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' , Adit plug construction monitoring 5 1 2.1.2 Infiltration french influent rate ' During times when adit seepage is directed to the infiltration trench, the influent rate to the trench will be measured daily. The influent rate is to be measured using a 60° V-notch weir. The weir is ' mounted in the middle of a rectangular box to allow for accurate measurement of the height of flow over the weir. To obtain accurate flow estimates, the height measurement will be taken directly upstream of the V-notch. The influent box for flow measurement may require modification ' to address seasonal cold weather conditions. In any event, flow measurement will be provided. ' 2.1.3 Infiltration trench standpipe waterlevel The infiltration trench is equipped with two standpipe piezometers, SP-1 and SP-2, to allow for the ' measurement of the water flow depth in the trench. SP-1 is located within 30 ft of the trench inlet and SP-2 is located within 30 ft of the end of the trench. During operation of the infiltration trench, water level measurements in each standpipe will be made daily. ' 2.1.4 Vadose zone piezometer water levels Two vadose zone piezometers, VP-1 and VP-2, are installed adjacent to the infiltration trench to monitor groundwater levels downyradient of the trench. VP-1 is located approximately 245 ft ' from the trench inlet and about 30 ft from the trench centerline. VP-2 is located approximately 200 ft from the downstream end of the trench and about 25 ft from the trench centerline. During operation of the infiltration trench, water levels in the vadose zone piezometers are to be ' measured weekly. ' 2.1.5 Visual inspection o(the infiltration trench In addition to water level monitoring in the standpipes and the vadose zone piezometers, the ' performance of the infiltration trench will also be monitored through visual inspection. Depending on weather conditions, the visual inspection will be performed to detect possible saturated ground adjacent to the trench and in the vicinity of the 9360 Portal. ' During operation of the trench during this monitoring period, the inspection will be made daily. The inspection will be made only if the ground is not already saturated with precipitation or ' covered with snowfall. Should saturated ground conditions be detected, it is to be noted and appropriate measures will be taken to remedy the situation. 2.2 Windy Gulch monitoring ' Windy Gulch water quality samples (WGWB) are to be taken monthly at the Windy Gulch weir, which is located about 200-300 ft upstream of the confluence of Windy Gulch and Willow Creek. Each sample will be gathered based on the procedures outlined in Attachment A. The samples obtained will be analyzed for the parameters presented in Table 2.2 (see Section 2.1.1). Flow ' measurements, at the time of water quality sampling will be taken at this location, when practical. Flows in Windy Gulch at this location will be estimated by measurement of the height of the water over the weir or other suitable method with documentation of the method used.