SR 06:163 - Laserfiche WebLink

Honorable Mayor and Members of the City Council: BACKGROUND The subject project was approved for funding under the Fiscal Year 2005/06 Capital Improvement Program budget. The McCloud Water Tank, built in the 1950's, as a 2 MG reinforced concrete water tank, is leaking and is currently losing approximately 12,000 gallons of water per day. Previous attempts to identify the leak location from inside the tank included the use of scuba divers to place water-quality safe dye in and around the bottom of the tank and all potential known areas of leakage (wall/floor joints, piping intrusions, etc.). However, these attempts were unsuccessful in identifying the location of the leak. There are visible signs of rust leaching through the concrete walls as well as spaulling (flaking) of the concrete walls of the reservoir. Previous trench excavations next to the tank have found that the trench will fIll with groundwater assumed to be leaching from the tank. The tank was built in the 1950's, and according to Public Works records, no major improvements were done to the tank since the time it was constructed. Two potential flaws in the existing tank are the amount of corrosion that has occurred over time on the existing steel reinforcing and the ability of the tank to meet current earthquake standards, due to it's 1950's design. On April 3, 2006, the City received proposals from three fmns for the evaluation of the subject tank, The three proposals were from TJC & Associates, Inc. of Rancho Cordova, Beyaz & Patel of Walnut Creek and Tetra Tech Inc. of Lafayette. A review of the submitted proposals resulted in the selection of the firms of Beyaz & Patel, Inc. and TJC & Associates to perform the required evaluations. The engineering scope of work within the two contracts consists of evaluating the McCloud Tank's ability to withstand a major earthquake by identifying existing seismic, structural and material strengths and weaknesses of the tank, prepare recommendations for leak repairs, and prepare alternatives for seismically bracing the tank, if possible. While it is unusual to have two consultants on the same project, the overall cost is the same as a single consultant doing the study. This process allow us to use the strengths of the two consultants to provide a more detailed and thorough study than that provided by a single consultant. TJC & Associates has expertise in the design and structural evaluation of concrete water storage tanks and will be doing an extensive study on the structural integrity of the tank. Beyaz & Patel, Inc. has expertise in evaluating concrete material quality and aging, corrosion control of steel reinforcing, as well as structural and seismic design and retrofit. SR 06:163 Page 2 of 4