2408 RAVENNA ST 2016-01-01 MF Import

� Geotechnical Engineering Repori t Lox�ell Short Plat • June 2, 1999 NCA File No. 259499 Page !0 meterinl should be placed ��p the back of the wap to within 1 foot of the ground surface. A less pmneab►o wil should be placed in the last I foot to raduce sucfaee inflltraUon into the wall drau�. 'I7�e on-site soils arc not suitablc for use as free-draining wall backfill. A perforated drainpipe having a minimtmi diameppr of 4 iaches should be cmbedded in pea gravel or some othet fret-dreining material,at the base of tho wa11, along its ent've length. This drainpipe should discharge into tighdines Ieading to an apptt,priete cqllection and discbarge point. Drainage composite can be used as en alternative to the drainege zone behiad the waiL Roof drains should not be connected to wall or footing dtalns. Pavements Raadway subgrade prepytratiort, and structum� filling where r¢yul�red, s6ould be completed aq recommended in the Site Prepandon aad Gndin�and Structural F711 subsations of this report. Tiae subgrade should be proofrolled with n hesvy, cubber-tired piece of equipment,to identify soft or yielding azaas that roquim repair. We should be tetained W observe the proofrolling,end recommend repafrs prior to placement of�5e asphalt or hard surfaces, Therc is a trade off between expxted pevement performauee end constivction costs for sites undetlaim by existing laose undocumented fill. The loweat risk end best performance can be achieved az high cost by excavating all existing fill end replacing with well compacted structiu�al fill. The hig6est risk and lowest cost would be to simply strip the existiag topsoil md place the eew pav'emeat sxtion on the existing fill. B'ud bath and other settlement features can be rcfleCted iut t]�e pavement surface over time from this option. Also,if a guitable subgrade is achieved,brcekup of the asphalt can occur. As a teesoneble compromise between cost and perfortnsnce, we recommend that a 2 foc+t thickness of imported shvchunl fill be placed under the pavemurt section in areas under(ain by exlst)ng fiU. If thc subgrade perfom�ance is poor under compaction, the f:ll material may need to cousist of roCk spalls. In wet or pumping silty soil areu a non-woven filter fnbric material may be needed under the aew fill. 'll�is would be to limit the migation of fines into the new$Il. Excessive fine migiaaon in.o the clean materiel could reduce performance and drainage ab(lity of the roedway subgrade. In all areas,wt recommend that a 6-inch layer of free draining soil be plaeed under the pavenpent section. � Il�is will intprove pavement performance by increaving drainage. It should be understood thst there is always some risk of pavement problems when a Qevement section is placed over undocumenbed Till. I NELSON-COWRETTE&ASSOCIA TES, INC�_ I � .........:............. ................................................ s �