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HomeMy WebLinkAboutREPORT - 16-00432 - 505 S Millhollow Rd - SFRI&-C13�, ® A16-169 Johnson Residence Limited Geotechnical Report July 18, 2016 Report Recommendations are Limited and Subject to Misinterpretation There is a possibility that conditions may exist that could not be identified within the scope of the investigation or that were not apparent during our site investigation. Findings of this report are limited to data collected from noted explorations advanced and do not account for unidentified fill zones, unsuitable soil types or conditions, and variability in soil moisture and groundwater conditions. To avoid possible misinterpretations of findings, conclusions, and implications of this report, NES should be retained to explain the report contents to other design professionals as well as construction professionals. Since actual subsurface conditions on the site can only be verified by earthwork, note that construction recommendations are based on general assumptions from selective observations and selective field exploratory sampling. During construction, such conditions may be identified that require corrective actions, and these required corrective actions may impact the project budget. Therefore, construction recommendations in this report should be considered preliminary, and NES should be retained to observe actual subsurface conditions during earthwork construction activities to provide additional construction recommendations as needed. If you have any questions please contact me at (208) 932-2720. Respectfully, Chris A. Park, P.E. NORTHWEST ENGINEERING SERVICES, P.C. 1680 Woodruff Park Idaho Falls, ID 83401 Reviewed By: DBS Northwest Engineering Services Idaho Falls, ID • Bend, OR • Salmon, ID 5 of 5 Northwest Engineering Services, P.C. July 18, 2016 TASK ORDER — JOHNSON RESIDENCE IN REXBURG, ID AN ATTACHMENT TO THE AGREEMENT BETWEEN JSM CONSTRUCTION AND NORTHWEST ENGINEERING SERVICES, P.C. General Services ARTICLE 1: ASSIGNMENT OF TASK ORDER JSM CONSTRUCTION hereby assigns this task order to NORTHWEST ENGINEERING SERVICES, P.C. (NES) for which the work included in this task order applies. Coordination for the execution of this task order shall be with Mr. Jonathan McMullen who will act as the managing entity for this task order. ARTICLE 2: SCOPE OF WORK Upon authorization to proceed, Northwest will prepare a limited geotechnical evaluation of onsite soils via previously excavated foundation footprint for the proposed Johnson Residence located at 505 S Mill Hollow in Rexburg, ID. The scope will include the following services: ■ Onsite evaluation of excavated footprint area for general foundation suitability • Limited geotechnical report including visual soils classification, visual slope stability recommendations, and soil foundation recommendations ARTICLE 3: COMPENSATION A. Project Budget The work described under the Scope of Work for this task order will be performed for a lump sum of $620.00. Additional scope items will be completed on a time -and -materials not -to -exceed basis in accordance with the NES billing rate schedule. Northwest will not exceed the total dollar amount of this Task Order without a signed amendment. NES billing rate schedule Hourly Rate Engineer - PE $ 110.00 Engineer - EI $ 90.00 Drafter $ 60.00 B. Invoicing The lump sum amount will be invoiced upon submittal of the final report due within 15 days of the invoice date. Jones Residence - Limited Geotechnical Report 1 of 4 ARTICLE 4: SCHEDULE We anticipate submitting the findings report approximately two (2) days after performing the field work. The schedule may be modified during the execution of the project as agreed to by both parties to this agreement. If you have any questions please contact me at (208) 932-2720. Respectfully, Chris A. Park, P.E. NORTHWEST ENGINEERING SERVICES, P.C. 1680 Woodruff Park Attached: Contract Agreement Jones Residence - Limited Geotechnical Report 2 of 4 AGREEMENT BETWEEN JSM CONSTRUCTION AND NORTHWEST ENGINEERING SERVICES, P.C. General Services THIS AGREEMENT (this "Agreement") is made and effective this _ day of 2016, by and between JSM CONSTRUCTION ("CLIENT"), and NORTHWEST ENGINEERING SERVICES. P.C. ("NES"), an Idaho professional corporation with offices located in Salmon, Idaho; Idaho Falls, Idaho; and Bend, Oregon. WITNESSETH: WHEREAS, CLIENT is desires professional services related to Civil Engineering and requires specialized technical advice and assistance therewith as specified hereinafter; and WHEREAS, NES represents that it is able, willing, and qualified to render the technical advice and assistance called for herein: NOW, THEREFORE, the parties hereto, in consideration of