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HomeMy WebLinkAboutSpecial Inspection Field Test & Inspection Report 2003-4-15 l l-)~;' Information ~.,. .To Build On Engineering. Consulting. Testing FINAL SUMMARY REPORT April 15,2003 Report No.: 722-10212-214 Mr. Ron Wilson Eugene Water & Electric Board P.O. Box 10148 Eugene, OR 97440 Re: EWEB Hayden Bridge Reservoir Project 3957 Hayden Bridge Road Springfield, Oregon D.P.: 01-00399-01 ,Dear Mr. Wilson: Professional Service Industries, Inc. is pleased to submit a final summary letter for the above listed project. Between July 12,2001 and December 19,2002, our firm obtained ,concrete test cylinders during concrete placement; performed in-place nuclear density testing on crushed aggregate backfill; constructed masonry prisms and grout samples, and performed structural welding inspections. The compaction tests met or exceeded the minimum strength compaction requirements of 95% and the concrete', .prisms and grout test specimens exceed design strengths (except as per attached letter dated November 21,2002). Note: For specific details regarding our inspection and testing services, please reference our previously submitted reports. Respectfully submitted, l:~~~KVA~ Department Manager C: City of Springfield Slayden Construction OBEC Consulting Engineers Attachment: Letter dated November 21,2002 Professional Service Industries, Inc.. 1040A Shelley St.. Springfield, OR 97477. Phone 541/746-9649. Fax 541/746-7163 ~O. OBEC CONSULTING ENGINEERS PROJECT DISCUSSION MEMO Project No: 30-31 Date: 11/21/02 Designer: Pete Slocum Project: EWEB 15 MG Reservoir, Pump Station & Electrical Upgrade Low Concrete Strength in two (2) reservoir columns The following is an updated technical memo to EWEB regarding the low strength concrete in two reservoir columns located at B-3 and C-3 (Slayden's grid scheme), Introduction Two (2) reservoir columns were given twice the air, 13% (air entrainment admixture had been added at both the batch and the site by Morse Brothers). Description After determining this condition, Gordon Drake (OBEC) directed Slayden Construction to stop the colunm pours using that load of concrete. On June 20, I received a call from the field (Ron Wilson (EWEB), Gordon Drake and Slayden's superintendent Scott) to discuss the allowable strength and measures to resolve this issue as Slayden was ready to pour the beams on top of the low strength columns. The COIUIIlllS have about 20 feet of low strength concrete in the bottom, and the rest of the 40-foot columns were poured with spec. concrete:. The 7-day cylinder break was approx 2350 psi, well below the anticipated 3500 psi for that concrete mix at that age. The resolutions and actions agreed upon were the following: 1) Proceed with pouring the beams on the columns. The low strength columns (2350 psi) can carry the beam self-weight and forming. 2) Prior to placing any of the roof (hollow core panels and topping slab), break another cylinder. The cylinder break strength was acceptable and the roof construction continued, After 5 months the last cylinder for that pour was broken and the strength was 3531 psi which is below the specified 28 day strength for column concrete (4000 psi per the plans and specifications). Low strength concrete is usually allowed by ODOT to 85% of specified (with compensation) which would be 3400 psi in this case. The 5 month break of 3531 meets the 85% , so is normally accepted, The required strength to support all design loads is 2600 psi, It is the determination of the responsible Engineer (Pete Slocum) that 3531 psi concrete provides the necessary strength for all loading conditions it will be subjected to, Conclusion We recommend that the material be accepted and no further action is required. It is hoped this memo provides EWEB with the information needed at this time. Please feel free to call OBEC at any time concerning this memo, . Copies: Gordon Drake, OBEC field Gary Rayor, OBEC project manager Guy Hakanson, OBEC assistant project manager Ron Wilson, EWEB Original: Correspondence file NOTE: Initial and date after last word message.