Attention: Ray Tardiff,

Transcription

1 D B 1A 1750 S.Quinn Prince George, B.C. V2N 1X3 PHONE: (250) FAX: (250) dwbpg@mag-net.com August 30, 2007 PC: MOF Ray Tardiff, Regional Roads Specialist Ministry of Forest, Northern Interior Forest Region Prince George Forest District th Ave, Prince George, BC V2L 3H9 Attention: Ray Tardiff, Dear Sir: RE: Post Construction Environmental Monitoring Report for the Cluculz Creek Detour Bridge Installation at 31km on the Bobtail FSR As requested, DWB Forestry Services Ltd (DWB) provided environmental monitoring services for the Ministry of Forests and Range (MOFR) during preparation and installation of the detour crossing over Cluculz Creek at 31km on the Bobtail FSR. The bridge and associated road works commenced August 22, DWB was on site to provide environmental monitoring Aug 22-24, The environmental monitor was onsite during all instream works to ensure that environmental concerns were addressed during construction of the bridge approach. Following this report are construction photos and completed daily journal log notes with additional details. August 22, 2007: The environmental monitor arrived on site at 8:50 hrs. An initial pre-work meeting was held with the contractor personnel and Carl Erickson (MOFR representative) to discuss environmental concerns and construction methods that would meet environmental and structural requirements. The Environmental Management Plan (EMP) for this project 1 (DWB, 2005) was discussed and modifications were considered. Upon review of the engineered plans for the project, there was concern by the monitor that a Harmful Alteration and Destruction of Fish Habitat (HADD) may occur due to infilling the entire side channel at the overflow CMP and 5m at the inlet and outlet. Ray Tardiff (MOFR) confirmed that DFO had reviewed the designs and did not have any concerns at that time. As per the EMP an upstream poly/sand bag dam was constructed 5m upstream from the CMP inlet to prevent flow into the low chain (north) high water CMP and associated downstream side channel. Due to beaver debris and organic substrate flow was not completely sealed. A downstream poly/sand bag coffer dam was then constructed to isolate the side channel, immediately before the confluence with the mainstem. These upstream and downstream coffer dams in conjunction with pumps provided isolation of the instream construction area. As per monitor recommendations, a CMP was ordered to ensure that flow was maintained through the side channel during detour bridge installation. Both Ray Tardiff and Carl Erickson agreed that this would be beneficial in both the short and long-term. This reduced the environmental disturbance at the site immediately and in the long-term as no additional side channel had to be constructed to force flow back into the mainstem. This would reduce the erosion potential in the future when the mainstem is diverted into the overflow CMP. During future works, the mainstem will be diverted into the high water/low chain CMP thereby forcing all flow through the side channel. By installing a CMP in the side channel water will be allowed to flow under the detour bridge approach, rather than directly against it. As the CMP was unavailable until the following day and not enough logs were ready to complete instream works, no instream construction commenced on this day. The road approach to the crossing was constructed via laying geotextile over the natural vegetation and covering the geotextile with road fill material (as per the EMP). The environmental monitor left the site at 14:15. 1 DWB Forestry Services Ltd Environmental Management Plan for Culvert and Bridge Replacements in the Vanderhoof Forest District on the Bobtail FSR Km 30.9 DWB Forestry Services Ltd. 1

