Ground Water RuleAssessment Source Monitoring

Chris MillerState of Alaska-Drinking Water

ProgramPublic Drinking Water Protection

chris.miller@alaska.gov

Ground Water Rule WorkshopDepartment of Environmental Conservation

September 22-23, 2009

Ground Water RuleAssessment Source Monitoring

Presentation Outline:Review Assessment Source Monitoring.

What it is. Risk factors considered .

Discuss data available to help determine whether assessment source monitoring is needed.

Ground Water Rule Monitoring Scenarios Ground Water Rule introduces two sampling

scenarios:Assessment Source Monitoring: State

discretion For systems identified as at higher risk for microbial

contamination. Assessing risk factors impacting a water system. Hydrogeologic Sensitivity Analysis.

Triggered Source Monitoring: All ground water systems are subject to, unless meeting 4-log treatment requirements.

This presentation focuses on Assessment Source Monitoring.

Targeted Monitoring = Assessment Source Monitoring

Also Please Note:

Source Assessment ≠

Source Water Assessment Reports

Better: Assessment Source Monitoring4

Before we begin:

Before we begin:Assessment Monitoring does not mean the

State of Alaska Drinking Water Program will actively track down current water systems and require monthly source monitoring.

But rather, it is an option to proactively identify at risk systems.

It will be risk-based.

Assessment Source

Monitoring

Triggered Source

Monitoring• Identified as higher risk system• Identified as sensitive aquifer by HSA

Regular TCR monitoring (TCR +)

Sample at source water

(frequency decided by the

State )

Follow-up sampling

(One sample has to be at the source).

EPA recommends monthly for 12 months

Corrective Action

Revert to Triggered

Status(Normal TCR Monitoring)

No Detection

No Detection

Positive fecal

indicator

Corrective Action

Corrective Actions

1. Correct significant deficiencies.

2. 4-Log treatment.3. Provide an

alternative source.

4. Remove source of contamination.

Positive indicator triggers 5 source water samples.

Positive indicator triggers

5 source water samples. (E. coli)

Assessment Source MonitoringWhich Public Water Systems may be

impacted by Assessment Source Monitoring? Sensitive Aquifers:

Hydrogeologic Sensitivity Analysis (HSAs)-not in Alaska at this time.

Desktop Analysis-existing data.Wells vulnerable to contamination:

Determined by State, High density of septic systems, Near sewer lines, and Construction deficiencies.

Hydrogeologic Sensitivity Assessments (HSAs)What is an HSA?

A tool used to determine sensitivity of the aquifer to fecal contamination.

Many different ways to conduct an HAS: Field observation.Tracer studies.Aquifer tests.

Alaska will not be using HSAs.

Assessment Source Monitoring-Risk FactorsSensitive aquifers.Aquifers in which viruses may travel

faster and farther than bacteria. Shallow unconfined aquifers.Aquifers with thin or absent soil cover.Wells previously identified as having been

fecally contaminated. High population density combined with

on-site wastewater treatment systems. Other risk factors.

Risk FactorsSensitive Aquifer

• The EPA classifies three aquifer types as Sensitive Aquifers:• Karst;• Fractured bedrock ; and• Gravel aquifer.

Risk Factors (cont’d.)Sensitive Aquifers

• Distribution in Alaska• Karst (cavernous limestone)

• SE Alaska(generally surface water systems)

• Northern Alaska(undeveloped areas)

Risk Factors (cont’d.)Sensitive Aquifers: Bedrock• Distribution: Bedrock aquifers in

Alaska (fractured)• Interior• S. Central• Kodiak

Groundwater Atlas of the US, USGS HA 730-N, 1999

Risk Factors (cont’d.)Sensitive Aquifers- Unconsolidated gravel with low

concentration of fines• Ex. Glacial lake outburst flood environments• Ex. Steep terrain flash flood environments

Groundwater Atlas of the US, USGS HA 730-N, 1999

Risk Factors (cont’d.)Shallow unconfined aquifers:

Aquifers close to the surface;Unprotected by a hydrogeological barrier; andTransport path is relatively short.

