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Drinking Water 101

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Title: Drinking Water 101


1
Drinking Water 101
Groundwater Basics Dennis Nelson
Source Water Assessments/Protection Amy Parmenter
2
Groundwater Basics
  • Where does ground-water come from?
  • How does ground-water occur?
  • How does ground-water move and how fast does it
    travel?
  • How susceptible is groundwater to contamination?

3
Important Groundwater Facts
  • Groundwater originates from precipitation
    sinking into the ground from the surface to the
    water table.
  • Groundwater occurs in the open spaces between
    silt, sand and gravel particles or in natural
    fractures in rocks (not underground rivers or
    lakes).
  • Groundwater moves from where the water table is
    high to where it is low.
  • How fast it moves depends on the slope of the
    water table and the aquifer permeability.
  • Groundwater is susceptible to contamination from
    surface activities.

4
Origin of Groundwater
5
Types of Aquifers
  • Unconfined
  • Shallow
  • Local Recharge
  • Water Table
  • Susceptible
  • Confined
  • Deeper
  • Confining Layer
  • Distant Recharge
  • Water under pressure
  • Less susceptible

6
Local vs. Distant Recharge
7
Groundwater Movement
8
Groundwater Flow Direction
9
The Nature of Aquifers and Groundwater Movement
10
Source of Information Well Logs
  • What are the geologic materials and where do they
    occur?
  • Where is the first water?
  • Compare static water level with level of
    water-bearing zone
  • Confined vs. Unconfined aquifer?

11
Unconfined vs. Confined Aquifers What does the
well log tell us?
12
Seasonal Water LevelsWinter
13
Seasonal Water Levels Summer
14
Groundwater and Surface Water Reactions
15
Streams and Groundwater
16
Hydrographs and Base Flow
17
Lakes and Groundwater Lakes may
receive Groundwater, Discharge to ground- Water,
or both
18
Pumping wells Close to Streams Drawing in
surface Water? How much pumped
How long pumped
19
Potential for Groundwater Contamination
  • Soil and subsurface materials as filtering
    mechanism
  • Particulates (Pt)
  • Dissolved (Ds)
  • Bacteria (Bc)
  • Chemical processes affect dissolved constituents
    Organic (Or) vs. Nitrate (NO3)

Or
Pt
Bc
Ds
NO3
20
Potential for Groundwater Contamination Aquifer
Sensitivity
  • Hydrogeologic
  • Soil (b, K, Org. C)
  • Vadose (b, K)
  • Depth to aquifer
  • Avail. H2O
  • Chemical Specific
  • Solubility
  • Sorption tendency
  • Persistance (T 1/2)

Soil
Vadose
Aquifer
21
Aquifer Sensitivity
  • Nature of vadose zone
  • Permeability of material is highly variable
  • Approximate travel time across 20 vertical feet
    under saturated conditions
  • Also aquifer character, old wells, depth to
    aquifer, rainfall,etc.

22
Groundwater Contamination
23
Seasonal Compositional Variations
  • Seasonal Differences within a single well
  • Recharge related
  • Infiltration of nitrate from a nitrate source (A)
  • Dilution of contaminated aquifer (B)
  • Significant Variations
  • Up to 100 have been observed, e.g., lt10 to gt20
    mg/L

B
A
24
Seasonal Pumping Variations
  • In winter months, dashed lines, groundwater flow,
    and therefore the capture zone of a domestic well
    may differ from that during irrigation season
    when large-capacity wells alter the flow pattern.

25
Between Wells Variability
  • Recharge and/or source related
  • Wells screened in different aquifers
  • Wells screened at different depths in the same
    aquifer

26
Important Groundwater Facts
  • Groundwater originates from precipitation
    sinking into the ground from the surface to the
    water table.
  • Groundwater occurs in the open spaces between
    silt, sand and gravel particles or in natural
    fractures in rocks (not underground rivers or
    lakes).
  • Groundwater moves from where the water table is
    high to where it is low.
  • How fast it moves depends on the slope of the
    water table and the aquifer permeability.
  • Groundwater is susceptible to contamination

27
Drinking Water 101
Groundwater Basics Dennis Nelson
Source Water Assessments/Protection Amy Parmenter
28
Oregon Source Water Assessments
  • Mandated by 1996 Amendments to the Safe Drinking
    Water Act
  • Applies to all federally-defined public water
    systems community, nontransient noncommunity and
    transient noncommunity
  • Goal encourage implementation of protection
    measures in order to
  • Insure the quality of future drinking water
    sources
  • Minimize the cost of future treatment costs

