green mountain power kingdom community wind transmission line ...
Erosion Prevention and Sediment Control Plan Narrative for Individual Discharge Permit for Stormwater Runoff from Construction Sites
GREEN MOUNTAIN POWER KINGDOM COMMUNITY WIND TRANSMISSION LINE PROJECT Lowell, Vermont
Prepared for
Green Mountain Power Corporation
Prepared by
Vanasse Hangen Brustlin, Inc. 7056 U.S. Route 7 North Ferrisburgh, VT 05473
March 15, 2011
GREEN MOUNTAIN POWER CORPORATION / KINGDOM COMMUNITY WIND / TRANSMISSION LINE PROJECT EROSION PREVENTION AND SEDIMENT CONTROL PLAN NARRATIVE
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Table of Contents
1.0 Introduction ............................................................................................................................. 1 2.0 Project Description .................................................................................................................. 3 3.0 Location Map ......................................................................................................................... 11 4.0 Preconstruction, Construction, and Stabilization Plan .................................................... 11 References ..................................................................................................................................... 11
GREEN MOUNTAIN POWER CORPORATION / KINGDOM COMMUNITY WIND / TRANSMISSION LINE PROJECT EROSION PREVENTION AND SEDIMENT CONTROL PLAN NARRATIVE
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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 to the Vermont Department of Environmental Conservation (VT DEC) for the planned construction of the Kingdom Community Wind’s Transmission Line Project (KCW’s Transmission Line Project) located in the Towns of Lowell, Westfield, and Jay, 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. Construction of approximately 2.5 miles of a 46 kV transmission line from the base of the wind farm site, running generally parallel and adjacent to Vermont Route 100 North, to Vermont Electric Cooperative’s (VEC’s) Lowell #5 Substation and Irasburg #21 Substation. This new transmission line will co-locate and consolidate existing electric distribution circuits (12 kV) and telecommunications lines along the Route 100 corridor, eliminating several existing double pole lines (one for electric and one for telecommunications). 2. Consolidation and upgrade of Lowell #5 Substation and Irasburg #21 Substation into the footprint of the Irasburg #21 Substation (renamed Lowell #5 Substation) and decommissioning of the existing Lowell #5 substation,
A petition for Section 248 approval of the Kingdom Community Wind Project from the Vermont Public Service Board (VT PSB) was initially filed on May 21, 2010 and is currently pending. Draft INDS and INDC permits were issued by VT DEC on January 27, 2011 and January 28, 2011, respectively, and are currently pending final issue.
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including removal of equipment and restoration of the decommissioned area of the existing Lowell #5 substation. 3. Replacement of the existing approximately 10.4-mile 34.5 kV transmission line to a 46 kV transmission line from the upgraded Lowell #5 Substation, running generally parallel and adjacent to Vermont Route 100 North, North Hill Road, and Cross Road, to VEC’s Jay #17 Substation at the intersection of Vermont Route 242 and Cross Road. The upgraded line will be relocated from field locations to roadside in several locations to facilitate simpler line maintenance in the future. 4. Upgrade of the existing 40+ year old Jay #17 Substation within the existing substation fence line and converting it to 46 kV. 5. Construction of approximately 2 miles of new 46 kV transmission line in an existing three phase distribution corridor. The newly constructed line will co-locate the transmission, distribution and telecommunications lines in this area. The line will extend from the Jay #17 substation north along Cross Road to an intersection with the VELCO transmission line that extends east/west along VT Route 105.
Completion of the Risk Evaluation determined that KCW’s Transmission Line Project is not eligible for coverage under General Permit 3-9020 as a Low Risk or 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 (enclosed 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 11 of the Appendix.
