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Erosion Prevention and Sediment Control Plan Narrative for Individual Discharge Permit for Stormwater Runoff from Construction Sites
GREEN MOUNTAIN POWER KINGDOM COMMUNITY WIND PROJECT
Lowell, Vermont
Prepared for
Prepared by
Green Mountain Power Corporation Vanasse Hangen Brustlin, Inc.
7056 U.S. Route 7 North Ferrisburgh, VT 05473 November 12, 2010
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Table of Contents
1.0 Introduction ............................................................................................................................. 1 2.0 Project Description .................................................................................................................. 2 3.0 Location Map ......................................................................................................................... 10 4.0 Preconstruction, Construction, and Stabilization Plan .................................................... 10 References ..................................................................................................................................... 11
GREEN MOUNTAIN POWER CORPORATION / KINGDOM COMMUNITY WIND EROSION PREVENTION AND SEDIMENT CONTROL PLAN NARRATIVE
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1
Introduction
On behalf of the applicant, Green Mountain Power Corporation, this Erosion Prevention and Sediment Control (EPSC) Plan narrative and EPSC Plan Summary Forms prepared by Vanasse Hangen Brustlin, Inc. (VHB) and associated EPSC Plan sheets, details, and notes prepared by VHB and Krebs and Lansing Consulting Engineers, Inc. (Krebs and Lansing) comprise an application for the planned construction of the Kingdom Community Wind Project located in the Town of Lowell, Orleans County, Vermont.1 For the purpose of this application filing, the project area comprises the following major project components, as shown on the Site Map on the cover sheet of the EPSC Plan. 1. Wind farm site, including the access road, crane paths, laydown/staging areas, substation, O&M building, and turbine pads 2. Underground collector lines 3. Overhead collector lines 4. Operational phase stormwater management system2 Separate construction stormwater discharge permit applications will be filed with the VT Department of Environmental Conservation (VT DEC) for the transmission line upgrade project and the Jay Tap substation project given that there are different applicants for these other projects and, therefore, they are not considered to be part of the Kingdom Community Wind project. Completion of the Risk Evaluation determined that the Kingdom Community Wind Project is not eligible for coverage under General
A petition for Section 248 approval of the Kingdom Community Wind Project from the Vermont Public Service Board (VT PSB) was filed on May 21, 2010 and is currently pending. 2 An application for an Individual Stormwater Discharge Permit (INDS) for the Kingdom Community Wind Project was filed with VT DEC on September 21, 2010; pending VT DEC review and approval. 1
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Permit 3‐9020 as a Moderate Risk construction activity (see pages 1 through 3 of the Appendix). Therefore, the project seeks construction stormwater discharge authorization from the VT DEC through the issuance of Individual Discharge Permit for Stormwater Runoff from Construction Sites. This EPSC Plan Narrative and the associated EPSC Plan (attached separately) have been prepared in conformance with the most recent edition of The Vermont Standards and Specifications for Erosion Prevention and Sediment Control (2006). The EPSC Plan Summary Forms have been included on pages 4 through 14 of the Appendix.
2.0
Project Description
The EPSC Plan has been prepared using General Permit 3‐9020, Part 4.1(C) and Appendix B of the General Permit 3‐9020, as guidance (in the absence of guidance that is specific to Individual Permit applications). The following sections (a) through (m) of this narrative address required EPSC Plan Narrative elements in the order that they are presented in Appendix B of General Permit 3‐9020. a. Project Type and Description The Kingdom Community Wind Project is a high elevation renewable energy project comprising twenty‐one 2.5 to 3.0 MW turbines, associated turbine pads, an 18‐foot wide gravel and/or stone access road that extends approximately 2.5 miles from Route 100 to the ridgeline, 34‐foot wide gravel and/or stone crane paths extending approximately 4.0 miles along the ridgeline, laydown/staging areas, an O&M building, an electrical substation, underground and overhead collector lines, and a permanent stormwater management system. In addition to the permanent access road and crane paths, the project will temporarily utilize an existing road (Meek Road / Town Highway 25) during
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the initial construction period in order to transport construction equipment, workmen, fuel, etc. to the site. b. Major Project Components As outlined in the Introduction, major project components consist of the wind farm, including the access road, crane paths, laydown/staging areas, substation, O&M building, and turbine pads; underground collector lines; overhead collector lines; and the operational phase stormwater management system. An overview of the general approach to construction and stabilization of these major project components is provided below, with more detailed sequencing provided in the Construction and Stabilization Sequence on pages 16 through 22 of the Appendix. Wind Farm and Underground Collector Lines Sequencing Construction of the wind farm and underground collector lines will be conducted with four separate earthwork crews. In addition to each separate earthwork crew, there will be several specialized sub‐crews supporting the earthwork crews, which will be attending to the different, orderly and repetitive, construction activities (such as survey layout, tree cutting, blasting, erosion control, etc.). Each earthwork crew foreman will be the On‐Site Plan Coordinator (OSPC) and will inspect, monitor and coordinate all earthwork crew and sub‐crew activities to ensure performance in accordance with the EPSC Plan requirements of site stabilization and drainage work (e.g., redirecting of upslope run‐on) whenever and wherever it may be required. These four work earthwork crews will conduct construction activities concurrently within each of their designated work areas (see Illustrative Sequencing Concept Map on EPSC Plan Sheet C‐ 134). For any one individual earthwork crew, transition from one work area to the next will be in the orderly sequencing of the construction activities performed by the earthwork crew and the support sub‐crews. It is proposed for any one individual earthwork crew working in one or more of the designated work crew areas that the total
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allowable area of non‐stabilized exposed earth surfaces be limited to 7.5 acres at any one time. This limiting requirement of each separate earthwork crew could translate to a maximum total for all four earthwork crews, of 30 acres of concurrent non‐stabilized exposed earth surfaces at any one time. Transition from one work area to the next will be coordinated with the earthwork crew’s OSPC, using the Illustrative Sequencing Concept Map on EPSC Plan Sheet C‐124, as guidance. Estimated total areas of disturbance within each work area and associated with each work crew are summarized in Tables 1 and 2, respectively, below:
Table 1: Wind Farm and Underground Collector Line Estimated Area of Disturbance Work Area ID Area of Disturbance (acres) #1 28.8 #2 26.5 #3 33.0 #4 35.3 Total Area of Disturbance 123.6
Table 2: Work Crew Estimated Area of Disturbance Work Crew ID Area of Disturbance (acres) #1 27.6 #2 31.9 #3 34.5 #4 29.6 Total Area of Disturbance 123.6 Overhead Collector Lines Construction of the overhead collector lines will be constructed concurrently with construction of the wind farm project and underground collector lines. The work area associated with the overhead collector lines is defined by the 10‐foot wide access routes and 20‐ by 20‐foot work boxes around each structure, as shown on the EPSC Plan. For the purpose of estimating the total area of disturbance associated with installation of the
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overhead collector lines, the entire work area (3.35 acres) as defined above has been included as a maximum in the overall total area of disturbance. However, it is anticipated that the actual earth disturbance associated with the overhead collector lines will be less than 3.35 acres due to the nature of the work and via utilization of specific EPSC measures (e.g., timber mats, stone on fabric, installation during frozen conditions), as well as limiting access, where possible, to those areas that are less susceptible to erosion. c. Total Earth Disturbance Based on the construction and stabilization sequencing provided in Section 2(b) of this EPSC Narrative and on pages 16 through 22 of the Appendix, the estimated total area of earth disturbance associated with the Kingdom Community Wind Project is approximately 127 acres (see Table 3 below). The Construction and Stabilization Sequence outlines how the earth disturbance will be minimized to the extent practicable in those areas (see pages 16 through 22 of the Appendix). In addition, the project design includes an erosion control zone, which is an approximately 10 foot buffer area located adjacent to earthwork areas, where vegetation will be cleared but not stumped or grubbed. Throughout the project area, this erosion control zone equals approximately 20 acres in area. Although certain EPSC measures such as silt fence and erosion control mix berms may be placed on the downslope side of the erosion control zone, it is not anticipated that this area will be disturbed but rather left intact with stumps in place. For the purposes of this plan, the 20‐acre erosion control zone has been included in the overall total area of disturbance (147 acres) associated with this project.
