<div class="chunk-title">Sec. 14-155. - Design and performance standards.</div>
<div class="chunk-content">
            <p class="incr0">
               (a)
               </p>
            		
            <p class="content1">
               Durham County has been included in the Falls Lake Nutrient Management Strategy and
               Neuse River Sensitive Waters Management Strategy. Accordingly, all developments and
               redevelopment to which this article applies shall comply with the standards of this
               section and of the current official North Carolina Division of Environmental Quality
               New Stormwater Design Manual. New development and redevelopment within the Durham
               County unincorporated limits must comply with the following:
               </p>
            		
            <p class="incr1">
               (1)
               </p>
            		
            <p class="content2">
               Runoff treatment or runoff volume match according to density calculations per subsection
               <a href="" data-chunk-id="COOR_CH14EN_ARTVST_DIV1STMA_S14-155DEPEST" class="section-link" data-product-id="12650">14-155</a>(a) and exemptions,
               </p>
            		
            <p class="incr1">
               (2)
               </p>
            		
            <p class="content2">
               Nutrient loading reduction per subsection <a href="" data-chunk-id="COOR_CH14EN_ARTVST_DIV1STMA_S14-155DEPEST" class="section-link" data-product-id="12650">14-155</a>(b),
               </p>
            		
            <p class="incr1">
               (3)
               </p>
            		
            <p class="content2">
               Riparian buffer areas must be protected and maintained per subsection <a href="" data-chunk-id="COOR_CH14EN_ARTVST_DIV1STMA_S14-155DEPEST" class="section-link" data-product-id="12650">14-155</a>(e),
               </p>
            		
            <p class="incr1">
               (4)
               </p>
            		
            <p class="content2">
               Stormwater systems shall be designed to control and treat at a minimum the runoff
               generated from all surfaces in the project area by one inch of rainfall,
               </p>
            		
            <p class="incr1">
               (5)
               </p>
            		
            <p class="content2">
               Total suspended solids (TSS) requirements per subsection <a href="" data-chunk-id="COOR_CH14EN_ARTVST_DIV1STMA_S14-153ENAD" class="section-link" data-product-id="12650">14-153</a>(f).
               </p>
            		
            <p class="incr0">
               (b)
               </p>
            		
            <p class="content1">
               <span class="ital">Runoff treatment and volume match.</span> For purposes of applying the runoff treatment and volume match requirements for the
               one-year storm, the land cover (including type and location) that existed as of March
               9, 2001 for land in the Falls Basin and Lower Neuse Basin, and as of March 17, 2009
               for land in the Jordan Basin shall be considered the "pre-development conditions."
               </p>
            		
            <p class="incr1">
               (1)
               </p>
            		
            <p class="content2">
               <span class="ital">Applicability.</span> Runoff treatment and volume match requirements are applicable to all developments
               that meet the following condition(s):
               </p>
            		
            <p class="incr2">
               a.
               </p>
            		
            <p class="content3">
               Increase in impervious area on any lot subject to limitations on impervious area in
               an approved plat or plan for reasons such as watershed protection or stormwater control
               measure requirements;
               </p>
            		
            <p class="incr2">
               b.
               </p>
            		
            <p class="content3">
               Increase of more than 500 square feet in impervious area on a detached and duplex
               residential development, recreational, commercial, industrial or institutional;
               </p>
            		
            <p class="incr2">
               c.
               </p>
            		
            <p class="content3">
               Increase of more than 2,000 square feet of impervious area on a single-family, detached
               and duplex residential development or a recreational facility;
               </p>
            		
            <p class="incr2">
               d.
               </p>
            		
            <p class="content3">
               Inclusive of an existing or proposed SCM (stormwater control measure) requiring:
               </p>
            		
            <p class="incr3">
               1.
               </p>
            		
            <p class="content4">
               Changes to the drainage area of an existing SCM; or
               </p>
            		
            <p class="incr3">
               2.
               </p>
            		
            <p class="content4">
               Change to the size, grades or outlet structure of an existing SCM.
               </p>
            		
            <p class="incr1">
               (2)
               </p>
            		
            <p class="content2">
               <span class="ital">Requirements.</span>
               </p>
            		
            <p class="incr2">
               a.
               </p>
            		
            <p class="content3">
               Low density projects shall not exceed the low density development thresholds set forth
               in the stormwater programs to which they are subject pursuant to Rules 15A NCAC 02H.1017,
               .1019, and .1021.
               </p>
            		
