5627 1ST AVE SE 2016-01-01 MF Import

.... - Geotechnical Consultation Services Page 5 - 93-1397 Hannebrook Rock Wall - Lots 39 through 45 July 26, 1993 immediately above the completed wall will be sloped up to the abutting properly, wo recommend that wherever the wall exceeds eight feet in maximum height the basal row of • rack consist of five-man size rock only. These rocks have an average dimension of between about forty-eight (48) and fifty-four (54) inches and exhibit an average weirht ir excess of four thousand (4,000) pounds. Where the wall is less than eight feet in height the basal row of rock should consist of `our- man sized rocks only. These rocks have an average dimension of between thirty-six (36) and forty-eight (48) inches and an average weight of at least two thousand (2,000) naunds. As each rock is set onto the keyway subgrade it should be placed in as close contact with the neighboring rock as possible to minimize void space, then tamped with the rock placement crane to firmly seat it into the underlying subgrade soil. Each rock should be placed in a manner that will achieve the best and closest rock-to-rock fit possible. All gaps or voids between rocks should be carefully chinked wkh smaller rocks, as described in the ARC Standard Guidelines, so that the rock face is as solid as can be achieved with the materials used. Rock Wail Construction: Once the basal row of rock has been placed, the construction of the rock wall can continue. We recommend that the remaining rows of rock be of no less than four-man sized rock. A!I of the rock should be placed so that the larger rocks are towards the base of the wall and the smaller rocks towards the top. Wherever possible, the rocks should be placed with the longest rock dimension back towards the soil face being protected. Here too, all gaps and voids should be carefully chinked with smaller, hand placed rocks as the wall is built. Chinki�g is described in the attachad ARC Standard Guidelines. It is also cHtical that the rocks r, �t be vertically stacked like shoe boxes since this generate wail instability. Face Better: The face of the new wall should be constructed with a slight inclination (batter) back towards the soil face being protected. For this wall we recommend that the batter be between 1:5 and 1:6 (horizortal:vertical). Draln Rock Layer: As the rock wall is raised, a layer of crushed drain rock must be placed between the rear face of the rocks and the soil face being protected. This rock should be about two to four inch sized crushed rock or crushed concrete and should be as soil free as poss�ble. As it is placed behind the rock, it should be tamped with the crane bucket to achieve as tight a fit as possible. The drain rock layer is raised contiguously with the rock wall. For this protective wall, we recommend that the drain rock layer be at least eighteen (18) inches thick. ' •