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Exhibit 1- Rittenhouse-Zeman Soils report.pdfRITTENHOUSE-ZEMAN & ASSOCIATES, INC. GEOLOGY & SOILS ENGINEERING 13837 N.E. 81h Sireot. Se!ievue, Wash nglon 98U?5 ;2061 746-8020 ac5:i S.W. Cirrus Drive. Seavenen, Oregon 97005 6331 644-9141 July 24, 1980 W-3355 1 Group IV t 19707 - 44th Avenue West Lynnwood, Washington 98036 Attention: Vern Bower : Subject: Soils Exploration and Engineering Report - Rehabilitation of Edmonds Shopping Center Parking Lot Edmonds, Washington i Gentlemen: In accordance with your request, we have completed our soils exploration and engineering studies concerning the rehabilitation of the Edmonds Shopping r Center parking lot. We have completed this report with the understanding that a rehabilitation program is to be undertaken for this poorly drained and differentially settled parking lot. The site is located on the northwest corner of the intersection of Sunset venue and Dayton Street in Edmonds, Washington. This shopping center was reportedly built during the summer of 1966 with the buildings being timber pile supported. Pile lenghts vary between 10 and 23 feet in embedment length. The original development work in the parking areas was apparently limited to a leveling course of fill and 2 inches of asphalt. During the past fourteen years substantial settlement has occurred in the parking lot area. Differential settlements on the order of 3 feet can be observed adjacent to Dayton Street and in the area between the hardware store and Sunset Avenue. Some rehabilitation has been done in the past, in the form of patching and repairing portions of the parking lot. ,y Group IV ` July 24, 1980 Page Two SUBSURFACE EXPLORATION Our subsurface exploration consisted of drilling3 borings o r' Ings in the shopping center parking lot. These borings were located adjacent to the areas of greatett differential settlement. Extending to depths of 3132 to 24 feet these borings have provided us with general soils and ground water information for the parking lot. The borings were advanced using a truck -mounted, hollow - stem, power auger. The Standard Penetration Test and pushed Shelby tubes were used as the primary methods of sampling. Boring logs and a site plan showing their approximate location has been included in the appendix of this report. Based upon the 3 borings completed ;_:.• 9 p eted for this exploration, the surficial soils consist of a medium dense to loose, saturated, gray, slightly silty sand' san. This fill was found at the borin ,•^;, gs to vary in thickness from 43Z feet to 9 feet. A zone of interbedded, very soft, brown peat and loose, gray, silty sand underlies the fill and extends to depths ranging from 17'2 to 22 feet in our borings. Dense to very dense, gray -brown, silty sand and gravel was encountered beneath the peat and extended through the depth of the completed boring. Ground water was encountered in all 3 borings within 5 feet of the present ground surface. The water level in this area is expected to experience some fluctuation throughout the year. i DESIGN CONSIDERATIONS 1. Our borings encountered substantial thicknesses of soft peat and inter- bedded, loose sands ranging from 9 to 13 feet at the borings. These materials are low density, saturated, and highly compressible even under very light loadings. The pavement cracking and settlement in the shopping s center parking lot can be directly attributed to the consolidation (compression) that has taken place in the last 14 years of this substantial :_ thickness of peat and loose sands. The settlement is in response to the 7_1 Group IV July 24, 1980 loads applied to the peat by the fill and pavement section. Page Three 2. The total amount of settlement that is apparent in the parking areas varies from approximately 6 inches to 1 foot in the north end to as great as 4 feet at the south end. Differential settlements are on the order of one-half to 2 feet in general. The condition of the pavement surface appears serviceable in most areas except along Dayton Street at the south end. In that area, "alligator" type cracking is a problem. 3. Based on our observations, it appears that compression of the peat is on the order of 10 to 25 percent of the original peat thickness. Although a majority of the settlement has taken place under the existing weight of the fill and pavement section, a portion of the settlement will continue for the next 20 to 40 years. This is graphically illustrated on Plate 1 which presents peat settlements as a function of time and peat thickness. In this illustration, a 200 psf loading is approximately equal to 2 feet of fill. As can be seen, about one-half of the settlement takes place in the first 6 months, with the remainder occurring over a long period of time. 4. The inposition of new loads on the peat causes additional settlement to take place. Although the magnitude of settlement will not be as great since the peat has been partially consolidated, the settlements will nonetheless be substantial. The only way to reduce settlement is thus to limit the thickness of additional fill or to utilize some form of light- weight fill such as styrofoam or expanded shale. These lightweight fill materials are typically quite costly and even then do not offer a fool- proof solution with regard to differential settlement. 