CHAPTER 3 - THE RESOURCE -BASED APPROACH 



Cape Cod Aquifer Managment Project Final Report Page 17 



computer models are also used to simulate complex hydrogeological 

 conditions. The use of the term "zone of contribution" is synonymous with 

 the terms "wellhead protection area" (federal term) and "Zone II area" 

 (the term used by Massachusetts) and all are used alternately throughout 



this report. 



Though Zone lis are simpler to protect than entire aquifers or 

 watershed basins, due to their confined area, the protection of ZOCs are 

 not without hydrogeological complexities, and political and economic 

 problems. For example, several hydrogeological assumptions must be made 

 to delineate Zone II boundaries. As an result. Zone II boundaries are not 

 permanently fixed but vary in size and shape, depending on hydrogeological 

 conditions and pumping stress. Another concern is that zones may overlap 

 the political boundaries of one or more towns, thus placing one town's 

 ZOC at risk from contamination by sources of contamination in another 

 town. 



Planning techniques that focus on the prevention of certain land uses 

 within Zone lis, are still highly experimental, but they are developing 

 rapidly. Promising innovative measures are emerging, such as land- 

 use -planning models that indicate if development will result in an 

 overload of a certain contaminant. Also, existing land uses within zones 

 of contribution can be intensively regulated to prevent contamination. 

 Prevention is premised on determinations of the level of risk that is 

 acceptable, i.e. the levels of a contaminant that will be tolerated and 

 those that are considered excessive in relation hioman health. 



Different types of protective measures are appropriate for different 

 potential sources of contamination. For example, it may be sufficient to 

 limit the density of certain land uses, while prohibitions may be required 

 for others. In the same way, certain contaminants are more mobile than 

 others and the protection zone size must be gauged accordingly. 



The resource -based approach, used during CCAMP, is an attempt to both 

 refine and advance the basic prevention-oriented philosophy. This ap- 

 proach features the following components: 



1. Thorough characterization of the aquifer system so that the zone 

 of contribution for the public-supply well can be delineated as 

 accurately as possible. 



2. Comprehensive inventory of all potential sources of contamination 

 located within the zone of contribution. 



3. Assessment of the federal, state, and local controls in place for 

 the regulation of all existing sources. 



4. A strategy for protecting the well based upon relative risk from 

 individual sources, cumulative impacts from existing sources, and 

 possible future problems from potential land uses. 