the mutual undertakings and agreements herein contained, agree as follows: SECTION 1— SCOPE OF WORK NES will perform all services as specified in specific TASK ORDERS between the parties included as Attachments to this Agreement. As additional services are agreed to between the parties, the TASK ORDERS for those services shall specify the scope of work for said services and be appended to this contract and will become a part of this contract. SECTION 2—SCHEDULE Schedule will be set by NES and client per client needs. SECTION 3 — COMPENSATION As consideration for performing the services specified herein, NES shall be paid the sums stipulated and be reimbursed for expenses incurred in accordance with the Compensation section of the TASK ORDERS and the NES billing rate schedule which included in Exhibit 1-1 and hereby made a part of this Agreement for said services provided in Attachments to this Agreement. SECTION 4 — GENERAL TERMS AND CONDITIONS This Agreement will be subject to the General Terms and Conditions included in Attachment A. For the purpose of the General Terms and Conditions, the term "Contract" shall refer to this agreement and its Attachments. Jones Residence - Limited Geotechnical Report 3 of 4 SECTION 5 — LEGAL NOTICE Any and all communication between the parties will be considered as having been legally delivered if sent to the following addresses: TO: JSM CONSTRUCTION 626 Sunflower Road Rexburg, ID 83440 (208) 569-2147 jsmconstruction.inc@gmail.com TO: NORTHWEST 1680 Woodruff Park Idaho Falls, ID 83401 (208)932-2720 dsharp@nwengring.com NG SERVICES, P.C. or 1680 Woodruff Park Idaho Falls, ID 83401 (208) 932-2720 cpark@nwengring.com If either of the parties should change its address, it shall, without delay, communicate the fact to the other by writing or by fax or by e-mail. SECTION 6 — LAW OF CONTRACT This Agreement shall be construed in accordance with the laws of the state of Idaho provided that nothing contained herein shall be interpreted in such manner as shall render it unenforceable under the laws of the United States. No action may be brought except in the state of Idaho. SECTION 7 — EXECUTION IN WITNESS WHEREOF, the parties hereto have made and executed this Agreement as of the day and year first above written. NORTHWEST ENGINEERING SERVICES, P.C. By: Name: Title: Date: JSM CONSTRUCTION By: Name: Title: Date: Jones Residence - Limited Geotechnical Report 4 of 4 ®July A16-169 Johnson Residence - Limited Geotechnical Report 18, 2016 Jonathan McMullen JSM Construction, Inc 626 Sunflower Road RexbuXg,ID 83440 Re: Johnson Residence - Limited Geotechnical Engineering Report 505 S Mill Hollow, Rexburg In compliance with your instructions, NES has conducted a limited foundation evaluation and visual slope stability assessment for the above referenced residence. Fieldwork for this investigation was conducted on July 18, 2016. The proposed residence development is located in the eastern portion of the City of Rexburg, Madison County, ID, and occupies a portion of the NWYaSEY4 of Section 29, Township 6 North, Range 40 East, Boise Meridian. Loads of up to 4,000 pounds per lineal foot for wall footings, and column loads of up to 50,000 pounds were assumed for settlement calculations. Retaining walls are not anticipated as part of this report. Authorization Authorization to perform this exploration and analysis was given in the form of verbal direction from Mr Jonathan McMullen of JSM Construction, Inc. to Chris Park of Northwest Engineering Services, PC (NES), on July 15, 2016. Said authorization is subject to terms, conditions, and limitations described in the Agreement entered into between JSM Construction and NES. Our scope of services for the proposed development has been provided in our proposal dated July 18, 2016 and repeated below. Scope of Investigation The scope of this investigation included a visual assessment of the natural slope and recently excavated foundation area. Our scope of work did not include physical subsurface exploration, numerical slope analysis, laboratory testing, pavement design, or earthwork recommendations. General Site Characteristics This proposed development consists of approximately 0.3 acres of sloping terrain. Throughout the majority of the site, surficial soils consist of fine-grained silt -sand mixtures. Vegetation primarily consists of sagebrush, bunchgrass, and other native grass varieties typical of and to semi -arid environments. Soil and Sediment Profile Surficial soil was observed to be sandy silt over naturally and partially exposed native basalt rock. Below the sandy silt, gray basalt rock was observed which was slightly weathered, widely fractured, and strong. Northwest Engineering Services Idaho