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HomeMy WebLinkAbout20160715 Ver 1_More Info Received_20160922 Homewood, Sue From:Mark Romulus <marksromulus@outlook.com> Sent:Thursday, September 22, 2016 7:25 AM To:Homewood, Sue Subject:Peace Haven Village Responses-WQC Attachments:Lewisville-Clemmons-Avoidance and Minimization Response - Fnl.pdf; Lewisville-Clemmons WQC Comment _5 Response - Fnl.pdf Good morning Sue: Attached are the responses to Comments 4 & 5..I assume your have received the responses to Comments 1-3 that I sent you.. Mark Romulus 1 Avoidance and Minimization Statement Proposed Peace Haven Village Clemmons, Forsyth County, North Carolina 1. Background In response to Comment #4 from the North Carolina Department of Environmental Quality, Division of Water Resources (see below), Lewisville-Clemmons Road Realty, LLC (i.e. applicant) has prepared the following response. "Please provide more details regarding avoidance and minimization of the impacts for this project. This should include alternative layouts which may reduce impacts to the intermittent streams and wetlands within the project boundary." [15A NCAC 02H .0506 (f)] As requested, the applicant has provided three (3) separate alternative concepts previously reviewed and accessed for engineering suitability and economic viability. Potential environmental impacts as related to avoidance and minimization strategies are clearly noted in the descriptions presented below. Alternative Concept A (i.e. Original Plan) �� a w.wna impacts aaasrn- Site Data Kev Constraints Ke�OppOrtunipes�M vw�' ea num S�treemBWellarid Imcacts Peace Haven Villaae Predminary Concept {OnjrA IPcW Sthyng 2, MimN! Original Plan: Shows full build -out to maximize use of all available developable space. Key opportunities include: 1) meets the Village's roadway connection requirement, 2) significantly increases financial value, and 3) adequately meets parking code. But in terms of least damaging alternative to the environment, this alternative further significantly impacts the streams as compared to eventually -approved site plan (i.e. Approved Plan). By maximizing the overall development, proposed stream impacts are increased by 64%, to a maximum of 440 LF. All of site wetland area (i.e. 810 square feet) would also be impacted. Alternative Concept B (i.e. Avoidance & Minimization Plan) Site Data a„m°L%°"' ,� a . '�4/ � �.,. �, ��� 'tr� .� Kev Constrolnase.P s r PN.— Hev Rae 5 "j w • i - U c SStraamMetland Imnacts �• �• . wen.m imwca , Peace Haven � I Pmfimin ry Concept � I � -�f l fs� m&H41a;Mavadancel � 1 summed ...qty ^, Avoidance and Minimization Plan: In reacting to potential environmental concerns associated with Alternative Concept A, site designers prepared a concept that avoids all impacts to on-site wetlands and streams. Thus, this alternative is the most practicable and least damaging to the environment. Key opportunities of this alternative include: 1) meets the Village's roadway connection requirement, and 2) avoids stream & wetland impacts. However, in terms of site constraints, Alternative Concept B reduces the overall use of site area, significantly rendering the property's economic viability. Key constraints for Alternative Concept B include: 1) does not meet parking space count requirements per Village of Clemmons ordinance or Publix, 2) shifts site access points closer to the intersection at Peace Haven and Lewisville-Clemmons Roads, 3) significantly reduces available retail / restaurant space, 4) reduces number of Outparcels than can be developed, 5) Future Development to the southwest cannot be served by the Stormwater Management Pond / BMP due to elevations and location, and 6) not economically viable. Alternative Concept C (i.e. Approved Plan) — _ i - --- -- � - Ker Const�inis ' -.. /��r hrr � `•..' Kev Onpurtunitiss 1. -_ - -- _ _ rre eHeveltasd... .r• �,r-Il; '•�re ��....��..,m.� �" Stream&Wetland lm c Waeand 1m W } — ' Peace Haven stri Imw b a ,i —••�•• ��546 LF .1. — ` � 1. , VIIIaa2 aw, 19 n e11 Prellminary Concept stlmmrel BF—M 1 Approved Plan: As a compromise, Alternative Concept C (i.e. Approved Plan) was drafted. Although this alternative is not the most practicable and least damaging to the environment, it more effectively balances the needs of the site development, with the known environmental constraints. The key opportunities of this alternative include: 1) meets the Village's roadway connection requirement, 2) significantly increase financial value, and 3) adequately meets parking code. This concept plan appealed to local planning authorities and was approved during the rezoning process for the proposed development. Stream impacts were reduced down from 440 LF, as proposed in the preliminary concept, to 146 LF. This represents a significant decrease, thus allowing viable stream habitat to remain. Wetland impacts are similar (i.e. 810 square feet). While Alternative Concept C (as noted above) legitimately minimizes impacts to on-site streams, this concept also provides well for economic viability while adequately meeting necessary requirements for roadway connectivity, parking code and provides stormwater management for the entire proposed development and outparcels. Summary Lewisville-Clemmons Road Reality LLC, as the Section 401 applicant, has adequately presented above its alternative analysis as it pertains to considerations of avoidance and minimization of potential impacts to on-site natural resources. �3, Primarily due to significant identifiable on-site constraints mentioned above such as: 1) appropriate future storm -water management facilitation, 2) meeting parking code requirements, and 3) overall necessary economic viability, the applicant has concluded that Alternative Concept C (i.e. Approved Plan) best represents the most responsible approach to avoiding and minimizing potential impacts to on-site jurisdictional wetlands and waters of the state. 