SEPA RULES
DETERMINATION OF NONSIGNIFICANCE
DESCRIPTION OF PROPOSAL: Frenchman Coulee Recreational Improvement Project.
RCW 197-11-970
DETERMINATION OF NONSIGNIFICANCE
DESCRIPTION OF PROPOSAL: Frenchman Coulee Recreational Improvement Project.
The proposed in-water and upland facilities, other than some of the trail work, will be constructed in the existing 4.1 acre disturbed footprint, A 5’ stabilized gravel trail will be developed on existing user defined paths for 800 feet south of the upper picnic area. The remaining user defined trails along the stabilized gravel trail corridor will be reclaimed using native upland seed. Beyond the stabilized gravel trail a single user defined path will be delineated with native stones and the remaining user defined paths will be reclaimed with native upland seed.
In water work includes the following:
• Boat Ramp -The proposed boat ramp would include a new concrete approach apron, a single 20’ ft. wide concrete launch lane and a concrete float abutment. The ramp would be constructed on a 12” thick prepared gravel foundation with steel rail frame to support the precast panels.
• Handling Floats - A series of five handling floats, each 6’ wide and 20’ long would be constructed to facilitate launching and retrieval of trailered boats. The floats would be secured with four 12.75” diameter steel pipe piles and connect to the concrete abutment via a 6’ wide by 10’ long transfer span.
• Navigation Channel - The proposed navigation channel would be formalized and improved by dredging to widen the channel to 30 ft. and deepened to an elevation of 563.3’. Five navigation aids will be installed to mark the navigation channel. These will consist of dayboards mounted on 12.75” diameter steel pipe piles meeting U.S. Coast Guard standards for private aids to navigation. The 12” diameter piles are standard in the pile driving industry. The very dense and cobble-laden setting necessitates the use of open-end cutting shoes, which are heat-treated cast flanges that reinforce the pile tip, and are available in standard dimensions. The 12” piles provide greater impact protection to the facility from potential vessel impacts.
• Navigation Channel Side Slope Stabilization - The proposed navigation channel side slopes will be stabilized with rock (quarry spalls) and will include riparian plantings within a limited elevation zone near OHWM (east side only). The purpose is to protect exposed slopes against waves and currents, to minimize new work and maintenance dredging, and provide riparian habitat as project mitigation along the channel near the boat launch. Channel slope stabilization will be installed along the edge of the boat ramp and navigation channel side slopes. Slopes will vary from 2:1 to 5:1 as shown on sheets 5 & 6 of 21. Slope stabilization materials will consist of 1.0 ft. to 1.75 ft. thick layer of quarry spall material with a maximum size of 10”.
• Rock Jetty - The proposed modified rock jetty will increase wave protection for the improved boat launch and provide a location for riparian plantings. It would consist of removing and/or reconfiguring the large existing jetty rock, installing new riprap to extend its width and raise the rock jetty, and backfilling the riprap jetty with suitable substrates to support native riparian vegetation as onsite mitigation. The modified jetty will extend along the improved boat ramp approximately 50 ft. south of existing OHWM line. The waterward slope of the jetty will be 2H:1V and the jetty crest will have an elevation of approximately OHWM (575.0’). The new riprap thickness will be approximately 2.5 ft. with median rock size of approximately 1.25 ft.
• Streambed Enhancement (Habitat Improvement) - The proposed improvements include the installation of natural rounded gravel/cobble habitat fill below OHWM to improve substrates along the existing submerged roadbed south of the jetty improvements as shown in sheet 5 of 21. Stabilization of the old roadbed beyond the proposed boat ramp may reduce future maintenance dredging activities. Fill material will be composed of a mixture of natural rounded gravel and cobble placed approximately 1 ft. thick atop the existing roadbed, including those areas where existing asphalt is to be removed.
• Existing Riprap Voids (Habitat Improvement) - This work item is contingent upon the availability of suitable dredged material from the Frenchman Coulee Project for beneficial reuse at this project site. Voids in the existing large riprap (2 feet to 6 feet in diameter) would be filled will native materials composed of gravel, cobble, and sand. Clean and appropriately sized granular dredged material from the Frenchman Coulee Project would be beneficially reused to fill the voids by evenly spreading the material from a barge, floating work platform, or from land based equipment.
Upland work includes the following:
• Access Road – The site access road, Old Vantage Highway, will become a one-way road south of the project boundary and will be reduced in width, increasing the buffer between the top of the bank and the edge of pavement from 2’+/- to 9’+/-. The pavement will be cut and removed along the west edge of the existing road and a gravel and planted filter strip will be installed on both sides of the roadbed to improve water quality from stormwater run-off. The entrance road will be repaired with asphalt patch crack sealer and the entire surface will be sealed to minimize future deterioration. No improvements to the access road are proposed north of the project boundary.
