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(a) Retaining walls shall not be placed within thirty feet of the intersection of two or more streets, where such work would impair the ability to observe traffic movement.
(b) Designs for retaining walls shall be engineered to comply with the following conditions:
(1) Curb walls (not over 1'-6" high), adjacent to and retained by hard-surfaced paving at the front of the wall, may be built without footings and with the bottom of the wall at the same level as the bottom of the retaining slab.
(2) Low retaining walls (up to 4'-0" high), adjacent to and retained by hard- surfaced paving at the front of the wall, may be built with the bottom of the retaining wall at 1'-6" below the finished grade at the front of the wall.
(3) All other retaining walls shall be built with the bottom of the footings at least 2'-6" below the finished grade at the front of the wall.
(4) In lieu of engineered design, gravity walls, with level backfill and level grade at the front of the wall shall have a minimum width at the top of 8 inches if of poured concrete or 12 inches if of brick, solid concrete block or stone. At any point along the height of the wall, the thickness of the wall shall be no less than 1/3 of the distance from this point to the top of the wall, if the wall is poured concrete or 2/5 of the distance if the wall is brick, solid concrete block, stone.
(5) Unengineered hollow concrete block walls shall not be permitted for the construction of curb walls or retaining walls.
(6) A granular backfill shall be placed behind the wall at an elevation coinciding with the finished grade in front of the wall extending to within 8 inches of the top of the wall. This backfill shall be at least 12 inches thick against the back of the retaining wall.
Earth backfill shall be carefully placed behind this granular backfill; the granular backfill shall be made sufficiently wide to assure a full 12 inches thick drainage strata.
(7) Provisions for drainage of the backfill shall be made either by means of weep holes (4" diameter max. 6'-0"o.c.) in the wall or with a system of perforated pipe of 4 inch minimum diameter laid at the base of the backfill and having a proper gradient to an outlet. (Ord. 18-93. Passed 9-7-93.)