29
Drinking Water Protection Process for Public
Water Systems (PWS)
DHS and DEQ contact PWS GPS intake or well and
request PWS assistance
Activate community citizens, gather input, select
a few strategies for protecting the source area
DELINEATION of the source area or Drinking Water
Protection Area
INVENTORY for Potential Sources of
Contamination per guidance
Source Water ASSESSMENT phase
OPTIONAL Consider writing a Drinking Water
Protection Plan and gaining certification from DEQ
Drinking Water PROTECTION phase
Determine SUSCEPTIBILITY to contamination
IMPLEMENT the strategies to prevent contamination
SOURCE WATER ASSESSMENT REPORT Sent to PWS
30
Oregon Source Water Assessments
  • GW - 948 systems (community and nontransient
    noncommunity)
  • SW - 142 systems
  • Total full assessments - 1090
  • TNCs - 1046 systems

31
Procedure for mapping of Surface Water DWP Area
  • Compiled base map with USGS topographic maps
    edge-matched
  • Used 5th-field HUC Oregon Sub-basins to delineate
    watershed if available
  • Completed mapping on GIS base map (up to state
    boundaries)

32
Sensitive Areas for SW
  • Characteristics
  • Setbacks 1000 from centerline of water body,
    includes all perennials
  • High soil erosion potential (NRCS)
  • High permeability soils (alluvials mapped by
    USGS)
  • High runoff potential (Class D soils)
  • Landslide hazard areas

33
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34
Oregon drinking water source areas for surface
water intakes
35
What weve learned from surface water assessments
  • Surface Water DWPAs include multiple PWSs
  • Surface Water DWPAs contain many different
    stakeholders
  • Headwaters of a lot of DWPAs are in forested land

36
Procedures for Delineation Groundwater
  • Identify that part of the aquifer that supplies
    water to the well or spring
  • Site-specific parameters
  • Radius a function of time
  • Project to the
  • surface

37
Procedures for Delineating Groundwater Sources
  • Dependent on population, number of wells and
    hydrogeologic setting
  • lt500 and single well calculated fixed radius
    (volume calculation) 63
  • lt500, multiple wells enhanced calculated fixed
    radius 4
  • gt500 analytical model 22
  • Complex hydrologic boundaries analytic element
    or numerical method 5
  • Springs hydrogeologic mapping 6
  • Transient NC systems outreach area - 1115

38
Drinking Water Protection Areas Oakhill School
39
Multiple Well Delineation
40
Adding Groundwater Flow
41
Drinking Water Protection Areas Junction City
42
Hydrogeologic Mapping
43
Oregon Drinking Water Protection Areas from
Groundwater Sources
44
What weve learned from groundwater assessments
  • 347 (55) of our CWSs have at least one source
    that rates as highly sensitive
  • General categories of highly sensitive
  • Chemical detection at the source
  • Coliform from the source
  • Aquifer character
  • Ease in which water can move from the surface to
    the aquifer
  • Well construction

45
What weve learned highly sensitive aquifer
  • Aquifer Character/Ease of Movement
  • Many systems use shallow unconfined aquifer
  • 255 (39) CWSs have 392 sources lt100 feet
  • 144 (22) CWSs have 209 sources lt50 feet
  • 58 (9) CWSs have a high infiltration potential

46
What weve learned highly sensitive well
construction
  • 116 (24) community water systems have no well
    report for at least one source
  • Older than 1960?
  • Cannot evaluate well construction
  • 171 (35) additional CWSs have sources with
    inadequate well construction
  • Casing seal

47
Inadequate Well Construction
Water
  • Too small of annular space
  • Incorrect method of emplacement
  • Incorrect materials, e.g., drill cuttings
  • Insufficient sealant to fill annular space
  • Inadequate depth to isolate or protect aquifer

Slab
Casing Seal
Casing/Liner
Bore Hole
Screen/Perforation
Pump
48
What weve learned future rule implementation
  • Groundwater under the direct influence
    (noncommunity systems)
  • 245 systems need to be evaluated others
    eliminated by assessment
  • Groundwater Rule (hydrogeologic assessment)
  • 211 CWSs are highly sensitive and have coliform
    sources within 2-year time-of-travel

