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Page eight H. Casing Guides: Centering guides shall be welded or attached in a an approved manner to the outside of conductor, screen and well casing sections to center the elements in the bore hole. Centering guides shall, at a minimum, consist of 2-inch-wide by 3/8-inch-thick steel, having a bearing area of at least 1-foot length at the casing/bore interface. Centering guides shall be of the same material as the casing and/or screen, welded at both ends to the casing and screen and bent to form a guide at the required depth. Centering guides shall be sized to create a uniform annular space around the casing in the bore hole. 1. On conductor casing, a minimum of three centering guides shall be provided at each of the following locations: 4 feet from the bottom, 4 feet from the ground surface and one in the middle. 2. On the screen, centering guides shall be provided at the top and bottom and in between at intervals of not over 40 feet. 3. On the well casing, centering guides shall be provided at the following locations: 4 feet from the bottom of the well screen, 4 feet up from the bottom of the conductor casing, 4 feet below ground level, and in between at intervals of not over 40 feet. ITEM NO. 16 The paragraph under item "B" of"Water Sampling"described in DIVISION Ill, Section 9 - "LEWIS MANOR WATER WELL AND NESTED MONITORING WELL DESIGN AND CONSTRUCTION", shown on page 22 is hereby amended to read: B. The Contractor shall take water samples in the pilot hole at as many as eight depth locations in the identified aquifers. Such sampling shall be completed by installing a temporary 4-inch casing with 5-foot-long screen at the bottom. Sampling shall begin from the deepest identified location and continue upward through the shallowest identified location. The screen shall be gravel packed and a water sample shall be obtained by pumping from the identified strata from the bottom of the casing at a minimum of 10 gallons per minute using a submersible pump and discharge hose. The hose and pump shall be of such a design and constructed of such materials that they do not contaminate the water sample being taken. After each aquifer is sampled, the screen shall be pulled up to the next aquifer, packed with gravel pack, and pumped until the sample is relatively clear or for a minimum of an hour before the next sample is pulled. This process shall be repeated successively until all identified aquifers have been sampled_ ITEM NO. 17 The paragraph under item "B" of "DEVELOPMENT" described in DIVISION Ill, Section 9- "LEWIS MANOR WATER WELL AND NESTED MONITORING WELL DESIGN AND CONSTRUCTION, shown on page 25 is hereby deleted and amended to read.