redacted summary of technical team meeting on ...boots can significantly reduce direct contact risk....

M E E T I N G S U M M A R Y

WYCKOFF MEETING MINUTES AUG 25 2015 FINAL.DOCX 1

Wyckoff Upland and Beach Operable Units - Focused Feasibility Study Revisions and Phasing/Sequencing of Recommended Remedial Action Alternatives

ATTENDEES: Helen Bottcher/EPA Rene Fuentes/EPA Kira Lynch/EPA Jim Cummins/EPA Ed Gilbert/EPA Justin Barton/EPA Elizabeth Allen/EPA Rich Brooks/Suquamish Tribe

Karl Kunas/USACE Mandy Michalsen/USACE Brenda Bachman/USACE Marlowe Laubach/USACE Scott McKinley/CH2M Ken Scheffler/CH2M Cassie Katzen/CH2M Bo Stewart/Praxis

PREPARED BY: CH2M/EPA

DATE: August 31, 2015

PROJECT: 438527.ET.01

This meeting was held on August 25, 2015 at the EPA Region 10 office in Seattle, WA. The meeting discussion was guided by the agenda included as Attachment A and the PowerPoint (PPT) presentation included as Attachment B.

Meeting Purpose and Objectives The meeting purpose and objectives are described on Slide 2 of the PPT.

Action Items OU2/OU4:

1. Need to revise remedial action objective (RAO) # 4 as this decision is for the upper aquifer only. Two options as follows:

Option 1 - Combine RAO #4 with RAO#2 to read as follows: “Prevent use of Upper Aquifer and Lower Aquifer groundwater for drinking water, irrigation, or industrial purposes which would result in unacceptable risks to human health.”

Option 2 – Revise RAO #4 to read like current RAO #2 as follows: “Restore the lower aquifer to beneficial use within a reasonable timeframe. Prevent use of Lower Aquifer groundwater for drinking water, irrigation, or industrial purposes which would result in unacceptable risk to human health until restoration goals are met.”

The goal to protect the lower aquifer from further degradation could also be captured as new RAO #4 (if old RAO #4 and #2 are combined) or as a new performance objective (PO) as follows:

PO#3 - Prevent further degradation of the Lower Aquifer where groundwater quality is suitable for drinking water.

WYCKOFF UPLAND AND BEACH OPERABLE UNITS - FOCUSED FEASIBILITY STUDY REVISIONS AND PHASING/SEQUENCING OF RECOMMENDED REMEDIAL ACTION ALTERNATIVES

2 WYCKOFF MEETING MINUTES AUG 25 2015 FINAL.DOCX

2. Update Table 1-2 from the draft FFS to include NAPL treatment area/volumes for each of the Alternative 7 technologies and to reflect the changes discussed in the May 20, 2015 meeting. This table can also be used to identify area/volume of material not treated (note: this was a question asked about Alternative 7).

3. Complete the conceptual design for: a) outboard bulkhead alignment, and 2) final grading plan that includes the OU1 beach sediments (up to 10,000 CY) and bulkhead excavation material. Develop -30/+50 percent cost estimates for each. This work to be presented in the phasing and sequencing technical memorandum.

4. It is expected that an outboard bulkhead alignment will require mitigation. The removal of several hundred wood piles from the North Shoal area has been suggested as the mitigation. Develop a brief description of what this would entail and -30/+50 percent cost estimate for this work as part of the outboard bulkhead design. CH2M will consult with Ecology and/or the USACE on this element.

5. Update Alternative 7 – Phase 2 Thermal Enhanced Recovery process flow diagram to reflect steam generator instead of boiler.

6. Complete draft final FFS in September 2015.

7. Send Alternative 7 drawings to Jim Cummins and Ed Gilbert.

OU1:

1. Given that the point of compliance is 2 feet, review the TarGOST logs to confirm if the Alternative 3 cap footprints would be different.

2. Indicate in the FFS that eelgrass, present within the Alternative 3 cap footprints, will be temporarily transplanted to the extent practicable during construction, and re-planted in the newly capped areas after these have stabilized.

