SECTION 01 14 10 USE OF SITE PART 1 GENERAL ... - IDEAS-EC

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Amendment 0005Red Bluff Pumping Plant and Fish Screen Specifications No. 20-C0752during excavation activities. Once excavation is complete in the fish screen area,all work shall be constructed in the dry. The depth of the water duringexcavation work is not limited, however as the excavation is nearing completion,the water must be removed from the excavation area and maintained at the levelsand for the durations given in these specifications.2. Excavation and construction in the dry is where the groundwater is maintained atleast 3 feet below the bottom of the excavation and the excavation bottom has novisible water present and it can be verified that the groundwater is at least 3 feetbelow the excavation bottom. This applies to the pumping plant footprint and to adistance of 10 feet beyond in all directions. It also applies to all areas receivingbackfill or concrete, anchorage system excavations behind sheet pile retainingwalls, and all areas not specifically allowing excavation and construction in thewet.E. The soil layers explored are described in Section 53 10 00 - Geologic Investigation,Section 53 20 00 - Records of Subsurface Exploration, and reports referenced in thesespecifications.1. Previous construction at the RBDD has required significant dewatering efforts.2. A well point system will be required to drain soils below the construction areaand within the work area to control the amount and velocity of water that mayflow under sheet pile walls or cofferdams, to permit construction on foundationsoils free of surface water.F. Where minimum tip elevations are shown on the drawings for permanent sheet piles,Contractor may, at Contractor’s cost, install sheet piles to deeper tip elevations to assistin dewatering or for shoring requirements.G. Sequence earthwork and construction of permanent and temporary facilities to maintaincontrol of the Sacramento River and Red Bank Creek within the existing channels orwork limits shown, and prevent flooding of adjacent or downstream areas.H. Fish Screen and Access Road Cofferdams:1. Design, install and maintain cofferdams:a. To allow excavation in the wet or in the dry with unwatering to the base ofthe excavation when the excavation is complete and until the fish screen iscompleted and the access roads backfilled to finish grade.b. To minimize leakage.c. To allow for appropriate marine construction methods for in-river workoutside the cofferdam and during installation of the cofferdam.d. To provide for worker safety and to protect work areas, partiallycompleted construction and completed construction from floodingdamage.Removing and Controlling Water During Construction31 03 33 - 6
Amendment 0005Red Bluff Pumping Plant and Fish Screen Specifications No. 20-C0752e. To meet permit requirements and water quality standards required inSection 01 57 30 - Water Pollution and Erosion Control.f. To meet other requirements for work in the Sacramento River or RedBank Creek.g. Provide access in accordance with RSHS.2. Cofferdam height to be selected by the Contractor taking into consideration workschedule, flooding potential, and operation of Lake Red Bluff.3. Contractor should anticipate leakage at sheet pile interlocks. Sealing of theinterlocks to minimize leakage shall be done at the Contractor’s expense.Frequent repair and improvement of sealing procedures shall be performed tominimize interlock leakage and leakage under the cofferdam.1.06 SITE CONDITIONSA. Hydrographs and Discharge Curves:1. Information on flood levels and flows in the Sacramento River are included inSection 51 10 00 - Hydrologic Information.2. Groundwater levels and Sacramento River water elevation will be affected by theoperation of Red Bluff Diversion Dam.a. The gates of Red Bluff Diversion Dam will go in (gates in) approximatelyJune 15 and come out approximately September 1 of years 2010, 2011,and 2012.b. The approximate water surface elevation in the lake with Red BluffDiversion Dam gates in is El. 255 at the dam and somewhat higher at thefish screen.3. Pumping of groundwater by industrial, municipal, and private owners in the areamay also effect water levels.4. The Government assumes no responsibility for deductions, interpretations, orconclusions made by the Contractor based on information made available by theGovernment, in accordance with the clause at FAR 52.236-3 “Site Investigationsand Conditions Affecting the Work.”B. Red Bluff Diversion Dam Settling Basin and TC/Corning canal operations will not berevised to accommodate construction under this contract.1.07 QUALIFICATIONSA. Dewatering and cofferdam systems shall be designed by a Professional Engineerregistered in the State of California with a minimum of 10 years of experience in thedesign, installation, and operation of dewatering and cofferdam systems of complexitycomparable to that required for this contract.Removing and Controlling Water During Construction31 03 33 - 7
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SECTION 01 14 10 USE OF SITE PART 1 GENERAL ... - IDEAS-EC

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