construction sites and shall keep streets and gutters clear of all sediment and debris from the site.
(p) Use, Safety, and Maintenance of Storm Water Practices.
(1) Storm water management practices shall be designed for the ultimate use of the site and function safely and with minimal maintenance.
(2) If an inspection reveals that a control practice is in need of repair or maintenance, with the exception of a sediment settling pond, it must be repaired or maintained within five days of the inspection. Sediment settling ponds must be repaired or maintained within ten days of the inspection.
(q) Inspection of Storm Water Controls. (See Section 1049.07(e) for specific requirements.)
(1) All on-site control practices shall be periodically inspected to ensure proper function and to identify failures. On- and off-site discharge locations shall be inspected to ascertain whether erosion and sediment control measures are effective in preventing significant impacts to the receiving waters.
(2) Detailed records of inspections shall be maintained for three years by the developer following the final stabilization of the site.
(r) Accessibility and Easements. (See Section 1049.07(c) for specific requirements.) All permanent storm water management measures shall have easements sufficient to cover the facility and to provide access for inspection and maintenance.
(s) Status of Standards. The standards identified in this section are general guidelines. Each application shall be reviewed on a case by case basis and some may require additional and more stringent requirements, while others may have individual requirements waived by the authorized agent.
(Ord. 5973. Passed 2-20-07.)