GREEN MOUNTAIN POWER CORPORATION / KINGDOM COMMUNITY WIND / TRANSMISSION LINE PROJECT EROSION PREVENTION AND SEDIMENT CONTROL PLAN NARRATIVE
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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 KCW’s Transmission Line Project involves the construction of a new 46 kV transmission line that is located at the base of the wind farm site and extends approximate 2.5 miles to VEC’s Lowell #5 Substation. From the newly rebuilt Lowell #5 substation, the existing 34.5 kV line will be reconstructed for approximately 10.4 miles north to VEC’s Jay #17 Substation, then 2.0 miles from the Jay #17 Substation to the existing Vermont Transco LLC (VELCO) 46 kV transmission line. The upgraded 46 kV transmission line will have a single pole configuration that is similar to the existing 34.5 kV line. In addition to transmission line upgrades, KCW’s Transmission Line Project also involves upgrades to these two aforementioned substations, with all improvements to occur within the existing fence lines. In general, the project is located within an existing corridor with the minor exception of a small portion of the right-of-way that will be moved closer to Vermont Route 100 for improved maintenance access and/or to address existing right-ofway infringements. Additional tree clearing is also anticipated to reclaim the existing right-of-way to 50-feet to maintain reliability and address potential presence of danger trees.
b. Major Project Components As outlined in the introduction, major project components consist of limited vegetation removal, access route and laydown/staging area preparation, installation of new pole
GREEN MOUNTAIN POWER CORPORATION / KINGDOM COMMUNITY WIND / TRANSMISSION LINE PROJECT EROSION PREVENTION AND SEDIMENT CONTROL PLAN NARRATIVE
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structures, removal of existing pole structures, substation upgrades, and final grading, stabilization and cleanup. The following is a brief description of each of these major project components, including installation of erosion prevention and sediment control (EPSC) measures prior to any major earth disturbing activities.
Vegetation Clearing: Minimal removal of vegetation is anticipated in areas where the right-of-way is to be reclaimed to the full 50-foot width in order to maximize reliability and address potential danger trees. Additional vegetation removal may involve mowing along access routes and adjacent to structures to facilitate construction activities.
Access Route and Laydown/Staging Area Preparation: Access routes and laydown/staging area preparation may include placement of stone on geotextile fabric at access points from public roads, as well as areas within the approximately 10-foot-wide access routes and staging/laydown yards where soil disturbance is anticipated. An alternative to stone on fabric may involve installation of swamp mats in order to provide a stable work surface.
New Pole Structure Installation: Installation of new pole structures may involve establishing a temporary work area of a typical 20-foot by 20-foot size followed by pole hole excavation. Pole hole excavation may include rock coring, and will be conducted via a backhoe, excavator, or track mounted auger, depending on ground conditions. Once installed, excavated material will be backfilled into the hole and around the outside of the pole, excess material evenly spread around the base of the pole, then seeded and mulched, as needed. Selected EPSC measures will be installed on the down-gradient side of work areas that are located in areas that have moderate to high potential for soil erosion, are on steep slopes, and/or are located adjacent to receiving waters. Staging of materials (e.g., soil
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stockpiles) will be located in upland areas with proper temporary stabilization. Determination of location of stockpiled materials and EPSC measures required shall be at the direction of the OSPC.
Old Pole Structure Removal: Access to old pole structures that are to be removed will generally be achieved by way of the same access routes that will be utilized for installation of new pole structures. Replaced poles will be removed from the ground and properly disposed. Holes left behind by the removal of the poles will generally be filled with sand, gravel, and/or soil and then covered with soil, seed, and mulch. Any disturbed soil resulting from these activities will be seeded (as needed) and mulched for stabilization.
Substation Upgrades: Upgrades to the Lowell #5 and Jay #17 substations will involve decommissioning and removal of components that are being replaced, including the removal of existing foundations, installation of new concrete foundations and underground conduits. Access of equipment to the substations will occur via existing driveways, with maintenance (e.g., street sweeping) to be conducted, as needed.
The Jay #17 substation will require construction of a temporary substation (approximately 30 feet x 50 feet). The temporary substation will be constructed in a field area north of the existing substation. The temporary substation will be constructed on a gravel fill placed over geo-textile fabric. The temporary substation will be constructed with proper oil containment for the installed equipment. Once the Jay #17 substation has been commissioned, the temporary substation will be removed in its entirety and the field area restored to its preconstruction condition.
