APPENDIX E: HYDROGEOLOGIC CONSIDERATIONS OF ZONE OF CONTRIBUTION METHODS 

 Cape Cod Aquifer Management Project Final Report Page E-10 



2. Aquifer pump- test data should be analyzed to determine the aquifer's 

 transmissivity and storage coefficient, the specific capacity of the 

 well and the depth and radius of the pumping well's cone of 

 depression. This information may be obtained by applying one of the 

 following analytical methods. Procedures outlined by these references 

 will give satisfactory results depending on the completeness of the 

 test data: 



a. "A Generalized Graphical Method for Evaluating Formation 

 Constants and Summarizing Well-Field History," by H. H. Cooper, 

 Jr. and C. E. Jacob, 1946, transactions of the American 

 Geophysical Union, Vol. 27, pp. 526-534, Washington, D.C. 



b. "Analysis of Pumping Test Data From Anisotropic Unconfined 

 Aquifers Considering Delayed Gravity Response," by S . P. Neuman, 

 1975, Water Resources Research, Vol. 11, No . 2 , pp . 329-342, 

 Washington, D.C. 



c. "A Computerized Technique for Estimating the Hydraulic 

 Conductivity of Aquifers from Specific Capacity Data", by K. R. 

 Bradbury and E. R. Rothschild, 1985, Ground Water, Vol. 23, No. 

 2, pp. 240-254, Worthington, Ohio. 



3. Water elevation maps should be drawn from data obtained at both 

 observation and non-pumping, public-supply wells. Maps constructed 

 from data taken at least every three months will reflect the seasonal 

 fluctuations in water-table elevations, flow directions and hydraulic 

 gradients which affect the geometry and orientation of a pumping 

 well's zone of contribution. In areas which have very gradual 

 hydraulic gradients, hydrogeological conditions may require that 

 elevation contours be drawn at one foot intervals to accurately 

 reflect local groundwater flow patterns in the vicinity of and 

 upgradient of public-supply wells. 



4. The zone of contribution of the wells should be defined as "Zone II" 

 in accordance with 310 CMR 24.00, Chapter 286, Acts of 1982. The size 

 and orientation of each zone should be determined by the use of the 

 analytical flow model as described by Todd (1980) , which requires 

 information about well discharge, aquifer transmissivity, hydraulic 

 gradient and hydrogeologic boundary conditions . Until vertical 

 groundwater gradients in the area between the well and the water-table 

 divide can be determined, the upgradient boundary of the zone of 

 contribution should be extended to the divide, as a conservative 

 protective measure. 



5. In localities having hydrogeologic conditions too complex to be 

 accurately described by an analytical flow model, the use of a finite 

 difference, three dimensional numerical model is recommended. Such a 

 model would be capable of simulating aquifer responses to variable 

 natural and artificial recharge, additional pumping wells and changes 

 in aquifer storage. 