Falls, ID • Bend, OR • Salmon, ID 1 of 5 A16-169 Johnson Residence - Limited Geotechnical Report July 18, 2016 Slopes and Setbacks A visual assessment of the slope was performed to determine possible instability issues relating to the existing slope, subsurface geology, and proposed structure. The proposed residence is expected to be constructed at the top of a natural slope with a minimal setback. The steepest part of the slope was observed near the bottom of the slope to be approximately 4 foot horizontal to 1 feet vertical (4:1). The general slope was observed to be approximately 6:1. Naturally exposed basalt rock was observed in places on the lot and down the slope to the east. As discussed earlier, the basalt was found to be slightly weathered, widely fractured, and strong. Fracture orientation and spacing did not appear to be detrimental to long-term slope stability (or rock toppling). No evidence of recent rock fall or toppling was observed. f Because the basalt was found to be intact, and the proposed structure will be built directly on the basalt rock, the slope setback requirements as outlined in the IBC can be adjusted to the currently planned location near the center of the lot. No potential visual slope stability deficiencies were identified during the investigation. It is noted that shallow footings and/or other structural elements (floor slabs, landscaping, etc.) should not be constructed on the slope face as the shallow silts are not suitable for support of loading bearing elements. Infiltration of water into the shallow silts is also prohibited, as this could lead to surficial slumping with the shallow silts. Foundation Design Recommendations Based on data obtained from the site NES recommends the following guidelines for the net allowable bearing capacity: Description Criteria Foundation type Conventional shallow spread footings Bearing material Footings must bear on competent, intact basalt formations (a 6 -inch separation with sand or aggregate base layer is required) or compacted structural fill bearing on competent, intact basalt formations. Existing sandy silt soils, basalt gravels/fractured basalt, excavatable basalt, and fill materials (if encountered) must be completely removed from below foundation elements. Any structural fill required to elevate the site to proposed footing elevations must be placed in a controlled and compacted manner as is outlined in the Structural Fill section of this report. Net allowable bearing pressure Intact basalt or compacted structural fill overlying intact basalt: 4,000 pounds per square -foot' ' Net allowable bearing capacity for rock found in the 2012 International Building Code, Table 1806.2. Northwest Engineering Services Idaho Falls, ID • Bend, OR • Salmon, ID 2 of 5 ES A16-169 Johnson Residence - Limited Geotechnical Report July 18, 2016 Based on our understanding of the project, it is anticipated that portions of the site will bear on competent, intact basalt rock (with the appropriate sand or aggregate separation layer) while other portiops of the structure will bear on up to 3 feet of structural fill material. It is likely that differential settlement will occur in areas where foundations transition from bearing on rock to bearing on fill material. The total settlement in these areas is still limited to 1 inch, but could primarily be differential settlement at the transition areas. NES recommends that additional reinforcement be provided in the transition areas to help mitigate the differential settlement. Objectionable soil types encountered at the bottom of footing excavations should be removed and replaced with structural fill. Excessively loose or soft areas that are encountered in the footings subgrade will require over -excavation and backfilling with structural fill. Floor. Garage, and Driveway Slab -on -Grade Organic, loose, or obviously compressive materials must be removed prior to placement of concrete floors or floor -supporting fill. Areas of excessive yielding should be excavated and backfilled with structural fill. Fill used to increase the elevation of the floor slab should meet requirements detailed in the Structural Fill section. Fill materials must be compacted to a minimum 95 percent of the maximum dry density as determined by ASTM -D1557. A free -draining granular mat (drainage fill course) should be provided below slabs -on -grade. This should be a minimum of 4 inches in thickness and properly compacted. The mat should consist of a sand and gravel mixture, complying with Idaho Standards for Public Works Construction (ISPWC) specifications for -inch (Type 1) crushed aggregate. A moisture -retarder should be placed beneath floor slabs to minimize potential ground moisture effects