Well Design and Equipping

The City of Delano was required to provide potable water to its users with arsenic concentrations less than 10 parts per billion. This regulation was adversely affecting nine of the eleven production wells in the City. A report entitled “Arsenic Mitigation of Water System” identified the drilling of new wells as the most cost-effective means of mitigating the arsenic levels above 10 parts per billion, and identified coagulation and filtration as the most cost-effective treatment for regularly used wells. In light of this, the City developed the mediation program to replace seven of the existing wells with nine new wells and installation of wellhead treatment on some of the existing wells.

Cannon’s original scope of services included equipping and designing the pumps and discharge piping to connect to the existing distribution system and coordinating the design of a sodium hypochloride disinfection system and electrical services to develop the seven wells. Drilling and developing of these wells was proposed in order to avoid the arsenic layer in the underlying aquifer, which had been influencing the site’s existing wells. As such, these wells were designed to improve the available potable water supply to the area. Cannon staff worked with the City of Delano’s hydrogeologist to design the 150- to 250-horsepower, 1,000- to 1,500-gpm pumps and motors. The project also included designing and preparing plans for all site work. The site work included the piping, electrical equipment and controls, SCADA, paving plans, curb and gutters, fencing, blockwalls, and a drainage system for initial well blow-off flows and site drainage. In the absence of storm drains within the city, the project captured the initial well discharge for flushing purposes in a 5,000-gallon underground sump and slowly discharged the water into the sanitary sewer using submersible pumps. Each well is enclosed in a building with a removable roof and three walls for easy access and maintenance for the well. Cannon also performed a topographic survey and boundary research.