1028 BROADWAY 2016-01-01 MF Import

� � ��crirtcicr di:�in� cLuuld bc tilu��cd Iu �Irun h�� gra�nq, i( pr,cucublc, tu :i tuit:ihlc ditiehaigc ��uinl. prrfcrably ;i stonn drain. N'c rccommcnd thc cicannuis hr covcrcd.and bc placcd in Oush m��untcd utilii� � huses. \1':der culleeied in roof do�vmpuu� liues ntus� nu1 be rouled Ie the footing drain lines. � S4AB ON GRADE FLOOR �� Subgrade Preparation \\'e recotnmend concrete slabs-on-grade be constnicted on a gravcl laycr lo provide uniloim support m�d � drainage, and �o act ati a capillary brcak. \1�e �Iso recomtnend that at Ieast 12 inches of gravcl borrow subbase be pI:ICL`lj IICION' Illl` (�OOf Slabs and capill�iy break grrnel. \Ve espect that s1aU-on-grade Ooors can be supported on �he nativc mcdium siiff tn veiy stiff sill and clay provided thal the capilla�y brcnk subbasc laycrs arc consuvctcd. Prior lo placing thc gravul laycr and suhbasc, the subgradc should bc � proof rolled as described previousiy in ihe "fi:uthwork"seciion uf this report. If neccssary, tlic subgride shuuld be rccompacted to a iirni and unyiclding conditiou. A geotextile separator, such as Mirati SOOa, may bc nccdcd bclow thc subbase laycr and IocalizeJ additional ovcrcscavatien of soft areas nmy bc � nccdcd during constn�ctiun. Design Parameters '� I'he gravel laycr helo�v slabs-on-gr;�de should consist oFG inches uf cican crushed gravel with a maximum particle size of I Y: inches and negligible sand or silt overlying Ihe 12 iuches subbase layee Por slabs designed ac a beam un au elastic foundation, a modulus of suUgrade rcaction of 50 pci may be used for :` subgrade soils prepared as recommended abo��c. III'waler vapor migc�tion through the slabs is o�jectiouable, the gravul should be covercd with a hcavy pl;�stic shcet, such ns 10-mil pl:�stic shccting, to act as :i v:ipnr rctardcr. Tliis will bc dcsirablc whcrc ihc 1 slabs will bc surl'accd with tilc or will be car��cicd. h nmy also he prudent to apply a scaler to the slab to ❑uYhcr retard thc migraliou of moisturc tlirougli Ihc 11ooc 'fhc contractor should bc madc responsibl� for maint.�ining ll�c intcgrity of Ihc vapur barricr during conslruction. � Undorslab Drainaga Groimd�e:der in boring 13-G �vas mcasurcd nt a depth of abom 3 fcet beluw ihe existiug ground sarface. � Grouud�e:uer could accmnulaic bclo�r the slab-on-gmde floor depeuding on the finished (loor eleealion. Io hcip mitigate potential builA-up of groundwater bclow the slabs, we rccommend Ihat the concrc�e sl;ibs-uu•gmde for Ihe gymnasium and the �vcight room be providcd with undcr drain�ge lo wllect and I Jischarge po�entiol grouudwater f'rom bclnw the slnb. 'I'his can be accomplished by installing a 4-inch diameter, heavy-�rall perforated colleclor pipe in a shallow trench placed below the capillary break gravel I�iyer. 'llie trench should measure about I fuot wide hy I.5 feet dcep nnd should bc backfilleJ with cican 3/8-inch pea gnvel. VJc recommend installing a single under drain colleclor pipe in an east-��est E dirceiion below tlic slabs along approxiroatcly gridlines G' and gridline IS and comiect each end of the � Jrain pipe inw the perimcier footiug drain pipe or in�o the exisliug subsurfuw dr�in pipe. 91ie condition of thc existing subsurfacc drain pipc slwulcl bc cvaluatcd lo makc surc it is not damagc and is frec of' t debris and functioning properly. If connected to the fouting drain system, thc invert of the under drain I pipe should be highcr thcm the invert of tlic fuoting dmin pipe whcre thcy conncc�. fhu colleclur pipe shuuld be sloped tu drnin aud discharge into the stam wa(er collection syslem lo I wnvcy �he waler ofl'site. 'fhe pipe should also incoq�orate cleanouls,if possiUle. T7ie cleanouts could be es�ended through thc fomidation walls lo bc nccessiblc from thc outside, or could bc placed in Ilusli-mo�mled access hores cas� inlo the tloor slabs. I ---- ---------- /'J,�.A'e S.q,so;m--rU 191gd7= GEOENGINEEP� � .hdr l . .dd.c I J� � f i