6301 36TH AVE W 2016-11-01 - Laserfiche WebLink

June 23,2014 Project No.T-6241 Subsurface We recommend installing perimeter foundation drains adjacent to shallow foundations where paved surfaces do not extend to building perimeter and positive drainage away from the structure is not provided. The drains can be laid to grade at an invert elevation equivalent to the bottom of footing grade. The drains can consist of four-inch diameter perforated PVC pipe that is enveloped in washed pea gravel-sized drainage aggregate. The aggregate should extend six inches above and to the sides of the pipe. Roof and foundation drains should be tightlined separately to the storin drains. All drains should be provided with cleanouts at easily accessible locations. 5.11 Utilities Utility pipes should be bedded and backfilled in accordance with American Public Works Association (APWA) or local jurisdictional requirements. At minimum, trench backfill should be placed and compacted as structural fill, as described in Section 5.2 of this report. As noted, the on-site soils should be suitable for use as backfill material. However, at the time of our study, the upper soil's moisture content appeared to be above optimum. Therefore, drying back or other means to condition the material will likely be necessary to facilitate proper compaction. If utility construction takes place during the winter, it may be necessary to import suitable wet weather fill for utility trench backfilling. 5.12 Pavements Pavements should be constructed on subgrades, as described in Section 5.2 of this report. Regardless of the degree of relative compaction achieved, the subgrade must be firm and relatively unyielding before paving. Proofrolling the subgrade with heavy construction equipment should be completed to verify this condition. The pavement design section is dependent upon the supporting capability of the subgrade soils and the traffic conditions to which it will be subjected. We expect traffic at the facility will consist of cars and light trucks, along with occasional heavy traffic in the form of tractor-trailer rigs. For design considerations, we have assumed traffic in parking and in car/light truck access pavement areas can be represented by an 18-kip Equivalent Single Axle Loading (ESAL) of 50,000 over a 20-year design life. For heavy traffic pavement areas, we have assumed an ESAL of 300,000 would be representative of the expected loading. With a stable subgrade prepared as recommended,we recommend the following pavement sections: Light Traffic and Parking: • Two inches of hot mix asphalt(HMA)over four inches of cruslied rock base (CRB) • 31/2 inches of full depth HMA Heavy Traffic: • Three inches of HMA over six inches of CRB • Five inches of full depth HMA Page No. 12