R2019-209 Resolution Approving Change Order No. 22 to the Contract with Great Lakes Dredge and Dock, LLC for Lake Decatur Dredging of Basin 1-4 and the Rehabilitation of the Oakley Sediment Basin City Project W1314

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February 15`,2019 Page 2 Ref:RI 102(SRMlDSC/SL-032 �-- T. BACKGROUND � � We notified the City as promptly as pre-bid with ane of our queries on November O1,2013,that by our calculafions based on the survey of the Oakley Sediment Basin("OSB")provided by Chastain at the time of bid,fhe OSB did not have s�xfficient capacity for the bullced dredged material after it has been dredged from its in-siht state.The response back fram the City in RFI Number 3 was a confirmation that the OSB was sufficient to hold alI the quantity of dredged material from Basins 1-4(refer to document in Exhibit 1).Unfortunately,the USB,as designed, feil well short of the capacity needed to even contain fhe neat Contract design qnantity without consideration of all the aniicipated over dredge,bullciztg of the material and the reduction in OSB capacity due to the clarifying/palishing pond required witiun the OSB to maintain water quality for effluent discharging from the OSB, which all should have also be taken into account. Change Order 13 date April 27,2018,was eventually issued to raise the containment dikes at the OSB so that it would then have su�cient capacity(discussed further below under item 1)and GLDD couid then complete the required dredging. As a result of the insufficient capacity of the OSB prior to the berm modification and Change Order 13 berm modifiaation work,we incurred a number af additional costs that we had included zn our Proposal.The insu�cient capacity af the OSB resulted in GLDD incurring costs for items 3—6listed above(detailed below),and the berm modification work forced GLDD into another stand-by as we were delayed from commencing dredging works at the start of the 201� dredging season{i#em 2 listed above and detailed below). Based on the survey of the OSB provided by Chastain at the time of bid,the OSB has a maximum capacity of only S,?13,000 cubic yards while maintaining three feet of freeboard as required.This capacity includes the addiriona! capacity GLDD created by removirig material from within the OSB to constzuct the original berms to Chastain's original design but has not been reduced for the necessary"polishing"pand that is required to allow fines to settle out and maintain the required water quality for effluent discharging from the OSB. As of November 19`h,2017, when GLDD was required to halt operations early during the 2017 dredging season,as a result of additional efforts to mitigate impacts to the City,GLDD had placed apgroximately 8,772,000 cubic yards of materzal into the OSB— nearly 60,000 cubic yards more than the 4SB's initiat design maximum capacity. Furthermore,we note that the design for the bem�modification work reduced fhe width at the crown of the berm as the side slopes of the raised section were aligned with the extrapotation of existing side slopes. Although we believe items 2—6 are representative of all af the costs incurred to date as a result af the insufficient design capacity isstces at the OSB and the berm modification work,we reserve our right to include any additional cost found or incuired until a final settlement of these matters is agreed. 1. CHANGE ORDER 13—COSTS FOR THE BERlY.[MODT�YCATIONS TO HOLD TT3E CONTRACT DESIGN QUANTITY Because the original Contract design included insufficient containment capacity at the OSB,it became necessary to raise the berms to an appropriate level to contain fhe rernainder of the Contract material to be dredged from Basins 3,4 and 6 while also maintaining all other Contract conditions including,but not limited to,freeboard at the berms and water quality. Chastain has provided Great Lakes bid documents that include a bid form and drawings for three different berm modification heights:717.5',718.5'and 719.5' which will be referred to as the 4',5' and 6'berm modifications. In response to Chastain's and the City's request to solicit bids to raise the OSB berm levels far this proposed Change to the Contract,GLDD solicited bids from six earthwork contractors. The bids requested were based on the bid documents aad drawings provided by Chastain&Assaciates via email on December � 13,2017 and npdated on January 2,2018 via Addendum No. 1. As a resutt of our solicitation we received �— three completed quotations and three regrets. Use�r ciisciosure of data cantain�c��n this sheet is subject to the restrictions on fhe fitle pac�€:of this submission.