6230 SPRING ST A&B 2016-01-01 MF Import

At !ha time of our field exploration the excevetion of the buildinp ped�, eech meeaurinq epproximetely 54 Eeet eeet-wesC by 60 feet norlh-socith, end placement oE the rock mate hed been compieted. Pumpinq o[ en eccumuletion oE eurfece Neter wes neceesery in order to complete the exploretion pite xithin the buildiny ped loceted on the rorth eide of Sprinq Street. Meteriels temoved from the verticel eided, buildiny ped excevetione were stock-piled eround the northetn, eeatern end eouthern meryins o[ the excevetiona. Sloughing from the etock-pilee hed covered the verkicel cute in tSie�a ereae, end eilt had eccumuleted on top oE the tock mefe. However, along the Weetern edge of the pad ereas there Mes e qood exposure oE the natur�l eediment proEile to a depth oE eboul�J feet. 7.0 BXPLOR]►TION PITS The eix"exploretion pita Mere exceveted with e• rubber-Eired,• tractor-mounted backhoe. Due to elouyhinp end repid water eeepege within the pits, subeurfece conditione Nere interpreted beaed on the digqinp ection oE 'fie beckhoe ee Nell ea eediment removed from the explorelion pite. Meteriele encountered in the exploCetion pits Nere etudied end cleeelEied in the Lield by e yeologist [rom our [irm. All exploretion pite Nere beckfilled immedietely eEter , exarnination end lopyiny. • . 6ubsurfece conditione et the project eite Nere inferred itom the field exploratione eccompliehed for thie etudy, end vieuel raconneissance oE the eite. In qenerel, the exploration pita encounEered e thin (ebout 3 to 6 inchea) leyer of eilt end eend ovarlying ebout 1 to 1 1/� Eee! of 1 to 6 inch querry epelle. Denee to v'ery denee, moiet to Net, mottled yrey, eilty, Eine send Nith en uhsorled mixture of cley, pebblee end cobbles wee encountered in ell oE the exploretion pita beneeth !he querry epella. Thie meteriel is interpreled to be Veshon ege (19,500 to 15,000 yeere beEore present) lodpement lill. Theee eedimenta Nere ;;epoeited et the eole oE the advencinq Veshon eqe ice eheet Mhicii hee reaulted in their high etrangth end loN permeebility charecterietica. Due to elouphiny of the Querry epells end very repid xeter eeepege in ell of•the exploretion pite, the pite vrere lermineted et deptha oE J to 3 1/1 ieet below the top of the rock mat elevetions. Till wae elso expoeed�'ih the cute elonq the weetern edge of the ped ereas et depths tenqing from ebout 1 1/7 to J Eeet beloN the pround aurfece, where it wee overlain by en orpanic rich topeoil horizon, end then e 1syeY of surficiel fill. The Neter enaountered in the exploration pits and present Mithin the ped ereee ie interpreted to represent e• perched ground water condition. Perched weter occura Nhen eurEece Meter infiltretee doun through reletively permeable materiela end becomes trepped or "perched" etop a comperdtively imperineekile barrier such ee the till. It ehould be noted thet fluctuetione in the level oE the eurEece Nate[ mey occur du• !o th• tim• oi th• y��r •nd v�r1�lien• in r�lnt�ll. 'r7