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House with stone structure that could be a well and a building being constructed in the back.

This Guidance is intended to supplement flood precautions issued by local health and environmental departments. It is recommended that any reworking of a well terminal and well disinfection be performed by a licensed well or pump contractor because it is difficult for the private owners to adequately disinfect wells and safely work with deep set pumps.

In summary, it was concluded that: Fluoride concentrations for 15 out of 18 360 deg monitoring wells in the vicinity of the north boundary, northwest boundary, and north side of Basin F at RMA are averaging above the State of Colorado standard of 2.4 mg/1. The evaluation of this data has resulted in a range of levels between 0.763 and 7.462 mg/1. At the north boundary in the vicinity of the pilot containment/treatment system, fluoride levels average approximately 3.5 mg/1. Evaluation of the data for seasonal trends over a two-year period 75127 (1 Jun 75) to 77003 (1 Jan 77) yielded inconclusive results. Limited success was realized in the determination of temporal trends. Several wells in the vicinity of Basin F show consistent decrease of fluoride concentration with time (approximately 0.5 mg/1 per year).

Water level recovery data collected in wells following controlled pumping tests are affected by both borehole and formation factors. The borehole factors comprise those effects attributed to the presence of the wellbore, such as step-increases in pumping rate, wellbore storage, well efficiency, and skin effects. The formation factors comprise those effects associated with the geologic environment in which an aquifer system occurs, such as variation of the coefficient of storage, and aquifer barrier boundaries. The recovery data should plot as a straight line on a semilogarithmic plot. Step-increases in the discharge rate during the pumping period cause the water level recovery plot to be concave downward. The curvature of the recovery data plot can be eliminated by applying a correction proposed by Harrill in 1970. However, the effect of step-increases in pumping rate on the recovery data is minimal so long as the duration of the pumping steps is less than about one-third of the total duration of pumping. The well efficiency and skin effects cause an additional component of drawdown in a pumped well, which is manifested as an initially rapid recovery rate after pumping stops. The effects of skin and well efficiency are usually dissipated within a few minutes after pumping stops. Wellbore storage effects can be critical in large diameter wells (wellbore radius greater than 0.5 feet) that penetrate aquifers with transmissivities less than about 2,700 feet squared per day. The time required to dissipate wellbore storage effects in the water level recovery data is inversely proportional to the aquifer transmissivity, and directly proportional to the borehole size. Variation of the coefficient of storage during the recovery period results in a semi-logarithmic recovery plot that is concave downward. The curvature of the recovery plot increases as the variation of the coefficient of storage increases. Variation in the coefficient of storage of one order of magnitude durin

A five-instrument array of vertical seismometers was operated near Franklin, West Virginia, and one triaxial seismometer and one vertical seismometer were operated as an array at the site near Apache, Oklahoma. The test site near Grapevine, Texas, was operated throughout the period. The coordinate transformed output of a triaxial seismograph was compared with the output of conventional seismographs. Minor differences were found. Wiener optimum filters were developed for use with digitally processed data. An example of the degree of noise suppression achieved with one of the contemplated processing techniques is presented. (Author)