Laserfiche WebLink
Maintenance Required: <br />Uncover burrows and re-compact in-situ backfill to dam cons[ruc[ion specifications to maintain the <br />integrity of the dam. Reseed disturbed areas. At the present degree of burrowing activity, [he burrows <br />can probably be uncovered by hand spade work, and the materials tamped back in place by hand [amping. <br />In the event burrows are too deep or extensive, backhoes and mechanical tampers might be required. This <br />maintenance work should be accomplished before the neat high water season. <br />Replace emergency spillway riprap with durable rock to protect [he integrity of the dam. The potential <br />for a rapid failure of the dam due to erosion at the emergency spillway is low. This conclusion is based <br />on the observation that the spillway is located at the north limit of the embankment, and the north <br />abutment is a gradual slope. Mechanism of failure would likely be a slow, progressive erosion of the dam <br />embankment to the south, slowly lowering the pond pool. This maintenance work should be accomplished <br />prior to the next high water season and period of higher probability of record s[orms (late summer). As <br />light equipment will be required to make these repairs (haul riprap), and a catastrophic failure is not <br />likely, this work could be scheduled during relative dry periods so that equipment access would not <br />significantly disrupt other land reclamation accomplishments. <br />Clear the principal spillway of the plastic sheeting and the outfall of excessive vegetation growth to avoid <br />restrictions of Flows. This work should be accomplished prior to the next anticipated discharge of water <br />from the primary spillway (high water season). <br />Revegetation of the upstream slope is not a high priority maintenance item. Erosion in the bare area is <br />not likely, nor is it threatening to the dam embankment. Reseeding is recommended a[ the next optimum <br />planting season. <br />Recommend: <br />Additional inspection at a time of high water is recommended. The area of accelerated vegetation growth <br />and areas of burrow activity need to be probed to determine if seepage is occurring (no seepage or signs <br />of prior seepage were noted during this inspection). <br />Monitoring of the erosion to the north upstream face of the dam at the high water level is recommended. <br />Stakes might be placed at the limits of current activity during the next quarterly inspection. If erosion is <br />persis[ent and progressive, stabilize with vegetation or riprap facing will be required eventually. Dam <br />integrity is not threatened at the present degree of erosion, nor is it anticipated to become so during the <br />next high water season. <br />Monitoring of rodent activity during quarterly inspections is recommended. Should burrows continue to <br />be a problem, implementation of additional rodent control procedures to halt the burrowing activity on <br />the dam may be required. <br />~j~ ~ G~~ <br />Fti~rfG. Walke- <br />Colcr.do ^~ Nu[rber 18378 <br />Canadian Mine Pond # 1 Inspection Report, l4 October 1993, Page 3 of 3 <br />