3. Confirm that OU1 transfer to the State for operations and maintenance (O&M) can occur if monitored natural recovery (MNR) is still underway. No. Transfer occur)s after the RAOs and remediation goals specified in the CERCLA decision document have been achieved (40 CFR 300.435 (f) - Operation and Maintenance.

3. Alternative 3 – Thin Inset Capping. Modify the alternative description to indicate that the cap footprints may change based on information collected during the predesign investigation. This change also applies to the other alternatives.

4. A follow-up call with Helen, Chung, Susanna and Scott will be scheduled to discuss long-term O&M activities.

5. EPA to issue technical memorandum from OU1 risk calculations with sediment PRGs for inclusion in the draft final FFS.

6. Complete draft final FFS in September 2015.

Design Issues 1. Design of the passive discharge/treatment systems:

An integrated collection system with one or two discharge points or independent systems with multiple discharge points? The benefits of each are discussed further below. A decision on which system to install will be more informed once the performance of the perimeter EAB, NAPL recovery, and ISS remedy components is defined through the Phase 1 performance monitoring program. The draft final FFS assumes that a multiple systems will be installed solely for the purpose of quantity definition and cost estimating. The description of this passive discharge/treatment system will be revised for the draft final



FFS to indicate that an integrated system or multiple independent systems may be installed to be determined based Phase 1 performance monitoring results.

2. DNAPL and LNAPL recovery system footprints:

The number of recovery/injection wells and their placement will likely be refined during RD based on predesign investigation results.

Summary Beach Risk Assessment

Elizabeth Allen presented risk assessment calculations for human health direct contact exposure and shellfish consumption using year 2011 beach sediment and tissue sampling results. Direct contact exposure was evaluated with and without boots and shellfish consumption using tribal consumption rates (498 g/day). Key determinations:

Risk estimates exceeded the upper bound of the CERCLA risk range. Majority of risk from shellfish consumption.

Direct contact risk orders of magnitude less than shellfish consumption. Boots can significantly reduce direct contact risk. Children or recreational users enjoying the beach could be barefoot.

Tribal consumption rates are high, and may not be sustainable based on shellfish populations.

Target PRGs for OU1 sediment will likely be the Puget Sound background levels from Bold study, since human health based PRGs are below background levels.

Beaches exposed 65 days (total hours) per year but daylight hour exposure would be less. Rich Brooks noted that folks harvest at night.

OU2/OU4 Summary – Discussion followed PowerPoint Slides

1. Reviewed agenda and goals of meeting for OU1, OU2/OU4.

2. Reviewed RAOs. Note change needed for RAO #4 as remediation of the lower aquifer is not included in the scope of the draft FFS, and will be addressed in a future decision document. RAO #4 to be revised as described in Action Items.

3. Review Performance Objectives

4. Review Alternative 7, which has now been developed and costed to the same level of detail as the other alternatives presented in the draft FFS.

a. Phase I – ISS; to targeted depth (equipment limited to 55 ft)

− Under Alternative 4, approximately 337,000 sq ft of area treated. For comparison, Alterative 7 treats 126,000 sq ft (37% of Alt 4 surface area and 30% of volume).

− Groundwater and surface water will continue to upwell/pool in area north of ISS and passive control methods will be required as a long-term water balance management tool.

− Helen: What percentage of the area are we not getting total ISS treatment depth (based on TarGOST) because of equipment limitation? Need to look at spreadsheet to identify areas where deep treatment not happening. How much evidence is actually available for those deep polygons? Is it detailed enough to justify treatment?

− Mandy: Can a basement be excavated to allow for ISS treatment to greater depth? Yes, this is possible but soil surface becomes less stable (due to increased water content). Could potentially require mats for the heavy ISS equipment.



− Jim: what is going to happen hydraulically after ISS? ISS will restrict options for deeper treatment if needed.

b. Phase I - NAPL Recovery

− DNAPL in North, LNAPL in East target area

− Jim: Proper NAPL recovery requires specific design and frequent redevelopment. Different than traditional water well design. Needs to be accounted for during design (note: CH2M sent a technical paper to Jim and Ed on creosote recovery well design on 8/31/2015).

