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Show Quittin' Time Study Points Out Geologic Hazards An engineering and geological geo-logical report on the proposed propos-ed Quittin' Time Development, Develop-ment, conducted by the Utah Geological Survey and requested re-quested by former City Planner David Preece, has pointed out new hazards surrounding hillside developments deve-lopments in Park City and . raised questions regarding a prior report compiled for project engineers J.J. Johnson John-son and Associates. r The Quittin' Time development deve-lopment proposed by Salt - Lake Stockbroker Jack , Sweeney calls for existing Norfolk Avenue to be extended exten-ded from 3rd the 7th Street. Along the new section of road would be built a network' of single and multi-family multi-family housing. The unit mix however, is apparently being reworked at this time to create a proposal more receptive to city officials and residents who have been vocal in their opposition of the project. ,: The piror geological and engineering report conducted conduct-ed by Rollins, Brown arid Gunnel Inc. at the request of J.J. Johnson Associates described des-cribed the geologic hazards of building on the 1 steep hillside as minimal providing proper engineering techniques techni-ques were employed. Not content to view the "developer's" "deve-loper's" survey as the last word on the proposed project, pro-ject, David Preece, with the authorization of the Planning Commission, solicited the Utah Geological Survey to conduct an independent study. Dated June 20, 1979! the state's survey draws attention atten-tion to seven potential geologic hazard areas and mends intercept drains be s constructed above and below c the site and that existing vegetation should be left 1 undisturbed whenever pos- ! sible. 1 A geological hazard as- 1 sociated with the site not formerly identified pertains to the presence of old mine workings. The state study indicates that a fiumber of the old workings were encountered on the site Which present an eventual danger of collapse. The report recommends that all mine workings in the area be identified and filled prior to construction. A complete list of the potential geologic hazards found by the state survey to be present at the site include? Foundation . and backfill problems associated with clayey soils; slope stability problems in the unconsolidated materials on iite due to the steep hillsides n which the development vould be built; potential for property damage and personal per-sonal injury from rocks rolling- down slope during construction; eroision, sedimentation sedi-mentation and localized flooding during spring snow melt; avalanche hazard, especially es-pecially if vegetation cover is removed from large areas of the hillside; ground subsidence subsi-dence and collapse over shallow mine workings; and site sensitivity to landslide, rockfall, and avalanche hazard haz-ard in the event of a large earthquake along the Wasatch Wa-satch fault. The survey was. described by Planning Commission Chairman Burnis Watts as "eye-opening" and will most likely be of value in assessing potential hazards associated with hillside developments deve-lopments in Park City in future years. points out several discrepen-cies discrepen-cies ki the prior study. In 1977, Rollins, Brown and Gunnel dug 11 test pits in the area where they conducted much of their analysis. The 1977 survey maintains that bedrock was encountered in the pits at depths averaging from 7 to 8 feet, and as high as 2 feet in ' one pit and as low as 15 in another. The state's survey however failed to identify bedrock in four of the pits in which the prior survey maintained it was found. The recent study asserts that in the prior; a "closely packed layer of quartzite cobbles in a clay mix" had been misiden-tified misiden-tified as bedrock. The composition of soils in secondary layer, was described des-cribed in the 1977 report as being composed of " angular' fragments in a matrix of silt." The recent survey, however, describes the two soils as "gravely clay." Since the engineering of the Quittin' Time development develop-ment is based on the presence of bedrock at between 7 and 8 feet and a silty soil composition in zone two, the .state recommends that engineering be reworked rework-ed to account for a lower bedrock level and an entirely different soil composure in zone two. The state survey was concerned that foundations founda-tions may be inadvertantly placed above the bedrock level and that the elasticity of clay soils in zone two may not be taken into account. The clay soils in zone two also have the characteristic of being rapidly saturated with ground water creating a heavier surface run-off than originally anticipated. Although the 1977 survey claimed no evidence of ground slippage, the state's Study found indications of "soil creep." Soil creep is described in the study as a very slow but continuous downhill movement of upper soil levels. This, the survey maintains, is evident by bent tree trunks and fence posts slanted at angles. The survey suggests that "unwise" construction practices prac-tices could aggrevate soil creep, and recommends that cut and fill slopes be designed according to recommendations re-commendations of a qualified quali-fied soils engineer "to prevent excessive settlement and failure of fill. sections"; the study also recommends that the city adopt a code of minimum construction specifications spec-ifications "which clearly outline acceptable gradation limits and compaction requirements re-quirements for all fill re-quiremen re-quiremen ; The w ,'s study Enumerates Enumer-ates the- r st severe problems pro-blems as;. being' related . to water. Jo" combat" this problem ' the state recom- |