5. As can be seen from the above discussion, there are only a limited number of alternatives with regard to correcting the problem. The major alternatives are: 1) Leave grades in their present configuration and patch the asphalt as necessary. 2) rill the lowest areas with compacted sand and gravel, then add new asphalt. With this approach, it must be understood that additional long term settlements will require similar w Respectfully submitted, ti R. I f R1TTENHOUSE-ZEISIAN & ASSOC. of µ'asy���4y /% Oil rai /".-LaVielle,~Geological Engineer Alvin R. Zeman, PSE. Page Four Group IV July 24, 1980 treatments in the future. 3) Use lightweight fill material to minimize future .settlement of the peat. This method is costly and still does not In eliminate all risk of pavement damage due to- differential.settlement. addition, where the repair will be thin, there may be a tendency for the styrofoam mat to float. If a heavier fill such as expanded shale is utilized, only a reduction in settlement may be obtained. 6. Although the decision is primarily one of economics which can only be made by the owner, our recommendation would be to merely fill the low areas with compacted sand and gravel and repave. Every attempt should be made to keep the fills thin and thus cut down on future settlements. Only limited amounts of fill should be placed close to any structure since compression of the peat adds substantial " downdrag" loads on the piles. This may well be the cause of the building settlements noted to date. 7. Some areas of the parking lot are experiencing alligator type cracking but will not require filling or relevelling. In these areas, the asphalt pavement should be removed, and the subgrade over -excavated to a depth of at least 6 inches below the base of the pavement. A clear gravel or crushed rock should then be compacted into place and then paved over. Even -then, future distress may return after severe freezing weather such as we experienced the last two years We appreciate this opportunity to be of service to you. Please call if you should have any questions. Respectfully submitted, ti R. I f R1TTENHOUSE-ZEISIAN & ASSOC. of µ'asy���4y /% Oil rai /".-LaVielle,~Geological Engineer Alvin R. Zeman, PSE. rlm", I m SETTLEMENT IN* FEET n an m o � VI— c:--i F— m rn 0 r- rri C)< 0 n 0 cn n N r, 0 0 0 > 2 -0, z I 0i ': STANDARD W < PENETRATION RESISTANCE ;H A Blow per toot w SOIL, DESCRIPTION w x (140 lb. hammer, 10" drop) o r a a 10 20 30 40 50 y t7 a Surface Elevation: 2As Asphalt 1 ttLoo bro% a Medium dense to loose, saturated, gray, ` 5 slightly silty, medium to coarse sand ..i._ `. z (Fill?) ! to T , - Interbedded, very soft, brown peat and ?: loose, saturated, gray, silty, fine to medium sand - - � t 15 Pi.. — Dense to very dense, saturated, gray-bro+;n, 25 silty sand and gravel ---: . i i Boring complete at 31.5 feet i �J ; 35 40 o W-Aer Content June 25, 193J � LEGEND 1 2.0" O.D. eplit y`oon sampler • Sample rot recovered p + p;ezcr:ieterup Edmonds Shopping Center it 2.0*• o.D. undls:'--bed adf.., ler Sampler ushed water level LOG OF BORT:^v NO.B-1 P same p Q Y:-3355 Atterberg limits: }--la} -j -�— Liquid limit ►— !:aturalRatercontent RITTE1,MOUSE-ZEIVLAN & ASSOC, i• I'D GtOLOGY Plalc Limit SotLS ENGINEETUNG A s u W SOIL DESCRIPTION a � a a W Surface Elevation: 2" Asphal�sand( Loose bro Medium dense, saturated, grey, slightly 5 silty medium to coarse sand (Fill?) I 1 Interbedded, very soft brown peat and loos L saturated, grey silty fine to medium sand t 15 Dense saturated, grey -brown, silty sand — J ,20 I and gravel. 25 Boring complete at 24:0 feet 30 i i 35 40 i ' 1.-GEND I 2.0" O.D. split Spain farnpler 0 Sample not recoccred 2 3.0'• O.D. urGisturhed sampler 1 Piezorneler tip p Sampler pushed S7 eater level Atterterg limits: --o-- Liquid limit '* Natural szter content Nazi: Limit SPA; -DAi117 < PEi+cTPZAVION RESISTANCE A Blows per foo: 0 a (140 lb. hammer, 30' drop) 10 20 30 40 50 LI f June 25, 1980 * `,i; Watcr Content Edmonds Shopping Center LOG OF SOR1.NG N0. B-2 1•l-3355 RITTENI-iOUSE-ZEN AIN L ASSOC. Son.S EN*(;l' E_:PJ-NCA :D GEOLOGY t STANDARD { t" V: PEN-ETRATIU N RESISTANCE w w w SOIL DESCRIPTION t"a a A, iilocs Pcr tont -3 0 (140 lb. hamaler, 3D" drop) u 10 20 30 40 5� a Surface Elevation: 5" Asphalt Loose, grU, medium to coarse sand (Fill1__ oose, saturated, grey, silty sand (Fill?) — — -- 5 Interbedded, very soft, brown peat, loose turated to medium dense, sa g re y, fine to •- --... medium sand 4 10 _� .. 15 T -brown silt sand Dense, saturated, grey , Y z 20 and gravel 25 Boring complete at 24.0 feet _30- 0 - — 35 -35 - 40 June 25, 1930 p `i ala!er Content 1.EG=ND I 2.0" O.D. spit sP oma sample: • ea np;. not recovered Edmonds shopping center +,. I( 1.0'• O.D. ur.dis:urbed sampler i Plezometer tip Q Water level LOG OF £iORL`:G *,,o. B-3 1 p Sam,^.ler pushed }1-3355 A:.ert_ 'i:::.ta: t C---1 4— L!gcid ltmtt RITTFii�LSF-ZERiAN ASSOC. y - Y.:: r:l Rz:er rcr.:eG: -- Plas:Ic Limit O^ S Et;G::T_EP1•;G A';D GLO! OGY r'a I '