Culvert No.
Dewatering
CONSTRUCTION METHODS Box/Bridge Culvert Exist. Culvert Prop. Culvert Station (W x H) (W x H) Replacement: At face value, replacement of the existing box/bridge culverts can 477+50 8’x9’ (x2) 8’x9’ (x2) YES present a challenge as daunting 1 as the phased demolition and 2 556+00 7’x9’ (x2) 96” (x2) YES construction of the bridges 556+00 7’x9’ (x2) 96” (x2) YES at CR 512. To disprove this 3 619+20 15’x12’ 15’x12’ NO notion, we have applied sound 4 engineering and performed 5 643+00 7’x5’ 58”x91” YES a comprehensive regional 668+40 8’x12’ (x2) 97”x151” (x2) YES drainage analysis; we examined 6 every crossing individually in 7 708+90 10’x7’ (x2) 87”x136” (x2) YES order to provide a solution 8 756+66 8’x12’ (x2) 87”x136” (x2) YES unique to each specific location 839+35 7’x4’ 43”x68” YES and constraint. We also 9 reviewed concepts with, and 10 891+60 6’x6’ 78” YES received feedback from the 10’x4’ 63”x98” YES jurisdictional agencies. The 11 917+50 8’x4’/8.5’x4’ 58”x91” (x2) YES table to the right summarizes 12 975+50 the type of crossing, proposed 13 1016+20 16’x5’/13’x5’ 9’x5’ (x3) YES materials, and geometry. We 7’x4’ 53”x83” YES also discuss four possible 14 1036+00 construction scenarios based 15 1073+60 11’x5’ 53”x83” (x2) YES on the challenges we anticipate 16 1073+60 11’x5’ 53”x83” (x2) YES at each box culvert location. The following are culvert replacement methods for the anticipated field conditions:
Bypass
SR-9/I-95 Widening from North of SR-60 (MP 6.611) to Indian River/Brevard County Line
NO YES YES NO NO YES YES YES NO NO NO NO
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10. Install new culvert and construct proposed west-side endwall. 11. Install new drainage inlet along the median 12. Restore and reconstruct SB portion of I-95 over the box culvert.
YES NO NO
Replacement Method No. 1: At the south end of the project near station 475+75, our Team is replacing a double 8’X9’ concrete box culvert which, as described in Section 2, provides west-to-east flood connection for the IRFWCD 26th Street/North Dike Ditch. Our Team discussed constructability issues associated with this culvert and requirements for maintaining flows through the ditch with Mr. David Gunter, Superintendent of the IRFWCD. Mr. Gunter suggested (and preliminarily approved) a conceptual dry season bypass plan for the ditch during construction. This plan essentially redirects flows within the North Dike Ditch to the Sub Lateral D-6 Ditch. Mr. Gunter suggested that we block flows from entering the work zone by installing a sheet-pile weir upstream of I-95. Sheet piling would resist erosion better than an embankment ditch block (earth dike) which has the potential for a “wash-out” during heavy storm events. He also Temporary Sheet Pile suggested the installation of a seepage pump upstream Diversion Structure Existing 2 - 9’ x 9’ (west) of I-95 to dissipate (WEIR) Box Culverts any groundwater intrusion. North Dike Ditch A sheet pile weir would be Temporary designed at an elevation Dewatering Pump that would be high enough Ditch Block to prevent dry season water Seepage Pump levels from entering the work zone, but at the same time low enough to allow flows from a large storm event to overtop it and enter into the construction area thereby preventing upstream flooding. Pumping after the storm can dissipate the runoff and restore the work zone. SubLateral D-6 Ditch
Replacement Method No. 2: Many of the existing culverts are partially submerged even during the dry season. At these locations, dewatering and bypass pumping will be necessary. Following the MOT scheme highlighted earlier, the sequence of construction for the replacement of these culverts will be as follows: 1. During the dry season and based on Phase A II of the MOT, install temporary concrete barrier walls along the median shoulders. 4 2. Install critical retaining wall along the east side of the median to prevent the collapse of the roadway during the removal of the existing culvert. 3. Begin excavation of embankment and 3 removal of the existing box culvert Partially remove a segment of the existing culvert as close to the east as possible to allow for installation of pump hose associated with bypass pumping. 4. Install upstream/downstream floating (or 2 3 staked) turbidity barriers.
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5. Construct upstream/downstream ditch blocks. 6. Excavate a ditch sump (pit) for dewatering and construct median ditch blocks to create a sedimentation basin for dewatering operations. 7. Install dewatering pumps and dewater work zone as necessary. 8. Install bypass pump and associated equipment. Pump will operate during storm events or as needed to prevent upstream flooding. 9. Perform excavation and preparation of proposed culvert bedding (i.e. coarse aggregate bedding).
D
With the replacement of the culvert under SB I-95 completed, and based on Phase III of our MOT, commence construction of the segment of the culvert under NB I-95. 13. Relocate bypass pump equipment and install temporary flexible pipe as shown in figure: the pipe will be installed through the newly constructed median drainage inlet and through the newly constructed SB segment of the box culvert. This will allow the remaining segment of culvert to be installed continuously from west to east until completed without the pump hose being in the way of the culvert installation. 14. Continue dewatering operations as necessary. 15. Remove existing culvert and install new culvert in the manner described in steps 9 and 12 above.
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