Report 2023-06-01

Abstract

The present and future water supply for Provincetown and Truro is highly dependent on the Walsh property.

The initial August 2022 report on Groundwater Protection Priorities for the Walsh Master Plan outlined drinking water security considerations in broad strategic terms.  Hydrogeological groundwater modeling is a best practice in addressing planning exercises of this nature but has not been provided to date.

In this Part 2 iteration we apply a hydrogeological groundwater model to accurately describe the critical parameters for the type of analysis that is required by an enlightened master planning process.

Detailed modeling of the aquifer under the Walsh property reveals the critical importance of the entire area to the continued quality of the water pumped from the adjacent municipal water supply at North Union Field.  The present and future water supply for Provincetown and Truro is highly dependent on the Walsh property.

This in turn has implications for development on the Walsh property.  Key conclusions include:

·   Wastewater discharged on the Walsh property will be drawn directly into the water supply wells for most cases.

·   The North Union Field wells presently produce pristine water with only background concentrations of nitrate.

·   The school wastewater system is located outside of the primary capture area to the North Union Field wells, and therefore there is no nitrogen credit for an offset.

·   Planning for wastewater infrastructure based on groundwater modeling is a primary requirement prior to proceeding with deliberations about what is reasonable to develop on the property.

·   The significant cost of mitigation for wastewater, stormwater, spill contingency, and regulatory performance monitoring should be articulated up front as a component of development costs.

Additional conclusions are included in the body of this report.