ESCP --- Blackwater.RiverBridgeProject MT/7,I BPermitApplication Erosion and Sediment Control Plan (ESCP) for the Blackwater River Bridge at Kilometre 784.1 of the Mackenzie Highway A document provided to the Mackenzie Valley Land and Water Board As part of the 2008 Land Use Permit Application Amendment Department of Transportation August 2008 1 ESCP — Black water River Bridge Project WIWB Permit Application TABLE of CONTENTS 1.0 Introduction .............................................................................................................................. 3 1.1 Objectives ............................................................................................................................ 3 2.0 Project and Site Description ................................................................................................. 3 2.1 Site Description .................................................................................................................. 3 2.2 Areas of Concern ................................................................................................................ 4 3.0 Erosion and Sediment Control Measures .............. ................... ...... 5 3.1 Temporary Control Measures ............ ...... ......... 5 3.1.1 Silt Fence Barrier ........................................................................................................ 5 3.1.2 Erosion Control Matting ............................................................................................ 6 3.1.3 Flow Isolation........„..... ....... ....... ............................. .............. 6 3.1.4 Rock Check Dam ............... ...,........... ................ ................... 6 3.1.5 Rehabilitation and Recontouring ........... ......... ...................... 6 3.1.6 Revegetation ................................................................................................................ 6 3.2 Permanent Control Measures ..................................................................................... 7 3.2.1 Scour and Erosion Protection ............................................................................ 7 3.2.1.1 Lateral stability of the Blaekwater River ........................................................ 7 3.2.1.2 General and Local Scour .................................................................................... 7 3.2.1.3 Pier Scour ............................................................................................................. 8 3.2.2 Pier Erosion Protection ...................................................................................... 8 3.2.2.1 Piers 1 and 2 ........................................................................................................ 8 3.2.2.2 Pier 3 ..................................................................................................................... 9 3.2.3 Abutment Erosion Protection ............................................................................ 9 3.2.4 Culvert Riprap ..................................................................................................... 9 4.0 I mplementation............................................................................................................... 10 4.1 Inspection, Maintenance and Record Keeping ...................................................... 10 4.2 Shut Down Considerations ....................................................................................... 10 4.3 Emergency Response Plan ....................................................................................... 10 5.0 Post construction monitoring ....................................................................................... 11 6.0 Accountability ................................................................................................................. 1I Attachments Site Photographs Figure 1 — General Arrangement (drawing H-301-S-05-07-DD-02) Figure 2 — Erosion and Sediment Control Plan Figure 3 — Typical Rock Sediment Barrier (Rock Check Dam) Figure 4 — Abutment and Pier Erosion Control (drawing H-301-C-02-07-DD-06) Figure 5 — General Arrangement norflex Details (drawing H-30 I-C-02-07) Figure 6 — Erosion and Sediment Control Details for culverts 2 ESOP — BlackwaterRileaBridgePr rgject Mb .WBPermitApplication 1.0 Introduction The Department of Transportation (DoT) proposes to build a new bridge to cross the Blackwater River. DoT has retained AMEC to undertake the design work for this project. Part of this work included an analysis of existing drainage and the design of long-term drainage controls. These measures are based upon field data and information obtained as part of the community consultation process. ti Objectives This ESCP was developed based on the requirements of the Design Guidelines for Erosion and Sediment control, for°. Highways (Alberta Transportation, 2003). The objective of the ESCP is to control erosion and other sediment producing activities during and post construction, thus reducing the potential for sediment mobilization and sediment input into the Blackwater River. The proposed Blackwater River Bridge is located approximately 90 km north from Wrigley at the Blackwater River along the Mackenzie Valley Winter Road. The purpose of the Blackwater River Bridge is to extend the useable time of the Mackenzie Valley Winter road, through the elimination of ice bridge construction. The bridge will be constructed approximately 600 metres upstream from the existing ice bridge location and is approximately 1.3 kin north of the Blackwater River and Mackenzie River confluence. Total bridge length is 296 metres (Figure 1 ---- General Arrangement drawing is attached). A new road, approximately 2.7 km long, will be required to align with the bridge. Alignment for the new bridge will comply with current geometric standards. The side ditches will be shallow to reduce pennafrost degradation and have gentle side slopes. Fill slopes are 4H: IV for roadway sections that do not have guardrails while roadway sections with guardrails have a slope of 2H: 1V. The four culverts will be corrugated steel pipes with diameters 600 man or 1000 m. The size and location of the bridge piers are shown on Figure 1 (General Arrangement drawing). 2.1 Site Description The Blackwater River crosses the Mackenzie Valley Winter Road at km 784.1. It is an alternately winding and meandering watercourse, the lower reaches of which run from their source, Blackwater Lake, approximately 50 km upstream of the confluence of the Blackwater River with the Mackenzie River, through a river valley which traverses the McConnell Range of the Franklin Mountains. Blackwater Lake lies immediately to the east of these mountains and possesses several significant inflow channels, not the least of which are the upper reaches of the Blackwater River itself The upper Blackwater receives inflows, as does the lake, from the eastern slopes and smaller tributaries across the lower elevations to the cast of the Franklin Mountains. Beyond the lake to the east, ESOP Blackwater River Bridge Project Mk114/B Permit Application the Blackwater River extends another 80 to 85 km. The drainage area for this river at the crossing is 10,640 km2 , according to the federal alignment study consulted by Trillium Engineering Ltd. for the hydrological component of this crossing's pre-engineering assessment. The Blackwater River channel is broad in definition and predominantly confined by the valley through which it flows to the crossing location. At the time of observation, the wet width of the stream's active channel at the proposed bridge site was approximately 70 in. A gravel bar toward the south bank of the Blackwater River occupies approximately 125 m of the channel, producing a full channel width of approximately 200 m, a figure which includes the inactive overflow plain which skirts the south bank at the proposed bridge location. Water depth is approximately 3 metres of darkly-stained but clear water flowing turbulently over a substrate comprised predominantly of gravel, cobble, and boulders. There is also a slight presence of sand and silt evident. Between the cobble, boulders, and darkly stained water, Blackwater River offers a reasonable level of instream cover for fish. The banks at the crossing seem very stable, with both banks exhibiting nearly full coverage by the dominant riparian species: willow and grasses. Sand, silty clay and small amounts of gravel and cobble constitute both banks, with a few boulders also in evidence. The north bank rises approximately 4.0 m in height before flattening out in a gently sloping and well-vegetated terrace towards the upland plain's elevation, approximately 75 m above bank height over a distance of about half a kilometer, while the south bank rises only about 2 m. 2.2 Areas of Concern The Blackwater River is a fish-bearing watercourse, therefore, disturbance of and sediment deposition into the river is of concern. During construction and post construction, the integrity of the river will need to be preserved. Drainage ways and erosion control measures will need to be incorporated during construction activities associated with the 2.7 km of new road construction and 2.4 km of existing winter road abandonment. Concerns expressed during consultation with stakeholders in 2007 regarding placement of the abutments and piers have resulted in a design change. There will be no pier in the active water channel eliminating construction and maintenance concerns related to erosion and