TAW/WRUD Water System Interconnection
Signal Mountain’s rock escarpments and steep wooded slopes rising into the clouds above Chattanooga make for majestic views and homesites, but they created numerous challenges during the recent design and construction of a new 16-inch water line up the mountainside. This line connects the Walden’s Ridge Utility District water system at the top of the mountain with the Tennessee-American Water (TAW) system over 1,000 vertical feet below. Among the design and construction challenges were:
Site selection: Seven separate water line routes were reviewed, including detailed cost estimates, and numerous pump station sites were considered. The search was complicated by the need to find sites that offered affordability in an area with high land values, constructability among steep rocky bluffs, and minimal disturbance of the natural setting.
CTI served as liaison between TAW and each property owner, initiating negotiations for utility easements and pump station property acquisition.
Design challenges: Over 500 LF of welded steel pipe was installed above-ground on steep terrain and attached to the vertical escarpment on concrete and steel supports. To accommodate high operating pressure and provide surge control, special design provisions were made for thrust restraint and thermal expansion/contraction.
Construction challenges: Due to the steep grade along much of the pipeline route, delivery of supplies and excavation for pipe supports had to be accomplished by hand. Tools and materials were brought to the site by a sled with skids and a cable/pulley system. CTI provided full-time resident project representation.
In order to reduce costs and speed up completion, the project was divided into five separate contracts. Contract Nos. 1 and 3 were completed while property and easements were being acquired for Contract Nos. 2 and 4.
» Contract 1: 7,231 LF of 16-inch DIP and 2,592 LF of 12-inch DIP
» Contract 2: 3,200 LF of 16-inch welded steel pipe
» Contract 3: 4,250 LF of 12-inch DIP
» Contract 4: Pumping station sitework, including a 22-foot-high reinforced blocked wall
» Contract 5: Prefabricated pump station with two 700-hp, 2,400-volt, 1,400-gpm pumps, 650 psi discharge
» Route evaluation
» Preliminary design
» Easement and property acquisition
» Bidding assistance
» CADD drawings, specifications, and contract documents
» Construction phase services
» Resident project representation