Description
Groundwater monitoring wells composing the North, South, and West Miramar Landfills groundwater monitoring program in San Diego, California are developed in erosional remnants of a Pleistocene-aged terraced mesa incised by San Clemente Canyon and its tributary canyons. The groundwater gradient reported for the vicinity comprising the North, South, and West Miramar Landfills is westward north of San Clemente Canyon and to the south, south of San Clemente Canyon (Ninyo and Moore, 1994). This disagreement between the two gradients separated by San Clemente Canyon could be caused by invalid water levels due to improper monitoring well development, well screen intervals completed in different formations, or to different depths between wells. Most wells were found to be completed to the same elevation and in the same formation (Friars). Water level measurements were taken from eight wells completed to the same elevation and screened in the Friars Formation. A slug test was then performed on the tested wells to determine if they are reflective of aquifer characteristics. Hydraulic conductivity values for the Friars Formation were determined and compared to existing data. Using water level measurements taken from these wells a site groundwater gradient contour map was constructed. The slug tests were successful in all but groundwater monitoring wells MW-1 and SMMW-2. Monitoring well MW-1 was found to be silted. The remainder of monitoring wells tested recovered to approximate static water height in 4 hrs or less. Hydraulic conductivity values obtained from the remainder of the tested wells for the Friars Formation ranged from 1.03 x 10-4 to 4.7 x 10-5 ft/min. The hydraulic gradient in the site vicinity is to the south. Calculated values for the hydraulic gradient ranged from 1.26 x 10-2 to 6.61 x 10-4 feet/foot. There appears to be mounded water in the vicinity of monitoring well MW-3 that could be influencing the ground water gradient in the site area. Settling ponds located on the Sim J. Harris property to the east ofMW-3 may be causing the mounding by recharging the groundwater in the north east vicinity of the study site.
