STREAM BANK STABILIZATION THORPS MORTIMER RECREATION AREA Grandfather Ranger District SITE LOCATION & DRAINAGE AREA

Transcription

1 STREAM BANK STABILIZATION THORPS MORTIMER RECREATION AREA SITE LOCATION & DRAINAGE AREA SITE LOCATION Drainage Area = 1.14 sq. miles

2 STREAM BANK STABILIZATION THORPS MORTIMER RECREATION AREA PROJECT SUMMARY PROJECT BACKGROUND: The stream channel is currently impacted by stream bank hardening from log crib walls and a loss in streamside vegetation from recreation site development and foot traffic. As a result, sections of stream bank within the reach are unstable; aquatic habitat diversity is lacking; and streamside and alluvial forests are degraded. The Thorps Creek drainage is 1.14 square miles in size and is mostly forested and predominantly in federal ownership. Past management in the watershed within the last hundred years included logging much of the timber using roads, railroads, and possibly splash dams to transport timber downstream to local mills. Following harvest, much of the flatter terrain was used for farming and small homesteads. PROJECT PURPOSE & NEED: The goals of this project are to improve the health of the stream ecosystem by improving channel stability and habitat quality, along with improving riparian and streamside vegetation conditions. The desired condition is to have high quality riparian areas and aquatic habitat features that maintain hydrologic function, enhance stream stability, minimize erosion, and maintain the attributes which qualify Wilson Creek as a Wild and Scenic River, and maintain the State classification for Thorps Creek of Class C, Trout, and Outstanding Resource Waters. The proposed action is needed at this time, at these locations, because taking no action would lead to further erosion and sedimentation which, in turn, would cause further damage to aquatic habitat and recreation sites. SUMMARY OF PROPOSED WORK: 1) Lay back ~ 700 feet of eroding stream bank to a 2:1 (rise:run) slope and replace the footbridge following the proposed stream work, 2) Remove three old fish structures, 3) Construct up to three log and boulder vanes and two constructed riffles. The instream structure below the fish barrier would create a pool to improve passage of trout, and 4) Implement erosion control measures, including native seed, straw mulch, coir matting on stream banks, planting trees and shrubs, and installing split rail fence for long term stabilization. A medium sized trackhoe shall be used, along with a dump track truck in the construction of this project. All disturbed area shall be seeded and mulched. This work is estimated to cost $48,290, including NEPA, design, permitting, and contract and Force Account implementation. 5) At the existing FSR 116 crossing of Thorps Creek, remove the vented ford crossing and install a crossing designed to pass fish. This part of the project would be accomplished using funds other than Watershed Condition Improvement funding.

3 Cross Section A A A A SIDESLOPE LOWER STREAM BANK STABILIZATION THORPS MORTIMER RECREATION AREA PLAN VIEW SKETCH EXISTING CONDITION CHANNEL & SMALL FLOODPLAIN FEATURES MORTIMER WORK CENTER TO VENTED FORD XING BATHROOM HWY 90 FOOTBRIDGE CAMP SITE #2 A TERRACE KIOSK ACCESS ROAD FSR 116 OLD FISH STRUCTURE () Picnic area A TERRACE BANK EROSION FAILING CRIB WALL SEASONAL FISH BARRIER CRIB WALL 2004 FLOOD DEPOSITION FLOODPLAIN BANK EROSION ESTES MILL CR. CONFLUENCE PARTIAL FISH PASSAGE BARRIER DUE TO 1 DROP & HIGH VELOSITY THRU PIPE TERRACE

4 Cross Section A A A A SIDESLOPE LOWER STREAM BANK STABILIZATION THORPS MORTIMER RECREATION AREA PLAN VIEW SKETCH W/ PHOTO POINTS CHANNEL & SMALL FLOODPLAIN FEATURES MORTIMER WORK CENTER TO VENTED FORD XING (PP #1) BATHROOM HWY 90 FOOTBRIDGE OLD FISH STRUCTURE () CAMP SITE #2 A TERRACE PP #3 PP #4 PP #2 A TERRACE BANK EROSION PP #6 PP #5 FAILING CRIB WALL SEASONAL FISH BARRIER CRIB WALLPP #7 KIOSK ACCESS ROAD FSR FLOOD DEPOSITION FLOODPLAIN BANK EROSION PP #8 ESTES MILL CR. CONFLUENCE PARTIAL FISH PASSAGE BARRIER DUE TO 1 DROP & HIGH VELOSITY THRU PIPE Photo Log: PP#1 Vented ford crossing PP#2 Old fish structure () PP#3 Thorps Cr. between and fish barrier, looking downstream PP#4 Natural Fish barrier PP#5 Failing crib wall, right bank PP#6 crib wall, left bank PP#7 Thorps Cr. looking upstream at crib wall & footbridge PP#8 Thorps Cr. looking upstream from Hwy 90 culvert TERRACE

