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Home My WebLink AboutEngineer's Letter 06.13.2020Grand Valley Consulting, LLC dba June 13, 2020 Groundworks Colorado, LLC Dba Foundation Repair of Western Colorado 2575 Hwy 6&50 Grand Junction, CO 81505 Email: catherine@repaircracks.com Phone: 970-374-6202 Subject: ail GEOTECHNICAL ENGINEERING GROUP Consultation- Foundation Underpinning Eric and Julie Kaufman Residence 108 River Bend Way, Glenwood Springs, Colorado GVC Job No. 4,428 As requested, Geotechnical Engineering Group visited the site as shown on Fig. 1 to observe surface conditions, make analysis and design of the proposed foundation underpinning using push pin piles. At the time of visit June 1, 2020, we observed the residence consisted of a 2 story structure with full walkout style basement and attached main level garage. We understand there are existing grade beam and footing foundations. Portions of the existing structure were reportedly underpinned at four past events prior to 2014, 2014, 2016 and 2017. Our site observations at time of visit indicate continued wetting from off site and on site sources combined with a hydro-compactive site geology are driving ongoing movements and damages. This scope of work requested by the owner is to help stabilize the portions of the foundation where underpinning is installed. It is not intended to be a complete repair. A more robust effort to repair should include details to arrest continued soil wetting. The purpose of this letter is to transmit a design including a Piering Plan and Design Notes. This design and the manufacturers guidelines should be strictly adhered. This report with attached stamped Figures 1 thru 4 should be submitted to the appropriate building department to assist with the necessary building permit(s). A laser level survey was reported by Foundation Repair of Western Colorado (FRWC) on April 30, 2020 and used as basis for design as shown on Fig. 2 attached. Upon review, we believe the structure is experiencing settlement / soil consolidation related movements. A plan of elevation differential is included as Fig. 3. A piering plan and design notes are attached as Fig. 4. Field conditions encountered during foundation stabilization projects may cause a change in the number of piers and/or pier spacing. Unknown subsurface conditions that may cause a change in plan include but not limited to the following: Location of buried pipe or cables or former repair extended footings, Actual foundation dimensions and/or condition of materials, (970) 261-3415 ° jwithers@geotechnicalgroup.net 3510 Ponderosa Way, Grand Junction, Colorado 81506 Grand Valley Consulting, LLC dba Amount and size of rebar in footings and walls, Presence of cobble or boulder conditions, The ability of the structure deadload to effectively allow pushing of pins, The practical ability of installation equipment to penetrate the zone of hydro compressive soils, and Other unknown conditions that may become known during installation. There are situations that may become known at time of installation that warrant use of short steel beams of HSS cross-section installed between the bottom of footing and pier bracket to help reduce point loading and help provide support over a larger section of footing and wall and to expand pier spacing. VI GEOTECHNICAL ENGINEERING GROUP In our experience, it is not unusual or abnormal to underpin or pier only portions of the foundation where evidence of movement exists. However, the owner must be aware and accept the risk that those portions of foundations not piered are more susceptible to future movements than piered areas and require more work in the future. Unknown geologic factors and other subsurface conditions can also affect performance. We understand deep foundations in this area that do not fully penetrate a hydro -compressive layer (unknown thickness) are not fully expected to solve settlement concerns. Improper soil wetting and site drainage conditions can influence performance of the structural system. The owner should be advised at minimum to convey water quickly away from the foundation areas and convey all waters to the low side southeast portion of the site to help mitigate continuing damages / issues at this site. We believe there may be additional off site impacts which should also be evaluated and corrected to further mitigate damages. These considerations made, we make no warranty, express or implied, with this evaluation or plan. Regular and continual monitoring of the foundation and structural components is recommended. The scope of work performed is