            <p class="incr2">
               b.
               </p>
            		
            <p class="content3">
               High density projects SCMs shall be designed, constructed, and maintained so that
               the project achieves either "runoff treatment" or "runoff volume match" per 15A NCAC
               02H.1003.
               </p>
            		
            <p class="incr2">
               c.
               </p>
            		
            <p class="content3">
               The same methodology must be used for calculating both the pre- and post-development
               flow rates. Approved calculation methodologies include:
               </p>
            		
            <p class="incr3">
               1.
               </p>
            		
            <p class="content4">
               Rational method.
               </p>
            		
            <p class="incr3">
               2.
               </p>
            		
            <p class="content4">
               Peak discharge method as described in the USDA Soil Conservation Service's Technical
               Release Number 55 (TR-55).
               </p>
            		
            <p class="incr3">
               3.
               </p>
            		
            <p class="content4">
               Alternative peak flow calculation methods must be approved by the county at the time
               of site plan submittal.
               </p>
            		
            <p class="incr2">
               d.
               </p>
            		
            <p class="content3">
               Stormwater outlets shall be designed so that they do not cause erosion downslope of
               the discharge point during the peak flow from the ten-year storm event as shown by
               engineering calculations.
               </p>
            		
            <p class="incr0">
               (c)
               </p>
            		
            <p class="content1">
               <span class="ital">Nutrient loading.</span>
               </p>
            		
            <p class="incr1">
               (1)
               </p>
            		
            <p class="content2">
               <span class="ital">Applicability.</span>
               </p>
            		
            <p class="incr2">
               a.
               </p>
            		
            <p class="content3">
               Properties located within the Falls Lake Drainage Basin, are exempt from nutrient
               requirements when:
               </p>
            		
            <p class="incr3">
               1.
               </p>
            		
            <p class="content4">
               Disturbs less than one-half acre of land in order to establish, expand, or modify
               a single-family, detached and duplex residential development or a recreational facility;
               or
               </p>
            		
            <p class="incr3">
               2.
               </p>
            		
            <p class="content4">
               Disturbs less than 12,000 square feet of land in order to establish, expand, or modify
               a multifamily residential development or a commercial, industrial, or institutional
               facility.
               </p>
            		
            <p class="incr2">
               b.
               </p>
            		
            <p class="content3">
               Nutrient requirements apply to properties located within the Neuse River Basin but
               outside of the Falls Lake Drainage Basin, are exempt from nutrient requirements when:
               </p>
            		
            <p class="incr3">
               1.
               </p>
            		
            <p class="content4">
               Projects disturbing less than:
               </p>
            		
            <p class="incr4">
               i.
               </p>
            		
            <p class="content5">
               One acre for single-family and duplex residential property and recreational facilities;
               or
               </p>
            		
            <p class="incr4">
               ii.
               </p>
            		
            <p class="content5">
               One-half acre for commercial, industrial, institutional, multifamily residential,
               or local government land uses with the following exception.
               </p>
            		
            <p class="incr2">
               b.
               </p>
            		
            <p class="content3">
               Projects below one-half acre that would replace or expand existing structures on a
               parcel, resulting in a cumulative built-upon area for the parcel exceeding 24 percent,
               shall be subject to item (5) of this rule:
               </p>
            		
            <p class="incr3">
               1.
               </p>
            		
            <p class="content4">
               Development of an individual single-family or duplex residential lot that:
               </p>
            		
            <p class="incr4">
               i.
               </p>
            		
            <p class="content5">
               Is not part of a larger common plan of development or sale as defined in 15A NCAC
               02H.1002; and
               </p>
            		
            <p class="incr4">
               ii.
               </p>
            		
            <p class="content5">
               Does not result in greater than five percent built upon area on the lot.
               </p>
            		
            <p class="incr3">
               2.
               </p>
            		
            <p class="content4">
               Existing development as defined in 15A NCAC 02H.1002;
               </p>
            		
            <p class="incr3">
               3.
               </p>
            		
            <p class="content4">
               Redevelopment as defined in G.S. 143-214.7(al)(2); and
               </p>
            		
            <p class="incr1">
               (2)
               </p>
            		
            <p class="content2">
               <span class="ital">Requirements.</span>
               </p>
            		