− Footprint has biggest effect on cost, current costs include additional wells and are conservative.

− Common elements include removal of debris near sheet pile to allow for installation of DNAPL wells, although this may not be necessary as most drilling methods can advance temporary casing through debris.

c. Phase I - EAB

− Installed with NAPL recovery, will start operations immediately, before ISS

− Goal is to get performance data to understand how effective EAB is for dissolved phase to inform design of passive discharge/treatment system.

− Jim: Why not just oxygen instead of atmospheric air? May want higher DO levels (50 ppm vs 5 ppm with air). An oxygen source (generator or bottles) would be needed for the former.

d. Phase I - GW Extraction

− Kyra: Do we really need to have new extraction wells after ISS? ISS treatment will require plugging and abandoning of 6 of the 7 existing containment wells. FFS assumes need to continue hydraulic containment until Phase 1 performance monitoring indicates it’s no longer needed, and this is assumed to occur, about 1 year after ISS is complete. Managing water inside the wall will also help reduce the risk of flooding. By preventing saturation of the top several feet of soil, extraction wells will benefit the overall project – no getting large equipment stuck in the mud. Design may reduce the number of replacement extraction wells needed.

e. Phase II - Thermal Enhanced Recovery

− Phase II area for costing includes 25% RE instead of 10% RE.

− Phase II assumes all Phase I NAPL extraction wells are reused.

− Purpose of thermal is to maximize NAPL recovery and deplete NAPL so minimal treatment required by passive discharge system.

− Enough energy (steam) to maintain soil at 125F using steam generator. 1 year to heat, 4 years of maintaining heating for treatment.

− Kyra: What is thickness of DNAPL in North area?

Based on the Theissen polygons:

Polygon NAPL Thickness (ft) for 10% RE NAPL Thickness (ft) for 25% RE

156 4.2 (1), 3.5 (2/3) 4 (1/2/3)

157 3.7 (1, 4.2 (2/3) 3 (1/2/3)

106 3.7 (1), 2.9 (2/3) 4 (1/2/3)

047 5.2 (1), 1.5 (2/3) 5 (1/2/3)



Phase 1 NAPL recovery in the North Deep (DNAPL) area is designed to prevent further lower aquifer degradation, which may be occurring based on dissolved phase COC concentrations trends shown on Figure 3 of the Lower Aquifer Groundwater Monitoring Report (see below).

− Phase II can be reshaped after Phase I is completed using all of the information collected during Phase 1 performance monitoring. Also option to pilot thermal with a little heat to see how heat effects NAPL recovery in Phase I.

− Mandy: NAPL recovery Phase I is self-contained, Phase I needs to be designed to be compatible with Phase 2 (wells, OWS, pumps). Yes, all Phase 1 NAPL recovery wells are re-purposed for use in Phase 2.

f. Common Elements

− Previously discussed single point discharge system versus a multi-point (up to 10 points), system. What is rationale for a multi-point system?

Response. A multi-point system provides greater process control allowing clean areas to be segregated from contaminated areas lessening the need for treatment of the entire flow stream. With a single discharge system, flow from a contaminated area could contaminate the whole influent stream and drive up the treatment costs. A more detailed evaluation of one versus multi-point system can be performed during the Phase 1 RA data evaluation - design step when information on EAB dissolved phase treatment effectiveness in Compartment 1 is known.

− Mandy: Why does EAB/Passive need to go in early? Why do we have so many discharge points instead of one or two focused points?

− Response. The purpose for installing the EAB system early is to develop several years of operations and performance data to inform design of the passive discharge/treatment system. This data set may suggest no granular activated carbon treatment is needed or only a subset of systems need treatment while others can direct discharge. See response above for single point versus multi-point discharge rationale.



− Ideally, the passive discharge points would be located outside OU1 cap footprints. These points will most likely be located several feet below the mudline. If placed outside the OU1 cap footprints there will be less potential for erosion of cap material and hydraulic channeling that could create new NAPL migration pathways.

− Design consideration: Optimize design of bulkhead wall to reduce costs (reduce thickness from 4')

− Potential to reduce concrete demo if don't need to demo all foundations.

