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HomeMy WebLinkAboutAgenda - 06-27-2006-5eeORANGE COUNTY BOARD OF COMMISSIONERS ACTION AGENDA ITEM ABSTRACT Meeting Date: .June 27, 2006 Action Agenda Item No. ~-~~..~. SUBJECT: Amendments to the Orange County Stormwater Ordinance for Lands within the Neuse River Basin DEPARTMENT: Planning and Inspections ATTACHMENT(S): 1. Required Amendments to Orange County Stormwater Ordinance PUBLIC HEARING: (Y/N) No INFORMATION CONTACT: Craig Benedict, Planning Director, 245-2592 Ren Ivins, Erosion Control Supervisor, 245- 2586 PURPOSE: To incorporate amendments in the Orange County Stormwater Ordinance to conform to requirements of the North Carolina Department of Environment and Natural Resources (DENR) for counties within the Neuse and Tar-Pamlico River Basins. BACKGROUND: To protect water quality at the local level and provide a higher level of service to citizens and clients, Orange County adopted the State's model stormwater ordinance in March 2001. The title of the ordinance as adopted is, "Stormwater Ordinance for Lands within the Neuse River Basin". The Neuse basin covers most of northern Orange County including the Town of Hillsborough. The Neuse Basin does not include the Chapel Hill/Carrboro area which lies in the Cape Fear River Basin. Hillsborough, which is now under a NPDES Phase II permit, is required to take additional actions as its permit action plan identifies. Orange County Sedimentation and Erasion Control is contracted to help the Town of Hillsborough in many aspects. In year three of the project, the Town of Hillsborough has planned to include "Nutrient Export Reduction Options", but it may request that it be implemented earlier as part of the annual contract work plan. Control of nitrogen runoff, or export, from development projects is a key feature of the program. The Stormwater Ordinance provides Nutrient Export Reduction Options for residential or commercial development contributing mare than 3.6 Ibs/ac/yr of nitrogen, The options include installation of best management practices (BMPs); a one-time offset payment of $330/Ib; or a combination of BMPs and offset payments. Recognizing that costs do not remain static, the State removed the $330 one-time payment (effective March 1, 2006) and inserted a nitrogen offset payment formula to be adjusted annually based on the construction cost index factor published each December in the Engineering News Record. Additionally, the name of the program to which offset payments are directed was changed from the Wetlands Restoration Program (W RP) to the North Carolina Ecosystem Enhancement Program (NCEEP). The Nutrient Export Reduction Options (NERO) part of the program is an aspect of the overall land disturbance permit. The Erosion Control Division evaluates the design, verifies the NERO method, and forwards the compensation payment to the DENR Division of Water Quality for use in Orange County restoration projects as part of the NCEEP program. Presently, the Erosion Control Division and Natural Resources Conservation Service (NRCS) staffs are looking for sites to retrofit to improve water quality, manage peak flow, and ameliorate overall erosion issues. The amendments referenced above are contained in Attachment 1 with deletions shown in held sEriket#reugl~ and additions in bold underline. Orange County's Stormwater Ordinance is taken directly from the State's model ordinance and the amendments likewise originate at the State level. Given the state-to-local transfer of amendments, staff does not envision the need for a public hearing as would be the case with Orange County's zoning ordinance or subdivision regulations. FINANCIAL IMPACT: As the Board may recall, this overall stormwater program was delegated to Orange County by the State. The program in Orange County's portion of the Neuse River Basin is partially funded by developer fees. Existing Erosion control staff is currently implementing and administering the program. RECOMMENDATION(S): The Administration recommends incorporation of the amendments into the Orange County Stormwater Ordinance far Lands within the Neuse River Basin consistent with State requirements. Amendments to the Orange County Stonnwater Ordinance Apri12006 NOTE: The underlined text will be added to the Ordinance and the struck-through text will be deleted. The attached Stormwater Ordinance amendments conform to requirements