49
Drinking Water Protection Process for Public
Water Systems (PWS)
DHS and DEQ contact PWS GPS intake or well and
request PWS assistance
Activate community citizens, gather input, select
a few strategies for protecting the source area
DELINEATION of the source area or Drinking Water
Protection Area
INVENTORY for Potential Sources of
Contamination per guidance
Source Water ASSESSMENT phase
OPTIONAL Consider writing a Drinking Water
Protection Plan and gaining certification from DEQ
Drinking Water PROTECTION phase
Determine SUSCEPTIBILITY to contamination
IMPLEMENT the strategies to prevent contamination
SOURCE WATER ASSESSMENT REPORT Sent to PWS
50
Potential contaminant source
  • a location where there is any activity having the
    potential to release one or more contaminants
    into water at a concentration of concern
  • Database queries (14), field locating in
    sensitive areas, PWS consultations
  • 96 separate categories of PCSs
  • As of 7/05, over 15,300 PCS locations have been
    identified
  • focus must be on HIGHER risks

51
Important points about the SWA Inventory
  • listed potential sources not all inclusive
  • contaminants of concern SDWA
  • potential sources store/uses/produces levels
    that could contaminate PWS sufficient
    likelihood of release
  • not all listed sources were inventoried
  • microbes within 2-yr. TOT
  • watersheds gt100 sq. miles sensitive area focus
  • not all listed sources pose actual high risk
  • worst-case assumptions for POTENTIAL
  • not all inventoried sources need managing
  • screen out lower risks focus only on higher
    ones

52
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53
Oregons SWA Inventory Results Surface Water
Systems Highest Potential Risks in Sensitive Areas
54
Oregons SWA Inventory Results Groundwater
Systems Highest Potential Risks in 2-yr TOT
(wells) Zone 1 (springs)
55
Drinking Water Protection Process for Public
Water Systems (PWS)
DHS and DEQ contact PWS GPS intake or well and
request PWS assistance
Activate community citizens, gather input, select
a few strategies for protecting the source area
DELINEATION of the source area or Drinking Water
Protection Area
INVENTORY for Potential Sources of
Contamination per guidance
Source Water ASSESSMENT phase
OPTIONAL Consider writing a Drinking Water
Protection Plan and gaining certification from DEQ
Drinking Water PROTECTION phase
Determine SUSCEPTIBILITY to contamination
IMPLEMENT the strategies to prevent contamination
SOURCE WATER ASSESSMENT REPORT Sent to PWS
56
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57
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58
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59
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60
Drinking Water Protection Process for Public
Water Systems (PWS)
DHS and DEQ contact PWS GPS intake or well and
request PWS assistance
Activate community citizens, gather input, select
a few strategies for protecting the source area
DELINEATION of the source area or Drinking Water
Protection Area
INVENTORY for Potential Sources of
Contamination per guidance
Source Water ASSESSMENT phase
OPTIONAL Consider writing a Drinking Water
Protection Plan and gaining certification from DEQ
Drinking Water PROTECTION phase
Determine SUSCEPTIBILITY to contamination
IMPLEMENT the strategies to prevent contamination
SOURCE WATER ASSESSMENT REPORT Sent to PWS
61
Knowledge of Risks Promotes Resource Protection
  • Facilitates better community planning
  • Cost effective
  • Expensive to treat or replace
  • Better public health/economic health
  • Protect property values
  • Preserve economic growth potential
  • Increased public understanding of DW resource and
    responsibility to protect it

62
Reasons to Protect the Source
  • Population increase
  • Increased water needs
  • Increased threats to watershed health
  • Water infrastructure is aging
  • Water Quality standards are tightening
  • Emerging pollutants of concern
  • Limited funds for treatment upgrades
  • Security Issues

63
Discrete land use areas help focus risk reduction
activities
  • Residential
  • household hazardous wastes
  • septic system maintenance
  • stormwater management
  • Commercial / Industrial
  • pollution prevention TA
  • mentoring/partnerships
  • Agricultural
  • improved irrigation practices
  • nutrient/pesticide BMP
  • Forest
  • reduce road densities
  • sediment control
  • pesticide BMPs

64
Purpose of Management Plan or pollution
prevention measures
  • REDUCTION of contamination risks, not
    elimination
  • encouragement of community-based decisions on
    how to implement plan
  • increased public understanding of drinking
    water resource and responsibility to protect it
  • recognition of good-neighbor businesses,
    farmers, etc.