2 August 23, 2007: The environmental monitor arrived onsite at 7:45 hrs. The isolated area within the side channel was immediately electrofished and 3 rainbow trout ranging in size from 6-18cm were captured and released upstream from the site. Pump intakes were installed immediately above the lower coffer dam (one 3 pump, and one 2 pump) and water was pumped to an upland vegetated area on the low chain, downstream side of the crossing to prevent any sediment laden water from flowing into the mainstem. Geotextile was then placed across the entire footprint of the detour crossing approach including instream in the side channel. Logs were placed on top of the geotextile to function as corduroy within the wetted perimeter of the stream. This was required to raise the detour road fill grade to above the wetted perimeter of the side channel. At 9:50 the 3 pump seized thereby allowing water to flow out of the isolated construction site. A new pump was immediately ordered and instream works ceased until the construction area could once again be isolated. At 12:00 several juvenile fish were observed within the isolated area at the downstream edge of the geotextile. These fish were too small (1-2cm) to be caught via electrofishing so they were captured via a hand net and released downstream. All 10 of the juvenile fish were cyprinids, likely northern pikeminnow. Visual surveys throughout the day did not reveal the presence of any more fish within the isolated area. At 13:10 a new 3 pump arrived and the instream work area was once again isolated. Instream construction commenced and the CMP was installed in the side channel. Logs were then placed along the sides of the CMP and built up to above the water level. At 14:20 the monitor left the site. Lock blocks were scheduled to arrive the following day. Aug 24, 2007: The environmental monitor arrived onsite at 7:30 hrs. Upon arrival it was noted that the CMP and logs installed the previous day were removed as a 1400mm CMP was now to be installed. The geotextile placed within the stream channel was still in place. The site was electrofished to ensure no fish had entered the isolated work area overnight while the pumps were turned off. One 3 pump was placed at the top of the isolated area to reduce the water levels in the pool and two pumps, one 3 and one 2 were placed at the bottom of the isolated area to pump sediment laden water into the upland vegetated area on the downstream side of the crossing. At 12:30, the lock blocks and 1400mm CMP arrived. At 13:30 the CMP was installed in the stream channel and logs were placed around the CMP, within the wetted perimeter of the stream. Geotextile was the placed on top of the culvert and logs. Geotextile and logs were also placed in the pool at the edge of the CMP inlet to dissipate flow velocities and prevent erosion of the road fill. At 15:00 one row of lock blocks were placed at the CMP outlet. Geotextile was placed on top of the CMP and along the sides of the lock blocks to prevent fill from entering the stream. After the first row of lock blocks were in place and the geotextile was installed, fill was placed around and on top of the CMP. The upstream and downstream dams were left in place. At 17:30, when instream works were completed, the monitor left the site. The remaining lock blocks and fill were to be installed the following day. The monitor directed that geotextile should be placed along the sides of all lock blocks that were installed the following day to hold the fill back from the stream. Additional Recommendations The site should be inspected during heavy precipitation events and any increases in stream flow to ensure that erosion mitigation methods are effective, and that stream flows are not eroding the detour bridge footings and approaches. Should you have any questions or concerns regarding this report, please do not hesitate to contact the undersigned. Sincerely, Jason Hooft, AScT, BIT Environmental Specialist DWB Forestry Services Ltd. Phone: (250) DWB Forestry Services Ltd. 2

3 APPENDIX 1 SITE PHOTOGRAPHS August 22, 2007 Photo #1 Upstream poly/sand bag dam. Photo #2 Downstream poly/sand bag dam. Photo #3 Pump installations at the downstream dam. Photo #4 Geotextile placement over the native vegetation. Photo #5 Geotextile being overlayed with road fill. Photo #6 Geotextile being overlayed with road fill. DWB Forestry Services Ltd. 3

4 August 23, 2007 Photo #7 RB caught during electrofishing the isolated work area. Photo #8 Poly armored pump outlets located in an upland vegetated area. Photo #9 Log infill of side channel on top of geotextile underlay. Photo #10 Breached downstream dam after the 3 pump seized. Photo #11 Entire geotextile lined detour bridge road approach on the low chain side. Photo #12 Juvenile northern pikeminnow caught (10) with a hand net within the isolated work area. DWB Forestry Services Ltd. 4

5 Photo #13 CMP installation in the side channel. Photo #14 CMP installation in the side channel with logs alongside. August 24, 2007 Photo #15 Photo of the 1400mm CMP being placed within the stream channel. Photo #16 Photo of the logs placed along the edge of the CMP, within the wetted perimeter of the stream. Photo #17 Photo of the geotextile placed on top of the culvert and along the lock blocks. Photo #18 Photo of fill being placed along the CMP. DWB Forestry Services Ltd. 5

6 Appendix 2: Daily Monitor Journal and Notes DWB Forestry Services Ltd. 6

7 DWB Forestry Services Ltd. 7

8 DWB Forestry Services Ltd. 8

9 DWB Forestry Services Ltd. 9

10 DWB Forestry Services Ltd. 10

11 DWB Forestry Services Ltd. 11

12 DWB Forestry Services Ltd. 12

13 DWB Forestry Services Ltd. 13