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. _ __ _ - - - . <br /> ,_ . , <br /> . , { <br /> Clcnwood Tcrrace • <br /> Filc Numbcr 126994 <br /> hlay l2, 1994 <br /> Page 19 <br /> Silc Urainage <br /> Surtace Drainaea The fi�uslied ground surfacc sh�uld bc gradcd such that storni water is directed into an <br /> appropriatc systcm. Water should not be nllo���ed to stand in any area �vhere footings, slabs, ta�td��ay or <br /> pavements are to bc constructed. Final sitc gradcs should allow for drainage away from [he buildings. We <br /> suggcst tlio finish ground bc slopcd at a gradicnt of 3 percent minimum for a di5lancc of at least 10 teet <br /> away from Uie building, except in the arcas that are to be pavcd. Surface �vater should be collected by <br /> permanent catch basins and drain lincs and be dischargcd into a slomi drain system. Stomi drain systcm <br /> gradicnts should be ucccntuated a�here placed in fill to compcnsate for fiiture pokntial setticmcnts. <br /> Subsurfate Droinagc: Ground watcr was encountered in many of our tcst pits. 71�e ground watcr <br /> elevations at the timc of construction and the dcpll�s of excavations will bc important to dctcrtnine prior to <br /> starting earlh��•ork. CutofF drains could be uscd on the north side of Uie planncd road�vay to lower thc <br /> watcr lablc prior to stripping fill, if needed. It may be dcsirable to incorporatc thcse drains into the <br /> perm:u�ent drainage system. Drains may also be needed at Uic tce of the cut slopc to increase d�e slability <br /> of U�e exposcd facc from erosion or sloughage. We rccommcnd qiat the existing vcrtical pipc systcm be <br /> explored :uid cvaluated if it is or could bc a part of the cut-ofT drain systcm. If significant cuts arc not <br /> made and ground water is signi6cantly below the planned cut elevations, thc use of cut�otT drains may not <br /> be necess�ry. �Ve recommend that tlie wt-off drain not encroach irto the wetland butTar are.�s. [C the <br /> drains are to outlet inlu Uiu �ecdands, a tighdine should bc uscd from U�c cdgc of dic bu(Tcr. pro��ding <br /> d sc bu(Pcrs conditions arc met, it is our opinion that die cut-of£drains «ill not significarilly iuFlocnce tlic <br /> near6y�vetlands area. <br /> �Vhcn ground «mler seepagc is cncountcrcd during �onstniotion, «�e reconvnend Ihat tl�e wntractor slopc <br /> lDc bottom of cxcavation during construction v�d collcct Uic walcr to ditchcs nnd small sump pits, Gom <br /> ��hich Uw�vatcr can be pumped nnJ discharged inro a permancnt drain. <br /> A footing subdrain systcro should bc installcd around tlie perimeter of each planned building. 71ie subdrnin <br /> should consist of a four-inch-minimum-dianteter, pedoratcd or slolted, rigid, PVC pipe µ•ith a gndient <br /> suETicicnt to gencrate ilo�v by gra��ity. 71u drain line sl�ould be imbcdded in, surroundcd by, and covcrcd <br /> with a Gce�clreining w�shed rock,pea gravcl, or otl�er frce-draining granular matcrial wrapped in a layer of <br /> filtcr fnbric. The footing subdrain should 6c lightlined to discharge into a pemianent stortn drain. The <br /> founJation drain should be at t1�e base of thc foundation/pile cap or a minimum of 6 inches bclow adjacent <br /> slnb on gmdcs or crawl space clevation, whichcvcr is dccper. Wc recormncnd diat thc cra�vl spaccs below <br /> tl�e structurcs bc sloped to drain. A positivo coruicction sliould be madc from the crawl space to U�e <br /> drain�gc systcm. <br /> NELSON-COUVRE77E& ASSOC/ATES, INC. <br /> rr_�+-�s-i9�r i2:i� 2�6 nei asio 9s� P.zi <br />