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All activities associated with upgrade of the two substations will be occurring within existing fence-lines. After decommissioning of the existing Lowell #5 substation, the area will be covered with topsoil then seeded and mulched, as needed, to stabilize and restore the area.
Final Grading, Stabilization and Cleanup: As pole installation and removal is completed, areas of earth disturbance will be properly graded (as needed) and stabilized. In addition, any excessive rutting that was caused during construction will be repaired, as needed. Final stabilization will involve seeding (as needed) and mulching and/or applying erosion control matting to areas of disturbed soil, where final grad has been achieved. All scrap materials will be removed from the right-of-way and salvaged or scrapped, as appropriate.
c. Total Earth Disturbance The total area of disturbance associated with the project is estimated to be 10.4 acres. 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 per the permit.
d. Sequence of Major Project Components The sequence of construction of major project components will involve multiple work crews, with specific work crews associated with substation upgrades and other work crews associated with the transmission line. The following is an overview of sequencing associated with each of those two major project components.
SUBSTATIONS: Jay #17 Substation
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1. Temporary construction of Jay #17 substation and transfer of electric load to the temporary substation 2. Decommissioning of the existing substation 3. Below grade construction (foundations, conduit, etc.) 4. Erection of substation structure 5. Commissioning of new substation 6. Removal of temporary substation 7. Final stabilization and restoration
Lowell #5 Substation
1. Decommissioning of existing equipment in Irasburg #21 2. Below grade construction (foundations, conduit, etc.) 3. Erection of substation structure 4. Commissioning of substation 5. Decommissioning of Lowell #5 substation 6. Final stabilization and restoration
TRANSMISSION LINE: Phase I
1. Construction of the transmission corridor from the VELCO 46 kV line at the intersection of Route 105 and Cross Road to the temporary substation at Jay #17 2. Construction of the transmission corridor from the Kingdom Community Wind Farm to the new Lowell #5 substation (formerly the Irasburg #21 substation)
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3. Transfer of distribution lines to the newly constructed transmission corridors 4. Removal of the existing lines and poles 5. Final stabilization and restoration
Phase II
1. Re-construction of the transmission corridor from Lowell #5 to Jay #17 2. Transfer of distribution lines to the newly constructed transmission corridors 3. Removal of the existing lines and poles 4. Final stabilization and restoration
e. Maximum Concurrent Earth Disturbance The total maximum concurrent earth disturbance will be 7 acres, as referenced in the Risk Evaluation (see pages 1 through 3 of the Appendix).
f.
Vegetated Buffers
Vegetative buffers will be utilized to the extent possible to supplement structural EPSC measures. 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).
g. Duration of Exposed Soils The total duration of exposed soil will be 14 days from initial disturbance, as referenced in the Risk Evaluation (see pages 1 through 3 of the Appendix).
h. Receiving Waters
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There are eleven (11) potential receiving waters that are located within the project areas, as shown on the Site Location Map on page 12 of the Appendix. These receiving waters include: Coburn Brook, Crook Brook, East Branch of the Mississquoi River, Jay Branch, LeClair Brook, Mill Brook, Mississquoi River, Taft Brook, and three unnamed tributaries to Mississquoi River. As shown on the EPSC Plan, EPSC measures will be installed as needed to protect receiving waters during construction.
These measures will be
installed in compliance with the Vermont Standards and Specifications for Erosion Prevention and Sediment Control.
i.
