Pathways to Long-Term Solutions for Post-Closure Care

SWANA Evergreen Technical

Session November 9, 2017

Glen Wallace LG RG PhDAssociate Geologist

Pacific Groundwater Group

Goals and Elements

� Primary Goal: able to walk

away

� Interim Goal: long term plan

with regulatory approval

� Legacy facilities: WAC 173-304

� Modern facilities: WAC 173-351

� “What could go wrong?”

� Model Toxics Control Act

(MTCA)

� Case study: groundwater

contamination RI/FS path

Who’s Involved?

� Facility Owner/Operator

� Responsible for implementation

� Health Department

� Solid waste regulatory authority

� Department of Ecology

� Usual technical role for solid

waste issues

� MTCA regulatory authority if

contamination present

Allocation Tools, Attribution, Multiple Lines

173-304-407 Closure Criteria

� (7)post-closure includes

groundwater monitoring;

surface water monitoring; gas monitoring; and

maintenance of the facility,

facility structures, and

monitoring systems for their

intended use for a period of

twenty years.

� Note: 20 years is 2013 for

facilities closed under 173-304

� (8)(c) If the jurisdictional

health department finds that

post-closure monitoring has

established that the facility is

stabilized (i.e., little or no

settlement, gas production, or leachate generation), the

health department may

authorize the owner or

operator to discontinue post-

closure maintenance and

monitoring activities.

Allocation Tools, Attribution, Multiple Lines

173-351-500(2) Closure Criteria

� (iii) The jurisdictional health department and owner or operator will consider at least the following factors when determining when a landfill unit is functionally

stable or whether to decrease or increase the post-closure care period:

� (A) Leachate. Leachate production and quality must be such that maintenance

and operation of the leachate collection system can be ceased beyond the post-closure care period without posing a threat to human health or the

environment.

� (B) Landfill gas. Landfill gas production and composition must be such that

maintenance and operation of the gas collection system can be ceased beyond the post-closure care period while meeting the criteria in WAC 173-351-

200 (4)(a)(i) through (iii) and not pose a threat to human health or the

environment from methane or nonmethane compounds.

� (C) Settlement and cover integrity. The cover system must attain geotechnical

stability for slope and settlement. Vegetation and other erosion controls must

prevent exposing waste or otherwise threaten integrity of the cover system. The

cover system must stabilize such that no additional care is required beyond the post-closure care period to ensure its integrity from settlement or erosion.

� (D) Groundwater quality. Groundwater quality must remain in compliance with the protection standards established in WAC 173-351-440(8) at the relevant point

of compliance.

“What Could Go Wrong?”

� Landfill gas beyond

perimeter

� Groundwater

contamination

� Settlement and cover

performance

� When does MTCA

apply?

� When there is

contamination!

173-304 Path to Closure

Is this a 304 facility?

Do we have

monitoring data?

Stable?

LFG generation minimal?

Groundwater clean?

Prepare documentation

Regulatory Approval?

No

No

No

No

No

Close facility or alternate

regulatory approach.

Conduct post-closure

monitoring.

Repair and stabilize as needed.

May require engineered solution.

Control migration if needed.

Wait for methane curve...

MTCA applies: RI/FS/CAP/Action.

Consider AO vs VCP.

Regulatory negotiation, move

back up flow chartNo

Yes = Done!

Landfill Gas: The Long Tail

� Perimeter Monitoring

� Gas Control Systems

� What is “little or no” LFG generation?

Alshareedah (2016)

0

10

20

30

40

50

60

70

2003 2005 2008 2012 2015 2018

Me

tha

ne

Vo

lum

e %

GW-1 GW-10 GW-2 GW-3 GW-4

GW-5 GW-6 GW-7 GW-8 GW-9

Groundwater Issues

� Unlined landfills and anaerobic metals migration

� Volatile Organic Compounds (VOCs)

� Nitrate and inorganics

Groundwater Strategy

� Detection monitoring vs. MTCA requirements

� Understand: Nature and Extent, Fate and Transport

� Site vs. property boundaries

� Realistic options for addressing impacts

MTCA (WAC 173-340) Process

� Recognize a release has occurred

� Remedial Investigation (RI): How bad is it?

� Feasibility Study (FS): What can we do about it?

� Cleanup Action Plan (CAP): What we will do!

� Engineering & Implementation

� Reporting: What we did and did it work

Case Study: 173-304 Landfill

� City facility in former

gravel pit

� Capped and closed

under 173-304

� Some LFG

generation

� Historic VOC and

metals issues; metals

remain issue

Case Study: 173-304 Landfill

� Remedial Investigation:

Metals primary concern

� Feasibility Study: 3 options

evaluated, DCA ranking

� Long Term Plan: natural

attenuation, compliance

monitoring (groundwater +

LFG), institutional controls

� Cleanup Action Plan &

Implementation: coming

soon!

Reading Between The Lines

� Just because it has been 20 years does not mean

guaranteed closure.

� Form a team with all stakeholders:

Owner/Operator, Health, Ecology, any other PLPs.

� Make sure your team understands both solid waste

and MTCA if contamination issues are present.

� Form reasonable expectations for: timeline (years),

technical feasibility, and priorities.

� Prioritize use of resources: monitoring, action, etc.

� Look for insurance coverage for pre 1980 facilities.

� Good data makes for good decisions

173-304 Path to Closure

Is this a 304 facility?

Do we have

monitoring data?

Stable?

LFG generation minimal?

Groundwater clean?

Prepare documentation

Regulatory Approval?

No

No

No

No

No

Close facility or alternate

regulatory approach.

Conduct post-closure

monitoring.

Repair and stabilize as needed.

May require engineered solution.

Control migration if needed.

Wait for methane curve...

MTCA applies: RI/FS/CAP/Action.

Consider AO vs VCP.

Regulatory negotiation, move

back up flow chartNo

Yes = Done!

2377 Eastlake Avenue East,

Seattle, Washington 98102

(206) 329-0141

Remedial InvestigationGroundwater MonitoringGIS

Database

ManagementModeling

Statistic

sDetail Oriented

Research

Referencing Water Resources

Thank You