Pipeline Replacement


Owner: Colusa County Water District
Arbuckle, California
Funding Source: Colusa County Water District
Completion Date: May 2012

Lateral 6A County Road Crossing.

The Colusa County Water District (CCWD) serves approximately 37,000 acres of almonds and other crops (field crops, pasture, other orchard crops, vineyards, and rice) on the west side of the Sacramento Valley in southern Colusa County. The District’s current distribution system was built in the 1980’s to allow for delivery of water from the Tehama-Colusa Canal under contract with the U.S. Bureau of Reclamation. The distribution system consists of several lateral pipelines, pumping plants, and storage facilities (reservoirs and water tanks) distributed along the canal.

At the time of construction, the selected pipe material for 27-inch and 30-inch diameter pipe included in the district’s Laterals 5B and 6A was fiberglass reinforced plastic mortar pipe (trade name, “Techite”) manufactured by Armco, Inc.  In recent years, the Techite pipe began to fail, resulting in service outages, costly repairs, and lost revenue from water sales.  In late 2010 the District’s board of directors decided to replace the entire approximately 2.2 miles of Techite pipe over a two-year period.

Davids Engineering was hired by the District to evaluate potential causes of the breaks; to evaluate alternative materials for the replacement pipe; and to provide engineering services for the surveying, design, permitting, contracting, contract administration, and construction inspection for the project.

Approximately 6,500 feet of Techite pipe were replaced in early 2011 through separate construction contracts with Teichert Construction and Ford Construction. Construction was completed by the two contractors concurrently on the District’s Laterals 6A and 5B. During 2012, an additional 5,100 feet of pipe were replaced through a contract with Cox & Cox Construction.  In both years, it was necessary to complete construction on time to avoid delays in providing irrigation water for early season fertilization and, as the season progressed, irrigation to meet crop water needs.  These deadlines required efficient and timely completion of various project tasks to avoid potential crop impacts.

Davids Engineering provided initial support in the specification and procurement of pipe material and large diameter fittings by CCWD directly, while simultaneously conducting the bidding process to avoid delays in the construction due to lead times for the PVC pipe and fittings selected. A licensed land surveyor was hired as a subcontractor to provide topographic surveying services and legal descriptions for new easements in areas where the existing pipeline was abandoned in place.

Trench shoring system for pipe laying through an existing almond orchard.

Design responsibilities included performing necessary calculations and preparing drawings and technical specifications for each contract. Project administrative responsibilities during the design process included support of environmental permitting, obtainment of encroachment permits, and negation of new easements. Prior to construction, Davids Engineering assembled complete contract documents, conducted the bidding process, and supported selection of the contractor for each contract by the board of directors.

Following contract award, Davids Engineering administered each contract on behalf of the District, reviewing contractor submittals and progress payment requests, reviewing change requests and preparing change orders, and providing certification of substantial and final completion. Additionally, construction management responsibilities included daily construction inspection services for each contract, including supervision of soils testing by geotechnical engineering subcontractor.