The bentonite-water slurries (4 to 10% dry bentonite by mass) were prepared in order to evaluate the optimum bentonite content for using in slurry vertical cutoff wall
The largest project currently booked involves seepage remediation by constructing a concrete cutoff wall
at the East Branch Dam in Western Pennsylvania.
It would be impracticable or very expensive to extend the cutoff wall
to an impervious stratum (Ghobadi et al.
"A concrete cutoff wall
in the middle of the dam would definitely solve the problem.
The dam, built in 1925, consists of stone masonry with concrete training walls and earth embankments at each abutment, QCC's design repairs of the deteriorated dam consisted of an upstream concrete facing, apron and short cutoff wall
to seal the existing stone dam from leakage, and reduce seepage potential under the structure.
Slurry Systems Inc., Gary, IN, was awarded a $7,000,000 increment as part of a $9,297,757 firm-fixed-price contract for construction of a Soil-Bentonite Cutoff Wall
at the CUP McCook Reservoir Site.
Completion of the cutoff wall
paved the way for the water quality improvement program and led to an estimated savings of $23 million in avoided impacts to the nearby community versus use of conventional dewatering.
The findings led to several conclusions: significant groundwater flows were occurring around the existing cutoff wall
and were merging with the natural groundwater movement from the upland area; a large area of loose, potentially unstable soil existed behind the downstream retaining wall; vertical seepage via connection with voids in the limestone aquifer was not believed to be a significant component of groundwater flows; and the downstream retaining wall's flexural capacity was unacceptable for groundwater elevations at or above the upper level of weepholes, but was acceptable for groundwater elevations at or below the lower level of weepholes.
River projects ($33.1 million total) -- $18.8 million White River Beaver Dam cutoff wall
rehabilitation construction; $7.9 million Helena harbor construction; $6.4 million grading and structures on Illinois River.
It is anticipated that the order book at closing will be around USD 160m, of which about USD 120m relates to the East Branch Dam Cutoff Wall
Rehabilitation Project in Pennsylvania.
He said the concrete cutoff wall
repair could be modified somewhat based on the result of the test borings yet to be conducted.