WPC  2"BR ZpX#|VArial ItalicArialArial BoldHP LaserJet 4 PlusIIHPLA4PLU.PRS2xCQ\'sZXh9ND,C2xjAG;Xi1mC9,  Xm2PG;XP/qC:,cXq2pPG;Xet 4HPLAS4.PRS 4dp@~fQ@\2n T|TOO "4^DDV6OOYAOAADDAwDADn6wD66w6RwDwwwuR?ROAnOOODOOOOOOuOAwCCCCCCCCwwwwwwA6AAA6AAgww6A6[6RRRwwwwTDDwuuu6RwDwwDu414WddddddddddddddddddddddddddddddddddddddddNTT~PYVPTO33PPPPTTyuu3OuO"uu~uu"m+^99Ipp.DDNt9D99pppppppppp99tttp̅}9ep}}999\p.ppepp9pp..e.ppppDe9peeeeE5EtD9sZDDD9DDDDDDpD|9pppppȰepppp99999999pppppppppepp|pepppppeeee|pppppppppppp9.999.99Xeep.p:p.pDp.pxppppȼDDDeeee}L}9}9ppppppe}e}e}epp.pDe}9ee|pp8dp,(,WddddddddddddddddddddddddddddddddddddddddNHxxHlpD|pppppLJpDHpD,,DDpDDxppxHxxHsdd,DdD"dxdldtxxd"m+^:D`pp8DDLt8D88ppppppppppDDttt|Đ|8p|||D8Dtp8p|p|pD||88p8||||LpD|pppdL8LtD8ttDDD8DDDDDDpD|8pppppȰppppp88888888|||||||||pp|||p||ppppppppppp||||||||88888888ppp|8|L|8|`|8|||||ȼLLLpppp|`|D|D||||||p|d|d|d||8|Lp|Dpp||:dp,0,WddddddddddddddddddddddddddddddddddddddddNHxxHppD|pppppLHpDPpD88ddpDDxppxHxxHs||8ddD"dxxldtxxd2  P #Xp2PQ XP#e  yxdddy Jicarilla Lower Mundo|'`v(#5Conceptual Design   II.INTRODUCTION AND DAM DESCRIPTION   R A.` ` Purpose(#` XX` ` The purpose of this report is to develop conceptual design alternatives for the Lower Mundo Lake Dam Safety project and to determine the most feasible alternative for final design.(#`  R B.` ` Lower Mundo Lake Dam Description(#` ` ` Lower Mundo Lake Dam is located on the Jicarilla Apache Indian Reservation in northcentral New Mexico approximately five miles southeast of the town of Dulce. The dam is owned and operated by the Jicarilla Apache Tribe (Tribe). The Tribe utilizes the lake for recreation. Lower Mundo Lake was constructed in 1969 by the Tribe with support from the Bureau of Indian Affairs (BIA).(#` XX` ` The dam is a homogeneous earthfill embankment with a downstream rockfill toe below Elev. 7300. The crest is at Elev. 7,330.6 NGVD. The crest width is 10 feet. The structural height, as measured from the crest to the bottom of the cutoff trench, is 64.5 feet. The maximum height is 46.4 feet. The spillway is a 160 foot long concrete uncontrolled weir and is cut through alluvial soils and gravels near the left abutment of the dam. The concrete weir is protected against undercutting by use of wire wrapped stone for 5 feet upstream and 15 feet downstream. The remainder of the spillway floor is unprotected.(#` ` ` The outlet works consists of a 250 foot long, 18 inch inside diameter, steel conduit located in the bottom of the valley. The pipe was not placed on a concrete cradle. Seepage collars were installed along the pipe. The outlet is equipped with a low level steel slide gate operated from the crest by a(,)) removable hand wheel. The outlet is also equipped with an integral 24 inch diameter trickle tube overflow spillway with trash screen and ice cone.(#`   ` ` The dam impounds approximately 1,124 acrefeet of water, at the spillway crest, Elev. 7326.9.(#`  R. C.` ` Lower Mundo Lake Dam Deficiencies(#` XX` ` (#` XThe most immediate concern was the concentrated seepage which exits just above the outlet pipe on the downstream slope and that the seepage was flowing along the outlet pipe from the reservoir. An investigation was made to determine the source of the seepage. The results led to the conclusion that the seepage from the foundation to the right of the outlet works was accumulating in the rockfill toe and then flowing out of the rockfill above the outlet pipe. The flow is not through the embankment or along the outlet pipe as initially thought possible. Although the right side seepage is a problem, it is not an imminent threat.(# X(# The remaining deficiencies are as follows: X(#  R X` ` 1) "The uncontrolled seepage through the foundation of the right abutment is a serious dam safety problem. In addition, in most years there is a concern over recreation usage since the seepage results in a continually decreasing lake level after the spring runoff.(#  R X` ` 2) "There are alluvial materials in the embankment foundation between the right abutment bedrock and to the outlet works which are potentially liquefiable.(#  R,& X` ` 3) "The existing spillway is inadequate to handle the inflow design flood. In addition, the spillway channel is subject to erosion, the concrete',)) sill block does not extend into rock and the right bank of the spillway has the potential to erode into the left end of the embankment dam.(#   R X` ` 4) "Calculated factors of safety for the steady state downstream condition are slightly below generally accepted values.(# X(#  R. ` ` 5)X "The existing crest needs an allweather surfacing.(#  R X` ` 6) "It is reported that when the reservoir level goes below the bottom of the upstream riprap, there is embankment undercutting from wave action.(#  R\ ` ` 7) "It is reported the outlet works air locks during discharge through the trickle tube overflow.(# XX` ` It would appear that all deficiencies can be remedied without replacing the dam.(#`