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Table 3: Estimated Total Area of Disturbance Major Project Component Area of Disturbance (acres) Wind Farm and Underground 123.6 Collector Lines Overhead Collector Lines 3.35 Erosion Control Zone 20 Estimated Total Area of 147 Disturbance Oversight of construction and stabilization sequencing will be conducted by the OSPC and the EPSC Specialist. In the event of visibly discolored discharge from the site, the OSPC will follow protocols provided by VT DEC for EPSC measure implementation, turbidity monitoring, and reporting, as required (see EPSC Plan Sheet C‐131). Furthermore, it is expected that the OPSC and EPSC Specialist may modify the Construction and Stabilization Sequence and associated EPSC measures provided on the EPSC Plan, as needed, throughout the construction of the project. Modifications will be made in response to actual construction conditions and/or limitations encountered. It is the responsibility of the OPSC and EPSC Specialist to report significant plan modifications and to review those modifications and any updates of the Construction and Stabilization Sequence with VT DEC throughout the construction of the Project, as required, and as such modifications and updates occur. d. Sequence of Major Project Components Sequencing and timing of major project components is described in detail in Section 2(b) of this EPSC Narrative and in the Construction and Stabilization Sequence on pages 16 through 22 of the Appendix. e. Maximum Concurrent Earth Disturbance Based on the construction and stabilization sequencing provided in Section 2(b) of this EPSC Narrative and as outlined in the Construction and Stabilization Sequence on pages
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16 through 22 of the Appendix, the site construction of the Kingdom Community Wind Project will be conducted with four earthwork crews each being designated four work areas. The foremen of the earthwork crews will be the OSPC and will have the control and support of the specialized sub‐crew that will attend to EPSC Plan requirements, site stabilization, and drainage work (e.g., redirecting of upslope run‐on). These four earthwork crews will conduct construction activities concurrently within each of the four designated crew work areas (see Illustrative Sequencing Concept Map on EPSC Plan Sheet C‐134). For any one individual earthwork crew, transition from one work area to the next will be in the orderly sequencing of the construction activities performed by the earthwork crew and the support sub‐crews. It is proposed for any one individual earthwork crew working in one or more of the designated work crew areas that the total allowable area of non‐stabilized exposed earth surfaces be limited to 7.5 acres at any one time. This limiting requirement of each separate earthwork crew could translate to a maximum total for all four earthwork crews, of 30 acres of concurrent non‐stabilized exposed earth surfaces at any one time. Transition from one work area to the next will be coordinated with the earthwork crew’s On‐Site Plan Coordinator (OSPC), using the Illustrative Sequencing Concept Map on EPSC Plan Sheet C‐124, as guidance. f.
Vegetated Buffers
Vegetative buffers will be utilized to the extent possible to supplement structural EPSC measures, as outlined in the Natural Resource Assessment Report and associated buffer matrix (Exh. Pet.‐JAN‐2), which was filed as a component of the project’s Section 248 petition to the VT PSB. Also, to the extent possible, existing vegetative buffers between down slope receiving waters and the construction site will remain. However, due to the linear layout of the proposed project and the resultant buffer width variability, use of vegetative buffers was not used to score this project in the Risk Evaluation (see pages 1 through 3 of the Appendix).
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g. Duration of Exposed Soils The Kingdom Community Wind Project will not have exposed earth surfaces in any one location for more than 14 consecutive calendar days without temporary or permanent stabilization, as indicated in the scoring of the project in the Risk Evaluation (see pages 2 through 4 of the Appendix). The EPSC Plan and Construction and Stabilization Sequence provide specific measures for achieving temporary and permanent stabilization. h. Receiving Waters There are numerous potential receiving waters located within the Kingdom Community Wind Project area, as shown on the Post‐Development Subwatershed Map (see map pocket) and as reported in the Natural Resources Assessment Report (prepared by VHB and dated February 26, 2010, Exh. Pet.‐JAN‐2). The seven major drainage areas include: Ace Brook, East Branch Missisquoi River, McCleary Brook, Rogers Branch, Seaver Branch, Shalney Branch, and Truland Brook (see Pre‐Construction Subwatershed Map in map pocket). To the extent practicable, stormwater runoff will flow overland from the construction site with maximum potential for infiltration, dispersal, settling, and/or containment by select EPSC measures prior to discharge to receiving waters (see EPSC Plan). i.
Drainage Areas and Soil Types
For this large, generally linear project, drainage areas have been determined by major watershed areas, as outlined in section 2(h) above. A summary table on page 15 of the Appendix provides the required information for each major watershed area, including name, drainage area size, area of disturbance within each drainage area, Natural Resources Conservation Service (NRCS) erodibility index, and average slope. Soil types are listed in the EPSC Plan Summary Forms (see page 5 of the Appendix) and shown on the Soils Map included on page 23 of the Appendix. Of the approximately 147 acres of
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potential soil disturbance that has been estimated for this project, 8.08 acres has an erodibility rating of K 0.36*
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High High High High High High Medium Low Medium High g High High High High High Low Medium Low High High High High High Medium Medium High High High Medium High High High High High High High High High High High High High Medium High High High High High Medium Medium High High High Medium High
Risk2
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ABC ABC ABC ABC ABC ABC ABC ABC A AB AB AB ABC ABC ABC A A A AB ABC AB AB AB A A ABC AB AB ABC AB AB ABC AB ABC ABC ABC ABC ABC ABC AB ABC AB AB ABC ABC ABC ABC ABC AB A AB ABC ABC A ABC
EPSC Standards3
\\VTDATA\Projects\57346.00\GIS\vector\shape\Stormwater\Geoprocesses\RiskEval\SoilImpactSheet.xlsxSummary Table11/8/2010
Area Weighted 2 Low, Medium, or High. Refer to Table 3.2 in VT Standards and Specifications for Erosion Prevention and 3 Refer to Table 3.3 A = Limit Disturbed Soil, Temporary Stabilization, Small Area Sediment Control B = Slope Protection, Runoff Control, Flow Protection C = Large Area Sediment Control *K factors for collector line and erosion control zone assigned as K>0.36 to remain conservative.
1
20.0
> 0.36*
3.1 Approximate Area within Erosion Control Zone
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6.9 5.4 2.2 8.2 6.4 6.8 2.3 5.3 0.6 0.8 0.8 0.9 1.7 2.1 1.1 0.5 0.5 0.7 0.5 1.4 1.0 1.0 0.6 0.6 0.5 1.0 0.7 0.8 1.2 0.9 0.9 1.7 0.6 6.5 1.5 6.3 6.5 5.0 1.2 0.8 3.4 0.6 1.1 3.1 2.1 1.1 1.5 2.5 1.3 0.7 0.7 1.8 1.7 1.0 1.6
A1 A3 A4 A9 EBMR1 EBMR3 EBMR4 EBMR5 EBMR6 LS/DP‐A4 LS/DP‐C10 LS/DP‐C15 LS/DP‐C19 LS/DP‐C4 LS/DP‐D2 LS‐A1 (Infiltration) LS‐A15 LS‐A2 LS‐A22 LS‐A23 LS‐A24 LS‐A25 LS‐A3 LS‐A7 LS‐A9 LS‐C1 LS‐C11 LS‐C18 LS‐C2 LS‐C3 LS‐C5 LS‐C7 LS‐D1 M1 M2 R1 R2 S1 Sh1 Sh2 Sh3 T1 WP‐A WP‐B WP‐C WP‐D WP‐E WP‐F WP‐G WP‐H WP‐I WP‐J WP‐K WP‐L WP‐M Total area beyond subwatersheds with greater than 0.5 acres of disturbance Approximate Area disturbed due to Collector Line
Weighted Average Soil K Slope 1 (%) factor 0.44 22 0.37 20 0.25 16 0.46 23 0.49 26 0.49 25 0.28 14 0.17 6 0.24 13 0.28 16 0.49 18 0.49 27 0.49 23 0.49 24 0.49 15 0.17 5 0.24 12 0.17 10 0.24 28 0.40 30 0.49 16 0.49 16 0.21 17 0.26 13 0.28 15 0.41 15 0.49 17 0.49 24 0.35 12 0.48 15 0.49 19 20 0.31 0.49 15 0.41 29 0.31 26 0.49 29 0.47 20 0.48 30 0.49 28 0.49 28 0.40 27 0.49 23 0.24 13 0.49 17 0.49 19 0.49 9 0.49 10 0.49 18 0.28 12 0.32 12 0.49 27 0.49 16 0.49 18 0.32 8 0.49 15 5.6
Disturbance (Acres)
Drainage Area # (Subwatershed ID)
For each drainage area with disturbance of 0.5 acres or more
Discharge Area Summary
Kingdom Community Wind Discharge Area Summary Table Prepared by VHB/Vanasse Hangen Brustlin, Inc. 11/8/2010
