SR 06:060 - Laserfiche WebLink

Ms. Kerry Sinnott 3909 Vineyard Avenue 10 November 2005 Page 5 DeadwelI&RoIIo We anticipate soil at the site may be trenched with conventional earth-moving equipment such as excavators and backhoes. Unsupported vertical cuts to a depth of five feet may be possible. Vertical cuts greater than five' feet should be shored, If sloped excavations are used, the slopes should be no steeper than I: I (horizontal: vertical) for temporary conditions. During the rainy season, the ground surface may become wet or saturated. This could result in pumping and yielding bf the soil sub grade under construction traffic. It may not be possible to use heavy construction equipment without waiting fot the ground surface to dry out. . Additionally, the creek channel level may fluctuate several feet seasonally, impeding construction. .RECOMMENDATIONS From a geotechnical standpoint, we conclude the .storm water outfall can be constructed as planned, provided recommendations presented in this report are incorporated into the design and contract documents. A design of the outfall system has been completed and our comments regarding various aspects are included below, The storm sewer pipeline will require trenching and backfill, Placement of backfill should be performed according to the utility trench backfill recommendations inCluded in our geotechnical investigation report, The energy dissipation system will consist of a reinforced concrete ch~el with a minimum width of three feet. The channel will have weep holes, be filled with rip-rap and underlain by pervious material where the weep holes are installed. The channel will have down-turned edges of up to four feet deep, below the bottom of the channel. Subgrade preparation and placement of backfill should be performed according to the site preparation and grading recommendations included in our geotechnical Investigation report. . Erosion control will consist of installation of permanent turf reinforcement mat from North American Green. The reinforcement mat will be installed from the crest of the slope to the termination of the energy dissipation system, A minimum width of 10 feet of reinforcement mat will be installed. During fmal design we should be retained to consult with the design team as changes and geotechnical questions arise. Prior to construction, we should review the project plans and specifications to check their conformance with the intent of our recommendations. During construction:, we should observe trenching, site preparation, compaction of trench backfill, and installation ofthe energy dissipation system and erosion control. These observations will allow