- Reliance on imported water sources
- Need for supplemental and emergency supply
- Potential impacts including drawdown, salt water intrusion, and subsidence
- Identification and evaluation of potential municipal well sites
- Feasibility study of reactivating and treating an existing municipal well
- Development of a MODFLOW model to evaluate pumping impacts
- Preparation of a groundwater development and management strategy
- Evaluation of potential impacts on groundwater levels and quality of proposed municipal wells
- Preparation of NEPA and CEQA IS/EA
Municipal Groundwater Development: Evaluation of Alternatives and Impacts
City of East Palo Alto,
San Mateo County, California
At this time, the most practical method of increasing supply is development of local groundwater resources, including an existing well (the Gloria Way Well) that had been taken out of service because of water quality issues. The City obtained a US Environmental Protection Agency grant to fund an analysis of potential groundwater development. Todd Groundwater conducted the analysis, which included characterization of the hydrogeologic setting, evaluation of constraints (including contamination sites, seawater intrusion and subsidence), identification and evaluation of potential well sites in the City, analysis of the feasibility of using the Gloria Way Well (including a pumping test and sampling), and preparation of a groundwater development and management strategy. A numerical model was developed and applied to analysis of drawdown impacts of pumping the Gloria Way Well. Todd Groundwater developed recommendations, including a groundwater management plan, a treatment system for Gloria Way Well, and a hydrogeologic investigation of a preferred test well site.
The City is moving ahead actively with the groundwater development and management strategy. A first step (completed in 2013) was to attain compliance with both CEQA and NEPA. Todd Groundwater contributed hydrogeologic support to a joint initial study and environmental assessment that addressed the rehabilitation of the Gloria Way Well, construction of the treatment system, and pumping of the well to provide up to 420 acre-feet per year of potable supply. Analysis of potential impacts included evaluation of potential drawdown impacts on nearby wells, contaminant migration, salt water intrusion from the bay, and subsidence. Recognition of potential impacts resulted in collaborative discussions among the City and stakeholders, and a commitment by the City to:
- Develop a Groundwater Management Plan
- Conduct groundwater monitoring
- Conduct baseline surveying for subsidence
- Seek funding for additional numerical modeling
- Control initial pumping rates of the Gloria Way Well to assess and manage any adverse impacts.
The City currently is developing a groundwater management plan — including groundwater monitoring — in accordance with the California Water Code.