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KINGDOM COMMUNITY WIND PROJECT LOWELL, VERMONT CONSTRUCTION AND STABILIZATION SEQUENCE November 8, 2010 1.0 INTRODUCTION The primary intent of the Construction and Stabilization Sequence is to provide a thorough understanding of the following: • The project’s intended sequence of construction and earth disturbing activities • The extent of estimated earth disturbance associated with each major activity (or in this case, each work area) • Means of minimizing the amount of disturbed area that is open at any one time • Means of minimizing the potential for erosion • Means of providing sediment control in the event of stormwater runoff and erosion • Means and timing of conducting temporary and permanent stabilization The target audience, with regard to review and implementation of the Construction and Stabilization Sequence, includes regulators (e.g., VT DEC), the project’s On‐Site Plan Coordinator (OSPC), the Erosion Prevention and Sediment Control (EPSC) Specialist(s), and, perhaps most importantly, the contractors. The content of the Construction and Stabilization Sequence includes: • Sections 2.1 and 2.2, which provide an overview of construction and stabilization sequencing associated with the two major project areas: (1) Wind Farm and Underground Collector Line areas, and (2) Overhead Collector Line areas. • Sections 3.1 through 3.5, which provide an overview of construction and stabilization sequencing associated with each of the major construction activities (building of roads, building of turbine pads, building of the substation, etc). Where appropriate, references have been made to specific EPSC Plan sheets, notes, and details of the EPSC Plan set; Civil Site Design Drawings; and operational phase Stormwater Plan Set, as a means of limiting potential for contradiction between the three project plan sets. 2.0 GENERAL CONSTRUCTION AND STABILIZATION SEQUENCES 2.1 Wind Farm and Underground Collector Lines The wind farm portion of the project, as described herein, encompasses the access road, crane paths, laydown/staging areas, substation, O&M building, turbine pads, and underground collector lines. Construction of the wind farm and underground collector lines shall be constructed with four separate earthwork crews that are supported by Page 1 of 7
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sub‐crews, one of which will be attending to EPSC Plan requirements, site stabilization, and drainage work (e.g., redirecting of upslope run‐on). These four earthwork crews will conduct construction activities concurrently within each of their designated work areas, and will be guided by the Illustrative Sequencing Concept Map on EPSC Plan Sheet C‐134. For any one individual earthwork crew, transition from one work area to the next will be in the orderly sequencing of the construction activities performed by the earthwork crew and the support sub‐crews. It is proposed for any one individual earthwork crew working in one or more of the designated work crew areas that the total allowable area of non‐stabilized exposed earth surfaces be limited to 7.5 acres at any one time. This limiting requirement of each separate earthwork crew could translate to a maximum total for all four earthwork crews, of 30 acres of concurrent non‐ stabilized exposed earth surfaces at any one time. Transition from one work area to the next will be coordinated with the earthwork crew’s OSPC, using the Illustrative Sequencing Concept Map on EPSC Plan Sheet C‐124, as guidance. Estimated total areas of disturbance within each work area and associated with each work crew are summarized in Tables 1 and 2, respectively. These areas do not include the erosion control zone of approximately 20 acres, which is anticipated to remain intact with stumps left in place to the extent practicable. Table 1: Wind Farm and Underground Collector Line Estimated Area of Disturbance Work Area ID Area of Disturbance (acres) #1 28.8 #2 26.5 #3 33.0 #4 35.3 Total Area of Disturbance 123.6 Table 2: Work Crew Estimated Area of Disturbance Work Crew ID Area of Disturbance (acres) #1 27.6 #2 31.9 #3 34.5 #4 39.6 Total Area of Disturbance 123.6 Within each work area, the sequence of construction activities shall typically involve: 1. Flag centerline of work area (e.g., centerline of access road and crane path, as depicted on Civil Site Design Drawings) 2. Clear trees necessary for surveying extent of the centerline of access road and crane path with the VT ANR Acceptable Management Practices for Maintaining Water Quality on Logging Jobs (1987), at a minimum; no stumping and grubbing at this time 3. Flag extent of work area limits 4. Installation of initial EPSC measures (e.g., construction barrier flagging, stabilized construction entrance) Page 2 of 7
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2.2
5. Tree clearing in accordance with the Vermont Agency of Natural Resources (VT ANR) Acceptable Management Practices for Maintaining Water Quality on Logging Jobs (1987), at a minimum; no stumping and grubbing at this point 6. Installation of additional EPSC measures as needed (e.g., silt fence, filter logs, etc.) 7. Stumping and grubbing, with installation of additional EPSC measures as needed (e.g., wood chips, erosion control mix berms, etc.) 8. Earthwork pursuant to specific construction activity (access road, crane path, turbine pad, etc.) 9. Temporary or permanent stabilization of all exposed soil; see EPSC Plan Sheet C‐ 131 for temporary and permanent stabilization measures Overhead Collector Lines Construction of the overhead collector lines shall be constructed concurrent with construction of the wind farm project and underground collector lines. The work area associated with the overhead collector lines is defined by the approximately 10‐foot wide access routes and approximately 20‐ by 20‐foot work boxes around each structure, as shown on EPSC Plan set. For the purpose of estimating the total area of disturbance associated with installation of the overhead collector lines, the entire work area (3.35 acres) as defined above has been included as a maximum in the overall total area of disturbance. However, it is anticipated that the actual earth disturbance associated with the overhead collector lines will be less that 3.35 acres due to the nature of the work and via utilization of specific EPSC measures (e.g., timber mats, stone on fabric, installation during frozen conditions), as well as limiting access, where possible, to those areas that are less susceptible to erosion.
Installation of the overhead collector lines shall be conducted, as follows: 1. Structure locations are to be accessed via collector line access routes within the right‐of‐way, as shown on EPSC Plan set 2. Equipment is to remain within the approximately 10‐foot wide access routes and approximately 20 x 20 foot work boxes; access outside of these areas requires prior approval by the OSPC 3. Construction demarcation is to be conducted per Table 1 on EPSC Plan Sheet C‐ 130 prior to tree clearing and earth disturbing activities 4. Tree clearing is to be conducted in accordance with the VT ANR Acceptable Management Practices for Maintaining Water Quality on Logging Jobs (1987), at a minimum 5. EPSC measures are to be installed as needed prior to earth disturbing activities; see Table 2 on EPSC Plan Sheet C‐130 6. Equipment is not to cross a wetland without the use of matting without prior approval by the OSPC, following a Dry Evaluation or Frozen Ground Evaluation (see EPSC Plan Sheet C‐133) 7. The OSCP may direct that equipment and materials are to be stored in upland locations Page 3 of 7
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3.0
MAJOR CONSTRUCTION AND STABILIZATION ACTIVITIES 3.1
3.2
Access Road, Crane Path, Underground Collector Lines, and Permanent Stormwater Management System Construction and Stabilization Sequence 1. Flag centerline of access road and crane paths 2. Clear trees necessary for surveying of access road and crane path centerlines in accordance with the VT ANR Acceptable Management Practices for Maintaining Water Quality on Logging Jobs (1987), at a minimum; no stumping and grubbing at this time 3. Flag extent of access road and crane path clearing limits, including modifications allowed by the Variable Road Location Detail (see EPSC Plan Sheet C‐129) 4. Install EPSC measures, including construction demarcation and perimeter erosion controls (see EPSC Plan Sheet C‐130) 5. Cut, stump, and grub areas within demarcated clearing limits 6. Stockpile material for chipping and grinding to use for EPSC measures 7. Remove overburden necessary for road building; stockpile material in designated area with appropriate EPSC measures 8. Conduct drilling and blasting; use mobile crushers to process material for use in road building 9. Conduct earth and ledge excavation with cuts and fills pursuant to Civil Site Design Drawings; concurrently, install sediment traps (level spreaders, dry ponds) and sediment basins (wet ponds) located immediately downslope of active areas of earthwork per details provided on the EPSC Plan Sheets C‐127, C‐128, and C‐133 10. Construct access roads and crane paths, including vehicle pull‐over lanes, pursuant to Civil Site Design Drawings 11. Concurrent with construction of crane paths, install underground collector lines pursuant to Civil Site Design Drawings 12. Continuously apply EPSC measures to limit the amount of earth disturbance at any one time; apply temporary or permanent stabilization per the EPSC Plan set 13. Repair/replace/refresh EPSC measures (e.g., silt fence, erosion control mix, etc.), as needed to maintain their effectiveness until areas are fully stabilized 14. As needed to maintain proper performance, remove accumulated sediment from sediment traps and sediment basins; deposit in an appropriate upslope location and stabilize 15. Once upslope area is fully stabilized, reconstruct sediment traps as level spreaders or dry ponds and sediment basins as permanent stormwater basins per the EPSC Plan set and pursuant to operational phase Stormwater Plan Set 16. Remove all temporary EPSC measures (e.g., silt fence, etc) once upslope area is fully stabilized; apply seed and mulch to remaining exposed soils, as needed Laydown/Staging Area Construction and Stabilization Sequence 1. Flag extent of laydown/staging area to be cleared of trees 2. Clear trees within laydown/staging area footprint in accordance with the VT ANR Acceptable Management Practices for Maintaining Water Quality on Logging Jobs (1987), at a minimum; no stumping and grubbing at this time
