Phase 2 - construction of an earthen dam on richland creek approx 125 LF in height and approx 4,150 LF in length, including dewatering, excavation, grout curtain
, earthfill, cutoff wall, principal outlet structure & pipe, seepage drains, stilling basin, erosion & sedimentation control, appurtenances, and all other work.
It was concluded that upstream blanket is very efficient as compared to grout curtain
in controlling seepage on downstream of Khanpur Dam (Farooq et al.
A common method to rehabilitate a dam is to create a seal--a concrete wall or a grout curtain
, for example--usually accomplished by drilling boreholes up to 100 m or more deep, then injecting grout into the holes to seal any cavities.
The project originally called for sealing 440 manholes by creating a grout curtain
around each structure.
To secure the dam to the surrounding foundation, a grout curtain
reaches to a depth of 200m beneath the dam and extends 100m into the rock on either side of the valley.
2011) while discussing the post impounding problems of dams constructed in carbonate geology have described, "A number of seepage control measures such as grout curtain
, dental treatment and impervious blanket were provided at the time of construction which did not prove sufficient".
The first step was to isolate the shaft from groundwater by grouting the rock fissures around it and creating a grout curtain
to reduce ingress, minimising potential contamination.
Drain holes in diversion tunnel and downstream of right saddle and strengthening of grout curtain
of left abutment of main dam were also carried out.
If Obama signs the bill, the corps would receive the $44 million to help extend a grout curtain
as a temporary fix for the next several years as engineers design and construct a permanent fix to stop a leak through a damaged abutment next to the Hanson Dam.
If you are tunnelling and drilling holes for grouting then the quality of the grout curtain
and the safety in the tunnel is depending on the pattern of the holes.
Geostudio analysis as well as field data has indicated that previous grout work at left and right abutments has failed to produce the required results and seepage which is being measured at the downstream toe of the dam is through the abutments instead of through the body or foundations of the dam and recommends that by extending the grout curtain
up to a depth of 140' in case of left abutment and to a depth of 160' in case of right abutment, the quantities of seepage can significantly be reduced.
The solution was to design and construct a circular grout curtain
around the footprint of the shafts that extended through the contact zone and bedrock to significantly reduce water inflow during construction.