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HomeMy WebLinkAbout20070168 Ver 1_More Info Received_20080925MACTEC Engineering and Consulting 4 MA 1 T 13 Patton Avenue E Asheville, North Carolina Phone: (828) 252-8130 Fax: (828) 251-9690 LETTER OF TRANSMITTAL 01-01('08 TO: Mr. Ian McMillan DATE: 09/23/2008 NC Division of Water Quality MACTEC PROJECT NO.: 6229-05-2914; Task 15 2321 Crabtree Boulevard; Sv;k 250 PROJECT NAME: Grandview Peaks Raki?gh, NC 27604 SUBJECT: DWQ Alternative to Predictability Study (919) 715-4631 WE TRANSMIT TO YOU: ® HEREWITH ? UNDER SEPARATE COVER SUBJECT: ACTION: SENT BY: ?DRAWINGS ?FOR YOUR INFORMATION ?MAIL ?SPECIFICATIONS ®FOR YOUR COMMENT OR APPROVAL ?CERTIFIED MAIL ?CALCULATIONS ?RETURNED FOR CORRECTION: RESUBMIT ®EXPRESS FED ®REPORT ?APPROVED AS NOTED ?COURIER ?COST ESTIMATE ?AS REQUESTED ?HAND DELIVERED ?AS NOTED ?FACSIMILE: transmittal sheet COPIES DATE DESCRIPTION 1 09/23/08 Impoundments Watershed Modeling and Adaptive Management REMARKS: Please find attached one copy-On-site, Impoundments Watershed Modeling and Adaptive Management Plan. Should you have any questions, please contact Robert Sain at (828)-252-8130 or Allen Conger (803)-798-1200 FohR HR?61!2'161 `- S E P s/ .5 2008 r~?k . vgxr GI;AU IY S' C1ftl?..t1iTri'6 CC: Todd Black; Fall Creek Land Company Cyndi Karoly; DWQ; Raleigh Headquarters Kevin Barnett, DWQ, Asheville Field Office Amanda Jones, USACE, Asheville Regulatory Field By: 12_ L <-"' -a- Robert L. Sain Direct Phone: (828) 252-8130 CONFIDENTIALITY NOTICE: This message is intended only for the use of the individual or entity to which it is addressed, and may contain information that is privileged, confidential, and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, or the employee or agent responsible for delivering the message to the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by telephone and return the original message to us at the above address via the U.S. Postal Service. Thank you. If transmission is not received in good order, please call Tracy Effler at (828) 252-8130 Docvment5 Form Revised 10/78/02 MACTEC engineering and constructing a better tomorrow September 23, 2008 Ms. Cyndi Karoly N.C. Division of Water Quality 401 Oversight/ Express Review Permitting Unit 1650 Mail Service Center Raleigh, North Carolina 27699 FRI? 1 S?.P 1 2`0 Subject: The Grandview Peaks Development On-site Impoundments Modeling and Adaptive Management Plan USACE Action ID: 2007-200-359 DWQ Project # 07-0168 McDowell County, North Carolina MACTEC Project No. 6229052914 Dear Ms. Karoly: MACTEC Engineering and Consulting, Inc. (MACTEC), on behalf of the applicant, the Fall Creek Land Company (FCLC), would like to address Division of Water Quality (DWQ)'s request for a watershed modeling plan; request made during a meeting at the DWQ, Raleigh office July 21, 2008 (see Attachment A). The purpose of this document is to present a scientifically valid watershed modeling plan, to accomplish the goal of preserving water quality. We would appreciate your timely review of this information and your written response regarding the acceptability of this modified procedure for the required analyses. cc: Todd Black, Fall Creek Land Company Amanda Jones, Asheville Regulatory Field Office, USACE Ion McMillan, Raleigh Headquarters, DWQ Kevin Barnett, Asheville Regional Office, DWQ MACTEC Engineering and Consulting, Inc. 1308 Patton Avenue • Asheville, NC 28806 • Phone: 828.252.8 130 9 Fax: 828.25 1.9690 www.mactec.com Project Overview: The Fall Creek Land Company's (FCLC) "Grandview Peaks (GP)" development contains 54,392 linear feet of jurisdictional, perennial, and intermittent stream channels. The north-western portion of the property contains two networks of unnamed tributary streams that drain to Hopper's Creek. The FCLC plans to impound these unnamed, tributary stream systems to create small reservoir lakes (27.1 acre and a 6.8 acre). Both lakes are down gradient from existing development activity and are the most feasible location on the property-having the right combination of drainage area, perennial stream flow, constricted valleys (see Figure 1). Both proposed impoundment(s) will be located in the upper Catawba River Basin (HUC 03050101; sub basin 03-08-30) within the Northern Inner Piedmont Ecoregion. Background Information: A list of project milestones has been provided in Appendix A. The DWQ recently (March 