65
Why is citizen involvement so critical to
drinking water protection?
  • The largest percentage of pollution in Oregon
    comes from sources not regulated by permits, so
    we must engage individual citizens in the
    communities
  • Some of the most effective prevention tools will
    be individual actions by landowners and
    unregulated sources
  • We must promote water quality protection through
    effective education and outreach materials

66
Drinking Water Protection Challenges
  • DWP time-consuming involves many players. PWS
    staff time/capability is often limited
  • Most PWSs dont have jurisdiction over their
    entire DWPA
  • Easier to fund/justify treatment (reactive) vs.
    protection (proactive)
  • Common misconceptions
  • Required water testing is enough
  • Detections below the MCL not a risk
  • Think protection is covered in emergency
    response/vulnerability planning/plan review

67
Drinking Water Protection Challenges
  • DWP is an unknown process to most PWSs
  • PWS hesitate to tell consumers there is a risk
  • Lack of data to support protection (detection
    levels, focus is on MCL concentration, risk not
    known for synergistic effects)
  • More common misconceptions
  • Protection means excluding land uses
  • Polluter pays right?
  • Water systems with low risk assume no risk
  • Area immediately adjacent to well is all that
    matters

68
Drinking Water Protection Opportunities
  • Completed SWAs provide a tremendous amount of
    information
  • GIS resources can be used by other
    agencies/organizations
  • DEQ programs, Counties, Cities, USFS, BLM, ODOT,
    OERS
  • Adds to Multi-Barrier approach
  • DWP planning is complementary to proper system
    operation, treatment and emergency response
    planning
  • Can be used to set local priorities
  • Staff finally available to provide TA

69
Funds Available
  • Source Water Protection Grants
  • C or non-profit NC systems w/SWA
  • 200,000 in 2007
  • Up to 20,000/PWS/year
  • Eligible Activities that reduce risk of
    contamination of DW source
  • Not eligible OM of system/treatment
  • Regional or local projects
  • Scoring system

70
Drinking Water Protection Next Steps - DHS
  • Implementation of Drinking Water Protection
    Strategies groundwater systems
  • Assess new systems (since June 99)
  • Finish TNC assessments (175 need site visits)
  • Review delineations every 5 years
  • Update modified systems

71
Drinking Water Protection Next Steps - DHS
  • Coordinate remaining assessments and review with
    sanitary surveys
  • 646 groundwater sanitary surveys due this year
    174 CWS, 58 NTNC, 412 TNC
  • Region 1 194 systems
  • Region 2 253 systems
  • Region 3 199 systems

72
DHS Implementation Strategies
  • Focus on community systems with local governments
    (including Boards)
  • Prioritize based on interest, risks, sensitivity
  • Increased public involvement
  • Encourage regional strategy development
  • Large system with embedded small sys
  • Involve local planning authorities
  • Integrate SWAs in land use planning
  • Communication
  • Follow-up letters/surveys, workshops, factsheets,
    etc.

73
Drinking Water Protection Next Steps - DEQ
  • Get the word out conferences, program/agency
    meetings, watershed councils
  • Coordinate more with OAWU/RCAC
  • Prepare written implementation tools
    factsheets, handouts, DWPP template

74
Drinking Water Protection Next Steps - DEQ
  • Integrate into CWA and watershed approach
  • Coordinate/Leverage other programs and agencies
  • Transfer data lists of high risk PCS to other
    programs for potential prioritization (ex DEQ
    programs like tanks, WWTP, ODF-private
    forestlands)
  • Work to integrate DWP into policy priority for
    agencies (ex County planning, USFS, BLM, ODOT,
    ODA, SWCD, Watershed councils)

75
Emerging Issues Potential focus ?
  • Pharmaceuticals in Oregon waters
  • USGS data
  • Treatment effectiveness?
  • Focused collection events, TA
  • Microbial sources within 2-year time-of-travel of
    public supply wells
  • PWS detections as priorities for protection
    technical assistance
  • Rural schools
  • Others ?

76
What we need from county staff
  • PWS changes on Source Info Pg
  • Water usage
  • New/modified well (including irrigation?)
  • GPS locations of new wells
  • Datum (WGS 84, NAD 27)
  • TNC special projects (see handouts)

77
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79
For More Information
  • Dennis Nelson DHS GW Coordinator
  • (541) 726-2587 x21
  • Dennis.O.Nelson_at_state.or.us
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