Greater likelihood that infectious fecal contamination will reach the PWS well.

Examples: Matanuska Susitna Borough, MOA-upper Hillside.

Risk Factors (cont’d.) Aquifers in which viruses may travel

faster and farther than bacteria.Viruses are much smaller and difficult to

filter out.Two Broad Aquifer Categories:

Porous: Sand, Sand/Gravel, and Gravel Rate of flow varies:

Slow: Sand Fast: Sand/Gravel

Non-porous: Fractured bedrock, karst Rapid transport.

Risk Factors (cont’d.)Aquifers with thin or absent soil

cover-issues of concern. Soils have high organic matter:

Efficient in retarding pathogen transport.Absence of soil occurs when:

Erosion by wind and water,Anthropogenic activity (e.g., gravel pits ), andGlaciers.

Risk Factors (cont’d.)Wells previously identified as having

been fecally contaminated. Wells with a history of E. coli contamination

are more likely to experience additional fecal contamination.

Not many confirmed incidents in Alaska: ~ 6 identified over a year ago.

Historical TCR + result may lead to further review of a system if Sanitary Survey deficiencies are noted.

Risk Factors (cont’d.)High population density combined with

on-site waste water treatment systems:Population density is high and aquifer yield is

limited relative to septage discharge.Attenuation processes are limited. (Rapid

transport)

Note: This process looks at density of septic and sewer lines, not set-back distance.

Risk Factors (cont’d.)Other Risk Factors (Charley Palmer

will cover in detail)Well near a source (Separation Distance

Waivers) of fecal contamination.Well in a flood zone.Improperly or unknown constructed well.Other non-microbial indicators are present:

high chloride, nitrate detergents.

Important Point:Viral pathogens can remain infectious in the

subsurface for a maximum of about one year. (Varies depending upon environmental factors such as temperature, pH, nutrients, aquifer material, detergents,

etc.)Example: 2 year Time of Travel (TOT) or Zone B is an average. Some of the source water will travel within 1 year and some within 3 years. (Average is 2 yr TOT).2 year TOT is a good starting point to examine potential sources of contamination.

Existing Data: GIS Spatial Database- Drinking Water Protection Areas and Public Water System locations.

2 year time of travel(Zone B Protection Area)

Several Months Time of Travel(Zone A Protection Area)

200 ft Set-Back

Existing Data (cont’d.)GIS Spatial Database- Inferred septic systems

Drinking Water Protection Database- Well and Aquifer Information

Existing Data (cont’d.)

Drinking Water Protection Database-Wellhead, Aquifer and Contaminant Risk Rankings

Existing Data (cont’d.)

Existing Data (cont’d.)Hydrogeologic Data Sources:State and Federal hydrogeologic

investigations.Wellhead Protection and Source Water

Assessment Studies.State Geologic Survey, USGS, and Other

Hydrogeologic Investigations.Hydrogeologic and geologic maps.Soil Maps.Topographic Maps.

ObservationsCurrent set-back regulations do not take into

account hydrologic conductivity or pumping rates. Two-year TOT should be considered, at a minimum, when examining potential contaminant sources.

Earlier presentation by Cindy:Demonstrated that small systems historically

have a higher incidence of fecal contamination. Septic/Sewer lines are the largest risk source.

These risk factors should be considered when completing a Sanitary Survey.

SummaryAssessment Source Monitoring will be an option in

Alaska. Assessment source monitoring will only apply to

systems that have been identified as at higher risk based on other surveys or assessments.

Hydrogeologic Sensitivity Analysis (HSA) will not be used in Alaska at this time.

Two year Time of Travel (Zone B) can be considered a good starting point when assessing microbial risks.

Alaska’s Drinking Water Regulations (18 AAC 80) will allow the tools needed to address Alaska’s unique situations.