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3. Install EPSC measures, including construction demarcation and perimeter erosion controls (see EPSC Plan Sheet C‐130) 4. Cut, stump, and grub areas within demarcated clearing limits 5. Stockpile materials for chipping and grinding 6. Remove overburden; stockpile material in designated area with appropriate EPSC measures 7. Conduct drilling and blasting, as needed; use mobile crusher to process material as needed 8. Conduct earthwork with cuts and fills pursuant to Civil Site Design Drawings 9. Construct laydown/staging area pursuant to Civil Site Design Drawings 10. Continuously apply EPSC measures to limit the amount of earth disturbance at any one time; apply temporary or permanent stabilization per the EPSC Plan set 11. Repair/replace/refresh EPSC measures (e.g., silt fence, erosion control mix, etc.), as needed to maintain their effectiveness until area is fully stabilized 12. Remove all temporary EPSC measures (e.g., silt fence, etc.) once upslope area is fully stabilized; apply seed and mulch to remaining exposed soils, as needed 3.3
Substation and O&M Building Construction and Stabilization Sequence
1. Flag extent of substation area to be cleared of trees 2. Clear trees within substation area footprint in accordance with the VT ANR Acceptable Management Practices for Maintaining Water Quality on Logging Jobs (1987), at a minimum; no stumping and grubbing at this time 3. Install EPSC measures, including construction demarcation and perimeter erosion controls (see EPSC Plan Sheet C‐130) 4. Cut, stump, and grub areas within demarcated clearing limits 5. Stockpile materials for chipping and grinding 6. Remove overburden; stockpile material in designated area with appropriate EPSC measures 7. Conduct drilling and blasting, as needed; use mobile crusher to process material as needed 8. Conduct geotechnical borings for O&M building design 9. Conduct earthwork with cuts and fills pursuant to Civil Site Design Drawings 10. Construct substation, O&M building, and related infrastructure pursuant to Civil Site Design Drawings 11. Continuously apply EPSC measures to limit the amount of earth disturbance at any one time; apply temporary or permanent stabilization per the EPSC Plan set 12. Repair/replace/refresh EPSC measures (e.g., silt fence, erosion control mix, etc.), as needed to maintain their effectiveness until area is fully stabilized 13. Remove all temporary EPSC measures (e.g., silt fence, etc.) once upslope area is fully stabilized; apply seed and mulch to remaining exposed soils, as needed 3.4
Turbine Pad and Permanent Stormwater Management System Construction and Stabilization Sequence
1. Flag extent of turbine pad area to be cleared of trees
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3.5
2. Clear trees within turbine pad footprint in accordance with the VT ANR Acceptable Management Practices for Maintaining Water Quality on Logging Jobs (1987), at a minimum; no stumping and grubbing at this time 3. Conduct geotechnical borings for foundation design 4. Install EPSC measures, including construction demarcation and perimeter erosion controls (see EPSC Plan Sheet C‐130) 5. Cut, stump, and grub areas within demarcated clearing limits 6. Stockpile materials for chipping and grinding 7. Remove overburden; stockpile material in designated area with appropriate EPSC measures 8. Conduct drilling and blasting, as needed; use mobile crusher to process material as needed 9. Conduct earthwork with cuts and fills pursuant to Civil Site Design Drawings; concurrently, install sediment traps (level spreaders, dry ponds) and sediment basins (wet ponds) located immediately downslope of active areas of earthwork per sediment details provided on EPSC Plan Sheets C‐127, C‐128, and C‐133 10. Excavate for turbine foundations; install foundations 11. Continuously apply EPSC measures to limit the amount of earth disturbance at any one time; apply temporary or permanent stabilization per the EPSC Plan set 12. Repair/replace/refresh EPSC measures (e.g., silt fence, erosion control mix, etc.), as needed to maintain their effectiveness until area is fully stabilized 13. As needed to maintain proper performance, remove accumulated sediment from sediment traps and sediment basins; deposit in an appropriate upslope location and stabilize per Temporary and Final Stabilization Notes on EPSC Plan Sheet C‐131 14. Once upslope area is fully stabilized, reconstruct sediment traps as level spreaders, and dry ponds and sediment basins as permanent stormwater basins per EPSC Plan Sheets C‐127 and C‐128 and pursuant to operational phase Stormwater Plan Set 15. Remove all temporary EPSC measures (e.g., silt fence, etc.) once upslope area is fully stabilized; apply seed and mulch to remaining exposed soils, as needed Overhead Collector Line Construction and Stabilization Sequence
1. Flag extent of overhead collector line right‐of‐way (ROW) to be cleared of trees 2. Clear trees within ROW footprint in accordance with the VT ANR Acceptable Management Practices for Maintaining Water Quality on Logging Jobs (1987), at a minimum; no stumping and grubbing at this time 3. Demarcate extent of ROW to be used for installation of approximately 10‐foot wide access routes and approximately 20‐ by 20‐foot work areas surrounding each pole. 4. Install EPSC measures, including perimeter erosion controls, where needed (see EPSC Plan Sheet C‐130) 5. Stockpile materials for chipping and grinding (note that other areas of the project may be used for this operation, such as the access road) 6. Install poles pursuant to collector design drawings; holes for poles are approximately 2 feet in diameter and approximately 8 feet in depth 7. Spread drill spoils material adjacent to hole in non‐wetland areas then seed and mulch when required 8. Conduct wire installation and any other collector line installation activities pursuant to collector design plans Page 6 of 7
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9. Continuously apply EPSC measures to limit the amount of earth disturbance at any one time; see Temporary and Final Stabilization Notes on EPSC Plan Sheet C‐131 10. Repair/replace/refresh EPSC measures (e.g., silt fence, erosion control mix, etc.), as needed to maintain their effectiveness until areas are fully stabilized 11. Remove all temporary EPSC measures (e.g., silt fence, etc.) once upslope area is fully stabilized; apply seed and mulch to remaining exposed soils, as needed 3.6
Changes in Work
It is expected that the OPSC and EPSC Specialist may modify the Construction and Stabilization Sequence and associated EPSC measures provided on the EPSC Plan, as needed, throughout the construction of the project. Modifications will be made in response to actual construction conditions and/or limitations encountered. It is the responsibility of the OPSC and EPSC Specialist to report significant plan modifications and to review those modifications and any updates of the Construction and Stabilization Sequence with VT DEC throughout the construction of the Project, as required, and as such modifications and updates occur. \\VTDATA\Projects\57346.03 GMP KCW SW Permitting\tech\KCW Const Phasing Plan_110810.doc
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YR D
TH
Indirect Study Area
not rated
D
C
B
A
NRCS Soil Hydrogroup
500 ft. Contour
100 ft. Contour
Wind Farm Direct Study Limits
Town/County Boundary
Parcel Boundaries
Vermont State Highway
Local Road
12D K Factor 0.24
12D K Factor 0.24
247C K Factor 0.26
247B K Factor 0.2
LyE K Factor 0.26
100
"
RD
26C K Factor 0.17
EK ME
0 250
Legend
26C K Factor 0.17
0
Y
RD
November 4, 2010
N BA L A
RD
0
Scale - 1" = 2000'
1,000
2,000 Feet
0 15
0
0 15
0
23 Prepared by: SEM/JAT
Sources: Town/County Layer (2004), roads layer (2009), Soils (2008) provided by VCGI (2010); Direct Study Limits and Indirect Study Area by VHBP (2009).
Soil Description Lyman-Tunbridge fine sandy loams, very rocky, 25 to 60 percent slopes Londonderry-Stratton complex, 25 to 60 percent slopes Monadnock fine sandy loam, 15 to 35 percent slopes, very stony Cabot silt loam, 0 to 8 percent slopes, very stony Sheepscot gravelly fine sandy loam, 3 to 8 percent slopes Adams loamy fine sand, 25 to 60 percent slopes Adams loamy fine sand, 8 to 15 percent slopes Adams loamy fine sand, 3 to 8 percent slopes Colonel-Cabot complex, 8 to 15 percent slopes Colonel-Cabot complex, 3 to 8 percent slopes Dixfield sandy loam, 15 to 35 percent slopes, very stony Tunbridge-Lyman complex, 35 to 60 percent slopes, very rocky Tunbridge-Lyman complex, 15 to 35 percent slopes, very rocky Hogback-Rawsonville complex, 35 to 60 percent slopes, very rocky Hogback-Rawsonville complex, 15 to 35 percent slopes, very rocky Tunbridge-Dixfield complex, 15 to 35 percent slopes, very stony
112D K Factor 0.49
12E K Factor 0.24
EDEN RD
RD LL HI
F:\57346.00\GIS\project\Stormwater\KCW_Site_soils_reformat_11x17.mxd
Soil ID LyE LoE 93D 59B 31B 26E 26C 26B 247C 247B 16D 12E 12D 112E 112D 101D
SH IRI
12E K Factor 0.24
112E K Factor 0.49
Kingdom Community Wind Lowell, Vermont Soils Map - Wind Farm
LoE K Factor 0.46
U
L
U IE
101D K Factor 0.26
LO RL WE L EA NS L (L CO AM EDE .) N OI LL E C O. ) (O
A BE
93D K Factor 0.28
59B K Factor 0.32
12E K Factor 0.24
16D K Factor 0.28
0 15
0
16D K Factor 0.28
31B K Factor 0.17
TH 3
RD W
E
26E K Factor 0.17
SO
U
G PA
D ER
CH EN E
26C K Factor 0.17
26B K Factor 0.17
1500 FID
RD
RD MINK FARM RD DL ER S EL BO W
0 10 0
BOU
250 0
0 25 0
D ET R S QU
0
2 TH 5
(O LOW RL E E AN LL S (O ALB C R O. LE AN ) AN Y S CO .)
ER
200 0
1500
0
1500
HAZEN
10 0
FARM RD
RD
15 0
Y BAILE
W CO S LE
GREEN MOUNTAIN POWER KINGDOM COMMUNITY WIND PROJECT
Lowell, Vermont
Prepared for
Prepared by
Green Mountain Power Corporation Vanasse Hangen Brustlin, Inc.
