R2013-74 ACCEPTING THE BID AND AUTHORIZING CONTRACT FOR LAKE DECATUR DAM REPAIRS

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I 1 ' City of Decatur Lake Decatur Dam Repairs City Project 2012-25 ' May 28, 2013 ADDENDUM N0. 3 ' TO PLANS, SPECIFICATIONS AND CONTRACT DOCUMENTS FOR: LAKE DECATUR DAM REPAIRS CITY PROJECT 2012-25 DATED MAY 28, 2013 ' AD-3-1 NOTICE 3.01 This Addendum No. 3, dated May 28, 2013, to the Plans, Speci cations, and Contract Documents for the above captioned project, supersedesll contrary and conflicting information of the above mentioned project documents, which are hereby supplemented in certain particulars as follows: 1 AD-3-2 ALTERNATE BID ITEM No. A-5 ' 3.02 This alternate contains the option for an engineered system for scour protection in lieu of placing Stone Dumped Riprap 24 in. and 36 in. Diameter. ' Sheet C4: In lieu of placing Stone Dumped Riprap as shown below the spillway apron, contractor may install an engineered system for scour prot ction within the same limits shown on the plan for riprap placement. The system shall be designed ' by the contractor and shall be subject to approval of the Engineer. The engineered scour protection system shall be designed to mee�the following ' conditions: 1. Capable of providing hydraulic stability under peak velo ties of 20 feet per second. 2. Capable of withstanding peak shear stresses of 21 pounds per square foot. 3. All systems shall have a minimum factor of safety of 3.5. An acceptable system would be a combination of an Articulated Concrete Block ' (ACB) Mat System meeting the design standards of Shoretec SD 900 OCT, Armortec Armor Flex 70-T,or equivalent and Concrete Armor nits meeting the design standards of Shoretec ShoreJax, Armor Flex A-Jacks, or equivalent. The ' materials and configuration of ACB and concrete armor unit systems shall be designed and specified by the manufacturer and performance testing data in accordance with the hydraulic performance testing protocol esta ished by the U.S.