LAC 43:XV.5367. Disposal of Excess Spoil: Valley Fills

A. Valley fills shall meet all of the requirements of §5365 and the additional requirements of this Section. 1. The fill shall be designed to attain a long-term static safety factor of 1.5 based upon data obtained from subsurface exploration, geotechnical testing, foundation design and accepted engineering analyses. 2. A subdrainage system for the fill shall be constructed in accordance with the following: a. a system of underdrains constructed of durable rock shall meet the requirements of §5367.A.2.d; and i. be installed along the natural drainage system; ii. extend from the toe to the head of the fill; and iii. contain lateral drains to each area of potential drainage or seepage; b. a filter system to insure the proper functioning of the rock underdrain system shall be designed and constructed using standard geotechnical engineering methods; c. in constructing the underdrains, no more than 10 percent of the rock may be less than 12 inches in size and no single rock may be larger than 25 percent of the width of the drain. Rock used in underdrains shall meet the requirements of §5367.A.2.d. The minimum size of the main underdrain shall be: Total Amount of Fill Material | Predominant Type of Fill Materials | Minimum Size of Drain, in Feet Total Amount of Fill Material | Predominant Type of Fill Materials | Width | Height Less than 1,000,000 yd3 | Sandstone | 10 | 4 Do | Shale | 16 | 8 More than 1,000,000 yd3 | Sandstone | 16 | 8 Do | Shale | 16 d. underdrains shall consist of nondegradable, non-acid or non-toxic-forming rock such as natural sand and gravel, sandstone, limestone or other durable rock that will not slake in water and will be free of coal, clay or shale. 3. Spoil shall be hauled or conveyed and placed in a controlled manner and concurrently compacted as specified by the office, in lifts no greater than 4 feet or less if required by the office to: a. achieve the densities designed to ensure mass stability; b. prevent mass movement; c. avoid contamination of the rock underdrain or rock core; and d. prevent formation of voids. 4. Surface water runoff from the area above the fill shall be diverted away from the fill and into stabilized diversion channels designed to pass safely the runoff from a 100-year, 6-hour precipitation event or larger event specified by the office. Surface runoff from the fill surface shall be diverted to stabilized channels off the fill which will safely pass the runoff from a 100-year, 6-hour precipitation event. Diversion design shall comply with the requirements of §5323. 5. The tops of the fill and any terrace constructed to stabilize the face shall be graded no steeper than 1v:20h (5 percent). The vertical distance between terraces shall not exceed 50 feet. 6. Drainage shall not be directed over the outslope of the fill. 7. The outslope of the fill shall not exceed 1v:2h (50 percent). The office may require a flatter slope.