SEPA checklist guidance, Section B: Groundwater
1. Will groundwater be withdrawn from a well for drinking water or other purposes? If so, give a general description of the well, proposed uses and approximate quantities withdrawn from the well? Will water be discharged to groundwater? Give general description, purpose, and approximate quantities if known.
Describe any new or increased groundwater extractions, including use or purpose and approximate quantities if known. Ecology’s water resources database map may be a helpful tool.
For water discharges to ground, remember to consider how stormwater runoff collected from impervious surfaces is managed onsite. Is the project in a drinking water wellhead protection area, the area where groundwater flows to a water supply well? The state Department of Health has a web tool—Source Water Assessment Program Maps—that can be used to locate wellhead areas in each county.
2. Describe waste material that will be discharged into the ground from septic tanks or other sources, if any.
Waste material includes chemicals, sediments, agricultural runoff involving pesticides, herbicides, and fertilizers, wash water, logging slash, log booming or storage debris, treated wood pilings, and oil or other fuels from equipment used for construction or operational activities.
While septic systems are a primary source of waste discharges to ground, unlined ponds or trenches used for discharge or storage of liquid waste such as manure, food processing waste, and contaminated waters, should also be considered. Remember to include size and quantities and describe the known nature and characteristics of the waste.
When applicable, include discharges to injection wells such as dry wells. Injection wells are those in which water or other fluids are injected back into the ground. Injection may be directly to a groundwater aquifer or to unsaturated substrate overlying an aquifer. Mention any unlined ponds or trenches that store or discharge waste. Include size, quantities and type of waste. If the project is located above a sole source aquifer, that needs to be mentioned.
Additional Resources: USGS Water Quality information for Washington State
c. Water runoff (including stormwater)
1. Describe the sources of runoff and method of collection and disposal, if any.
Describe the following: source runoff; intended management systems; where and how the runoff will be discharged off the project site; and where and how the runoff will flow to ground or surface waters:
For Forest Practice proposals this may include road-cut slopes with the water being collected in the ditches with cross drains placing the water on the forest floor away from flowing streams. Skid trails, water bars, or silt traps would be other sources of water collection. The runoff may be caused by both ground-based and/or cable logging equipment.
For Surface Mining proposals or mining expansions, include the pre and post mining configuration of water bodies. Please note any new surface water locations that stormwater runoff might enter due to expanded mining activity. For projects involving underground drilling include the water control plan for the drill pad and slurry pond.
2. Could waste materials enter ground or surface waters?
Consider potential sources of contamination such as parking lots, equipment storage, agricultural practices, lawn and landscaping maintenance, animal waste, treated wood, eroding soils, etc., as well as any treatment provided, and where runoff will flow or be discharged. Describe the type and source of potential contamination and the water body or aquifer where it is likely to end up. If located in a wellhead protection area, describe the area where the groundwater flows to the water supply well or other type of groundwater protection area.
3. Does the proposal alter or otherwise affect drainage patterns in the vicinity of the site? If so, describe?
Identify any effects the proposal would have on drainage patterns, including effects on existing groundwater resources.