REV07942 - Laserfiche WebLink

Home Browse Search

Technical Revision No. 42 Adequacy Review 1. Map 150 submitted with the TR shows proposed final contours and drainage pattern for the combined RP-2/3/4. The proposed crown elevation and location is not specifically indicated, but it would appear that the crown would be in the center portion of the pile at around 5615' , with a 1$ slope away from the crown to the 5610' elevation. The proposed 1% grade might be difficult to maintain on the enlarged top portion of the pile, and could result in low spots where water would be ponded. We recommend that the top of the pile be designed to slope away from the crown at 2-3$, rather than 1$, to ensure that ponding will not occur. Crown location and elevation should be depicted on the amended map. 2. The SEDCAD+ models for the refuse pile should be based on a scenario where drainage and/or sediment contribution would be at their maximum amount. We would predict this to be at the closure of the pile, when topsoil has been redistributed, prior to vegetation emergence. WFU should revise the models using a curve number of 94 (D type soil - newly graded area, pervious, no vegetation) for the drainage areas. 3. The SEDCAD+ runs for the ponds indicate there are trickle tube spillways in each. Because the dewatering orifices in the spillway risers have been sealed, the ponds do not de-water passively, but must be pumped. The SEDCAD+ runs should be amended as appropriate, to reflect this fact. 4. The SEDCAD+ runs indicate the riser elevations for ponds RP 2- 3 and RP-4, respectively, are 5496' and 5506'. Maps 79 and 80 indicate the elevations are 5495.47' and 5504.48'. If the elevations used in the model are correct, the maps should be revised, or vice-versa. Map and model elevations should be consistent. The model for RP 2-3 indicates the riser is 7' tall, with a top elevation of 5496'. If this were the case, based on Map 79 elevations, the bottom 2' of the riser would be below the pond bottom elevation. The same problem exists for Pond RP-4, with the lower .5' of the riser below ground level. 5. All the maps submitted with the revision need to be certified by the designing engineer or the engineer who reviewed the designs. The maps submitted were certified in 1983. 6. The culvert associated with the dozer crossing in the east ditch of Refuse Pile 5A should be indicated on Map 80A or other map showing the ditch. 7. Map 76 includes a disposal area development plan table which sets forth projected acreages, refuse capacities and timeframes for refuse sub-areas. The table will need to be updated to reflect the changes associated with the combination of sub-areas 2/3 and 4.