            <p class="incr2">
               a.
               </p>
            		
            <p class="content3">
               Nitrogen and phosphorous loads contributed by proposed new development shall not exceed
               the following unit-area mass loading rates:
               </p>
            		
            <p class="incr3">
               1.
               </p>
            		
            <p class="content4">
               <span class="ital">Falls Lake Watershed.</span>
               </p>
            		
            <p class="incr4">
               i.
               </p>
            		
            <p class="content5">
               Nitrogen: 2.2 lb/ac/yr.
               </p>
            		
            <p class="incr4">
               ii.
               </p>
            		
            <p class="content5">
               Phosphorous: 0.33 lb/ac/yr.
               </p>
            		
            <p class="incr3">
               2.
               </p>
            		
            <p class="content4">
               <span class="ital">Neuse River Basin (Outside of the Falls Lake Watershed).</span>
               </p>
            		
            <p class="incr4">
               i.
               </p>
            		
            <p class="content5">
               Nitrogen: 3.6 lb/ac/yr or runoff volume match.
               </p>
            		
            <p class="incr2">
               b.
               </p>
            		
            <p class="content3">
               The developer shall determine the need for engineered stormwater controls to meet
               these loading rate targets by using the most recent Nutrient Accounting Tool approved
               by the North Carolina Environmental Management Commission.
               </p>
            		
            <p class="incr0">
               (d)
               </p>
            		
            <p class="content1">
               <span class="ital">Total suspended solids.</span> Developments within the Cape Fear River Basin shall plan for, and implement, stormwater
               management controls designed to have a minimum of 85 percent average annual removal
               for total suspended solids (TSS).
               </p>
            		
            <p class="incr0">
               (e)
               </p>
            		
            <p class="content1">
               <span class="ital">Offset payments.</span>
               </p>
            		
            <p class="incr1">
               (1)
               </p>
            		
            <p class="content2">
               Developers subject to this article may achieve additional reductions in nitrogen and
               phosphorous loading required by this article by making offset payments to the NC Ecosystem
               Enhancement Program contingent upon acceptance of payments by that program.
               </p>
            		
            <p class="incr1">
               (2)
               </p>
            		
            <p class="content2">
               <span class="ital">Falls Lake Watershed.</span> Developers who desire to pursue off-site reduction measures for developments subject
               to this article shall attain nitrogen and phosphorus loading rate reductions on-site
               that meet the following criteria prior to using an offset measure:
               </p>
            		
            <p class="incr2">
               a.
               </p>
            		
            <p class="content3">
               Thirty percent or more reduction in both nitrogen and phosphorus loading from the
               untreated conditions for any single-family, detached and duplex residential development
               disturbing one-half acre but less than one acre.
               </p>
            		
            <p class="incr2">
               b.
               </p>
            		
            <p class="content3">
               Fifty percent or more reduction in both nitrogen and phosphorus loading from the untreated
               conditions for any single-family, detached and duplex residential development disturbing
               more than one acre.
               </p>
            		
            <p class="incr2">
               c.
               </p>
            		
            <p class="content3">
               Thirty percent or more reduction in both nitrogen and phosphorus loading from the
               untreated condition for other development, including multi-family residential, commercial,
               and industrial development disturbing 12,000 square feet but less than one acre.
               </p>
            		
            <p class="incr2">
               d.
               </p>
            		
            <p class="content3">
               Fifty percent or more reduction in both nitrogen and phosphorus loading from the untreated
               condition for other development, including multi-family residential, commercial and
               industrial development disturbing more than one acre.
               </p>
            		
            <p class="incr2">
               e.
               </p>
            		
            <p class="content3">
               Thirty percent or more reduction in both nitrogen and phosphorus loading from the
               untreated condition for proposed redevelopment activities in a designated downtown
               area that would replace or expand structures or improvements that existed as of December
               2006.
               </p>
            		
            <p class="incr2">
               f.
               </p>
            		
            <p class="content3">
               Notwithstanding 15A NCAC 2B.0282, redevelopment subject to this article that would
               replace or expand existing structures or improvements and would result in a net increase
               in built-upon area shall have the option of either meeting a loading standards identified
               in subsection (a) or meeting a loading rate that achieves the following nutrient loads
               compared to the existing development: 40 percent and 77 percent reduction for nitrogen
               and phosphorous, respectively.
               </p>
            		