2008) came out with an analytical monitoring protocol to predict how water quality will affect future impoundment(s) (March 2008, Predictability Study Protocol for Sampling Reference Impoundment(s) NCDWQ, 2008). These guidelines currently state that applicants wishing to build new impoundment(s) conduct rigorous monitoring of two "similar, existing" lakes as reference for what to expect. The Fall Creek Land Company (FCLC) provided an altemative to the DWQ's guidelines on July 8, 2008; FCLC proposing a stand-a-lone procedure for predicting water quality, on-site. The GP alternative procedure uses watershed loading analyses consistent with the currently accepted and recommended DWQ lakes modeling procedures. The GP alternative procedure will ensure that appropriate BMPs are in place to establish and maintain impoundment(s) water quality. Purpose: During a meeting held on July 21, 2008 to discuss the project, MACTEC provided a modified monitoring plan, and the DWQ requested to see a draft of the Fall Creek Land Company's, proposed watershed modeling and adaptive management plan for the proposed reservoirs. The plans initial step required on-site assessment of existing water quality prior to development of the two proposed lakes. Pre-development existing water quality, can be used to set baseline parameters which the Fall Creek Land Company (FCLC) may use to set target threshold indicators for water quality for after the lakes have been created. The Draft Grandview Peaks Lakes watershed modeling and adaptive management plan is outlined as follows. Grandview Lakes Monitoring Plan September 23, 2008 McDowell Lakes Development Site, McDowell County, North Carolina MACTEC Project No. 6229052914 2 ? r.?. 111 f ?-. ?g r Lake #3 Down stream Y Sampling Station °-? Lake #2 Down stream i 4" ' Sampling Statio GP-L3-D1 -- --- - n ' { GP-L2-D1 - i ?•t,,`? { ,'. I ?) 1 ?,??- Lake #2 Up stream Sampling Station ! "?"< - ~ A GP-L2-U1 H Sko s ` ' reek Mt w , Lake #3 Up stream Sampling Station G -L3-U1 y: ? Lake #2 Up stream Lake Sampling Station Sam GP L2 U2 #2 Up stream pling Station f; . L - - GP-L 2-U3 own Ce Y 1 , f I 0 '17 V, Y -, 3I6 1y Mc Lowkadoa v n5. y , Creek i f.. LEGEND Streams 0 0.25 0.5 0.75 1 Miles Property Boundary F ? eet r Proposed Lake Boundaries 0 1,250 2,500 3.750 5,000 Source: USDA DRG Mosaic for McDowell Co., North Carolina 2007 SAMPLIN GRANDVIEW PEAKS DEVELOPMENT G LOCATIONS FOR PROPOSED LAKES #2 AND #3 MACTEC MCDOWELL COUNTY, NORTH CAROLINA PREPARED r SJM PATE 09/12/08 CHECKED By RLS DATE 09/12108 JOB NUMBER 6229-05-2914 FIGURE 1 I. Watershed Modeling A detailed watershed model will be developed to quantify loading contributions from both upstream portions of the watershed as well as changes to water quality loading parameters that are anticipated (in the absence of appropriate BMPS) with the development of low-density residential housing on site. Estimates of annual nutrient contributions entering via runoff from the residential community will be determined by identifying sub-basin drainage areas within the watershed. Watershed sub-basin delineation will be performed by incorporating aerial photographs of the site, topographic contours, and proposed conveyance structures within the community into a GIS platform for analysis. Calculation of annual runoff volumes and associated loading from the identified sub-basins will incorporate the following information into the watershed model: A. Precipitation Precipitation data will be collected from several local rain gauge stations near the proposed development. Multiple years of daily rainfall data, up to a maximum of 10 years, will be used in the model to most accurately reflect weather variations from drought, normal, and significant storm event rainfall periods. B. Watershed Characteristics Determination of surface water runoff during an individual rain event requires a known amount of precipitation falling on the project site as well as generated runoff curve numbers (CN). To determine the CN for the project area, land use type and hydrologic soil group values will be defined using Geographic Information Systems (GIS). Land use within the project area will incorporate the proposed residential development and newly constructed reservoirs to reflect future loading characteristics following the completion of construction. Interconnected Pond Routing Stormwater (ICPR) or similar modeling platform will be used