Grouting 
Service Co. 
February 14, 2008
RE:	2008 Pressure Grouting Proposal 
Right Abutment Area 
Lake Tishomingo Dam
Jefferson County, MO 

Dear Mr. Hirsch and Board Members, 
We are pleased to present our proposal to perform pressure grouting services at the referenced location. 
MISSION
Our action plan is to construct a grout curtain consisting of twenty-one exploration/grout holes drilled in alignment along the axis of the dam spanning the apparent subsurface leakage zone. Within this zone, leakage of lake water is occurring through solutioned conduits within the underlying dolomite bedrock at an approximate depth of 50 feet below the top of the dam. This leakage exfiltrates downstream from the seepage collector structure in the form of a 300 GPM spring. Previous remedial work attempted in the 1960’s utilizing bitumen had questionable success. Over time, the bitumen placed has been naturally degraded. Our proposed grout curtain will overlap and define the suspect leakage zone. Subsequent permeation grouting, utilizing permanent grout materials, will provide closure of lake water leakage presently occurring through the solutioned conduits. Primary benefit of this work will be water conservation, by significantly reducing leakage. The secondary benefit will be to improve the integrity of the dam. 
SCOPE OF SERVICES
1.	The Owner’s engineer, Mr. Don Eskridge, will be responsible to prepare an application for a construction permit to modify the dam as required by Missouri DNR/Dam Safety Program.
We suggest Mr. Eskridge completes this application in early March, 2008 to facilitate an approximate project start by April 14, 2008. 
We will work directly with Mr. Eskridge to draft applicable remedial procedures that will be accepted by DNR/Dam Safety. 
Mr. Eskridge will also be responsible to reestablish and mark the baseline from Station 6+00 through 8+36 and provide engineering support including surveying and preparation of a planview drawing. 
2.	The Owner will be responsible to provide required project access along North Lake Shore Drive. 
The Owner will be responsible to trim back limbs on the row of cedar trees to a height of 12.5’ along the dam approach lane. The asphalt along this approach lane is thin and narrow. Any damage to the asphalt during the project duration will be the responsibility of the Owner. 
The Owner will be responsible to locate and clearly mark all underground utilities within and overlapping the work area. 
If cement exfiltration becomes a problem, the Owner will be responsible to temporarily divert and control the exfiltration. 
3.	Grouting Service Co. will mobilize all required equipment, men and materials to project location. A total of 21 exploration/grout holes are estimated for project completion. All drilling, testing and grouting techniques utilized will be per DNR/Dam Safety approved procedures and supervised by a Missouri Registered Geologist as required by law.
4.	Begin construction of grout curtain by drilling vertical primary holes on ten foot intervals. Advance nominal 6-1/2” φ holes through dam embankment. Holes will be drilled utilizing clear water as a circulation medium. Continue to advance 6-1/2” φ hole through dam embankment and approximately 6” into underlying dolomite bedrock. During drilling, materials penetrated and anomalous features encountered will be accurately logged in detail to within 1/10 of a foot by Missouri Registered Geologist, as required by law. 
5.	Immediately install, in hole, permanent 4-1/2” O.D. API 9#/L.F. threaded and coupled steel conductor casing and seat firmly 6” into bedrock socket. If sloughing conditions are encountered, drill rig will be equipped to circulate water and rotate casing to penetrate any obstructions and to assure that casing is firmly seated in bedrock socket. 
6.	Reenter cased hole and slowly advance 4” φ hole to 60 foot total depth through dolomite bedrock utilizing clear water as a circulation medium. During drilling, rock types penetrated, lithologic changes and anomalous features encountered will be accurately logged in detail to within 1/10 of a foot by Missouri Registered Geologist, as required by law. 
7.	Following drilling, each hole will be inflow water tested at gravity pressure. The testing manifold will be complete with pressure gauge, air relief valve and totalizing water meter recording in gallons. After testing all holes, the holes with the greatest take or hydraulic conductivity will be inflow dye traced to verify connection and travel time to the downstream spring. 
8.	After allowing a period of stabilization, the piezometric level in each hole will be accurately recorded to within 1/10 foot. 
9.	As applicable, a water temperature profile from static level to bottom of hole will be recorded and logged for select holes. This technique may help locate conduit leakage in proximity to the borehole, but not directly intersected. 
10.	As applicable, select holes may be wireline probed with underwater acoustic emissions equipment. Acoustic emissions probing will assist with detection of 40 KHz range anomalies associated with conduit leakage in proximity to drilled holes. This technique may be used to assist with locations of isolated leakage flow paths possibly near or in between holes if conditions are applicable. 
11.	Following completion of the afore outlined work, review with Engineer and Owner subsurface data gathered including detailed drill logs and cross- sectional drawing along hole alignment showing soil characteristics, bedrock lithology and anomalous features, piezometric profile, temperature profile, inflow water test results, dye trace results, acoustic emissions anomalies, verified leakage zones and suspect leakage zones. As leakage zones are delineated, grouting will commence as outlined below. 
12.	Grouting will proceed by affixing cement manifold complete with pressure gauge and air relief valve to top of 4” φ grout conductor casing. Two-inch φ grout hose will be used to convey cementaceous grout from the pump to the grout manifold. All cementaceous grout will be pumped with a positive displacement grout pump with rated capacity of 100 GPM @250 PSI. All cementaceous grout may be premixed and delivered to the pump location in ready-mix trucks or hand batched. Each load will be accompanied with a certified tabulation of contents and precise time batched. Any load not correctly batched or containing aggregate contamination or deleterious material will be rejected. Grout will be thinned or thickened at the site as required. Required admixes may also be blended in at the job site. If grout is discharged from the leaks or a cavernous condition is encountered, “Strata Seal”, a coagulating admix or sodium silicate may be added to stop grout loss and seal water courses. All grout will be pumped per specified pressure limitation of 1/2 PSI/L.F. of hole depth. Each hole exhibiting significant permeability will be injected at controlled pressure until all void space penetrated is thoroughly filled. During grouting, piezometric levels in adjoining holes will be continually monitored to trace subsurface grout movement. The downstream spring will be monitored for grout communication and reduction in flow. 
13.	At completion of primary grouting, conduct meeting with Engineer and Owner and DNR/Dam Safety to review progress. Secondary drilling and grouting may be required to split ten foot intervals or extend the grout curtain to provide closure and complete a watertight grout curtain. Procedures #4 through #12 may be repeated until all subsurface voids are thoroughly filled and sealed. 
Please be aware, the degree of success of this project is not guaranteed. Dam grouting projects are speculative in nature and the degree of success is directly controlled by unobservable subsurface geological conditions. We have had outstanding success effectively grouting leakage on many other similar lake and dam related projects and will make every effort to reduce as much leakage as possible on your project. I will personally be present during all field activities to direct the operation, update you on progress and provide cost updates.