Stormwater Management Updates
The City of Johnston’s Municipal Separate Storm Sewer System (MS4) permit includes an erosion and sediment control ordinance. In addition, a “post-construction” ordinance is included that addresses stormwater management of water quality and quantity. Amendments to the original ordinance were approved by the City Council in December 2007.
The following is a partial summary of the amendments:
- There is a $150 application fee for a Grading Permit that includes a Stormwater Pollution Prevention Plan (SWPPP) and/or Iowa DNR General Permit no. 2
- A $50 application fee has been established for a Grading Permit that includes a Stormwater Runoff Control Plan (cases in which the Iowa DNR General Permit no. 2 is not required, was discontinued, or a transfer of liability has occurred)
- The stormwater calculations must show evidence that stormwater detention and retention was considered in the original design (use of the Natural Resources Conservation Service WinTr-55 analysis is required for stormwater calculations);
- Stormwater best management practices that will be permanent facilities must be illustrated on the SWPPP or the Stormwater Runoff Control Plan and future management responsibilities documented
- Storm sewer intakes must be protected and maintained during construction;
- Regulations have been developed for concrete waste management on construction sites;
- Stream buffer regulations have been developed to help maintain and protect the existing streams;
- For more information, refer to the Iowa Stormwater Management Manual for design guidance on stormwater facilities and BMP’s. And, the City of Johnston hydrology map
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