7056 U.S. Route 7 North Ferrisburgh, VT 05473 November 12, 2010
GREEN MOUNTAIN POWER CORPORATION / KINGDOM COMMUNITY WIND EROSION PREVENTION AND SEDIMENT CONTROL PLAN NARRATIVE
i
Table of Contents
1.0 Introduction ............................................................................................................................. 1 2.0 Project Description .................................................................................................................. 2 3.0 Location Map ......................................................................................................................... 10 4.0 Preconstruction, Construction, and Stabilization Plan .................................................... 10 References ..................................................................................................................................... 11
GREEN MOUNTAIN POWER CORPORATION / KINGDOM COMMUNITY WIND EROSION PREVENTION AND SEDIMENT CONTROL PLAN NARRATIVE
1.0
1
Introduction
On behalf of the applicant, Green Mountain Power Corporation, this Erosion Prevention and Sediment Control (EPSC) Plan narrative and EPSC Plan Summary Forms prepared by Vanasse Hangen Brustlin, Inc. (VHB) and associated EPSC Plan sheets, details, and notes prepared by VHB and Krebs and Lansing Consulting Engineers, Inc. (Krebs and Lansing) comprise an application for the planned construction of the Kingdom Community Wind Project located in the Town of Lowell, Orleans County, Vermont.1 For the purpose of this application filing, the project area comprises the following major project components, as shown on the Site Map on the cover sheet of the EPSC Plan. 1. Wind farm site, including the access road, crane paths, laydown/staging areas, substation, O&M building, and turbine pads 2. Underground collector lines 3. Overhead collector lines 4. Operational phase stormwater management system2 Separate construction stormwater discharge permit applications will be filed with the VT Department of Environmental Conservation (VT DEC) for the transmission line upgrade project and the Jay Tap substation project given that there are different applicants for these other projects and, therefore, they are not considered to be part of the Kingdom Community Wind project. Completion of the Risk Evaluation determined that the Kingdom Community Wind Project is not eligible for coverage under General
A petition for Section 248 approval of the Kingdom Community Wind Project from the Vermont Public Service Board (VT PSB) was filed on May 21, 2010 and is currently pending. 2 An application for an Individual Stormwater Discharge Permit (INDS) for the Kingdom Community Wind Project was filed with VT DEC on September 21, 2010; pending VT DEC review and approval. 1
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Permit 3‐9020 as a Moderate Risk construction activity (see pages 1 through 3 of the Appendix). Therefore, the project seeks construction stormwater discharge authorization from the VT DEC through the issuance of Individual Discharge Permit for Stormwater Runoff from Construction Sites. This EPSC Plan Narrative and the associated EPSC Plan (attached separately) have been prepared in conformance with the most recent edition of The Vermont Standards and Specifications for Erosion Prevention and Sediment Control (2006). The EPSC Plan Summary Forms have been included on pages 4 through 14 of the Appendix.
2.0
Project Description
The EPSC Plan has been prepared using General Permit 3‐9020, Part 4.1(C) and Appendix B of the General Permit 3‐9020, as guidance (in the absence of guidance that is specific to Individual Permit applications). The following sections (a) through (m) of this narrative address required EPSC Plan Narrative elements in the order that they are presented in Appendix B of General Permit 3‐9020. a. Project Type and Description The Kingdom Community Wind Project is a high elevation renewable energy project comprising twenty‐one 2.5 to 3.0 MW turbines, associated turbine pads, an 18‐foot wide gravel and/or stone access road that extends approximately 2.5 miles from Route 100 to the ridgeline, 34‐foot wide gravel and/or stone crane paths extending approximately 4.0 miles along the ridgeline, laydown/staging areas, an O&M building, an electrical substation, underground and overhead collector lines, and a permanent stormwater management system. In addition to the permanent access road and crane paths, the project will temporarily utilize an existing road (Meek Road / Town Highway 25) during
GREEN MOUNTAIN POWER CORPORATION / KINGDOM COMMUNITY WIND EROSION PREVENTION AND SEDIMENT CONTROL PLAN NARRATIVE
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the initial construction period in order to transport construction equipment, workmen, fuel, etc. to the site. b. Major Project Components As outlined in the Introduction, major project components consist of the wind farm, including the access road, crane paths, laydown/staging areas, substation, O&M building, and turbine pads; underground collector lines; overhead collector lines; and the operational phase stormwater management system. An overview of the general approach to construction and stabilization of these major project components is provided below, with more detailed sequencing provided in the Construction and Stabilization Sequence on pages 16 through 22 of the Appendix. Wind Farm and Underground Collector Lines Sequencing Construction of the wind farm and underground collector lines will be conducted with four separate earthwork crews. In addition to each separate earthwork crew, there will be several specialized sub‐crews supporting the earthwork crews, which will be attending to the different, orderly and repetitive, construction activities (such as survey layout, tree cutting, blasting, erosion control, etc.). Each earthwork crew foreman will be the On‐Site Plan Coordinator (OSPC) and will inspect, monitor and coordinate all earthwork crew and sub‐crew activities to ensure performance in accordance with the EPSC Plan requirements of site stabilization and drainage work (e.g., redirecting of upslope run‐on) whenever and wherever it may be required. These four work earthwork crews will conduct construction activities concurrently within each of their designated work areas (see Illustrative Sequencing Concept Map on EPSC Plan Sheet C‐ 134). For any one individual earthwork crew, transition from one work area to the next will be in the orderly sequencing of the construction activities performed by the earthwork crew and the support sub‐crews. It is proposed for any one individual earthwork crew working in one or more of the designated work crew areas that the total
GREEN MOUNTAIN POWER CORPORATION / KINGDOM COMMUNITY WIND EROSION PREVENTION AND SEDIMENT CONTROL PLAN NARRATIVE
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allowable area of non‐stabilized exposed earth surfaces be limited to 7.5 acres at any one time. This limiting requirement of each separate earthwork crew could translate to a maximum total for all four earthwork crews, of 30 acres of concurrent non‐stabilized exposed earth surfaces at any one time. Transition from one work area to the next will be coordinated with the earthwork crew’s OSPC, using the Illustrative Sequencing Concept Map on EPSC Plan Sheet C‐124, as guidance. Estimated total areas of disturbance within each work area and associated with each work crew are summarized in Tables 1 and 2, respectively, below:
Table 1: Wind Farm and Underground Collector Line Estimated Area of Disturbance Work Area ID Area of Disturbance (acres) #1 28.8 #2 26.5 #3 33.0 #4 35.3 Total Area of Disturbance 123.6
Table 2: Work Crew Estimated Area of Disturbance Work Crew ID Area of Disturbance (acres) #1 27.6 #2 31.9 #3 34.5 #4 29.6 Total Area of Disturbance 123.6 Overhead Collector Lines Construction of the overhead collector lines will be constructed concurrently with construction of the wind farm project and underground collector lines. The work area associated with the overhead collector lines is defined by the 10‐foot wide access routes and 20‐ by 20‐foot work boxes around each structure, as shown on the EPSC Plan. For the purpose of estimating the total area of disturbance associated with installation of the
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overhead collector lines, the entire work area (3.35 acres) as defined above has been included as a maximum in the overall total area of disturbance. However, it is anticipated that the actual earth disturbance associated with the overhead collector lines will be less than 3.35 acres due to the nature of the work and via utilization of specific EPSC measures (e.g., timber mats, stone on fabric, installation during frozen conditions), as well as limiting access, where possible, to those areas that are less susceptible to erosion. c. Total Earth Disturbance Based on the construction and stabilization sequencing provided in Section 2(b) of this EPSC Narrative and on pages 16 through 22 of the Appendix, the estimated total area of earth disturbance associated with the Kingdom Community Wind Project is approximately 127 acres (see Table 3 below). The Construction and Stabilization Sequence outlines how the earth disturbance will be minimized to the extent practicable in those areas (see pages 16 through 22 of the Appendix). In addition, the project design includes an erosion control zone, which is an approximately 10 foot buffer area located adjacent to earthwork areas, where vegetation will be cleared but not stumped or grubbed. Throughout the project area, this erosion control zone equals approximately 20 acres in area. Although certain EPSC measures such as silt fence and erosion control mix berms may be placed on the downslope side of the erosion control zone, it is not anticipated that this area will be disturbed but rather left intact with stumps in place. For the purposes of this plan, the 20‐acre erosion control zone has been included in the overall total area of disturbance (147 acres) associated with this project.
