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• � i I . I Dr. Michael Caselnova's Office 3 Geohazards Project No.2008674 December 9,2008 f � 7.0 PRESSURE GROUTING PROCEDURE I Pipe InstalIation Grout pipes shall be installed to a depth sufficient to encounter bearing limestone or other bearing ' material(e.g., dense sand), approximately 65 feet on average below the ground surface. If this '' estimated average depth is exceeded by more than 15 feet,the drilling procedure shall cease and the � Geotechnical Engineer notified. Drilling may continue at the Geotechnical Engineer's discretion. i The Contractor may rotary drill or drive the injection pipes to the refusal depth. However,the j method of installation shall ensure a good seal between the pipe and the surrounding soil. The j installation method may be modified subject to the Geotechnical Engineer or his or her 1 '� representative's approval if grout seeps up around the outside of the pipe during injection. j I Grout Injection � Following satisfactory installation of an injection pipe, grouting operations may begin. During the i grouting operation the injection pipes sha11 be incrementally raised to inject the entire zone between 1 depths of approximately 65 feet and 10 feet below the ground surface. If feasible, the sequence of i grouting should be performed at altemating locations to allow sufficient time for the mix to set prior to drilling and grouting adjacent points. The rate of pumping shall not exceed twelve cubic feet per minute. The pumping pressure at the top of the casing is planned to be in the range of 200 to 300 psi or as required by the Geotechnical Engineer or his or her representative. j Unless otherwise directed by the Geotechnical Engineer or his or her representative,pumping shall � cease for at least a 24-hour period if a 1-foot zone takes 20 or more cubic yards of grout at a slump : of 4 inches. If this excessive pumping occurs, the grout pipe shall be raised and flushed to prevent �i the pipe from being cemented in place. Pumping can then proceed at another grout pipe location. ; Pumping may resume at the excessive grout pipe location and depth after a period of 24 hours has � passed. The slump maybe reduced further to 2 inches if a grout point fails to produce resistant � pressure during the pumping operation. Once a resistance pressure of 250—300 psi is reached,the � slump may be increased to not more than 6 inches to improve migration of the grout into the soil in � order to compact loose zones adjacent to the pipe. � i Grouting procedures should be terminated once the grout point is filled to within 6- 10 feet of the 4 surface in order to minimize collateral damage to the structure. ' i Contractor Submittals � ' Methods of the work: � � a. Grout pipe installation procedures � b. Proposed grout pipe locations, depths, and intervals � c. Increments of depth for installation of grout ; d. Maximum grout quantities at each increment of depth ! e. Grout pressures at depths ' f. Equipment to be used in the work ; g. List of vendors and suppliers ' h. Daily records � i. Grout mix design, design slump and tolerances i � I i I