            <p class="incr1">
               (3)
               </p>
            		
            <p class="content2">
               <span class="ital">Neuse River Basin (Outside the Falls Lake Watershed).</span> Developers who have obtained an offset by participation in the North Carolina Wetland
               Restoration Fund established by the North Carolina Department of Environment and Natural
               Resources, shall plan for and implement management controls which will limit the nitrogen
               load of runoff from the site to:
               </p>
            		
            <p class="incr2">
               a.
               </p>
            		
            <p class="content3">
               Six pounds per acre per year for single-family, detached and duplex residential development.
               </p>
            		
            <p class="incr2">
               b.
               </p>
            		
            <p class="content3">
               Ten pounds per acre per year for other development including commercial, industrial,
               and multi-family residential.
               </p>
            		
            <p class="incr0">
               (f)
               </p>
            		
            <p class="content1">
               <span class="ital">Riparian buffers.</span>
               </p>
            		
            <p class="incr1">
               (1)
               </p>
            		
            <p class="content2">
               <span class="ital">Neuse River Basin.</span> Plans for developments shall protect and maintain existing riparian areas in accordance
               with 15A N.C.A.C. 02B.0610, .0612, .0714, which is hereby incorporated by reference
               as well as the requirements of the Durham City-County Unified Development Ordinance.
               Consistent with the requirements of 15A N.C.A.C 2B.0233, no developments shall be
               approved which are proposed within the first 50 feet adjacent to a waterbody that
               is shown on the most recent version of either the U.S.G.S. 7Â½-Minute Quadrangle Topographic
               Map or the U.S.D.A. Soil Survey of Durham County, North Carolina, unless the developer
               can demonstrate to the county engineer, or designee's satisfaction that the North
               Carolina Department of Environment and Natural Resources/Division of Water Quality
               has approved the development.
               </p>
            		
            <p class="incr1">
               (2)
               </p>
            		
            <p class="content2">
               <span class="ital">Cape Fear River Basin.</span>
               </p>
            		
            <p class="incr2">
               a.
               </p>
            		
            <p class="content3">
               Plans for developments shall protect and maintain existing riparian areas in accordance
               with 15A N.C.A.C. 2B.0233 which is hereby incorporated by reference, as well as the
               requirements of the Durham City-County Unified Development Ordinance. Consistent with
               the requirements of 15A N.C.A.C. 2B.0267, no developments shall be approved which
               are proposed within the first 50 feet adjacent to a waterbody that is shown on the
               most recent version of either the U.S.G.S. 7Â½-Minute Quadrangle Topographic Map or
               the U.S.D.A. Soil Survey of Durham County, North Carolina, unless the developer can
               demonstrate to the County Engineer, or designee's satisfaction that the North Carolina
               Department of Environment and Natural Resources/Division of Water Quality has approved
               the development.
               </p>
            		
            <p class="incr2">
               b.
               </p>
            		
            <p class="content3">
               Notwithstanding the foregoing, developments may be approved within the first 50 feet
               adjacent to a waterbody that is shown on the most recent version of either the U.S.G.S.
               7Â½-Minute Quadrangle Topographic Map or the version U.S.D.A. Soil Survey of Durham
               County, North Carolina provided:
               </p>
            		
            <p class="incr3">
               1.
               </p>
            		
            <p class="content4">
               For streams, a stream delineation is performed by a member of Durham County staff
               to determine the presence and location of waters of the county if requested by applicant.
               Staff will have completed the North Carolina Division of Water Resources Surface Water
               Identification Training and Certification Course. The determination between a perennial
               and intermittent stream is based on a combination of hydrological, physical and biological
               characteristics of the stream. Stream determinations are made using a standardized
               methodology developed by the North Carolina Department of Environmental Quality. The
               current version is 4.11 effective September 1, 2010. Any person requesting a stream
               delineation to be performed shall fill out an application and pay a fee to cover the
               cost of said delineation in an amount as determined by the board of commissioners.
               Aerials of the stream shown on the most recent version of the U.S.G.S. 7Â½-minute Quadrangle
               Topographic Map and the U.S.D.A. Soil Survey of Durham County shall be submitted with
               the application.
               </p>
            		
            <p class="incr3">
               2.
               </p>
            		
            <p class="content4">
               For ponds and lakes, that the ponds or lakes are manmade and are located outside natural
               drainage ways.
               </p>
            		
            <p class="historynote0">
               (Ord. of 11-23-20(3))
               </p></div>