Big Gulch Sanitary Sewer Reconstruction Project
A Brief Historical Overview
Construction Segments
The Big Gulch project was divided into four bid schedules to optimize access, address the differing geologic conditions, and coordinate the scheduling of construction seasons.
 Segment No.1
– begins on the south fork of Big Gulch Creek at Harbour Point Drive adjacent to the library and follows the creek downstream to the confluence with the north fork. This segment is characterized by very steep hillsides.
Segment No. 2 – begins at the junction with the north fork and proceeds down stream to the access road entering the gulch from 52nd Street.
Segments No. 1 and No. 2 are about 5,000 feet long and were constructed using the buried pipelines for sewerage and stormwater. Segment No. 1 was completed in the 2007 construction season, and Segment No. 2 was completed in the 2008 construction season.
Also constructed in the summer of 2008 was a segment of temporary repairs to the old pipeline downstream of Segment No. 3, which is the area that was extensively damaged from the large storm event in December of 2007. This work stabilized the pipeline in place through this past winter until the last segment is constructed this coming summer.
Segment No. 3 – begins at the 52nd Street access road and extends downstream the last 3,000 feet to the wastewater treatment plant access road. The new pipeline will be connected into the existing pipeline which flows into the treatment plant at that point. This segment will be constructed this summer, 2009, using trenchless technologies called horizontal directional drilling.
Segment No.3 also includes the drilling of a second sewer line to connect the existing 101st Street cul-de-sac. This is necessary in order to address the lower elevation of the sewer pipeline and to avoid the sensitive geology of the hillside.
Horizontal directional drilling does not require work in the stream and avoids the use of large open cut trenches. The pipeline is drilled underground and will require open access pits only at the ends. This technique minimizes environmental damages by going under the sensitive areas. We expect construction of this segment to be completed by the end of this summer, 2009.
Segment No. 4 – consists of replacing the bridge at the base of the Gulch, which is the access route to the treatment plant, and to close out all the preceding construction schedules. Completion of this final phase of the project is expected by the end of 2009.
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