to incorporate existing and proposed conveyance systems within the watershed. Using the predetermined curve numbers and regional precipitation data as inputs to the ICPR model, annual runoff volumes will be calculated for each sub-basin area within the watershed. Results of the Grandview Lakes Monitoring Plan September 23, 2008 McDowell Lakes Development Site, McDowell County, North Carolina MACTEC Project No. 6229052914 3 ICPR model will provide accurate estimates of annual sub-basin runoff volumes based on changing land use and conveyance systems anticipated with the proposed development. Runoff volumes calculated within the watershed model will be used to estimate the annual nutrient load entering the proposed reservoirs via the project site. Nutrient loads are estimated by multiplying the annual runoff volume by the event mean concentration (EMC). EMCs are established for specific parameters of interest (TSS, TN and TP for this analysis) and vary by land use. Proposed BMPs developed during construction may also be incorporated into the annual loading estimates by identifying the portion of stormwater runoff treated through a given BMP. Characterization of existing water quality in several streams within the watershed was completed to provide an assessment of baseline water quality conditions and upstream loading contributions. Water quality monitoring was performed at six sampling stations in flowing portions of upstream tributaries. Based on field observations, one of the possible locations entering proposed impoundment(s) was found to be an intermittent stream, and did not have adequate flow for sampling. Five stations were sampled on August 6, 2008 within "the hottest period of the year" between the August 1st and August 30th. The five stations included sample locations in two sub- watersheds; the proposed Lake#2 impoundment(s) and the proposed Lake#3 impoundment(s) (see Figure 1). • Station GP-L2-U 1: Downstream of confluence at the dendriditic tributary split. • Station GP-L2-U2: Located 105 stream meters up stream of gravel road (wet crossing). • Station GP-L2-U3: Located approx 80 meters up stream of culvert at gravel road. • Station GP-L2-D1: Located in run section, just upstream of large bedrock pool. 30 meters up stream of waterfall section. • Station GP-L3-U1: Located 30 meters north of gravel road. • Station GP-L3-D1: Located 20 meters downstream of flag line for dam. Water sampling protocols adhered to the requirements described in the Predictability Study Protocol for Sampling Reference Impoundment(s) (NCDWQ, 2008). Water quality parameters measured included water temperature, dissolved oxygen saturation, pH, turbidity, nutrients (total phosphorus, total Kjeldahl nitrogen, ammonia [NH3], nitrate + nitrite [NO2+NO31), chlorophyll-a (corrected for pheophytin), and fecal coliform. Grandview Lakes Monitoring Plan September 23, 2008 McDowell Lakes Development Site, McDowell County, North Carolina MACTEC Project No. 6229052914 4 Water Quality results for August 6, 2008 monitoring data provided in Table 1. Table 1: Draft On-site results; August 6, 2008. Grandview Peaks / MACTEC Water Quality sampling (August 6, 2008) prelim results. On-Site Meter A-I,hi-I I ah Proposed Lake #2 Proposed Lake #3 Stream Monitoring Parameters GP-L24U7 GP-L2-U2 GP-L2-U3 GP-L2-01 GP-L3-U1 GP4.3-01 8.09 8.5 7.95 7.9 n/a 8.04 Conduct' ' mS 2.2 0.39 0.036 0.05 n/a 0.03 Dissotwed qnSen (mgIL 10.7 9.8 10.6 10.2 n/a 10.24 Temperature (degrees C 21.6 21.4 21.4 21.1 n/a 22.2 Safi ' 0.00 0.00 0.00 0.00 n/a 0.00 Fecal Coliforms CFU/ 100mL SM 9222D 112 12 152 304 n/a 104 Turbidity (NTtJ) EPA 180.1 16 2.6 4.2 13 n/a 5.7 Total Suspended Solid (mg/L) SM 2540D 34 40.3 8 7.3 n/a 19.3 Ammonia m L EPA 350.1 nd nd nd nd n/a rid Nitrogen N02 plus N03 m L EPA 353.2 0.02 0.09 0.08 0.17 n/a 0.04 TKN m L EPA 351.2 0.54 0.36 0.57 0.55 n/a 0.41 Total Nitrogen EPA 353.2 0.55 0.45 0.66 0.73 n/a 0.45 Total Phosphorus (mg/L) (EPA 365.1) 0.028 0.015 0.006 0.016 nla 0.012 Estimated Gradient (%) 1.8 3 to 6.8 4 0.7 n/a 0.3 Wetted Width of stream ft 1.9 3.5 3.2 3.5 n/a 2.5 Max Depth of stream ft 0.9 0.3 0.28 0.65 n/a 0.14 Location GPS see ma see ma see ma see ma see ma see ma Weather description sunny sunny sunny sunny sunny sunny Air Temperature (degrees C 32 32.6 31.6 32 33 33.5 Comments pink fla in pink flagging pink flagging ink flagging no water pink flagging Created By: RLS, Sept, 2008 Checked