Secondary and Cumulative Impacts Master Management Plan - 2014

SECTON 6 – MITIGATION FOR SECONDARY AND CUMULATIVE IMPACTS

that results from the first inch of precipitation from storm events, and to remove 85 percent of TSS from stormwater runoff using approved BMPs. These rules are addressed in the UDO’s stormwater Section 7. All new impervious areas within the Town are being tracked for future analysis. 6.2.5.5 Neuse River Basin: Nutrient Sensitive Waters Management Strategy (Neuse Basin Rules) The buffer requirements of the Neuse Basin Rules are met through the Town’s UDO. The Town was not named a community for stormwater controls in the Neuse Basin Rules but does implement these nitrogen control performance standards. The buffer component of the Neuse Basin Rules do apply though, and is met by the Town’s buffer requirements discussed previously in Section 6.2. Morrisville is one of only a few municipalities that has obtained delegation from NCDWR to locally implement the buffer rules. Cooperative efforts in the Neuse River Basin include the Regional Watershed Plan in the upper Neuse River Basin. This project, managed by EEP, encompasses 580 square miles across Wake and Johnston Counties, including the upper Middle Creek and Swift Creek Watersheds. The goal of this project is to identify and prioritize potential EEP mitigation projects in the Neuse 01 subwatershed. These projects may include traditional stream and wetland mitigation as well as buffer restoration; nutrient offset; urban stormwater and agricultural BMPs; regenerative stormwater conveyances; fish and aquatic organism passage; aquatic habitat improvements; removal of flow obstructions; and species habitats preservation or enhancement (NCDENR, 2013b) 6.2.5.6 Jordan Water Supply Nutrient Strategy (Jordan Lake Rules) The Town is subject to the Jordan Lake Rules, as required by the North Carolina General Assembly. Nitrogen and phosphorus loads contributed by the proposed new development will not exceed the following unit-area mass loading rates: 2.2 and 0.82 pounds per acre per year for nitrogen and phosphorus, respectively. The State has delayed implementation of the Jordan Rules regarding nutrient management until 2016. However, the Town voluntarily began implementing the Jordan new development stormwater rules in February, 2012 throughout the Town’s entire jurisdiction. This is discussed in the UDO (Section 7.3). The portion of the regulation relating to buffers was not put on hold and application of this portion has been voluntarily expanded Town-wide. Morrisville is one of only a few municipalities that has obtained delegation from NCDWR to locally implement the buffer rules. As part of the Jordan Lake Rules, the Town initiated the Jordan Lake Stage I Adaptive Management Strategy Program to address nutrient loading from existing development. In addition to the measures already in place as a result of the Town's NPDES Phase II permit, the Town is required annually to identify one potential stormwater BMP retrofit location in an existing development. NCDWR will determine in the future if the Town will be required to construct the BMP retrofits that were previously identified. In 2013, the Town had an assessment performed for Kit Creek watershed in order to determine potential mitigation opportunities. The assessment considered streams, buffers, and outfalls, with metrics evaluated including bank stability, sediment deposition, aquatic habitat, water quality and presence of invasive species (Stantec, 2013).

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