Drainage Areas and Soil Types
For this generally linear project, drainage areas have been determined by major watershed areas, as outlined in section 2(h) above. A summary table on page 13 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 also shown on a corresponding Soils Map on page 14 of the Appendix. Soil types are also listed in the EPSC Plan Summary Forms (see page 6 of the Appendix). Of the approximately 10.4 acres of potential soil disturbance that have been estimated for this project, 2.08 acres have an erodibility rating of K≤0.18, 6.99 acres have an erodibility rating of 0.18
GREEN MOUNTAIN POWER KINGDOM COMMUNITY WIND TRANSMISSION LINE PROJECT Lowell, Vermont
Prepared for
Green Mountain Power Corporation
Prepared by
Vanasse Hangen Brustlin, Inc. 7056 U.S. Route 7 North Ferrisburgh, VT 05473
March 15, 2011
GREEN MOUNTAIN POWER CORPORATION / KINGDOM COMMUNITY WIND / TRANSMISSION LINE PROJECT EROSION PREVENTION AND SEDIMENT CONTROL PLAN NARRATIVE
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Table of Contents
1.0 Introduction ............................................................................................................................. 1 2.0 Project Description .................................................................................................................. 3 3.0 Location Map ......................................................................................................................... 11 4.0 Preconstruction, Construction, and Stabilization Plan .................................................... 11 References ..................................................................................................................................... 11
GREEN MOUNTAIN POWER CORPORATION / KINGDOM COMMUNITY WIND / TRANSMISSION LINE PROJECT EROSION PREVENTION AND SEDIMENT CONTROL PLAN NARRATIVE
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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 to the Vermont Department of Environmental Conservation (VT DEC) for the planned construction of the Kingdom Community Wind’s Transmission Line Project (KCW’s Transmission Line Project) located in the Towns of Lowell, Westfield, and Jay, 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. Construction of approximately 2.5 miles of a 46 kV transmission line from the base of the wind farm site, running generally parallel and adjacent to Vermont Route 100 North, to Vermont Electric Cooperative’s (VEC’s) Lowell #5 Substation and Irasburg #21 Substation. This new transmission line will co-locate and consolidate existing electric distribution circuits (12 kV) and telecommunications lines along the Route 100 corridor, eliminating several existing double pole lines (one for electric and one for telecommunications). 2. Consolidation and upgrade of Lowell #5 Substation and Irasburg #21 Substation into the footprint of the Irasburg #21 Substation (renamed Lowell #5 Substation) and decommissioning of the existing Lowell #5 substation,
A petition for Section 248 approval of the Kingdom Community Wind Project from the Vermont Public Service Board (VT PSB) was initially filed on May 21, 2010 and is currently pending. Draft INDS and INDC permits were issued by VT DEC on January 27, 2011 and January 28, 2011, respectively, and are currently pending final issue.
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including removal of equipment and restoration of the decommissioned area of the existing Lowell #5 substation. 3. Replacement of the existing approximately 10.4-mile 34.5 kV transmission line to a 46 kV transmission line from the upgraded Lowell #5 Substation, running generally parallel and adjacent to Vermont Route 100 North, North Hill Road, and Cross Road, to VEC’s Jay #17 Substation at the intersection of Vermont Route 242 and Cross Road. The upgraded line will be relocated from field locations to roadside in several locations to facilitate simpler line maintenance in the future. 4. Upgrade of the existing 40+ year old Jay #17 Substation within the existing substation fence line and converting it to 46 kV. 5. Construction of approximately 2 miles of new 46 kV transmission line in an existing three phase distribution corridor. The newly constructed line will co-locate the transmission, distribution and telecommunications lines in this area. The line will extend from the Jay #17 substation north along Cross Road to an intersection with the VELCO transmission line that extends east/west along VT Route 105.
Completion of the Risk Evaluation determined that KCW’s Transmission Line Project is not eligible for coverage under General Permit 3-9020 as a Low Risk or 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 (enclosed 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 11 of the Appendix.
