Laserfiche WebLink
<br />November 3, 1997 <br /> <br />MEMORANDUM <br /> <br />To: <br /> <br />File <br /> <br />From: <br /> <br />Dea... G. Miller -ycS-.v\ <br /> <br />Subiec~ <br /> <br />Lake Maadestcr Dam; W. 01... I, DAMID: 060307 <br />Meetilll witlt oWller aad tagiaeer to discuss design issues <br /> <br />On Oc;tober 30, 1991, Mark Haynes and I mef. in the Denver offic.e, with representatives from the <br />ownership group (or Lake Manchemr and with their engineer, Tim Dolen. The purpose of the meeting <br />was to discuss the noted deficiencies with the dam, as documented by my inspection report of 912/94 and <br />subsequent follow-up inspection memos, to evaluate design concepts, and to describe what i$ required fo <br />be done with the dam to retum it to satisfactory condition. A list of attendees is attached. <br /> <br />The meeting was scheduled in response to my letter of 719/91, requiring the owner to provide a <br />work plan for Npairs to the dam by 12/31/97. Tim provided a copy of 8 report of observations and <br />recommendations prepared by Tom McDaniel. P.E, who will apparently serve as design engineer of <br />record for the repair work. Tim is currently employed by the USBR, and is therefore restricted in the <br />types of oonsulting activities he can certify. Tom i$ a former USSR gf;(l~hnic:a' engineer. currenlly <br />retired, who has c"tensive dams experience. <br /> <br />The noted deficiencies with the dam were first discussed. These include the following: <br /> <br />· Non-func:tionallow level oullet pipe which has been buried at the downstream end and has <br />no apparent operator at the upstream end; pipe condition is unknown. <br />· Seepage along the toe and lower slope of both the main dam and the north dike. <br />. Over-steep downstream slope on both the main dam and the north dike, which, when <br />considered with soft soil conditions caused by the observed seepage, leads to concerns for <br />embankment stability. <br />· Excessive tree (especially aspen) and brush growth on the north dike. which is a relati\'cly <br />small embankment of narrow section, and along its downstream toe. <br />· Insufficient freeboard provided by the "emergency spillway" low area on the left abutment <br />of the north dike. <br /> <br />Tim ;s aware of aU of these issues, and the design wilf address them. The intent is to properly abandon <br />the low level outlet by pumping it full of grout. Since the last time I observed the dam on 6/24/97, the <br />owner has located the downstream end of the outlet conduit and has uncovered it. II appears to be a 12- <br />tneh diameter steel pipe, and it drained water readily once uncovered. We discussed what would need to <br />be do~ to accomplish grouting; the pipe wiU need fo be cleaned thoroughly inside by jetting to ensure <br />removal of the sediment observed to have accumulated in the invert. Grouting will need to incorporate an <br />air vent pipe in the crown of the outlet conduit to ensure complete filling ofthe conduit inferior. Grouting <br />would proceed from the downstream end. <br />