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HomeMy WebLinkAboutPermit Field Test & Inspection Report 1996-7-17 SpIT :Iliio.: GR/,IICH ENGINEERING; .7-18-96 8: 31 AMi 541 746 0389 . .---- ...' 't 503 726 3689 i it? i::3 ~ Branch Engineering '\ JUi,' 17, 199G 310 Nor'ul 5r.h Scr".,r. Springfield, Or'egon 97477 (541) 746-0637 FAX (541) 748-0389 SOilS INSPECTION REPORT /,ODRESS: P~lOJECT NO. F:-lEPARED BY: q I.tD1VfO X61363:lvyzStreet;::SurinafieJd::-Or",fQon 96.-. ~05 Steve Keating I,,, inspection was made at the above listed site for the purpose of assessing 1l1e suitability l'( Ihe .existing soils for superimposed loads, These loads are identified as foundation footings ;'>lId stemwalls with interior strip footings and isolated piers, together with an overlying residential structure of generally regular shape, with a maximum load of 1000 PSF. There are three soil units (SU) exposed by the excavation. SU #1 consists ot dtJrk brown Silty clay loam, approximately 12 to 24 inches in depth. Which will be above the base of excavation in rnost areas. SU 1/2 consists of a light brown colored plastic Clay with little granular content. approximately ~o to 48 inches thick. It has become wetted to a depth of 1/2 to 1 inch where exposed to recent rains, and is uniformly moist through the thickness at the unit where e"pos.~d on the sides of the excavated area. SU tt3 consists of a cobbly silty clay of indeterminate depth, and is exposed only on a smiill portion of the rear ot the excavation. Tlie exposed areiiS appear to be uniformly moist. There is no evidence of plastic cracking in any of Ihe soil units, and no evidence of water seepage from uphill snllrces.. Wllile clay soils can provide competent bearing for building strJctures, this/i~ highly dependent on soil mnisture conditions, both present and future, Saturated soils have vinually no sllear strength and (;armot provide useful bearing. Since most local clay soils are expansive, they will also shrink when drying, and cause senlements. We recommend that the site be overlaid with a light geotextile (Typar 3401 or equal) and a 12 inch compacted crushed rock fill be plaCed to distribute building loads and protect the clay soils from variations in moisture content. For placing the structural fill, please refer to the following instructions:. I, Install a geotextile barrier (Typar 3-101 or equal) a barrier to prevent intermixing of the rock topping and the subgrade soils. Without a barrier the base will "pump". and adequtJl<J compaction will not be achieved. 2, Import 1-1/2" - (0) crushed quarry rock fill (or an approved substitute). Place till material in two 6 inch lifts compacting at each lift with at least a 6.ton rated roller compactor. C' J. /II/hen the ti"haS-~~-~onwleJed;-d'ld'-IY,~ for, a, den.sitVtes(ff~Er;U;a certifie~testin-g' laEora"tory'(BraOn~l?teE!1~h'9~~r'PSI~a,!~~81:.~~~~~c};~~~@I~ , fompl~tJon o,f the~ te,sl: tfie~ngl,~~!3r ~}I!,,~~,s~e a rcpo~ IO~he owner c_ertltyrng <~e .fl~,~as /dequate'fo( re"s~dentlal foundahon loads of 1000 pounUs-per-square-foOl Ofib..~?JAf19!l TAIl,NSPORTATION SUI-lVI=YING ./ CIVIL - -".J . sEj!:r ~~ BHANCH E~JGINEERING; -18~96 8:32AM; 541 746 0389 .~ .. .. .. eJ 503 726 3689; #3/;3 It is aiso important that all concrete foundations and flatwork be reinforced, as they are otherwise unable to resist soil and temperature related stress without cracking, We have included a typical foundation reinforcing detail. Special consideralion must be given 10 Slr"ps in the foundation, to ensure that the reinforcing is continuous through the step, so that a weakened area is not created. It is much simpler and far less expensive to prevent structural damage than it is to repair it. Once the foundation has been installed. the building's owners should observe the lollowing steps, which will reduce shrink-swell in the underlying soils, and further reduce the potential of rlamage to the building structure: 1. Never permit the soils to completely dry out in the summer. When the average monthly fainfall varies excessively. it invites shrinking or swelling. An irrigation system can be used to provide water during drier periods, and evaporation rates can be retarded by landscaping materials Which cover the soils, and\or bark-mulching, which will require periodic replacement, Other sources of water should be kept away from the foundations If an off-site water SOllrce develops (a natural drainage way, or run-off from a neighboring property) or tlle downspouts or 9utter begin to leak, it is important to intervene, and direct this water away from the foundation area. After the excavation of saturated clay soils and compaclion of fills as specified, the site Will be suirable for the intended use, subject (0 the following provisions: ') ~, 1. The foundation areas are backfilleo to a minimum depth of 18" below finisherl grarle 2, The building fo01ings are to be provided with perforated PVC drain lines bedded in a minimum 12" depth of 1 -1/2" open graded drain rock. with piping draining to the lower portion of the site The building underfloor drain may be connected to this pipe at an elevation at least 12" below the lowest point of the subfloor grade. The owner will have to make provisions for stormwater discharge on site as storm sewers are not available. J. The rainwater piping will be installed parallel. but not connected to, the foundation am1 sublloor area drains. The above provisions will ensure that subsurface moisture levels will remain (:()"'ii~teTJ! tltruughout the year, and the piping will not conduct air currents which may tend to dry the footing area soils during periOdS of warm dry weather. If you have any questions concerning the above report, or require further intorm<ltion. please lee I free to call. . Soils report: 6863 Ivy Street, Springfield Branch Engineering - 310 North Fifth Street, Springfield, OR - 9 Page 2