GREEN MOUNTAIN POWER CORPORATION / KINGDOM COMMUNITY WIND EROSION PREVENTION AND SEDIMENT CONTROL PLAN NARRATIVE
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Table 3: Estimated Total Area of Disturbance Major Project Component Area of Disturbance (acres) Wind Farm and Underground 123.6 Collector Lines Overhead Collector Lines 3.35 Erosion Control Zone 20 Estimated Total Area of 147 Disturbance Oversight of construction and stabilization sequencing will be conducted by the OSPC and the EPSC Specialist. In the event of visibly discolored discharge from the site, the OSPC will follow protocols provided by VT DEC for EPSC measure implementation, turbidity monitoring, and reporting, as required (see EPSC Plan Sheet C‐131). Furthermore, it is expected that the OPSC and EPSC Specialist may modify the Construction and Stabilization Sequence and associated EPSC measures provided on the EPSC Plan, as needed, throughout the construction of the project. Modifications will be made in response to actual construction conditions and/or limitations encountered. It is the responsibility of the OPSC and EPSC Specialist to report significant plan modifications and to review those modifications and any updates of the Construction and Stabilization Sequence with VT DEC throughout the construction of the Project, as required, and as such modifications and updates occur. d. Sequence of Major Project Components Sequencing and timing of major project components is described in detail in Section 2(b) of this EPSC Narrative and in the Construction and Stabilization Sequence on pages 16 through 22 of the Appendix. e. Maximum Concurrent Earth Disturbance Based on the construction and stabilization sequencing provided in Section 2(b) of this EPSC Narrative and as outlined in the Construction and Stabilization Sequence on pages
GREEN MOUNTAIN POWER CORPORATION / KINGDOM COMMUNITY WIND EROSION PREVENTION AND SEDIMENT CONTROL PLAN NARRATIVE
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16 through 22 of the Appendix, the site construction of the Kingdom Community Wind Project will be conducted with four earthwork crews each being designated four work areas. The foremen of the earthwork crews will be the OSPC and will have the control and support of the specialized sub‐crew that will attend to EPSC Plan requirements, site stabilization, and drainage work (e.g., redirecting of upslope run‐on). These four earthwork crews will conduct construction activities concurrently within each of the four designated crew work areas (see Illustrative Sequencing Concept Map on EPSC Plan Sheet C‐134). For any one individual earthwork crew, transition from one work area to the next will be in the orderly sequencing of the construction activities performed by the earthwork crew and the support sub‐crews. It is proposed for any one individual earthwork crew working in one or more of the designated work crew areas that the total allowable area of non‐stabilized exposed earth surfaces be limited to 7.5 acres at any one time. This limiting requirement of each separate earthwork crew could translate to a maximum total for all four earthwork crews, of 30 acres of concurrent non‐stabilized exposed earth surfaces at any one time. Transition from one work area to the next will be coordinated with the earthwork crew’s On‐Site Plan Coordinator (OSPC), using the Illustrative Sequencing Concept Map on EPSC Plan Sheet C‐124, as guidance. f.
Vegetated Buffers
Vegetative buffers will be utilized to the extent possible to supplement structural EPSC measures, as outlined in the Natural Resource Assessment Report and associated buffer matrix (Exh. Pet.‐JAN‐2), which was filed as a component of the project’s Section 248 petition to the VT PSB. Also, to the extent possible, existing vegetative buffers between down slope receiving waters and the construction site will remain. However, due to the linear layout of the proposed project and the resultant buffer width variability, use of vegetative buffers was not used to score this project in the Risk Evaluation (see pages 1 through 3 of the Appendix).
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g. Duration of Exposed Soils The Kingdom Community Wind Project will not have exposed earth surfaces in any one location for more than 14 consecutive calendar days without temporary or permanent stabilization, as indicated in the scoring of the project in the Risk Evaluation (see pages 2 through 4 of the Appendix). The EPSC Plan and Construction and Stabilization Sequence provide specific measures for achieving temporary and permanent stabilization. h. Receiving Waters There are numerous potential receiving waters located within the Kingdom Community Wind Project area, as shown on the Post‐Development Subwatershed Map (see map pocket) and as reported in the Natural Resources Assessment Report (prepared by VHB and dated February 26, 2010, Exh. Pet.‐JAN‐2). The seven major drainage areas include: Ace Brook, East Branch Missisquoi River, McCleary Brook, Rogers Branch, Seaver Branch, Shalney Branch, and Truland Brook (see Pre‐Construction Subwatershed Map in map pocket). To the extent practicable, stormwater runoff will flow overland from the construction site with maximum potential for infiltration, dispersal, settling, and/or containment by select EPSC measures prior to discharge to receiving waters (see EPSC Plan). i.
Drainage Areas and Soil Types
For this large, generally linear project, drainage areas have been determined by major watershed areas, as outlined in section 2(h) above. A summary table on page 15 of the Appendix provides the required information for each major watershed area, including name, drainage area size, area of disturbance within each drainage area, Natural Resources Conservation Service (NRCS) erodibility index, and average slope. Soil types are listed in the EPSC Plan Summary Forms (see page 5 of the Appendix) and shown on the Soils Map included on page 23 of the Appendix. Of the approximately 147 acres of
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potential soil disturbance that has been estimated for this project, 8.08 acres has an erodibility rating of K 0.36*
‐
‐
‐
‐
‐
‐
High High High High High High Medium Low Medium High g High High High High High Low Medium Low High High High High High Medium Medium High High High Medium High High High High High High High High High High High High High Medium High High High High High Medium Medium High High High Medium High
Risk2
‐
‐
‐
ABC ABC ABC ABC ABC ABC ABC ABC A AB AB AB ABC ABC ABC A A A AB ABC AB AB AB A A ABC AB AB ABC AB AB ABC AB ABC ABC ABC ABC ABC ABC AB ABC AB AB ABC ABC ABC ABC ABC AB A AB ABC ABC A ABC
EPSC Standards3
\\VTDATA\Projects\57346.00\GIS\vector\shape\Stormwater\Geoprocesses\RiskEval\SoilImpactSheet.xlsxSummary Table11/8/2010
Area Weighted 2 Low, Medium, or High. Refer to Table 3.2 in VT Standards and Specifications for Erosion Prevention and 3 Refer to Table 3.3 A = Limit Disturbed Soil, Temporary Stabilization, Small Area Sediment Control B = Slope Protection, Runoff Control, Flow Protection C = Large Area Sediment Control *K factors for collector line and erosion control zone assigned as K>0.36 to remain conservative.
1
20.0
> 0.36*
3.1 Approximate Area within Erosion Control Zone
‐
6.9 5.4 2.2 8.2 6.4 6.8 2.3 5.3 0.6 0.8 0.8 0.9 1.7 2.1 1.1 0.5 0.5 0.7 0.5 1.4 1.0 1.0 0.6 0.6 0.5 1.0 0.7 0.8 1.2 0.9 0.9 1.7 0.6 6.5 1.5 6.3 6.5 5.0 1.2 0.8 3.4 0.6 1.1 3.1 2.1 1.1 1.5 2.5 1.3 0.7 0.7 1.8 1.7 1.0 1.6
A1 A3 A4 A9 EBMR1 EBMR3 EBMR4 EBMR5 EBMR6 LS/DP‐A4 LS/DP‐C10 LS/DP‐C15 LS/DP‐C19 LS/DP‐C4 LS/DP‐D2 LS‐A1 (Infiltration) LS‐A15 LS‐A2 LS‐A22 LS‐A23 LS‐A24 LS‐A25 LS‐A3 LS‐A7 LS‐A9 LS‐C1 LS‐C11 LS‐C18 LS‐C2 LS‐C3 LS‐C5 LS‐C7 LS‐D1 M1 M2 R1 R2 S1 Sh1 Sh2 Sh3 T1 WP‐A WP‐B WP‐C WP‐D WP‐E WP‐F WP‐G WP‐H WP‐I WP‐J WP‐K WP‐L WP‐M Total area beyond subwatersheds with greater than 0.5 acres of disturbance Approximate Area disturbed due to Collector Line
Weighted Average Soil K Slope 1 (%) factor 0.44 22 0.37 20 0.25 16 0.46 23 0.49 26 0.49 25 0.28 14 0.17 6 0.24 13 0.28 16 0.49 18 0.49 27 0.49 23 0.49 24 0.49 15 0.17 5 0.24 12 0.17 10 0.24 28 0.40 30 0.49 16 0.49 16 0.21 17 0.26 13 0.28 15 0.41 15 0.49 17 0.49 24 0.35 12 0.48 15 0.49 19 20 0.31 0.49 15 0.41 29 0.31 26 0.49 29 0.47 20 0.48 30 0.49 28 0.49 28 0.40 27 0.49 23 0.24 13 0.49 17 0.49 19 0.49 9 0.49 10 0.49 18 0.28 12 0.32 12 0.49 27 0.49 16 0.49 18 0.32 8 0.49 15 5.6
Disturbance (Acres)
Drainage Area # (Subwatershed ID)
For each drainage area with disturbance of 0.5 acres or more
Discharge Area Summary
Kingdom Community Wind Discharge Area Summary Table Prepared by VHB/Vanasse Hangen Brustlin, Inc. 11/8/2010
15
16
