STRATEGIC PRIORITY: Mobility Solutions, Infrastructure, and Sustainability
AGENDA DATE: January 8, 2020
COUNCIL DISTRICT(S):|910|DEPARTMENT: Department of Public Works
EXECUTIVE: Majed Al-Ghafry
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SUBJECT
Title
Authorize Supplemental Agreement No. 5 to the professional services contract with WSP USA, Inc., formerly known as Parsons Brinkerhoff, Inc., for additional engineering design of retaining walls required to prevent encroachment into adjacent properties and design modifications to mitigate high soil sulphates along Chalk Hill Road from Interstate Highway 30 (IH-30) westbound frontage road to Singleton Boulevard and the revision of the soil nail wall plan due to a gas main conflict along Chalk Hill Road from Davis Street to 800 feet south of IH-30 - Not to exceed $125,446.48, from $1,430,649.28 to $1,556,095.76 - Financing: Street and Transportation Improvements Fund (2006 Bond Funds)
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BACKGROUND
On January 23, 2008, City Council authorized a professional services contract for two thoroughfare improvement projects with PB Americas, Inc. dba Parsons Brinckerhoff Americas, Inc. for the engineering design of street paving, storm drainage, railroad crossing, and water and wastewater main improvements on Chalk Hill Road from Davis Street to 800 feet south of IH-30 (Chalk Hill Road, South Project) and Chalk Hill Road from IH-30 frontage road to Singleton Boulevard (Chalk Hill Road, North Project) by Resolution No. 08-0324.
During the construction of the Chalk Hill Road, South Project, a section of the existing 8-inch gas main was discovered to be in conflict with the soil nail wall. Consequently, it is necessary to redesign the wall to avoid the gas main. The ongoing geotechnical testing during construction shows a much higher soil sulphate content than was originally anticipated and this needs to be mitigated for the Chalk Hill Road, North Project. In addition, due to the terrain along...
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