5. Pursuant to 15A NCAC 02K 0506(a), a water quality certification may only be issued upon determining that existing uses are not removed or degraded by a discharge to classified surface waters. Based on the information provided in the application and associated documents, all surface flow from the project is proposed to be rerouted through a storm -water wet weather detention basin. The outlet from the wet detention basin is proposed to be located a significant distance downstream. The rerouting of the drainage area and surface flow has the potential to remove existing hydrology and therefore remove existing uses within the stream channels from impact limits to the proposed storm -water outlet location. Please provide any additional information relative to this issue for further review by the Division. Response: According to a hydrologic analysis conducted by the site civil engineer, the following tables below summarize watershed drainage area and pre -development and post -development peak flowrates to each of the 3 streams (i.e. West, East, and Mid). Analysis points were evaluated at the property line where each stream discharges off-site. Peak flowrates were calculated for the 1 -year & 2 -year return events based on SCS 6 -hr storm distribution model using Hydraflow Hydrographs software. Pre -and Post -Development Watershed Areas Stream Pre - Development Area Estimated Post Development Area Predicted Percent Change West 19.90 ac 0.52 ac 97% East 29.92 ac 21.80 ac 27% Mid 1.01 ac 0.41 ac 59% Pre -and Post -Development Predicted Flow Rates Stream Pre -Development Flow Rate (1 & 2 r) Estimated Post Development Flow Rate (1 & 2 r) Predicted Percent Change West 1.499 cfs/4.126 cfs 0.017 cfs/0.050 cfs 99%/99% East 6.489 cfs/10.40 cfs 4.934 cfs/7.191 cfs 24%/31% Mid 0.231 cfs/0.412 cfs 0.012 cfs/0.030 cfs 95%/93% In summary, the East stream has the largest watershed contribution (drawing flows collected from the eastside of Lewisville-Clemmons Road) and the lowest percentage of predicted change in watershed area and flowrates. As a result, the applicant feels the overall impact to uses associated with the East stream will be minimal, and most likely will remain the same. The West and Mid streams will have the greatest predicted watershed area and flowrate reduction due to impacts directly associated with the proposed shopping center development. Furthermore, hydrologic flow patterns are already set by the presence of existing roadway culverts near the Lewisville Clemmons and South Peace Haven intersection, and the lower Lewisville-Clemmons Road crossing. The predicted result in these streams is that uses will be fully impacted by significant changes to the hydrologic regime resulting from re-routing storm -water to the southernmost parcel and the off-site. Thus, in conclusion, it is this discussion above that supports the applicants proposed 146 linear feet of stream impact, thus need for a Section 401 WQC. Environmental Discussion: Upon walking the three (3) streams noted above on several different occasions and over four (4) different seasons, in terms of existing ecological habitat very little or even no aquatic fauna, macrobenthos, or macrophytes were observed in either the ephemeral or intermittent portions of these systems. In addition, no amphibians, mussels, nor freshwater crustaceans were noted in the perennial portion of these streams. During two (2) site visits where storm events had occurred, flows in these streams were observed not to be flash and not constant. As there is very little grade change, in -stream features such as riffles, pools, and gravel bars are essentially non-existent. As these streams formed over the last several decades from incision and transport related to primarily overland flows, in terms of ecological function and value, habitat opportunity, connection to a relic floodplain, and groundwater recharge, it appears that each of these three (3) streams is having a very limited ecological impact within the watershed. As a result, the applicant is of the opinion (in an overall ecological sense) that the proposed development longterm is going to have a minimal adverse impact on other more significant resources occurring within the Blanket Creek Watershed. Brief Summary of Engineering & Design: A wet detention pond (Best Management Practice / BMP) was designed for the site development in accordance with NCDEQ BMP Manual to meet the Village of Clemmons watershed protection and stormwater management requirements per the Unified Development Ordinance. The Village of Clemmons requires peak discharge control of the 2-, 10-, & 25 -year storm events from pre- to post -development conditions. Volume control is required for the 25 -year storm event. The BMP was located to best fit the site as described above and to provide stormwater quality and quantity treatment to the entire site, including all outparcels. The outlet control structure and discharge point from the pond were located to avoid short-circuiting of the BMP (i.e. to provide proper quality treatment and settlement time) and to avoid potential impact to the existing detention pond south of the site. Existing runoff from the site is conveyed via the three (3) existing subject streams which combine and discharge into an existing pipe system just south of the site. The existing pipe system bypasses runoff around the existing detention pond utilized by the adjacent properties to the south. The pipe system and existing detention pond then discharge to a point just downstream of the existing pond. The proposed wet detention pond discharges to the same point where the existing detention pond and pipe system conveying the subject streams currently discharge. This maintains the overall drainage patterns of the site and adjacent properties from this point. With the understanding that peak flowrates are only detained by the proposed pond up to the 25 -year storm event, it is not desirable to discharge runoff from the proposed pond into the existing pond or the existing pipe system. We do not anticipate that these systems were adequately designed to handle larger storm events such as the 100 -year storm event. Therefore, we propose the wet detention pond discharge to the same point as the outlets of the existing detention pond and existing pipe system. Note, as part of the adjacent Village Point Drive project (by others), runoff from the existing detention pond, existing pipe system, and proposed wet detention pond will be combined and conveyed via new stormwater piping below the proposed Village Point Drive and will discharge into the existing stream south of Village Point Drive.