KINGDOM COMMUNITY WIND PROJECT LOWELL, VERMONT CONSTRUCTION AND STABILIZATION SEQUENCE November 8, 2010 1.0 INTRODUCTION The primary intent of the Construction and Stabilization Sequence is to provide a thorough understanding of the following: • The project’s intended sequence of construction and earth disturbing activities • The extent of estimated earth disturbance associated with each major activity (or in this case, each work area) • Means of minimizing the amount of disturbed area that is open at any one time • Means of minimizing the potential for erosion • Means of providing sediment control in the event of stormwater runoff and erosion • Means and timing of conducting temporary and permanent stabilization The target audience, with regard to review and implementation of the Construction and Stabilization Sequence, includes regulators (e.g., VT DEC), the project’s On‐Site Plan Coordinator (OSPC), the Erosion Prevention and Sediment Control (EPSC) Specialist(s), and, perhaps most importantly, the contractors. The content of the Construction and Stabilization Sequence includes: • Sections 2.1 and 2.2, which provide an overview of construction and stabilization sequencing associated with the two major project areas: (1) Wind Farm and Underground Collector Line areas, and (2) Overhead Collector Line areas. • Sections 3.1 through 3.5, which provide an overview of construction and stabilization sequencing associated with each of the major construction activities (building of roads, building of turbine pads, building of the substation, etc). Where appropriate, references have been made to specific EPSC Plan sheets, notes, and details of the EPSC Plan set; Civil Site Design Drawings; and operational phase Stormwater Plan Set, as a means of limiting potential for contradiction between the three project plan sets. 2.0 GENERAL CONSTRUCTION AND STABILIZATION SEQUENCES 2.1 Wind Farm and Underground Collector Lines The wind farm portion of the project, as described herein, encompasses the access road, crane paths, laydown/staging areas, substation, O&M building, turbine pads, and underground collector lines. Construction of the wind farm and underground collector lines shall be constructed with four separate earthwork crews that are supported by Page 1 of 7
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sub‐crews, one of which will be attending to EPSC Plan requirements, site stabilization, and drainage work (e.g., redirecting of upslope run‐on). These four earthwork crews will conduct construction activities concurrently within each of their designated work areas, and will be guided by the Illustrative Sequencing Concept Map on EPSC Plan Sheet C‐134. For any one individual earthwork crew, transition from one work area to the next will be in the orderly sequencing of the construction activities performed by the earthwork crew and the support sub‐crews. It is proposed for any one individual earthwork crew working in one or more of the designated work crew areas that the total allowable area of non‐stabilized exposed earth surfaces be limited to 7.5 acres at any one time. This limiting requirement of each separate earthwork crew could translate to a maximum total for all four earthwork crews, of 30 acres of concurrent non‐ stabilized exposed earth surfaces at any one time. Transition from one work area to the next will be coordinated with the earthwork crew’s OSPC, using the Illustrative Sequencing Concept Map on EPSC Plan Sheet C‐124, as guidance. Estimated total areas of disturbance within each work area and associated with each work crew are summarized in Tables 1 and 2, respectively. These areas do not include the erosion control zone of approximately 20 acres, which is anticipated to remain intact with stumps left in place to the extent practicable. Table 1: Wind Farm and Underground Collector Line Estimated Area of Disturbance Work Area ID Area of Disturbance (acres) #1 28.8 #2 26.5 #3 33.0 #4 35.3 Total Area of Disturbance 123.6 Table 2: Work Crew Estimated Area of Disturbance Work Crew ID Area of Disturbance (acres) #1 27.6 #2 31.9 #3 34.5 #4 39.6 Total Area of Disturbance 123.6 Within each work area, the sequence of construction activities shall typically involve: 1. Flag centerline of work area (e.g., centerline of access road and crane path, as depicted on Civil Site Design Drawings) 2. Clear trees necessary for surveying extent of the centerline of access road and crane path with the VT ANR Acceptable Management Practices for Maintaining Water Quality on Logging Jobs (1987), at a minimum; no stumping and grubbing at this time 3. Flag extent of work area limits 4. Installation of initial EPSC measures (e.g., construction barrier flagging, stabilized construction entrance) Page 2 of 7
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2.2
5. Tree clearing in accordance with the Vermont Agency of Natural Resources (VT ANR) Acceptable Management Practices for Maintaining Water Quality on Logging Jobs (1987), at a minimum; no stumping and grubbing at this point 6. Installation of additional EPSC measures as needed (e.g., silt fence, filter logs, etc.) 7. Stumping and grubbing, with installation of additional EPSC measures as needed (e.g., wood chips, erosion control mix berms, etc.) 8. Earthwork pursuant to specific construction activity (access road, crane path, turbine pad, etc.) 9. Temporary or permanent stabilization of all exposed soil; see EPSC Plan Sheet C‐ 131 for temporary and permanent stabilization measures Overhead Collector Lines Construction of the overhead collector lines shall be constructed concurrent with construction of the wind farm project and underground collector lines. The work area associated with the overhead collector lines is defined by the approximately 10‐foot wide access routes and approximately 20‐ by 20‐foot work boxes around each structure, as shown on EPSC Plan set. For the purpose of estimating the total area of disturbance associated with installation of the overhead collector lines, the entire work area (3.35 acres) as defined above has been included as a maximum in the overall total area of disturbance. However, it is anticipated that the actual earth disturbance associated with the overhead collector lines will be less that 3.35 acres due to the nature of the work and via utilization of specific EPSC measures (e.g., timber mats, stone on fabric, installation during frozen conditions), as well as limiting access, where possible, to those areas that are less susceptible to erosion.
Installation of the overhead collector lines shall be conducted, as follows: 1. Structure locations are to be accessed via collector line access routes within the right‐of‐way, as shown on EPSC Plan set 2. Equipment is to remain within the approximately 10‐foot wide access routes and approximately 20 x 20 foot work boxes; access outside of these areas requires prior approval by the OSPC 3. Construction demarcation is to be conducted per Table 1 on EPSC Plan Sheet C‐ 130 prior to tree clearing and earth disturbing activities 4. Tree clearing is to be conducted in accordance with the VT ANR Acceptable Management Practices for Maintaining Water Quality on Logging Jobs (1987), at a minimum 5. EPSC measures are to be installed as needed prior to earth disturbing activities; see Table 2 on EPSC Plan Sheet C‐130 6. Equipment is not to cross a wetland without the use of matting without prior approval by the OSPC, following a Dry Evaluation or Frozen Ground Evaluation (see EPSC Plan Sheet C‐133) 7. The OSCP may direct that equipment and materials are to be stored in upland locations Page 3 of 7
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3.0
MAJOR CONSTRUCTION AND STABILIZATION ACTIVITIES 3.1
3.2
Access Road, Crane Path, Underground Collector Lines, and Permanent Stormwater Management System Construction and Stabilization Sequence 1. Flag centerline of access road and crane paths 2. Clear trees necessary for surveying of access road and crane path centerlines in accordance with the VT ANR Acceptable Management Practices for Maintaining Water Quality on Logging Jobs (1987), at a minimum; no stumping and grubbing at this time 3. Flag extent of access road and crane path clearing limits, including modifications allowed by the Variable Road Location Detail (see EPSC Plan Sheet C‐129) 4. Install EPSC measures, including construction demarcation and perimeter erosion controls (see EPSC Plan Sheet C‐130) 5. Cut, stump, and grub areas within demarcated clearing limits 6. Stockpile material for chipping and grinding to use for EPSC measures 7. Remove overburden necessary for road building; stockpile material in designated area with appropriate EPSC measures 8. Conduct drilling and blasting; use mobile crushers to process material for use in road building 9. Conduct earth and ledge excavation with cuts and fills pursuant to Civil Site Design Drawings; concurrently, install sediment traps (level spreaders, dry ponds) and sediment basins (wet ponds) located immediately downslope of active areas of earthwork per details provided on the EPSC Plan Sheets C‐127, C‐128, and C‐133 10. Construct access roads and crane paths, including vehicle pull‐over lanes, pursuant to Civil Site Design Drawings 11. Concurrent with construction of crane paths, install underground collector lines pursuant to Civil Site Design Drawings 12. Continuously apply EPSC measures to limit the amount of earth disturbance at any one time; apply temporary or permanent stabilization per the EPSC Plan set 13. Repair/replace/refresh EPSC measures (e.g., silt fence, erosion control mix, etc.), as needed to maintain their effectiveness until areas are fully stabilized 14. As needed to maintain proper performance, remove accumulated sediment from sediment traps and sediment basins; deposit in an appropriate upslope location and stabilize 15. Once upslope area is fully stabilized, reconstruct sediment traps as level spreaders or dry ponds and sediment basins as permanent stormwater basins per the EPSC Plan set and pursuant to operational phase Stormwater Plan Set 16. Remove all temporary EPSC measures (e.g., silt fence, etc) once upslope area is fully stabilized; apply seed and mulch to remaining exposed soils, as needed Laydown/Staging Area Construction and Stabilization Sequence 1. Flag extent of laydown/staging area to be cleared of trees 2. Clear trees within laydown/staging area footprint in accordance with the VT ANR Acceptable Management Practices for Maintaining Water Quality on Logging Jobs (1987), at a minimum; no stumping and grubbing at this time
Page 4 of 7
