Construction Progress Report

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Simon Sharp
5 years ago
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Report Date: 4/8/2017 Subject: Construction Week 2 70% Complete Project: Sunset Pond EWP Stream Reclamation, Fourmile Creek, Boulder County, CO Report By: TJ Burr, Civil Engineer/Stream Restoration

Installation of step-pools and cross vane at station 4+16 at downstream end of project. This step-pool structure has 4-steps of 12-18 inches.

1 Report Date: 4/8/2017 Subject: Construction Week 2 70% Complete Project: Sunset Pond EWP Stream Reclamation, Fourmile Creek, Boulder County, CO Report By: TJ Burr, Civil Engineer/Stream Restoration Specialist, tee.burr@wv.usda.gov Reporting Period: April 3-7, 2017 DESCRIPTION OF WORK COMPLETED: Rock cross-vane and rock toe at Sta 3+18 completed, except for planting. Installation of step-pools and cross vane at station 4+16 at downstream end of project. This step-pool structure has 4-steps of inches. Gaps in the rocks will allow fish passage during low flows. The contractor did not work on April 4 because there was 8-inches of snow at the site. At the end of the day on April 7, the new channel was completed except for installing geotextile at cross-vane and backfilling. After the cross-vane at upstream end is completed, we will divert the stream flow into the new channel, and then install the irrigation box. There was about 0.5 cfs of seepage flowing into the new channel during construction. Total stream flow was about 6.0 cfs. Material deliveries: None. Equipment: Bobcat E85 Excavator with 3-ft wide bucket & outside track width of 7.6 ft; skid steer; truck & trailer. The E85 moved some 3 ton boulders, but that was near its upper limit. PHOTOGRAPHS Sta 3+18 View Downstream Before Sta 3+18 After

The stream is incised at this location. Added bankfull bench on left side.

2 Page 2 of 5 Sta 3+18 Cross Vane with rock toe and step-pool This structure features a rock cross vane with a one foot drop over the apex rock into a 2-ft deep pool at this flow level (approx. 6 cfs). The stream is incised at this location. Added bankfull bench on left side. The eroded right bank will be vegetated and protected with erosion control fabric. Small fish and trout (2-6 ) were observed in pools.

This series of structures will protect the upstream pond by stopping the advancement of a headcut at this location. I do not have any good before photos, but there was a nearly vertical 3.

3 Page 3 of 5 Sta 4+16: Completed 4-step structure at the downstream end of project. This structure provides stability for width-depth ratio of channel; reconnection of floodplain; grade control at a headcut location; fish passage; and enhanced fish habitat. This series of structures will protect the upstream pond by stopping the advancement of a headcut at this location. I do not have any good before photos, but there was a nearly vertical 3.5 foot drop at this location that formed an advancing headcut and was a barrier to upstream fish migration. Rock used for this structure was an average of 3.5 ft x 2.5 ft x 2.5 ft. The rock is larger than required for this stream, but we used locally available material to reduce haul distance. Smaller rock, 12-inch DIA fills unwanted gaps between boulders. We did not use geotextile on these structures because the sandy-gravel-cobble mix in the backfill should be adequate to seal the small gaps.

The photo on the right shows a 1 ft x 1 ft slot to allow passage of 3 cfs flow during low flow. The flow must be above 3 cfs before the fire department can divert water into the water storage pond.

4 Page 4 of 5 Sta 1+00 at upstream start of project. These photos show progress at the end of the week on April 7 th. The new channel in its pre-flood location was completed, except for geotextile and backfilling of the cross-vane. The photo on the right shows a 1 ft x 1 ft slot to allow passage of 3 cfs flow during low flow. The flow must be above 3 cfs before the fire department can divert water into the water storage pond. We field-fit the new channel to cause the least disturbance to the existing vegetation. The new channel length is about 150 feet with 7 steps including the steps at 3 cross-vanes. We installed rock toe for locations that had weaker banks needing enforcement. The bankfull width is feet with a low flow channel width of 6 feet. After the cross-vane is finished, we will divert the water into the new channel and set the diversion box on the left side of the cross vane just upstream of the trees shown in the left photo. Completion of this work will provide better separation of the diversion ditch and the stream channel. The contractor will use excavated material and sediment on left side of new channel to fill the existing channel, which will serve as a floodplain.

5 Page 5 of 5 REMARKS: The excavation and grading work should be completed by April 14 th. Planting/revegetation will occur the following week. Impact on the stream s water quality has been minimal. Contractor has been using two sediment check dams downstream of work area. Erosion control wattles are placed in areas of concentrated surface runoff from disturbed ground. When sediment is added to the stream by construction work, it settles out within 1,000 feet downstream of project site. In most work sites, except for new channel reach, the disturbed materials consist of sand-gravel-cobble, which settles quickly. For the new channel, the main stream flow passes around the work site. REMINDERS: The contractor will have to go back into the new channel reach to do some manual chinking and backfilling of rock toe, step-sills, and cross-vanes to fill voids that couldn t be done with the excavator. Rock cutoff-sills still need to be installed across the left side where the existing channel is located to prevent the stream from cutting back into this channel. The diversion cross-vane needs to be made as watertight as possible with geotextile, chinking, and backfilling with mix of sand-gravel-cobble material. Copies: Maya MacHamer, Watershed Coordinator, Fourmile Watershed (fourmilewatershed@gmail.com) John Andrews, NRCS State Conservation Engineer (john.andrews@co.usda.gov) Chris Sturm, CWCB (chris.sturm@state.co.us) Jeffrey Sickles, Project Manager for CWBC Technical Team (jsickles@enginuity-es.com) Tim Macklin, NRCS EWP Program Manager (tim.macklin@co.usda.gov) Rob Molacek, NRCS Design Engineer (Robert.Molacek@co.usda.gov) Todd Boldt, NRCS EWP Manager (Todd.Boldt@ftc.usda.gov) File: c:\users\tee.burr\documents\ewp_tj\02 projects_ewp\ewp_2013_ph2\boulder county\fourmile creek_upper\sunset pond\construction_sunset\construction status report_sunset_ docx

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

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