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AMENDMENT NO. ONE TO CONTRACT NO. K-1314-39: BY AND BETWEEN THE CITY OF NORMAN, OKLAHOMA, AND WILSON AND COMPANY INCREASING THE CONTRACT AMOUNT BY $3,433.16 FOR A REVISED CONTRACT AMOUNT OF $192,505 TO PROVIDE DIVING SERVICES IN ORDER TO COMPLETE THE SPILLWAY ANALYSIS FOR THE SUTTON WILDERNESS LAKE DAM AND SPILLWAY REPAIR PROJECT.
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BACKGROUND: The Oklahoma Water Resources Board (“OWRB”) reclassified the Sutton Wilderness Lake Dam as a high-hazard dam in a report developed in November of 2010. The City of Norman leases the Sutton Wilderness area, which encompasses the dam, from the State of Oklahoma. The City’s Department of Parks and Recreation operates the 53-acre tract for recreational use. City Staff began working with OWRB in December, 2010, to assess the condition and safety of the dam.
On September 10, 2013, the City of Norman entered into Contract No. K-1314-39 with Wilson & Company for full engineering analysis, rehabilitation design, recommendations and cost estimates to bring the dam into compliance with OWRB high-hazard dam requirements. This project will include clearing the dam of vegetation which could compromise the integrity of the earthen dam itself, provide for a clear and stabilized spillway to protect the dam from high water flows, bring the dam crest and faces into compliance with OWRB standards, and provide for continued recreational use and aesthetics to the citizens of the City of Norman. Throughout the design process, City staff has worked closely with the Sutton Urban Wilderness Committee to ensure that their priorities and concerns are addressed.
DISCUSSION: During the analysis and inspection of the dam and the surrounding area, it was discovered that the primary spillway, an eight-inch (8”) steel pipe, is located under the dam. In analyzing the possible replacement of the pipe or continuing to use this pipe as the primary spillway, it was determined to be desirable to retain the 8” pipe if at all possible, since it provides for both primary spillway and emergency lake drainage if necessary. The option of keeping the 8” pipe includes installing a valve for emergency drainage and constructing a proper riser to maintain lake levels at the desired elevation. The option for installing a new primary spillway would not provide for emergency lake drainage nor construction of a proper riser. However, in the analysis of the 8” pipe for continued use as the primary spillway, it was determined that the inlet point of the pipe in the lake could not be found by normal surveying methods nor visual inspection from the surface.
This made it impossible to complete the analysis of the pipe as the primary spillway. A proposal was made by Wilson and Company to hire a diver to find the end of the pipe in the lake. The cost estimate for this work is $3,433.16. The diver will determine location of the end of the pipe and obtain data to analyze the current condition of the pipe for continued use as the primary spillway and emergency lake drainage. This is a more cost effective option than simply moving forward with the construction phase without knowing the location of the end of the pipe and the pipe’s condition. In determining the location and condition of the pipe, the City will avoid costly change orders and delays during the construction phase of the project.
The field data collection was completed at contractor risk during the investigation phase of the contract in February, 2014, to maintain the project timelines. The design of the project will be completed by Wilson and Company in August, 2014. Construction of the project is anticipated to begin in November, 2014, and will require approximately five months for completion.
RECOMMENDATION: Staff recommends approval of Amendment No. 1 to Contract No. K-1314-39 between the City of Norman and Wilson and Company for the additional services proposed, in the amount of $3,433.16. Funds are available in Storm Drainage, Design (account 050-9968-431.62-01; project DR0059) and terminate existing Contract No. K-1314-64