− Brenda: The current sheet pile wall alignment had to be shifted seaward because refusal was encountered; this may have been buried debris. Locate historic reports from installing original sheet pile to identify areas of refusal when initially trying to go inside wall. CH2M should have these.

− Rich: Would discharge from the new outfall affect geoduck commercial zones? Consider moving to harbor discharge location.

k. Cost Summary

− Need to update cost to show State vs. EPA O&M costs

− Need to update presentation to show final cost summary when complete. The presented costs are still draft and may change during final review.

5. Phase II Trigger Criteria

a. Upper Aquifer Triggers include (per the Phase 2 trigger criteria logic diagram): 1) Recoverable NAPL present (based on thickness and transmissivity measurements); 2) excessive passive treatment costs; and 3) GW COC increasing in upper portion of aquifer > Dilution Factor x PRGs

− Passive treatment cost includes a large allowance for monitoring, need to look at reducing cost for this element (note: CH2M will look at this during finalization of the draft final FFS).

b. Lower Aquifer Triggers (potable zone): more likely to trigger targeted action versus full scale Phase II. COC concentrations increasing, expanding South, etc

6. Phasing and Sequencing

a. Kira: Consider installing ISS first and not install GWTP until after ISS complete. Is hydraulic containment actually needed still during source treatment? ISS can’t begin until shoreline bulkhead is complete. Hydraulic containment is the current remedy, and it’s presumed it will be needed until Phase 1 performance monitoring concludes otherwise. Will confirm that the draft final FSS clearly describes the mission for each of the Alternative 7 technologies.

b. Will want to consider another round of upper aquifer sampling as part of pre-design. Another round of TarGOST is already included for predesign. May signify less treatment area required.

c. Rene: Main point of GWTP operations is to manage water during ISS to maintain ideal conditions.

d. OU1: Phasing needs to move up 1 year to overlap with 2nd year of ISS

e. Rich: East beach is a priority area for the Tribe. Is there any way to start that earlier in the ISS phase to complete that project? Helen seconds this approach but needs to know how to do it. CH2M: as currently proposed, the beach work begins at the end of Phase 1 Upland ISS treatment. It’s possible it could occur earlier in the ISS treatment phase rather than at the end. CH2M team will discuss.

f. Bulkhead and OU1 work at same time if outboard wall? What is the management plan for hot spots found during outboard bulkhead? CH2M: Currently, it’s envisioned that all bulkhead and



beach sediment would be stabilized using ex situ stabilization. If the predesign investigation indicates that there are large areas of clean sediment, this material can be segregated and used elsewhere for grading and contouring lessening the volume of material that has to be treated.

Attachment 1 – Agenda

Attachment 2 – PowerPoint Presentation

DRAFT Agenda Wyckoff Eagle Harbor Technical Team Meeting FFS Revisions and Phasing & Sequencing Memo

Date: Tuesday, August 25 Time: 9:00 AM – 4:00 PM Location: EPA Region 10 Seattle Office, 1200 Sixth Ave, 1st floor, Huckleberry Room Dial-In Number: Code 9:00 – 9:10 Introductions, adjustments to Agenda 9:10 – 9:20 Overview of Alternative 7: CH2M HILL to review the site plan from the Alt 7 technical memorandum and discuss different phases and technologies (Ken) 9:20 – 10:30 CH2M HILL to present the Alt 7 technologies: ISS, NAPL Recovery, EAB, Passive Treatment and Phase 2 thermal technologies (Ken and/or CH2M HILL technology leads)

10:30 – 10:45 BREAK 10:45 – 11:00 Presentation of Phase 2 Triggers (Ken) 11:00 – 11:45 Discussion Alt 7 – questions, input, identification of unresolved issues

11:45 – 12:30 LUNCH 12:30 – 1:00 Construction Phasing and Sequencing – Presentation of Draft by CH2M HILL (Scott) 1:00 – 1:30 Discussion of Phasing and Sequencing

1:30 – 1:40 BREAK and transition to OU1 Issues 1:40 – 1:50 Reminder of RAOs for OU1 and Remedial Alternatives in Draft FFS (Helen) 1:50 – 2:20 Beach Risk Assessment and PRGs – presentation by Elizabeth Allen with time for Q&A 2:20 - 2:30 Field Observations from July 31 Site Visit (Helen) 2:30 – 3:30 Discussion of OU1 Remedy

Remedial Decision: Stick with Alt 3? Choose Alt 2 for the North Shoal but stay with Alt 3 for the East Beach?