By: ABS, Sept, 2008 This recent surface water monitoring data will be used to establish baseline water quality conditions within local streams and upstream tributaries, and will serve as a target for future stream water quality following construction. Existing water quality measurements recorded in the streams will be incorporated into the watershed model to provide a benchmark for current water quality conditions, which may then be compared to subsequent stream water quality following residential construction. Baseline water quality data provided in Table 1 will be used in the watershed model to develop loading estimates from contributing (upstream) portions of the watersheds. Results of the loading estimates from the surrounding watershed will then be combined with the measured nitrogen, phosphorus, and TSS load from these tributaries to determine a total annual load for the impoundment(s). Estimates of the annual nutrient load within each reservoir may then be used to determine appropriate Best Management Practices (BMPs) to eliminate the incremental loading difference associated with the construction of the residential community. Grandview Lakes Monitoring Plan September 23, 2008 McDowell Lakes Development Site, McDowell County, North Carolina MACTEC Project No. 6229052914 5 Best Management Practices (BMPs) will be selected to account for loading entering through additional residential development, as determined in the watershed model. If the results of the watershed model determine that additional BMPs are needed, BMP selection and design criteria will be guided using the North Carolina Division of Water Quality Stormwater Best Management Practices Manual (NCDWQ, 2007). A number of BMP design options may be chosen to capture excess runoff prior to entering local streams or the proposed impoundment(s), including, but not limited to: a. Dry retention basins; b. Wet detention basins; c. Stormwater wetlands; d. Bio-retention; e. Infiltration devices; and f. Grassed swales (etc.) Emphasis will be given to BMPs that are considered Low Impact Development (LID) and sustainable for preservation of water quality and quantity. A number of LID alternatives for stormwater management are available, including, but not limited to: a. Minimizing impervious area; b. Rainwater harvesting; c. Incorporating permeable surfaces; d. Depression storage; and e. Soil filtration To ensure that portions of each tributary below the impoundments are not negatively impacted by the construction of the proposed impoundment(s), out flowing water quality may also be preserved through best management practices within each impoundment(s). These practices are likely to focus on temperature, dissolved oxygen and related constituents, and may include conditions of management of water withdrawal from the impoundment(s), among other factors. BMP design and implementation will utilize watershed loading estimates, upstream and downstream surface water monitoring, and examples from similar impoundment(s) within the regional area as guidance for managing water quality exiting the impoundment(s). BMPs within Grandview Lakes Monitoring Plan September 23, 2008 McDowell Lakes Development Site, McDowell County, North Carolina MACTEC Project No. 6229052914 6 the impoundment(s) will be designed and implemented, if necessary, to ensure that water quality flowing downstream of the impoundment(s) is similar to the water quality of upstream tributaries. II. Adaptive Management Plan The purpose of an adaptive management plan is to provide for flexible management of the proposed reservoirs, based upon a feedback loop so that management strategies are adjusted to address changing field conditions, to maintain downstream water quality. Watershed BMPs are anticipated to be sufficient to maintain nutrient loading at current levels. Impoundment of the water will, however, potentially cause changes in surficial water temperature during summer months. Primary water quality indicator of the physical affects of impoundment may be captured by measuring temperature and dissolved oxygen at the surface and at depth during summer. It is anticipated that during seasons where water temperatures in the stream are similar to surficial impoundment temperatures (spring, winter, and fall), surficial water may be gravity fed over a spillway or other conveyance, to the stream. When the need arises (e.g. when the temperature and/or DO