specific to that requested in this report and the AUTHORIZATION TO PROCEED ENGINEERING AND TESTING SERVICES between Grand Valley Consulting, LLC and Groundworks Colorado, LLC dated 5-8-2020. We believe this investigation was conducted in a manner consistent with that level of care and skill ordinarily used by engineers practicing in this area at this time. If we can be of further service in discussing the contents of this report or the analysis of the influence of the subsurface conditions on the construction, please call. Sincerely, Grand Valley Consulting, dba GEOTECHNICAL ENGINEERING GROUP John Withers, P.E. Engineer (1 copy emailed) Attachments (4) Consultation- Foundation Underpinning 108 River Bend Way, Glenwood Springs, CO June 13, 2020 GVC Job No. 4,428 Page 2 of 2 HWY 82 Subject Site O 108 River :end Way, Glenwood Springs, CO 81601 Note: This figure was prepared based on an image from Bing mapping. Not to Scale Project No.: 4,428 Owner: Kaufman Scale: Not to scale Date: 611312020 III GEOTECHNICAL ENGINEERING GROUP 3510 Ponderosa Way, Grand Junction, Colorado 81506 (970) 261-3415 SITE VICINITY MAP 108 River Bend Way Glenwood Springs, Colorado Fig. 1 m-Tvq2tqN Eric and Julie Kaufman 1O8River Bend Way, Glenwood Springs, CO It * ~_ | � Job NO. 4.428 31' _ LEVEL SURVEY � LEGEND: 43/4" ' Indicates survey measurement recorded by representative using alevel measuring device, typical and represents inches below oreference point innortheast portion of basement, the area surveyed. VVe understand other portions ofthe residence have been treated with underpinning inthe past and the area desired with this treatment iothe south portion ofthe basement level. Reference: This a plan published by Foundation Repair of Western Colorado (FRWC/Groundworks) dated 4-30-2020 and is specific to 108 River Bend Way, Glenwood Springs, CO. The floor elevation survey reported by rmmCaused aoobasis for niennndesign uyoso6-1»-2o.<w Fig.2 5' 1\1 Eric and Julie Kaufman 108 River Bend Way, Glenwood Springs, CO 5• t •1 AC AItG 'fib #ice #38�3 .• •'• '•. ; <-2" •. filill8 '• •,• 17?Ffl*,fCifk�7i+rj^,�1JCi�53[`SAtiY.r: SAW �• .,•. -1/2" C} '•. -1 1/2" • L„iqmalco.,.,46.0...,0.041,6.waigu:N,Lruk otbxorlGke[t'roagAo_tig„. 0.,aw,(1,1I1,r.d r:x 5A. r:fiu. t[kde9Lahrtla w.c.. 0 REGo Wi° 30324 ` } 0 % 13-20200,/ 'l i PO(PON a 11' 114 31' Job No. 4,428 25' =fi IrlisitaakinZOiufteraltoxiienl.11:.ri,i1,1:-!;: , , '41W siutwyf'+!rArktilu[+5lt -e:o.c•:: ,iu.e L. ) 0) LEGEND Indicates location of temporary benchmark, Datum = 0 inches -1 1/2" Indicates elevation differential with contours of equal elevation expressed in inches (") with respect to datum as adjusted for anticipated mechanism of movement, ie high point. These contours were calculated based on the FRWC/ Groundworks laser survey report dated 4-30-2020. By: Geotechnical Engineering Group, John Withers, PE, engineer 970-261-3415 Reference: This figure was prepared from a plan published by Foundation Repair of Western Colorado (FRWC/Groundworks) dated 4-30-2020 and is specific to 108 River Bend Way, Glenwood Springs, CO. The floor elevation survey reported by FRWC is used as a basis for piering design by GEG 6-13-20. /jw ELEVATION DIFFERENTIAL Fig. 3 G ii e4T142IEw 'A 7 ing ijrwm LL '`1ciraviitl.:40jitt4 Nat anraTH E'S wltaui�lusl�= Job No. 4,428 Eric and Julie Kaufman 108 River Bend Way, Glenwood Springs, CO - t -v- 25' PIERING PLAN gMIfm'„8:r0;14OW,.-;o.;vnib[Rfts5 , 1nAd, ylr i,k$md6iid4nil:i sIsIt vratim• Milt: gip „rke:PiAtet 4t4164aatdlrwap'4triNag ar41444ivl lead* --+ 2.1 LEGEND r� Indicates location of IMG Push Pier Model No. IMG PP21617-34 DESIGN NOTES 1. Maximum Pier/Pin spacing by deadload and anticipated foundation analysis = 6 feet. Condition of existing foundation may warrant less spacing as determined at time of excavation. Unknown past extended footing repairs in this area may require field adjustments. 2. Anticipated depth to competent bearing strata is unknown. 3. Soil wetting and drainage concerns were identified at time of this design and must be corrected in order to mitigate further damages, including damages to these repairs. 4 This design does not consider erection or safety. Contractor is soley responsible for these issues. Please call the engineer if questions or concerns come to light during construction. Reference: This figure was prepared from a plan published by Foundation Repair of Western Colorado (FRWC/Groundworks) dated 4-30-2020 and is specific to 108 River Bend Way, Glenwood Springs, CO. The floor elevation survey reported by FRWC is used as a basis for piering design by GEG 6-13-20. /jw Fig. 4