GREEN MOUNTAIN POWER CORPORATION / KINGDOM COMMUNITY WIND / TRANSMISSION LINE PROJECT EROSION PREVENTION AND SEDIMENT CONTROL PLAN NARRATIVE
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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 KCW’s Transmission Line Project involves the construction of a new 46 kV transmission line that is located at the base of the wind farm site and extends approximate 2.5 miles to VEC’s Lowell #5 Substation. From the newly rebuilt Lowell #5 substation, the existing 34.5 kV line will be reconstructed for approximately 10.4 miles north to VEC’s Jay #17 Substation, then 2.0 miles from the Jay #17 Substation to the existing Vermont Transco LLC (VELCO) 46 kV transmission line. The upgraded 46 kV transmission line will have a single pole configuration that is similar to the existing 34.5 kV line. In addition to transmission line upgrades, KCW’s Transmission Line Project also involves upgrades to these two aforementioned substations, with all improvements to occur within the existing fence lines. In general, the project is located within an existing corridor with the minor exception of a small portion of the right-of-way that will be moved closer to Vermont Route 100 for improved maintenance access and/or to address existing right-ofway infringements. Additional tree clearing is also anticipated to reclaim the existing right-of-way to 50-feet to maintain reliability and address potential presence of danger trees.
b. Major Project Components As outlined in the introduction, major project components consist of limited vegetation removal, access route and laydown/staging area preparation, installation of new pole
GREEN MOUNTAIN POWER CORPORATION / KINGDOM COMMUNITY WIND / TRANSMISSION LINE PROJECT EROSION PREVENTION AND SEDIMENT CONTROL PLAN NARRATIVE
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structures, removal of existing pole structures, substation upgrades, and final grading, stabilization and cleanup. The following is a brief description of each of these major project components, including installation of erosion prevention and sediment control (EPSC) measures prior to any major earth disturbing activities.
Vegetation Clearing: Minimal removal of vegetation is anticipated in areas where the right-of-way is to be reclaimed to the full 50-foot width in order to maximize reliability and address potential danger trees. Additional vegetation removal may involve mowing along access routes and adjacent to structures to facilitate construction activities.
Access Route and Laydown/Staging Area Preparation: Access routes and laydown/staging area preparation may include placement of stone on geotextile fabric at access points from public roads, as well as areas within the approximately 10-foot-wide access routes and staging/laydown yards where soil disturbance is anticipated. An alternative to stone on fabric may involve installation of swamp mats in order to provide a stable work surface.
New Pole Structure Installation: Installation of new pole structures may involve establishing a temporary work area of a typical 20-foot by 20-foot size followed by pole hole excavation. Pole hole excavation may include rock coring, and will be conducted via a backhoe, excavator, or track mounted auger, depending on ground conditions. Once installed, excavated material will be backfilled into the hole and around the outside of the pole, excess material evenly spread around the base of the pole, then seeded and mulched, as needed. Selected EPSC measures will be installed on the down-gradient side of work areas that are located in areas that have moderate to high potential for soil erosion, are on steep slopes, and/or are located adjacent to receiving waters. Staging of materials (e.g., soil
GREEN MOUNTAIN POWER CORPORATION / KINGDOM COMMUNITY WIND / TRANSMISSION LINE PROJECT EROSION PREVENTION AND SEDIMENT CONTROL PLAN NARRATIVE
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stockpiles) will be located in upland areas with proper temporary stabilization. Determination of location of stockpiled materials and EPSC measures required shall be at the direction of the OSPC.
Old Pole Structure Removal: Access to old pole structures that are to be removed will generally be achieved by way of the same access routes that will be utilized for installation of new pole structures. Replaced poles will be removed from the ground and properly disposed. Holes left behind by the removal of the poles will generally be filled with sand, gravel, and/or soil and then covered with soil, seed, and mulch. Any disturbed soil resulting from these activities will be seeded (as needed) and mulched for stabilization.
Substation Upgrades: Upgrades to the Lowell #5 and Jay #17 substations will involve decommissioning and removal of components that are being replaced, including the removal of existing foundations, installation of new concrete foundations and underground conduits. Access of equipment to the substations will occur via existing driveways, with maintenance (e.g., street sweeping) to be conducted, as needed.
The Jay #17 substation will require construction of a temporary substation (approximately 30 feet x 50 feet). The temporary substation will be constructed in a field area north of the existing substation. The temporary substation will be constructed on a gravel fill placed over geo-textile fabric. The temporary substation will be constructed with proper oil containment for the installed equipment. Once the Jay #17 substation has been commissioned, the temporary substation will be removed in its entirety and the field area restored to its preconstruction condition.
