2015-02-06_HYDROLOGY - P2014019 - Laserfiche WebLink

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Based on the data shown above, approximately 0.4 -1.5 CFS of water has flowed from the mine historically. Therefore, a baseline flow of 1.5 CFS is proposed for flow comparison during NOI activity. The project manager and all workers in the project will be trained as to the importance of maintaining the water quality of the existing flows from the mine. As explained in the previous response, erosion waddles will be installed at each drill station and possible in the main mine ditch. Full drill hole plug material will be available at every drill station so that if a hole is producing water from fractures or any other source, the drill hole will be plugged if the flow is found to exceed proposed baseline level of 1.5 CFS. As daily field tests are taken for these parameters at the drill site underground and the mine portal, they will be compared to these baseline levels and if there are any variations above 20 %, a sample will be taken for full suite analysis and an immediate investigation will take place to find the cause for the exceedance. The 20% value is used since there will be normal fluctuations in parameters due to wet/dry years, seasonal fluctuations, etc. If it is seen that excess solids are, leaving the drill station, or that conductivity levels are too high as determined by the 20% variation, then immediate action will be taken to either improve sediment trapping, or in the case of high conductivity or pH, the hole will be plugged immediately. 2.3 Receiving stream standards for Mosquito Creek... The Hock Hocking Mine currently discharges into Lower Mosquito Creek. This creek drains into the middle fork of the Platte River. Mosquito Creek is in the Upper South Platte River basin. The stream segment of interest is Number 2b as listed in CDPHE Regulation Number 38 [1]. Segment number 2b as defined in CDPHE Regulation Number 38 on stream classifications and water quality standards for the South Platte River Basin, Laramie River Basin, Republican River Basin, and the Smoky Hill River Basin was used to classify Mosquito Creek [1]. These regulations are referred to as in- stream standards and are specific to the stream segment applicable to the Hock Hocking Mine site. The values as defined in the numeric standards table for Regulation No. 3 are shown below in Figure 2. REGION: O AND DESIG --- .CATION. NUMERIC STANDARDS TEMPORARY MODIFICATIONS BASIN: UPPER SOUTH PLATTE RIVER PHYSICAL srM BIOLOGICAL - ORGANIC P19A METALS PWI AND WAUF6`RS Sssam Segment Descsgpn Zb. Matnslem of Mo.qudo Creek hom Fe Aq We Cols 1 T•T VS(CS -I) C NH>(aUN)•NS S :0 As(ac)•0{D r.(ch)-WS(d.) Ni(Aekh)•TVS T..W..y npb6calon confluence wsh South Maequ it. CreeIt to ib UP Reaealwn E D O. • 6.0 nqs C@(ac)•00/9 B•0.T3 A.(N)•0.02(TreQ Fe(ch)•1000(Trec) Ss(eekh)•TVS As(N)4)Ln0 conf u.—.1h the Misde Fors of Ih. South Water Surd! 00 (110-7 0 MP Clich" 011 NO2•0.05 Cs(oc)•TVS(tr) Pb(ackh)•TVS Aq(x)•TVS E�ratwn sale of 121!141. P.a. R.— Agseulty PH - 6.5-9.0 CN•0.005 NOy.10 Cs(N)•TVS Mn(Wrh)•TVS A9(ch )-TVS(tr) E. COS•12fif100M CI-250 Cslgac)•50(Trec) Mn(NI•WS(d.) Zn(N) -Z20 So,•WS CNI(aNN)•TV$ Hq(eh}0o1(To0 cafoeleh)•TVS Figure 2 - Numeric Standards Table for Regulation No. 38 [I ] As shown in the figure above, this segment of Mosquito Creek is classified for Aquatic Life Cold 1, Recreation E, Water Supply, and Agriculture. Many of the water standards are based on the Table Value Standards (TVS), and thus may require a hardness calculation. Although many years of hardness data for Mosquito Creek downstream of the Hock Hocking Mine exist, corresponding flow data is not always present. Extensive hardness data was available from sampling location 5988 on the sampling location map shown in Figure 3. This data was collected by two different agencies: the CDPHE and The Rivers of Colorado Water Watch Network (also