5 Photo #1 Vented ford crossing. Photo #2 Old fish structure (). Photo #3 Thorps Cr. between and fish barrier, looking downstream. Photo #4 Seasonal Fish barrier.

6 Photo #5 Failing crib wall, right bank. Photo #6 crib wall, left bank. Photo #7 Thorps Cr. looking upstream at crib wall & footbridge. Photo #8 Thorps Cr. looking upstream from Hwy 90 culvert.

7 Cross Section A A A A SIDESLOPE LOWER STREAM BANK STABILIZATION THORPS MORTIMER RECREATION AREA PLAN VIEW SKETCH PROPOSED ACTION LAY BACK STREAM BANKS TO A 2:1 SLOPE CHANNEL & SMALL FLOODPLAIN FEATURES MORTIMER WORK CENTER TO VENTED FORD XING BATHROOM HWY 90 FOOTBRIDGE CAMP SITE #2 A TERRACE KIOSK ACCESS ROAD FSR FLOOD DEPOSITION ESTES MILL CR. CONFLUENCE OLD FISH STRUCTURE () A TERRACE SEASONAL FISH BARRIER Proposed Action: 1) Lay back ~ 700 feet of eroding stream bank to a 2:1 (rise:run) slope and replace the footbridge, 2) Remove three old fish structures, 3) Construct up to three log and boulder vanes and two constructed riffles, and 4) Implement erosion control measures, including native seed, straw mulch, coir matting on stream banks, planting trees and shrubs, and installing split rail fence for long term stabilization. A medium sized trackhoe shall be used, along with a dump track truck in the construction of this project. All disturbed area shall be seeded and mulched. 5) At the existing FSR 116 crossing of Thorps Creek, remove the vented ford crossing and install a crossing designed to pass fish. This part of the project would be accomplished using funds other than Watershed Condition Improvement funding. FLOODPLAIN TERRACE KEY: = log & boulder vane = constructed riffle = bank sloping = pool habitat PARTIAL FISH PASSAGE BARRIER DUE TO 1 DROP & HIGH VELOSITY THRU PIPE

8 STREAM BANK STABILIZATION THORPS MORTIMER RECREATION AREA ESTIMATED COSTS Description Quantity Unit Unit Price Totals ITEM 1. MORTIMER REC. AREA - Thorps CREEK WATERSHED IMPROVEMENT PROJECT 1A. EQUIPMENT & LABOR Track hoe w/ hydraulic thumb & operator 75 hours $130 $9,750 Mobilization 1 each $1,500 $1,500 Dump track-truck w/ operator 10 hours $100 $1,000 1B. MATERIALS Furnish boulders for Vanes (40 each) & Riffles (60 each) 100 ton $50 $5,000 Furnish and install nonwoven geotextile in log vanes 40 square yard $6 $240 1C. EROSION & SEDIMENT CONTROL Furnish & install silt fence 200 linear feet $4 $800 Seed & mulch all disturbed soil 1000 square yard $2 $2,000 Furnish & install riparian planting (bare root) 300 each $5 $1,500 Furnish & install coir mat 700 (includes live staking) 400 square yard $10 $4,000 Estimated Contract Cost: $25,790 ADMINISTRATION NEPA - EA 1 each $4,700 $4,700 Design & Inspection of Contract 20 days $390 $7,800 Estimated Admin. Cost: $12,500 GRANDFATHER DISTRICT FORCE ACCOUNT Furnish & install split-rail fence 1000 linear feet $10 $10,000 Estimated Force Account Cost: $10,000 Total Costs: $48,290