Pre-Design Sampling to Refine Cleanup Areas – Sampling Technique, Decision Rule to Adjust Boundary

Pier Pilings – should they be cut below the mud line or pulled? 3:30 4:00 Discussion of Long Term Monitoring Plan for the Beaches 4:00 ADJOURN

Non-Responsive Non-Responsive

Copyright [insert date set by system] by [CH2M HILL entity] • Company Confidential

Wyckoff Upland and Beach Operable Units Focused Feasibility Study Revisions and Phasing/Sequencing of Recommended Remedial Action Alternatives

August 25, 2015

Meeting Purpose and Objectives

Upland (OU2/OU4):

– Present additional information on scope of Alternative 7 and obtain feedback

– Discuss Phase 2 remedy implementation trigger criteria

– Discuss inboard versus outboard shoreline bulkhead wall

Phasing and Sequencing:

– Review the rationale used to parse the OU2/OU4 and OU1 recommended

alternatives into three discrete implementation phases

– Obtain feedback on the phasing and sequencing approach

– Does the overall timeline make sense?

Beach (OU1):

– Summarize field observations from recent site inspection

– Stay with Alternative 3 as the recommended alternative or shift to an

Alternative 2 (North Shoal) and Alternative 3 (East Beach) hybrid?

– Use of tiered approach for long-term monitoring

– Pier Pilings Removal: cut below mudline, pull, overdrill?

OU2/OU4 Background

OU2/OU4 - Remedial Action Objectives

RAO #1. Prevent human health risks associated with direct contact,

ingestion or inhalation of shallow soil contaminated above levels for

unrestricted outdoor recreational use.

– This objective was established to protect recreational users from potential

exposure to contaminants in the shallow soil that exceed the established

cleanup levels. The reasonable anticipated land use is a public park.

RAO #2. Prevent use of upper aquifer groundwater for drinking water,

irrigation, or industrial purposes which would result in unacceptable risks to

human health.

– This objective was established to prevent the withdrawal of upper aquifer

groundwater for drinking, irrigation, or industrial purposes. Some non-contact

industrial uses may be allowed.

These two RAOs will be met through installation of a soil cover and maintenance of

institutional controls (ICs)

OU2/OU4 - Remedial Action Objectives

RAO #3. Prevent discharge of contaminated upper aquifer groundwater to

Eagle Harbor and Puget Sound resulting in surface water contaminant

concentrations exceeding the levels protective of beach play, aquatic life, and

human consumption of resident fish and shellfish.

– This objective was established to prevent contaminated groundwater in the upper

aquifer from discharging to surface water such that it would result in unacceptable

risks to recreational users (fishers, shellfish gathers, or beach play), consumers of

resident fish and shellfish, and aquatic life of Eagle Harbor or Puget Sound.

RAO #4. Restore the lower aquifer to beneficial use within a reasonable

timeframe. Prevent use of lower aquifer groundwater which would result in

unacceptable risk to human health until restoration goals are met.

– This objective was established to restore the portions of the lower aquifer

impacted by the site to beneficial use. For that portion subject to salt water

intrusion, restore to levels protective of aquatic life at the point of discharge to

surface water. For that portion not subject to salt water intrusion, restore to

MCLs. Note: Former Process Area has been identified as area subject to salt

water intrusion.

These RAOs are the primary focus of the focused feasibility study (FFS).

OU2/OU4 - Performance Objectives

Established by EPA and Ecology - influenced alternative development:

#1 - Remove or treat mobile NAPL in the Upper Aquifer to the maximum extent

practicable such that migration and leaching of contaminants is significantly

reduced. This will remove principal threat materials, which allows for considering

monitored natural attenuation (MNA) as a remedial action technology for

residual concentrations, and allows for implementing Performance Objective #2.

