Groundwater and the Algona Plume- basic information for the community. Dr. Peter defur President, Environmental Stewardship Concepts, LLC

Transcription

1 Groundwater and the Algona Plume- basic information for the community Dr. Peter defur President, Environmental Stewardship Concepts, LLC

2 ESC, LLC -- PL defur Topics What is unique about Kent Valley geology How does groundwater flow work What do we know of the groundwater in the Algona area? Drinking water regulations and groundwater Basic vapor intrusion information

3 Glacial History of Puget Sound Washington 20,000 years ago

4 Sand & silt deposited by glacial epochs

5 Created quality aquifers Auburn/Algona

6 Layering of rock in Auburn/Algona area: Sandy and silty layers Remember this Osceola Mudflow

7 tapintoquality.com Groundwater 101

8 Image: What is groundwater?

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10 How groundwater is replenished

11 Image: unwater.org 30% of the earth s freshwater is groundwater.

12 How groundwater moves Image: pubs.usgs.gov

13 Groundwater moves very slowly Auburn/Algona area = 250 feet/year (8 inches per day!)

14 Water between sand grains

15 Groundwater: Aquifers Image: education.nationalgeographic.com

16 Aquifers in Puget Sound Region Auburn/Algona Puget-Willamette Regional Aquifer System

17 The Water Table Photo: pubs.usgs.gov

18 The Water Table: Wells Photo: pubs.usgs.gov

19 Pollution of Groundwater Rain or irrigation water can leach contaminants into groundwater. Image: pbisotopes.ess.sunysb.edu

20 Pollution of Groundwater: Sources Image:

21 Drinking Water 101- public supplies

22 Sources of Drinking Water 1. Groundwater Image: tapintoquality.com

23 Sources of Drinking Water 2. Surface Water Photos: en.wikipedia.org

24 Drinking Water Treatment Photo:

25 The Safe Drinking Water Act Main federal law that ensures the quality of Americans public drinking water and its sources Passed by Congress in 1974 Public water supplies Source:

26 The Safe Drinking Water Act Threats to drinking water: Animal and human wastes Pesticides Improperly disposed chemicals Wastes injected underground Consumerwatchdog.org wwf.panda.org Smithsonianmag.com

27 EPA sets Maximum Contaminant Levels for amounts of contaminants allowed in drinking water. Including for TCE and Vinyl Chloride.

28 National Primary Drinking Water Regulations for Public Supplies Regulated contaminants: Microorganisms Disinfectants Disinfection byproducts Inorganic chemicals Organic chemicals- such as TCE and vinyl chloride Radionuclides Source:

29 Regulatory Determination EPA considers: 1. Potential adverse effects of the contaminant on human health 2. Frequency and level of contaminant occurrence in public drinking water systems 3. Whether regulation of the contaminant presents a meaningful opportunity for reducing public health risks Source:

30 Hydrogeology of the Boeing Auburn Site and surrounding communities

31 King County scientists and the USGS are in charge of mapping and understanding the area s groundwater.

32 The Osceola Mudflow Clay-rich deposits below the surface deposited by volcanic mudflow Mt. Rainier Eruption ~ 5700 years ago. Varied depth ~ 80 meters Groundwater above and below the mudflow are separated (aquitard). Water above is perched Water below is confined Image: USGS, Crandell et al. 1979

33 Upper aquifer zones: Shallow 10 to 30 feet Intermediate 40 to 60 feet Deep 80 to 100 feet Images: Landau Associates, 2014

34 Boeing Site City of Algona City of Pacific City of Auburn Groundwater flow divide Image: USGS Contour lines -> areas of equal hydraulic head (pressure/level) GW flows from high to low hydraulic head - perpendicular to contour lines Flow is generally North to Northwest towards Green River. GW becomes surface water when hydraulic head is higher than surface.

35 Source: Landau Associates, 2014 Calibration Water Level Contours (June 2013 Intermediate Zone Water Levels)

36 Movement of Area Ground Water Groundwater Velocity: Landau Associates Model ~ 250 feet per year Aquifers recharge slowly. Contaminants can remain in the area for a long time. Aquifer Recharge Rate Model: Landau Associates, 2014

37 Vapor Intrusion Chemicals in soil or groundwater can migrate to indoor air aboveground Image: EPA

38 Sampling Algona surface water In northern Algona, ground- water is located within a few feet of the ground surface November 2013: Surface water in Algona yards was sampled for contaminants Ditch water Yard water Image: Landau Associates 9/25/14 Technical Memorandum, Figure 2

39 Groundwater Wells Image:

40 Drinking Water Wells Map from Dept. Ecology

41 Groundwater layers Wells: Upper Aquifer and Lower Aquifer Drinking water can be contaminated if chemicals leach into one or both aquifers. Image: Landau Associates, 2014

42 For more information, go to water.epa.gov water.epa.gov/drink/contaminants/ usgs.gov/water

43 Questions? Dr. Peter defur Environmental Stewardship Concepts, LLC