Laserfiche WebLink
Mr. Jim Peterson <br />May 5, 1989 <br />Page 2 <br /> <br />below grade. As we understand, the foundation is to be present <br />around the perimeter of the building. You have also indicated <br />that the building is to be located approximately 10 to 15 feet <br />east of the existing structure at the site. <br /> <br />Contaminated soils should be excavated by using a backhoe to the <br />water table and then stockpiling the soils at the facility. <br />Excavation limits should be determined by visual and olfactory <br />evidence or by the presence of organic vapors as detected by an <br />HNU photoionization detector. Excavation limits where soil <br />contamination is present must extend to a distance of <br />approximately 10 feet beyond the perimeter of the proposed <br />building. The slope of the excavation will result in additional <br />excavated area beyond the 10 foot distance. We anticipate that <br />the excavation will have a 1 horizontal to 1 vertical slope. If <br />during excavation, evidence for soil contamination is not <br />present, the soils need not be removed. The edge of the <br />excavation should extend no closer than 10 feet to the existing <br />building ~ <br /> <br />Contaminated soils must be stockpiled on site. Soil stockpiling <br />must consist of a polyethylene liner and cover for the stockpiled <br />soils. You should also be aware that stockpiling the soils for a <br />long period of time will not be allowed by the MPCA. <br /> <br />Once contaminated soils have been excavated, clean sand backfill <br />should be placed in the excavation. We recommend the backfill be <br />compacted in 12-inch thick lifts and compacted to 95% of Modified <br />Standard Proctor Density. <br /> <br />The excavation should be filled to the depth of the proposed <br />footings for the structure. Within the inner perimeter of the <br />footings, perforated PVC pipe should be installed and connected <br />to a riser pipe to act as a vapor ventilation system once the <br />remainder of the excavation has been filled. This vent system <br />should be constructed so that it can eventually be used to remove <br />soil vapors once the building has been completed. We do not <br />recommend placing any type of impermeable liner under the <br />structure due to potential drainage problems which might result <br />in the future. <br /> <br />WARZYN <br /> <br /> <br />