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HomeMy WebLinkAboutWPO201600057 Plan - As-built 2019-05-23Underhill ENGINEERING geotechnical I geodesign I geoconstruction May 23, 2019 Mr. Shareef Tahboub RoseWood Village 2029 Lockwood Drive Charlottesville, VA 22911 Subject: Report of Geotechnical Engineering Services During Construction, RoseWood Village Stormwater Management Basin, 500 Greenbrier Drive, Albemarle County, Virginia (Underhill Engineering Project No. 17030) Dear Mr. Tahboub: Underhill Engineering, LLC (Underhill) is pleased to present our updated report, summarizing Underhill's geotechnical engineering services during construction for the above -referenced project. This report summarizes Underhill's services relating to the observation of the installation of the stormwater management basin structure as installed by the contractor, FCE. Services provided consisted of Underhill's evaluation of fill materials for the embankment core, observation of the core subgrades, and a follow up visit to evaluate the completed embankment core. These services were provided in accordance with Underhill Engineering's agreement with RoseWood Village executed September 28, 2017. This report summarizes services provided from September 28 through November 1, 2017. The following services were not included: surveying for line and grade, environmental services, or other services not specifically identified above. Site and Project Description The project site is at the existing RoseWood Village Assisted Living Facility, located at 500 Greenbrier Drive in Albemarle County, Virginia. The proposed Storm Water Management (SWM) Basin is located just east of the existing Rosewood Village building. Evaluation of Core Fill Materials Underhill's Professional Engineer evaluated the proposed core fill material on October 2 and 4, 2017. Core material consisted of Fat Clay with sand (CH). Laboratory testing of the proposed core material was conducted under a separate contract and indicated the material to exhibit a hydraulic conductivity (permeability) value, k, of less than 10-7 cm/sec, suitable for use as core material for the stormwater management structure. Observation of Core Subgrades Underhill's Professional Engineer visited the site on October 31, 2017, to observe subgrades for the stormwater management basin core. Subgrades were evaluated by probing with a Geostick Penetrometer at select locations in the open core excavation. The subgrades observed generally consisted of stiff silt and clay residuum. Geostick Penetrometer readings of less than 1 inch were typically obtained. Soils were visually classified following ASTM criteria. During our visit, we T: 434.531.2565 327 W. Main Street, Suite 2, Charlottesville, VA 22903 underhillengineering.com recommended and observed the widening of the core trench excavation to extend to the width of the embankment. Based on Underhill's observations, the excavated subgrades were considered suitable for placement of the core material at the grades excavated to by the Contractor. Observation of Core Material Placement Underhill's Professional Engineer visited the site on October 31 and November 1, 2017, to make periodic visits to observe placement of the core material. The core material consisted of Fat Clay with sand (CH). Based on our visual observations, the soils were generally near or slightly above the optimum moisture content needed for compaction. Core material was placed in maximum 8-inch thick loose lifts and compacted using a vibratory sheepsfoot roller. The sheepsfoot was observed walking out during compaction of the lifts indicating sufficient compaction of the stormwater management structure core material. Underhill has endeavored to complete the services identified herein in a manner consistent with that level of care and skill ordinarily exercised by members of the profession currently practicing in the same locality and under similar conditions as this project. No other representation, express or implied, is included or intended, and no warranty or guarantee is included or intended in this report. Thank you for the opportunity to provide our services. If you have any questions or require additional information, please do not hesitate to contact me. Sincerely, UNDERHILL ENGINEERING, LLC D TH p� ZChlrisopler Webster, PE 0. CHRISTOPI[KR Principal U WEBSTPR �y Lic. No. 019910 a IOG ■, NAL Project 17030 / May 23, 2019 2 Underhill Engineering, LLC