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3. Install EPSC measures, including construction demarcation and perimeter erosion controls (see EPSC Plan Sheet C‐130) 4. Cut, stump, and grub areas within demarcated clearing limits 5. Stockpile materials for chipping and grinding 6. Remove overburden; stockpile material in designated area with appropriate EPSC measures 7. Conduct drilling and blasting, as needed; use mobile crusher to process material as needed 8. Conduct earthwork with cuts and fills pursuant to Civil Site Design Drawings 9. Construct laydown/staging area pursuant to Civil Site Design Drawings 10. Continuously apply EPSC measures to limit the amount of earth disturbance at any one time; apply temporary or permanent stabilization per the EPSC Plan set 11. Repair/replace/refresh EPSC measures (e.g., silt fence, erosion control mix, etc.), as needed to maintain their effectiveness until area is fully stabilized 12. Remove all temporary EPSC measures (e.g., silt fence, etc.) once upslope area is fully stabilized; apply seed and mulch to remaining exposed soils, as needed 3.3
Substation and O&M Building Construction and Stabilization Sequence
1. Flag extent of substation area to be cleared of trees 2. Clear trees within substation area footprint in accordance with the VT ANR Acceptable Management Practices for Maintaining Water Quality on Logging Jobs (1987), at a minimum; no stumping and grubbing at this time 3. Install EPSC measures, including construction demarcation and perimeter erosion controls (see EPSC Plan Sheet C‐130) 4. Cut, stump, and grub areas within demarcated clearing limits 5. Stockpile materials for chipping and grinding 6. Remove overburden; stockpile material in designated area with appropriate EPSC measures 7. Conduct drilling and blasting, as needed; use mobile crusher to process material as needed 8. Conduct geotechnical borings for O&M building design 9. Conduct earthwork with cuts and fills pursuant to Civil Site Design Drawings 10. Construct substation, O&M building, and related infrastructure pursuant to Civil Site Design Drawings 11. Continuously apply EPSC measures to limit the amount of earth disturbance at any one time; apply temporary or permanent stabilization per the EPSC Plan set 12. Repair/replace/refresh EPSC measures (e.g., silt fence, erosion control mix, etc.), as needed to maintain their effectiveness until area is fully stabilized 13. Remove all temporary EPSC measures (e.g., silt fence, etc.) once upslope area is fully stabilized; apply seed and mulch to remaining exposed soils, as needed 3.4
Turbine Pad and Permanent Stormwater Management System Construction and Stabilization Sequence
1. Flag extent of turbine pad area to be cleared of trees
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3.5
2. Clear trees within turbine pad footprint in accordance with the VT ANR Acceptable Management Practices for Maintaining Water Quality on Logging Jobs (1987), at a minimum; no stumping and grubbing at this time 3. Conduct geotechnical borings for foundation design 4. Install EPSC measures, including construction demarcation and perimeter erosion controls (see EPSC Plan Sheet C‐130) 5. Cut, stump, and grub areas within demarcated clearing limits 6. Stockpile materials for chipping and grinding 7. Remove overburden; stockpile material in designated area with appropriate EPSC measures 8. Conduct drilling and blasting, as needed; use mobile crusher to process material as needed 9. Conduct earthwork with cuts and fills pursuant to Civil Site Design Drawings; concurrently, install sediment traps (level spreaders, dry ponds) and sediment basins (wet ponds) located immediately downslope of active areas of earthwork per sediment details provided on EPSC Plan Sheets C‐127, C‐128, and C‐133 10. Excavate for turbine foundations; install foundations 11. Continuously apply EPSC measures to limit the amount of earth disturbance at any one time; apply temporary or permanent stabilization per the EPSC Plan set 12. Repair/replace/refresh EPSC measures (e.g., silt fence, erosion control mix, etc.), as needed to maintain their effectiveness until area is fully stabilized 13. As needed to maintain proper performance, remove accumulated sediment from sediment traps and sediment basins; deposit in an appropriate upslope location and stabilize per Temporary and Final Stabilization Notes on EPSC Plan Sheet C‐131 14. Once upslope area is fully stabilized, reconstruct sediment traps as level spreaders, and dry ponds and sediment basins as permanent stormwater basins per EPSC Plan Sheets C‐127 and C‐128 and pursuant to operational phase Stormwater Plan Set 15. Remove all temporary EPSC measures (e.g., silt fence, etc.) once upslope area is fully stabilized; apply seed and mulch to remaining exposed soils, as needed Overhead Collector Line Construction and Stabilization Sequence
1. Flag extent of overhead collector line right‐of‐way (ROW) to be cleared of trees 2. Clear trees within ROW footprint in accordance with the VT ANR Acceptable Management Practices for Maintaining Water Quality on Logging Jobs (1987), at a minimum; no stumping and grubbing at this time 3. Demarcate extent of ROW to be used for installation of approximately 10‐foot wide access routes and approximately 20‐ by 20‐foot work areas surrounding each pole. 4. Install EPSC measures, including perimeter erosion controls, where needed (see EPSC Plan Sheet C‐130) 5. Stockpile materials for chipping and grinding (note that other areas of the project may be used for this operation, such as the access road) 6. Install poles pursuant to collector design drawings; holes for poles are approximately 2 feet in diameter and approximately 8 feet in depth 7. Spread drill spoils material adjacent to hole in non‐wetland areas then seed and mulch when required 8. Conduct wire installation and any other collector line installation activities pursuant to collector design plans Page 6 of 7
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9. Continuously apply EPSC measures to limit the amount of earth disturbance at any one time; see Temporary and Final Stabilization Notes on EPSC Plan Sheet C‐131 10. Repair/replace/refresh EPSC measures (e.g., silt fence, erosion control mix, etc.), as needed to maintain their effectiveness until areas are fully stabilized 11. Remove all temporary EPSC measures (e.g., silt fence, etc.) once upslope area is fully stabilized; apply seed and mulch to remaining exposed soils, as needed 3.6
Changes in Work
It is expected that the OPSC and EPSC Specialist may modify the Construction and Stabilization Sequence and associated EPSC measures provided on the EPSC Plan, as needed, throughout the construction of the project. Modifications will be made in response to actual construction conditions and/or limitations encountered. It is the responsibility of the OPSC and EPSC Specialist to report significant plan modifications and to review those modifications and any updates of the Construction and Stabilization Sequence with VT DEC throughout the construction of the Project, as required, and as such modifications and updates occur. \\VTDATA\Projects\57346.03 GMP KCW SW Permitting\tech\KCW Const Phasing Plan_110810.doc
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YR D
TH
Indirect Study Area
not rated
D
C
B
A
NRCS Soil Hydrogroup
500 ft. Contour
100 ft. Contour
Wind Farm Direct Study Limits
Town/County Boundary
Parcel Boundaries
Vermont State Highway
Local Road
12D K Factor 0.24
12D K Factor 0.24
247C K Factor 0.26
247B K Factor 0.2
LyE K Factor 0.26
100
"
RD
26C K Factor 0.17
EK ME
0 250
Legend
26C K Factor 0.17
0
Y
RD
November 4, 2010
N BA L A
RD
0
Scale - 1" = 2000'
1,000
2,000 Feet
0 15
0
0 15
0
23 Prepared by: SEM/JAT
Sources: Town/County Layer (2004), roads layer (2009), Soils (2008) provided by VCGI (2010); Direct Study Limits and Indirect Study Area by VHBP (2009).
Soil Description Lyman-Tunbridge fine sandy loams, very rocky, 25 to 60 percent slopes Londonderry-Stratton complex, 25 to 60 percent slopes Monadnock fine sandy loam, 15 to 35 percent slopes, very stony Cabot silt loam, 0 to 8 percent slopes, very stony Sheepscot gravelly fine sandy loam, 3 to 8 percent slopes Adams loamy fine sand, 25 to 60 percent slopes Adams loamy fine sand, 8 to 15 percent slopes Adams loamy fine sand, 3 to 8 percent slopes Colonel-Cabot complex, 8 to 15 percent slopes Colonel-Cabot complex, 3 to 8 percent slopes Dixfield sandy loam, 15 to 35 percent slopes, very stony Tunbridge-Lyman complex, 35 to 60 percent slopes, very rocky Tunbridge-Lyman complex, 15 to 35 percent slopes, very rocky Hogback-Rawsonville complex, 35 to 60 percent slopes, very rocky Hogback-Rawsonville complex, 15 to 35 percent slopes, very rocky Tunbridge-Dixfield complex, 15 to 35 percent slopes, very stony
112D K Factor 0.49
12E K Factor 0.24
EDEN RD
RD LL HI
F:\57346.00\GIS\project\Stormwater\KCW_Site_soils_reformat_11x17.mxd
Soil ID LyE LoE 93D 59B 31B 26E 26C 26B 247C 247B 16D 12E 12D 112E 112D 101D
SH IRI
12E K Factor 0.24
112E K Factor 0.49
Kingdom Community Wind Lowell, Vermont Soils Map - Wind Farm
LoE K Factor 0.46
U
L
U IE
101D K Factor 0.26
LO RL WE L EA NS L (L CO AM EDE .) N OI LL E C O. ) (O
A BE
93D K Factor 0.28
59B K Factor 0.32
12E K Factor 0.24
16D K Factor 0.28
0 15
0
16D K Factor 0.28
31B K Factor 0.17
TH 3
RD W
E
26E K Factor 0.17
SO
U
G PA
D ER
CH EN E
26C K Factor 0.17
26B K Factor 0.17
1500 FID
RD
RD MINK FARM RD DL ER S EL BO W
0 10 0
BOU
250 0
0 25 0
D ET R S QU
0
2 TH 5
(O LOW RL E E AN LL S (O ALB C R O. LE AN ) AN Y S CO .)
ER
200 0
1500
0
1500
HAZEN
10 0
FARM RD
RD
15 0
Y BAILE
W CO S LE
