AG 2007 03 26 - Laserfiche WebLink

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Mr. Steve tattle, Dtragar FebrWry 71, 7006 Page 2 happened to pull the moisture up so quickly. The soil was being placed correctly and the fill was placed on fabric to ensure a good sub base for fill placement. There was a meeting of the Owner, WKD and Trigon to observe an additional proof roll after some undercutting, rolling and compaction of the area to sea if the soli could be stabilized. The lower tfiird of the parking area was in poor condition. The soil pumped up and down and rutted 6 to 8 inches. The conclusion by Trigon was to undercut an additional 12 inches of the soil and add additional stone in compacted lifts on geogrid as a bridging device. WKD asked about conducting some borings to check moisture and original sub base for springs, Trigon stated that the borings would not tell the state of the original subbase at this point. The stone had-been overworked and it may have pulled moisture up into the fill section. This would have changed the sub base from the time of the original observation. Some preliminary estimates were derived on site based on the area of poor coriditions. The estimates were to cover the whole parking area with geogrid to bridge the whole parking area and overlay the area with a minimal of ti" stone as called for in the plans and the lower half would get 18 inches of stone (12' additional stone under the original section). • After discussion with Tim Lowder, WKD branch manager, about finding on the site of two spring heads in the. pond area adjacent to the parking lot fill, WKD posed the question to Trigon about getting borings done for underground spring heads. There were several days of dry warm weather and Trigon recommended digging a minimum of two test pits in the lower end of the parking fill and observe if water would come up in the bottoms of the holes. 1.) It the water surface rose, then this should show that water was flowing out of the existing ground level up through the new compacted fill which softened the compaction. A possible solution could be using a French drain out to daylight into the pond. 2.} if water didn't rise up in the holes, then this would indicate the subsurface soli was in poor condition (clay soil which broke down under the weight of the trucks and movement) and the water in the original soil was pulled up through the new fill by wicking up in the material. If this was what had occurred, then using the original estimate of geogrid and additional stone would be a solution to stabilize the soil. It may also need to be a combination of the two items. WKD recommends due to the 5 week minimum t)me period to get finances resolved, that we have the contractor temporarily seed the areas to comply with the state requirements of stabilizing the area when work is stopped for 14 days and to wait until spring to doing the testing which will allow the site water table in the over worked condition of the fill to settle down and dry up. If it is a springhead, then it will remain wet and give a better indication to use the French drains or a combination of the French drain at the bottom and additional stone/geogrid in the top. The winter months will be wet, but the parking area was compacted and smooth rolled to sheet water off the surface better. Aker a time period of waiting, there was a week of dry weather in January and Ike's dug the test pits and the pits were observed for 3 days. No water came up in the fioles. WKD and Trigon discussed the need of under drain. It is a recommendation that no under drain will be needed. ~'~~