• Maneuver Area –The proposed paved maneuver area provides access to the new concrete boat launch and parking area from the single lane entrance road. The paved surface will be hot mix asphalt (HMA) over a gravel base. There will be no accommodation at the site for a make ready or tie down area for boaters. A gutter will be placed at the top of the boat launch apron to collect stormwater and direct it to a basin located immediately to the west of the top of the proposed boat launch.
• Auto Parking and Ramp – The proposed auto parking area will be paved to provide long-term ADA accessibility and reduce maintenance. A 10% ramp is necessary on the site to provide accessible parking. The parking access ramp will be paved to prevent the erosion and corrugation associated with a gravel surface. Paint will delineate the spaces with the ADA spaces marked with signage and painted legends. The paved surface will be hot mix asphalt (HMA) over a gravel base. Stormwater run-off will be directed to the extent possible to new stormwater handling basins to the west and south of the paved parking area and ramp.
• Tow Vehicle Parking – The proposed parking improvements include 19 gravel tow vehicle spaces (10 ft. x 45 ft.). The tow vehicle spaces will be delineated with concrete wheel stops. Embedded basalt rocks will serve as vehicle barriers and will delineate parking areas from the channelization/stormwater treatment islands within the parking lot. The parking area will continue to be separated from the Old Vantage Highway by a swale, which will be slightly reshaped and re-vegetated with native grasses. The tow vehicle parking area will be accessed through the auto parking area by a 25 ft. wide one-way gravel drive aisle. A concrete gutter will provide stabilized overflow for the swale to the stormwater handling basin located west of the boat ramp.
• Lower Picnic Area and Vault Toilet - The proposed lower picnic area and single vault toilet will be accessed by an 8 ft. wide concrete walkway extending from the parking to the picnic area to the northeast and south to the single vault toilet. A single vault toilet will be placed along the west edge of the concrete walkway approximately 105 ft. from the ordinary high water line. The below grade storage vault for the restroom facility will be installed in an approximately 8 ft. deep excavation and backfilled with suitable native material or import backfill. The lower picnic facility will be proximate to the ADA parking spaces and will be concrete pavement. The picnic area includes 2 accessible concrete picnic tables and 2 above ground accessible barbecue grills. The walk at the picnic area will be bordered to the east by an approximately 2 ft. high rock retaining wall and fencing to retain slope and limit visitor access to undisturbed upland areas.
• Upper Picnic Area - The proposed upper picnic area will be accessed by an 8 ft. wide stabilized gravel accessible trail. The picnic plaza will be constructed of stabilized gravel and will include 3 concrete picnic tables and 3 above ground barbecue grills. The picnic plaza and a portion of the access trail will be bordered on the east edge by an approximately 2 ft. high rock retaining wall. Fencing will be installed at the intersection of the concrete walkway from the vault toilet and the gravel access trail to the upper picnic area to limit visitor access to undisturbed upland areas. Stormwater run-off from the plaza will pass through openings in the seat wall and discharge to a stabilized swale connecting to the riparian planting terrace between the upper picnic area and the proposed boat launch.
• Shoreline Trail - The proposed trail improvements at the site will formalize acceptable routes to the boat launch, picnic areas and the single vault toilet at the boat launch site. Approximately 910 lineal feet of stabilized gravel trail will travel south along the Columbia River shoreline to a loop at the end and return to the upper picnic plaza. This ADA accessible trail will be 5 ft. wide and 6” thick over geotechnical fabric. The shoreline trail will have an ADA accessible surface, width and vertical grade.
PROPONENT: Public Utility District No. 2 of Grant County, Washington
LOCATION OF PROPOSAL, INCLUDING STREET ADDRESS, IF ANY:
The proposal will be located at the existing public boat launch facility at Frenchman Coulee and is located on the Columbia River at the end of the Old Vantage Highway in Grant County in Sections 06 and 31, Township 17 North and 18 N, Range 23 E.
(46 59’58.33”N lat.; -119 59” 24.51” W long)
LEAD AGENCY: Public Utility District No. 2 of Grant County, Washington
The lead agency for this proposal has determined that it does not have a probable significant adverse impact on the environment. An environmental impact statement (EIS) is not required under RCW 43.21C.030 (2)(c). This decision was made after review of a completed environmental checklist and other information on file with the lead agency. This information is available to the public on request.
o There is no comment period for this DNS.
o This DNS is issued after using the optional DNS process in WAC 197-11-355. There is no further comment period on the DNS.
6 This DNS is issued under WAC 197–11–340(2); the lead agency will not act on this proposal for 14 days from the date below. Comments must be submitted by March 07, 2013 5:00 PM Pacific Standard Time.
Responsible official: J. Darrell Pock
Position/title: Project Specialist III
Phone: (509) 754-5098
Address: P.O. Box 878
30 C St. SW
Ephrata, WA 98823
Date: 2/14/2013 Signature: /s/ ____________________________________
J. Darrell Pock, Project Specialist III
6 There is no agency appeal.
#02079/2902330/2902423
Pub.: February 21 & 28, 2013