AWWU Northern Communities Water and Sewer Expansion
Start Date: May 2001.
End Date: July 2010
Project Location: Chugiak, Alaska
CRW designed and managed construction of water and sewer improvements for the Anchorage Water & Wastewater Utility as part of the Phase 1 Northern Communities Water and Sanitary Sewer expansion. Work included planning, public involvement, geotechnical investigations, surveying, easement acquisition, design, cost estimating and permitting for over 21,000 lineal feet of water and sewer mains and 2 wastewater lift stations. CRW prepared bid documents, managed construction and provided full time inspection support.
The primary purpose of the project was to extend sewer service to Chugiak High School from the existing sewer system located on the Old Glenn Highway near Lower Fire Lake. Additionally, the water system was extended as part of the project to complete a water system loop, connecting northern Eagle River to the Northern Communities, and to provide water service to adjacent communities. The project included the installation of approximately 11,700 lineal feet of ductile iron sewer main, approximately 5,500 lineal feet of sewer force main, and approximately 4,200 lineal feet of water main. A combination of ductile iron pipe and HDPE pipe was used ranging in size from 6” through 18”. Two wastewater lift stations were also constructed.
Water and sewer mains were primarily constructed by open trench excavation, including areas that contained bedrock. Approximately 1,600 lineal feet of rock drilling and blasting was required along South Birchwood Loop Road. A portion of the sewer main was required to be installed under the 54” Eklutna water transmission main. Two steel casings were bored under the water main to be used as a conduit for the gravity sewer main and force main.
The two lift stations were constructed on Anchorage School District (ASD) property. A smaller lift station was installed near Birchwood Elementary School which is owned and operated by the ASD. This lift station consists of a 6’ diameter wet well, a 6’ diameter valve vault, and exterior controls. The lift station discharges into a gravity sewer system which conveys wastewater to a larger lift station. The larger lift station is owned and operated by AWWU and required the acquisition of an easement. This facility consists of a 12’ diameter wet well, an 11’x13’ valve vault, a 20,000 gallon steel overflow tank and an 18’x28’ lift station control building which also houses a 215 kW natural gas backup generator. Due to the high head requirements, both static and friction, 135 horse power pumps were required to convey wastewater up South Birchwood Loop Road to the gravity sewer system constructed along the Old Glenn Highway.