on moisture -sensitive floor coverings. The moisture - retarder should be at least 15 -mil in thickness and have a permeance of less than 0.01 US perms as determined by ASTM E96. Placement of the moisture -retarder will require special consideration with regard to effects on the slab -on -grade and should adhere to recommendations outlined in the ACI 302.111 and ASTM E1745 publications. The granular mat should be compacted to no less than 95 percent of the maximum dry density as determined by ASTM -D1557. Structural Fill Soils recommended for use as structural fill are those classified as GW, GP, SW, and SP in accordance with the Unified Soil Classification System (USCS) (ASTM -D2487). Use of silty soils (USCS designation of GM, SM, and ML) as structural fill is not acceptable. Recommended granular structural fill materials should consist of a 6 -inch minus select, clean, granular soil with no more than 50 percent oversize (greater than %-inch) material and no more than 12 percent fines (passing No. 200 sieve). These fill materials should be placed in layers not to exceed 12 inches in loose thickness. Prior to placement of structural fill materials, surfaces must be prepared by removing organic and/or loose materials. Structural fill material should be moisture conditioned to achieve mum moisture content compaction. For structural fill below footings, areas of compacted backfill must extend outside the perimeter of the footings for a distance equal to the thickness of fill between the bottom of foundation Northwest Engineering Services Idaho Falls, ID • Bend, OR • Salmon, ID 3 of 5 A16-169 Johnson Residence - Limited Geotechnical Report July 18, 2016 and underlying soils, or 5 feet, whichever is less. All fill materials must be monitored during placement and tested to confirm compaction requirements, outlined below, have been achieved. Each Iyer of structural fill must be compacted, as outlined below: • Below Structures and Rigid Pavements: A minimum of 95 percent of the maximum dry density as determined by ASTM -D1557, • Below Flexible Pavements: A minimum of 92 percent of the maximum dry density as determined by ASTM -D1557 or 95 percent of the maximum dry density as determined by ASTM -D698. The ASTM -D1557 test method must be used for samples containing up to 40 pt-rcent oversize (greater than %-inch) particles. If material contains more than 40 percent but less than 50 percent oversize particles, compaction of fill must be confirmed by proof rolling each lift with a 10 -ton vibratory roller (or equivalent) until the maximum density has been achieved. Density testing must be performed after each proof rolling pass until the in-place density test results indicate a drop (or no increase) in the dry density, defined as maximum density or "break over' point. The number of required passes should be used as the requirements on the remainder of fill placement. Material should contain sufficient fines to fill void spaces, and must not contain more than 50 percent oversize particles. Warranty and Limiting Conditions NES warrants that findings and conclusions contained herein have been formulated in accordance with generally accepted professional engineering practice in the fields of foundation engineering, soil mechanics, and engineering geology only for the site and project described in this report. These engineering methods have been developed to provide the client with information regarding apparent or potential engineering conditions relating to the site within the scope cited above and are necessarily limited to conditions observed at the time of the site visit and research. Field observations and research reported herein are considered sufficient in detail and scope to form a reasonable basis for the purposes cited above. Exclusive Use This report was prepared for exclusive use of the Client. Conclusions and recommendations presented in this report are based on the agreed-upon scope of work outlined in this report together with the Agreement between the Client and Northwest Engineering Services, PC ("Consultant'). Use or misuse of this report, or reliance upon findings hereof, by parties other than the Client is at their own risk. Neither Client nor Consultant make representation of warranty to such other parties as to accuracy or completeness of this report or suitability of its use by such other parties for purposes whatsoever, known or unknown, to Client or Consultant. Neither Client nor Consultant shall have liability to indemnify or hold harmless third parties for losses incurred by actual or purported use or misuse of this report. No other warranties are implied or expressed. Northwest Engineering Services Idaho Falls, ID • Bend, OR • Salmon, ID 4 of 5