Alandfill is leaking an effluent with a concentration of chromium of 150 |mg/l. it seeps into an aquifer with a hydraulic conductivity of 7.5 m/day, a gradient of 0.0035, and an effective porosity of 0.15. a down-gradient monitoring well is located 75 m from the landfill. a) what would the sodium concentration be in this monitoring well 365 days after the leak begins? note: in this problem you will need to find erfc(-x), which is equal to 1+ erf(x)

Afoot bridge is made as a simple deck, 4 m long, with a cross section 2 m (wide) and 20 cm thick, and made of wood. the deck is supported at the two ends. the maximum load allowable on the bridge is 10 tons, provided it is uniformly distributed on the deck. to sense this load, a strain gauge is placed at the center of the bridge and its resistance is monitored. if the sensor has a nominal resistance of 350 s2 and a gauge factor of 3.6, what is the reading of the strain gauge at maximum load? the modulus of elasticity for the wood used in the construction is 10 gpa.