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i <br /> • � � ,�.. �.- <br /> Edgemoor fieights <br /> _ File ho. 8d2-IA <br /> August 14, 198a <br /> Page 2 <br /> and brush/low ground cover common to pcorly drained subgrade soils. <br /> The gentle slope area lyinq bclow aUout elevation 400' in the area <br /> of lots 26, 27 and 28 shows a poorly drained sandy subgrade. 7'his <br /> condition is suspected at a similar elevation within lots 22, 23 and <br /> 24 as well. Lots 24 through 28 are sited ❑djacent to the north-south <br /> trending major slope, while lots 22 and 23 rest atop of the east-west <br /> trending local slope fcature. <br /> The major slope attains a hcight of approximatcly t00' in the subjecL <br /> area, and maintains a slope face anglc of hetwcen 20° and 35°. Local <br /> portiorts of the slope were observed to attain face angles of as much <br /> as 35°. The smaller east-�iest trending drainage has an estimated ver- <br /> tical relief of 30 to 50 feet, aith measured slope angles ranging be- <br /> tween 28° and 37°. The slnpe height in thc area of lots 22 and 23 in- <br /> creases toward thr, east. <br /> ,\ <br /> Slope Stratigraphy <br /> Our stratigraphic intcrpretatiuns arc based on soils exposed within <br /> the recent sewer cut, ,� reconnaissance of the slope areas oE the sub- <br /> ject lots, interpretar.ion oF the sitc topography and correlation with <br /> infotmation contained in o:ir rcrort of Plarch i, 1984. <br /> The slope section :tlong the �ewer alignment cut hetween lots 25 and 26 <br /> consists of a sequence of dense ;;mds, hard c L•ry/silts :�nd a very dense <br /> basal sand unit. Thc upper slopr r,lcvations appc;ir tu bc comprised of <br /> dense, brown, medium to Finc s:uiJs with uccusiunal se,ims of gravel. <br /> The sands show good br,IJing an�l occ;�sional cross bcdding in thc coarscr <br /> sediments. I'he upper sands cxtend �lo�rn to ;ibout elcvation 400' , some <br /> 30 feet bclaw the slopc top. At :ibout clev:ition 400' thc s�nds cont�Ct <br /> a hard, grcy clay/silt imit. '1'hese m;iteri;ils are thinly laminated and <br /> jointed. .Joint surfaccs are generally coated and lie at random oricn- <br /> tations. [ndividual lnminac may bc as thin as sevcral millimeters :md <br /> are horizontal wherc obscrved. A light-dark pattern gives thc impres- <br /> sion of varving. Varved clays form in ,i glacio-lacustrine (glacial <br />