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All activities associated with upgrade of the two substations will be occurring within existing fence-lines. After decommissioning of the existing Lowell #5 substation, the area will be covered with topsoil then seeded and mulched, as needed, to stabilize and restore the area.
Final Grading, Stabilization and Cleanup: As pole installation and removal is completed, areas of earth disturbance will be properly graded (as needed) and stabilized. In addition, any excessive rutting that was caused during construction will be repaired, as needed. Final stabilization will involve seeding (as needed) and mulching and/or applying erosion control matting to areas of disturbed soil, where final grad has been achieved. All scrap materials will be removed from the right-of-way and salvaged or scrapped, as appropriate.
c. Total Earth Disturbance The total area of disturbance associated with the project is estimated to be 10.4 acres. 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 per the permit.
d. Sequence of Major Project Components The sequence of construction of major project components will involve multiple work crews, with specific work crews associated with substation upgrades and other work crews associated with the transmission line. The following is an overview of sequencing associated with each of those two major project components.
SUBSTATIONS: Jay #17 Substation
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1. Temporary construction of Jay #17 substation and transfer of electric load to the temporary substation 2. Decommissioning of the existing substation 3. Below grade construction (foundations, conduit, etc.) 4. Erection of substation structure 5. Commissioning of new substation 6. Removal of temporary substation 7. Final stabilization and restoration
Lowell #5 Substation
1. Decommissioning of existing equipment in Irasburg #21 2. Below grade construction (foundations, conduit, etc.) 3. Erection of substation structure 4. Commissioning of substation 5. Decommissioning of Lowell #5 substation 6. Final stabilization and restoration
TRANSMISSION LINE: Phase I
1. Construction of the transmission corridor from the VELCO 46 kV line at the intersection of Route 105 and Cross Road to the temporary substation at Jay #17 2. Construction of the transmission corridor from the Kingdom Community Wind Farm to the new Lowell #5 substation (formerly the Irasburg #21 substation)
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3. Transfer of distribution lines to the newly constructed transmission corridors 4. Removal of the existing lines and poles 5. Final stabilization and restoration
Phase II
1. Re-construction of the transmission corridor from Lowell #5 to Jay #17 2. Transfer of distribution lines to the newly constructed transmission corridors 3. Removal of the existing lines and poles 4. Final stabilization and restoration
e. Maximum Concurrent Earth Disturbance The total maximum concurrent earth disturbance will be 7 acres, as referenced in the Risk Evaluation (see pages 1 through 3 of the Appendix).
f.
Vegetated Buffers
Vegetative buffers will be utilized to the extent possible to supplement structural EPSC measures. 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).
g. Duration of Exposed Soils The total duration of exposed soil will be 14 days from initial disturbance, as referenced in the Risk Evaluation (see pages 1 through 3 of the Appendix).
h. Receiving Waters
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There are eleven (11) potential receiving waters that are located within the project areas, as shown on the Site Location Map on page 12 of the Appendix. These receiving waters include: Coburn Brook, Crook Brook, East Branch of the Mississquoi River, Jay Branch, LeClair Brook, Mill Brook, Mississquoi River, Taft Brook, and three unnamed tributaries to Mississquoi River. As shown on the EPSC Plan, EPSC measures will be installed as needed to protect receiving waters during construction.
These measures will be
installed in compliance with the Vermont Standards and Specifications for Erosion Prevention and Sediment Control.
i.
Drainage Areas and Soil Types
For this generally linear project, drainage areas have been determined by major watershed areas, as outlined in section 2(h) above. A summary table on page 13 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 also shown on a corresponding Soils Map on page 14 of the Appendix. Soil types are also listed in the EPSC Plan Summary Forms (see page 6 of the Appendix). Of the approximately 10.4 acres of potential soil disturbance that have been estimated for this project, 2.08 acres have an erodibility rating of K≤0.18, 6.99 acres have an erodibility rating of 0.18
