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- 16 - <br />• of each embankment. We also recommend a minimum of two observation <br />wells be provided along the maximum section in runoff pond #2 and <br />fresh water pond #2. One of the wells should be provided at approxi- <br />mate crest elevation on the downstream slope arxi one at_ the toe of the <br />slope. Both wells should extend to the underlying coarse granular <br />alluvial. Due to the low impoundment depth at runoff pond #3, and <br />relatively impervious conditions at runoff and fresh water pond #1, <br />installation of observation wells may not be required. <br />BRIDGE ABLTLS~1FSTr5 <br />We understand that bridge foundation construction will consist of <br />replacement of the abutments. Subsoils encountered at the abutment <br />areas consist of approximately 10 to 12 feet of fill and clayey sand <br />• and gravel overlying coarse river run material. We understand the <br /> existing channel and abutments were at one time severely eroded and <br />subsequently protected by the heavy boulder material presently on the <br />banks. Free water wes encountered at depth 8 and 9 feet or approxi- <br />mately equal to river level. <br />Abutments can be founded with either spread footings placed on <br />the coarse river run material or with piles driven to refusal on the <br />underlying bedrock formation. Ebr a driven pile alternative, we <br />recormiend H piles with acase-hardened protective point. Due to the <br />oxrse nature of the deposit, pre-drilling mould be required to <br />achieve bearing elevations. Allowable load can be calculated <br />utilizing the structural capacity of the pile. <br />• <br />