by the North Carolina Department of Environment and Natural Resources made effective as of March 1, 2006 for counties within the Neuse and Tar-Pamlico River Basins. Section 6 Nutrient Load Calculations For the purpose of this Ordinance new development shall be defined by as to include the following: Any activity that disturbs greater than one acre of land in order to establish, expand or modify a single family or duplex residential development or a recreational facility. Any activity that disturbs greater than one-half an acre of land in order to establish, expand, or modify a multifamily residential development or' a commercial, industrial or institutional facility. New development shall not include agriculture, mining, or forestry activities. Land disturbing activity is defined as grubbing, stump removal, and/or grading. A. The nitrogen export from each new development must be calculated. This export will be calculated in pounds per acre per year (Ibs/ac/yr). The two methodologies that are to be used are as follows. 1. Method 1 This method is intended for use where lots are shown but the actual footprint of buildings are not shown on site plans. This method does not require calculation of the area of building footprints. Rather, the impervious surface resulting from building footprints is estimated based on typical impervious areas associated with a given lot size. This method is shown in Appendix 1. 2. Method 2 This method is for residential, commercial, and industrial development when the entire footprint of the roads, parking lots, buildings, and any other built-upon area is shown on the site plans. This method is simpler and more accurate since it does not require estimating the impervious surface based on lot size, Method 2 is shown in Appendix 2. a) If anon-residential subdivision plan is submitted without impervious surfaces not shown, the following two options are 4 available: (1) Option A Property owner must specify the areas of impervious surface, undisturbed open space and managed open space on the property in a restrictive covenant. Method 2 would then be applied.. (2) Option B Planning staff will determine aworst-case scenario for the areas of impervious surface and managed open space for the type of development specified.. Method 2 would then be applied. B. Nutrient Export Figures Calculations must be in accordance with either Method 1 or' 2 shown in Appendix 1 and 2, respectively, of this Ordinance. C, Nutrient Export Reduction Options If calculations show that the development will contribute greater than 3.61bs/ac/yr of nitrogen, then the options shown below are available. Residential Development a) If the calculated nitrogen export is less than 6.0 ]bs/ac/yr, then the owner may: (1) Install BMPs specified in Section 8 to reduce nitrogen export amounts to 3.61bs/ac/yr. (2) Pay aone-time offset payment-e€$338Nh. This offset fee will go to the North Carolina Ecosystem Enhancement Program NCEEP .The ~Vl+<~'- NCEEP will utilize these fees in accordance with the Basinwide Wetlands and Riparian Restoration plans. It is the policy of the ~I~I'-NCEEP to utilize the funds where they are generated to the maximum extent possible. (.3) A combination of BMPs and offset payments maybe used to achieve 3.61bs/ac/yr. b) If the calculated export is greater than C.0 Ibs/ac/yr, the owner must use on-site BMPs to lower the nitrogen export to 6,0 Ibs/ac/yr, The owner may then use one of the above options to achieve a nitrogen export level of.3.6 Ibs/ac/yr. 2. Convnercial and Industrial a) If the calculated export is less than 10.0 lbs/ac/yr, then the owner may: (1) Install BMPs specified in Section 8 to reduce nitrogen export amounts to 3.6 lbs/ac/yr.. (2) Pay aone-time offset payment-ef-X33©N{~. This offset fee will go to the~etlarrcls-Iieste~atien-I§-egr-nrn-(~VItt'-) North Carolina Ecosystem Enhancement Program NCEEP .The WRI'- NCEEP will utilize these fees in accordance with the Basinwide Wetlands and Riparian Restoration plans. It is the policy of the ~1~1? NCEEP to utilize the funds where they are generated to the maximum extent possible. (.3) A combination of BMPs and offset payments maybe used to achieve.3.6 Ibs/ac/yr. b) If the calculated export is greater than 10.0 lbs/ac/yr, the owner must use BMPs to lower the nitrogen export to 10.01bs/ac/yr. The owner may then use one of the above options to achieve a nitrogen export level