#2 - Implement a remedial action that does not require active hydraulic control

as a long-term component of operations and maintenance (O&M) following

completion of source removal action.

OU2/OU4 - NAPL Source Area Identified for Treatment

Currently includes the area within the upper aquifer defined by the

10% RE – TarGOST footprint.

North/East/Periphery

Shallow (LNAPL)

Areas

Core Area

North Deep

(DNAPL) Area

10% RE Footprint

Review – Alternatives Developed for the draft FFS

Alternative 1 – No Action

Alternative 2 – Containment (Current Remedy)

Alternative 3 – Excavation, Thermal Desorption, and ISCO

Alternative 4 – In situ Solidification/Stabilization (ISS)

Alternative 5 – Thermal Enhanced Extraction and ISCO

Alternative 6 – Excavation, Thermal Desorption, and Thermal

Enhanced Extraction

Alternative 7 – ISS of the Core and Thermal Enhanced Recovery

Notes:

a. Alternatives 1, 2, and 6 eliminated from consideration by the technical team.

b. Alternative 3 – screened out in the draft FFS per CERCLA guidance based on

implementability (technical) challenges.

c. Alternatives 4, 5 and 7 – recommended by technical team to be carried forward

for further deliberation. Alternative 7 refined for draft final FFS.

OU2/OU4 Recommended Alternative

OU2/OU4 Recommended Alternative

Alternative 7 – In situ Solidification Stabilization (ISS) of Expanded Core

Area and Thermal Enhanced Recovery

– Uses an adaptive management approach that implements remedy in two

phases: Phase 1 and Phase 2.

– Phase 2 decision and scope based on Phase 1 performance monitoring and

comparison of the results to trigger criteria.

Phase 1 includes:

− ISS of an expanded core area

− NAPL recovery, hydraulic containment, and enhanced aerobic biodegradation

(EAB)

− Passive discharge/treatment

− Common elements (most constructed in Phase 1)

Phase 2 (if necessary) includes:

− Thermal enhanced recovery; assumed for the FFS but may change

− EAB

− Passive discharge/treatment

OU2/OU4 Alternative 7 - Technology Footprints

OU2/OU4 Alternative 7 – Phase 1 ISS Footprint

OU2/OU4 Alternative 7 – Phase 1 ISS Cross-Section

ISS columns do not

extend to base of upper

aquifer at all locations

Batch PlantCrane Mounted

ISS Rig

ISS ColumnsISS Hydraulic

Rig

OU2/OU4 Alternative 7 – Phase 1 ISS Depth Footprint

Upper aquifer

groundwater flow

blocked on west side

OU2/OU4 Alternative 7 - Phase 1 NAPL Recovery

Two Target Areas Identified

– North Deep: DNAPL present at base of upper aquifer advancing into

the aquitard. This source expected to pose greatest threat to lower

aquifer.

– East Shallow: LNAPL present at capillary fringe – water table.

Retained Technologies

– North Deep: DNAPL recovery using dual phase extraction, oil

separation, groundwater reinjection (water flooding, closed loop

system)

– East Shallow: LNAPL recovery using skimming pumps

OU2/OU4 Alternative 7 – Phase 1 NAPL Recovery Well Layout

DNAPL Recovery Area

LNAPL Recovery Area

North Deep: DNAPL Recovery via Dual Phase Pumping and Water Flood - Process Schematic

Groundwater extraction enhances DNAPL flow to extraction well

Pressurized OWS prevents iron precipitate formation

Water injection enhances gradient to extraction well

Closed loop system, no water conveyed to treatment plant

East Shallow: LNAPL Skimming Pumps

Daily water level change 5

feet

Self-adjusting LNAPL

skimming pump selected

Probe pumps only NAPL,

not water, senses NAPL-

water interface

Reel adjust to follow water

level

Each pump can convey to

common tank

East Shallow: LNAPL Skimming Pumps (cont.)

