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Smith to Carver/Sidewalk Construction PracticesCam ! 7 .7 ! r� c — F °�".1.. pKfl !1+y1 ` '� li_? ?#' n! Neu'.. c irk Cr September 6, 2005 Somer's Land Company c/o Carver Engineering 19953 d Avenue East Kalispell, MT 59901 Subject: Sidewalk Construction Ashley Park Phase 7 Kalispell, Montana Attention: Mr. Dennis Carver, P.E. At your request, CMG Engineering, Inc. (CMG) has reviewed your letter to the City of Kalispell Public Works Department, dated August 1.6, 2005, regarding the structural. integrity of the sidewalks constructed in the Ashley Park Phase 7 subdivision. It should be noted that CMG did not provide geotechnical engineering services for this project, nor did we observe construction of the sidewalks. The personnel at CMG have observed construction practices for many sidewalks within the Kalispell City limits and. other areas throughout the Northwest. Our experience indicates that in areas where the subgrade has been adequately prepared or consists of stiff, undisturbed native soils with minimal organics, it is common practice to use the base material beneath the concrete sidewalks as a leveling course to provide uniform bearing beneath the sidewalk. The leveling course is commonly placed and then compacted with a vibratory plate compactor until well -keyed. Leveling course thicknesses generally range from 0 to 4 inches with an average of about 2 inches. In our opinion, the benefit of using 6 inches of compacted base material beneath normally loaded sidewalks is minimal if the subgrade has been adequately prepared. In addition, it should be noted that if sidewalk construction is not adequate for the designed loading, deficiencies will generally be evident following construction of the houses near the sidewalk.. The vehicular traffic loads that sidewalks commonly experience during construction are typically greater than the loads the sidewalk will be subject to during the remainder of p its design life. CMG is uncertain of the Kalispell City Standard origin and the design loads for the sidewalks; however, our experience indicates that in the event that the sidewalk subgrade has been suitably prepared, using the base material as a generally leveling course in the manner described above, is ade quate for sidewalk construction. Please contact CM.G Engineering, Inc: if you have any questions or concerns regarding this letter. Sincerely, Joshua C. Smith, P.E. Senior Geotechnical Engineer