Laserfiche WebLink
l <br />.... _ ~.~a. ~..... u..Js4.~aW. _nwr~. ':...a.4 . <br />• <br />- 7 <br />It1. Installation of Culverts <br /> <br />Sunland proposes to install seven culverts at various .locations within the <br />permit area. Each culvert has been correctly sized to safely pass flow from <br />the 10-year, 2G-hour precipitation event for Cheir respective drainage areas. <br />The velocities through the culverts are all less than live feet per second, <br />which is desirabic. The proposed locations of. tl~~e culverts have bee^ reviewed <br />and found to be acceptable. However, no description of measures to be taken <br />to protect the inlet end of any and a1..1 ditch relief culverts is given. This <br />information must be submitted to OS?t f. or r.evi.e w. <br />I~1. Itegrnding and Uitchi.ng .41ong Ranch Road For Diversion of Undisnrrbed <br />drainage <br />Collector ditches designed to divert flow acaay from roads and the proposed <br />disturbed acres have been designed to conve; [he 10-;year, 24-hour storm runoff <br />volume. Duce again, however, design specifications have resulted in <br />potentially erosive velocities in ditch Nos. D1 and D~, and possibly Nos. <br />p~ and D5, dependent upon the type of matzria] [he ditches are to Yee <br />constructed in. 'C'ue soil type present as well as new design criteria for the <br />above mentioned ditches is required in order to determine maxj.mum permissible <br />veLor_i[ics (ref: Chow, 19.59). <br />l'. Installation of UDStream Atonitorin~ Station For Trout Creek <br />Sunland has proposed installing on Trout Creek above the mine site a Stevens <br />T+ype F Model 6fl continuous flow recorder for water quantity measurements. A <br />crest stage gauge will be located adjacent to the record?r housing: A rating <br />curve will he developed for the site. Therefore, water quantity should be <br />accurately measured at this site. With respect Co water quality, the <br />applicant states °The Frequency of co.llecti.on, nature of the data, and <br />reporting requirements will be determined on the advice of the regulatory <br />authorities." 'Che following mon.itoriog plan is recommended by OSM: <br />Sampling frequency: monthly, unless effluent limits are being exr_eeded <br />from the pond discharge, in which~r_ase a higher frequency is reyuired. <br />Sampling is required through mining and reclamation operations. <br />*Fn rame[e rs to be sampled: (i.n add.i tion to those listed in the mine <br />plan) <br />n. tot:r.1 iron <br />b. dissolved iron _ <br />c- totn.l dissolved solids ('CDS) <br />d. oil and grease <br />e. nitrate-nitrogen <br />*q uantity should he measured every time a water quality sam p.ie is <br />taken - sainp les should be grab sn mples and depth integrated with <br />respect Co flow. <br />- y' A.. .. <br />