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Article 6: Development Standards <br /> Section 6.14: Stormwater Management <br /> <br /> <br />Orange County, North Carolina – Unified Development Ordinance Page 6-98 <br /> <br />(3) No net increase in peak flow leaving the site from the predevelopment conditions <br />for the 1-year, 24-hour storm, 4 <br />(4)(3) Stormwater systems shall be designed to control and treat, at a minimum, the <br />stormwater runoff generated by one inch of rainfall from all project area surfaces. <br />The treatment volume shall be drawn down pursuant to standards specific to <br />each practice as determined by the current version of the NC DWQ DEQ <br />stormwater design manual. <br />(5)(4) New development that would exceed the nutrient loading rates set out in <br />subsection (A)(2) aboveherein, shall include engineered stormwater controls <br />designed to have a minimum of 85% average annual removal for Total <br />Suspended Solids (TSS) a Primary and/or Secondary Stormwater Control <br />Measure (SCM) per NCDEQ requirements.5 <br />(6)(5) Proposed new development may satisfy the review criteria standards of this <br />section by meeting the post-development hydrologic criteria set out in in the most <br />recent version of the North Carolina Low Impact Development Guidebook. <br />(B) Additional Standards – Falls Lake Watershed <br />(1) In addition to the standards contained in Section 6.14.6 (A) of the UDO, <br />development shall observe a no net increase in peak flow leaving the site from <br />predevelopment conditions for the 1 year, 24 hours, storm.6 <br />(C) Additional Standards – Jordan Lake Watershed <br />(1) In addition to the standards contained in Section 6.14.6 (A) of the UDO, <br />development shall abide by 15 A NCAC 02H.1002 (44). 7 <br />6.14.7 Nutrient Load <br />(A) Nitrogen and phosphorus loads contributed by proposed new development shall not <br />exceed the following unit-area mass loading rates: <br />(1) Falls Lake Watershed <br />(a) Nitrogen, 2.2 pounds per acre per year <br />(b) Phosphorus, 0.33 pounds per acre per year <br />(2) Jordan Lake Watershed8 <br />(a) Upper New Hope Creek Arm <br />(i) Nitrogen, 2.2 pounds per acre per year <br />(ii) Phosphorus, 0.82 pounds per acre per year <br />(b) Haw River Arm <br /> <br />4 Given recent changes in State law, this provision is only applicable in the Falls Lake Watershed.  Existing language  <br />is being moved to ensure consistency with applicable State standards.  <br />5 Change in language to reflect regulatory changes as codified in NC Administrative Code (NCAC) 15A NCAC 02H  <br />.1002 (37) and 15A NCAC 02H .1002 (46).  <br />6 This language is currently contained in Section 6.14.6 (A)(3) of the UDO.  As a result of recent changes in State law  <br />it now only has applicability for parcels located within the Falls Lake Watershed.  The proposed amendment is  <br />intended to address this change.  <br />7 This is commonly referred to as the ‘10% Rule’ which allows for a 10% of less increase in peak stormwater runoff  <br />between pre and post development conditions for a parcel.  Staff is recommending a specific reference to the  <br />applicable portion of the NCAC as part of this revision.  <br />8 As previously indicated in order to ensure consistency with State standards, staff is recommending the  <br />elimination of existing regulations designed to address water quality/nutrient reduction within the Jordan Lake  <br />Watershed.  Staff can only address these issues within the Falls Lake Watershed based on current State law.  <br /> 8