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7), D 4� Sec. 6.3 Liquid Containment (Pond) Liners aR = the average hotiwnW stress in anchor tratch - Kovv. a, — y H.,, y = the trait weight of backfill toil, He,. a the avatage depth of anchor trench (requi e$ an esiirnate), Ko g 1 -- sin 4, 0 — the Angk of shearing resistance of backfill soil. and dAr s the (unknown) depth of anchor trench. Note that this situation results in one equation with two unknowns, thus a choice of Lw or d T is necessary to calculate the other. As with the previous situation the factor of t afcty is placed on the geomcrnbrane fora T, which is used as act allowable value, i.e., La.... An example illustrates the procedure. Exampk: Repew the previous problem of a 30 mil CPE geomembnme of allowable stress 350 lb in. an an 3(H) to I (t7 ride slope. 'There is a 12 -in. cover soil placed ova the geonxm1brane weigh- ing 100 lb./ft.3 (also the unit w6ght of the backfill soil). Tho friction angle between the liner and soil is 20 deg. and the soil itself is 30 deg. Determine the requited length of runout for a 12 -in. -deep anchor trench and for a zero -de* anchor trench to check the previous. prob- lem. Solution: Using the previously dovelopod design equations based on Frgmo 5.28: T.u, — Fu + FL + 2FAT s 0 + q tan b (LRo) + 2(Koav, ran b (dAr) (350 x 144) �'030j a 0 + (1.0) (100) tau 20' (L)to)11 + 2(0.$)(2.0 X 100) tan W (dAr) 126 — 36.4 40 + 72.8 dAr which for dAr s 1.0 ft., L,0 — 1.5 ft., and for dAT = 01L, L*o — 3.3 ft. (which ebocis the previous answer reasonably well). Develop a set of design curves using the previous problem but now using vsrioua Mmcut- brane allowabk stresses of 700. 525 and 3501bAn.2. Setudon: As before, bort now with ate,,, being the variable:. (ate x 144) 10.030 ° 1Z34/ — 36.4 Lao + 72.8 dar 0.36 v,, - 36.4 L*o + 72.0 dA, which when plotted produces the following as of coma. Note that as an.. knctraaes the requited LRo and dAr vaIUOS also MCfe& a y.