of.3.61bs/ac/yr. D. Calculating Peak Runoff Volume For all new development, there shall be no net increase in peak flow leaving the site from the predevelopment conditions for the 1 year, 24 hour storm, 1. The following are acceptable methodologies for computing the pre- andpost- development conditions for the 1 year, 24 hour storm.. a) Rational Method b) Peak Discharge Method as described in the USDA Soil Conservation Service's Technical Release Number 55 (TR-55). c) Putnam Method d) Alternative methods must be approved by the County and the EMC 2. The same method must be used for both the pre- and post- development conditions. Raleigh Rainfall Depths a) 1 year, 24 hour depth: 3.00 inches b) 1 year, 24 hour intensity: under development by DWQ staff E. Exemptions to the Peak Flow Requirements Peak flow requirements are waived for development that meets the following criteria: 1. Increase in peak flow between pre- and post- development conditions does not exceed 10% (ten percent). 2. Proposed new development meets all of the following criteria: a) total impervious surface is less than 15% (fifteen percent), and b) remaining pervious surface maximizes storrnwater runoff control and conveyance.. 3. Detention will cause further flooding on lands that have experience 6 flooding during previous storm events. Ihis request for exemption must be prepared by a North Carolina registered professional engineer and submitted in writing to the Planning Director or Designee. Appeals of this decision will follow Section 7-E of this Ordinance.. Appendix 2 Table 2a: Nitrogen Export Reduction Options Residential Commercial /Industrial If the computed exportrs less than 6.0 If the computed export is less than 10..0 Ibs/ac/yr, then the owner may either: lbs/ac/yr, then the owner may either: 1. Install BMPs to remove enough nihogen I, Install BMPs to remove enough nitrogen to to bring the development down to 3.6 bring the development down to 3.6 ]bs/ac/yr, lbs/ac/yr. 2.. Pay aone-time offset payment ef-$3~OfFb 2. Pay aone-time offset payment ef-$338NH to bring the nitrogen down to the 3.6 to bring the nifrogen down to the 3.6 Ibs/ac/yr. lbs/ac/yr. 3. Do a combination of BMPs and offset 3. Do a combination of BMPs and offset payment to achieve a .3.61bs/ac/yr export, payment to achieve a 3.61bs/ac/yr export.. If the computed export is greater than 6,0 If the computed export is greater than 10.0 Ibs/ac/yr, then the owner must use on-site ]bs/ac/yr, then the owner must use on-site BMPs to bring the development's export BMPs to bring the development's export down down to 6,0 Ibs/ac/yr. Then, the owner may to 10,0 Ibs/ac/yr. Then, the owner may use one use one of the three options above to achieve of'the three options above to achieve the the reduction between 6.0 and 3.6 lbs/ac/yr. reduction between 10.0 and 3.6 Ibs/ac/yr. The table above discusses the option of using offset fees to meet the nitrogen export levels set for new development activities, These offset fees go to the N.C. Ecosystem Enhancement Progranl-{€or•••v'r:y-t::~ ~*'~•-.,-~~1:.~.a-s-P°~tor-:TRo°',~-~'-:-a^e-;~ N( CEEP1. The P~~-1'-NCEEP will utilize these fees in accordance with the Basinwide Wetlands and Riparian Restoration plans. It is the policy of the TE-I'-NCEEP to utilize the funds where they are generated to the maximum extent possible as long as they can obtain the cooperation of the local government. To calculate the total amount of offset payment, use the following formula: offset-I'ay r:.ent - fredttetion-"!o-rtryu9re,r~ r'T1 r r..~~ «zn .,..~ r«,.«..r ,. ,..,s} reduetien %o - ~r,v ,. ....« nti.,i.,,,i.,,.~ z.~ r *Nitrogen Offset Payment = ((557 / Ib) x (# of Ibs / Year) x (30 years) + (Land Cost 5 / Ac) x (1 Ac / 35 Ac) x fDevel. in Ac)1 x (1.1 Ad Costs) *This factor will be adjusted annually based anon the construction cost index factor published each December in the Engineering News 12ecord. Where: lbs /year represents the amount of nutrient exported or discharged per year for which mitigation is being requested; Land Cost $ / Ac represents current property value in dollars per acre of the property being developed, based on the most recent tax assessment; 1 Ac / 35 Ac ~°epresents an adjustment factor indicating that one acre of mitigation is required for every 35 acres of development and 1.1 Ad Costs represents an adjustment factor to cover administrative cost associated with the requested mitigation. 7