differential from upstream and impoundment require action), water for downstream replenishment will be pulled from cooler, deeper waters of the impoundment, and oxygenated, if necessary. These parameters (temperature and DO) provide a quick and reliable method of assessing water quality within the reservoir. Reports of impoundment(s) water quality may be provided to the NC DWQ 401 Oversight Unit as requested. This adaptive management plan focuses on the preservation of water quality both within the constructed impoundment(s) and in downstream creeks. This management follows existing recommendations from USEPA and the North American Lake Management Society. Existing water quality conditions as sampled prior to construction may be used as baseline standards for the preservation of water quality within downstream creeks. Select BMPs as described in Section I also are anticipated to be utilized to ensure preservation of baseline and state water quality standards. Grandview Lakes Monitoring Plan September 23, 2008 McDowell Lakes Development Site, McDowell County, North Carolina MACTEC Project No. 6229052914 7 References: EPA, 2000. Ambient Water Quality Criteria Recommendations. Lakes and reservoirs in Nutrient Ecoregion IX. United States Environmental Protection Agency. EPA 822-13-00-011. December 2000 NC DENR - Division of Water Quality "Redbook" Surface Waters and Wetlands Standards NC Administrative Code 15A NCAC 02B .0100, .0200 & .0300 Amended Effective: May 1, 2007; Raleigh, North Carolina: htttp://l12o.enr.state.ne.us/admin/rules/documents/redbook Imavtl7 full with cover ndf' Closing The Fall Creek Land Company appreciates your timely review of our response to your request to see a Watershed Modeling and Adaptive Management Plan for the Grandview Peaks Development. Sincerely, MACTEC ENGINEERING AND CONSULTING, INC. D.4" 12- Z. Robert L. Sain, CFM for auk &h (Vrk? Ann Blhortelle, PHD Project Scientist with permission Limnologist/ Chief Scientist Grandview Lakes Monitoring Plan September 23, 2008 McDowell Lakes Development Site, McDowell County, North Carolina MACTEC Project No. 6229052914 8 Recent Project Milestones: January 16, 2007: The FCLC submitted a combined "Individual 404/401 Permit application" to the USACE and DWQ. September 25, 2007: The USACE, DWQ commenting agencies, and public came back with public notice comments to be addressed. FCLC's "Response to Pubic Notice Comments" was submitted to the USACE and NC DWQ. September 2007 through January 2008: consistent efforts were made by the Fall Creek Land Company to contact regulators while the waiting for responses. January 4, 2008: The USACE responded, informally with an email dated. January 10, 2008: A site meeting occurred with Ms. Amanda Jones, Asheville field office of the USACE. January 23, 2008: The DWQ responded formally to the "Response to Public Notice Comments" with a letter stating that the application was "incomplete" pending analytical monitoring (Attachment A). February 6, 2008: a follow-up office meeting took place with the USACE-the USACE informally requested additional information. This additional information was submitted to the USACE, Asheville Field Office on June 24, 2008. February 2008 through June 2008: various correspondences took place between the Fall Creek Land Company and regulators while drafting additional response documents to address concerns and new protocols. June 23, 2008: a brief follow-up meeting took place with the USACE to discuss the draft Additional Comments Response document. June 24, 2008: The FCLC Draft - USACE Additional Comments Response document was submitted to the USACE and copied to the DWQ. July 8, 2008: the FCLC, On-Site Impoundment(s)s Sampling Protocol document was submitted to the DWQ and copied to the USACE July 21 2008: A meeting took place in Raleigh at the DWQ headquarters to discuss the FCLC sampling protocol document and the project status. Action to the FCLC to capture, on-site, August water quality and to carryon with the FCLC proposed sampling protocol. August 6, 2008: Per the DWQ meeting, the FCLC conducted in-situ and analytical on-site sampling at five locations adjacent to the proposed lakes. August 29, 2008: On-Site Grandview Peaks, analytical sampling data results back from labs. Grandview Lakes Monitoring Plan September 23, 2008 McDowell Lakes Development Site, McDowell County, North Carolina MACTEC Project No. 6229052914 2