• Stand-alone, well-mounted NAPL-only extraction system

• Local NAPL collection, periodic bulk transfer

Example Design

OU2/OU4 Alternative 7 – Phase 1 EAB Well Layout

EAB technology

injects air into the

Compartment 1 to

promote aerobic

biodegradation of

dissolved phase

contaminants

OU2/OU4 Alternative 7 – Phase 1 Passive Discharge/Treatment

Example Design

Passive groundwater treatment

includes:

– Collection system

– Treatment media (e.g. granular-

activated carbon) housed in a

vessel

– Outfall pipe to convey treated

water through sheet pile and

bulkhead below the mudline

Reduces contaminant flux through the

sheet pile wall protecting intertidal

area pore water and surface water

quality.

Design concept utilizes the hydraulic

head difference that occurs due to

tidal fluctuations.

Constructed at completion of active

remediation.

OU2/OU4 Alternative 7 - Phase I Performance Monitoring Activities

In well NAPL Thickness

NAPL Transmissivity Tests

Water Level Measurements

Groundwater Sampling and Analysis

Dilution Attenuation Factor Determination

Data Evaluation and Reporting

OU2/OU4 Phase 2 – Thermal Enhanced Recovery

Adaptive Approach

– Apply in the most contaminated areas (as indicated by Phase I monitoring)

– Concentrate on removing mobile NAPL and perimeter source material

– Expand based on monitoring data and field observations

Extraction wells and injection wells

– Closer spacing along perimeter less so toward the ISS monolith

– Include hydraulic containment extraction wells in the strategy

Thermal enhancements (and other potential methods)

– Thermal can be “judiciously” augmented with other methods

– Wells are compatible with multiple techniques

Keep the effluent treatment system simple

Recover and reinject heat as much as practical

OU2/OU4 Phase 2 – Thermal (Wet Steam) Well Layout

OU2/OU4 Phase 2 – Thermal Process Flow Diagram

OU2/OU4 Phase 2 - Operating Principles

Operate thermal (wet steam) injection as a NAPL recovery, solubilization,

and biological degradation enhancement (i.e., remove as much NAPL as

practical and expeditiously degrade the remainder)

Avoid complex treatment processes associated with extracting steam

laden with naphthalene vapors; promote NAPL mobilization and

dissolution of residual NAPL; minimize distillation

Target subsurface temperature of 120 to 125 F

Avoid complex treatment processes associated with chemical injection

(surfactants, co-solvents, polymers, oxidants) by considering “judicious”

applications

LEARN from Phase I NAPL Recovery “what works”

OU2/OU4 Alternative 7 Common Elements

The common elements include:

– New access road (Phase 1)

– Subsurface concrete demolition, decontamination and reuse (Phase 1)

– Shoreline bulkhead (Phase 1)

– Stormwater interceptor trench (Phase 1)

– Replacement outfall (Phase 2)

– Final Cap (Phase 1 or Phase 2 depending on trigger criteria)

OU2/OU4 Alternative 7 Common Elements – Access Road (Phase 1)

New Road

Current road not safe for large semi-

trucks and delivery of large equipment

Sharp turns and 15 percent grade

Improvements include:

– Temporary dock and offloading ramp

on beach located west of sheet pile

wall for large equipment delivery

– Improvements/modifications to

existing road

OU2/OU4 Alternative 7 Common Elements –Demolition (Phase 1)

Concrete demolition

OU2/OU4 Alternative 7 Common Elements –Shoreline Bulkhead (Phase 1)

• The FFS assumes new bulkhead installed

inboard of existing sheet pile wall. This

would require extensive debris removal

(see photos).

• Evaluating option to move bulkhead

outboard of existing sheet pile wall:

Improves constructability

Eliminates need for removal,

decontamination, and disposal of old

bulkhead and debris present inboard.

OU2/OU4 Alternative 7 Common Elements –Outboard Shoreline Bulkhead

Assumptions:

• Groundwater level at +12 ft

• Mean sea level at +5 ft

• Upper portion of the new wall (AZ 24-700N) will be

completely gone in the future

• Existing wall (BS5) will eventually leak and

bulkhead subjected to full hydrostatic pressure (up

to +12 ft) plus load from 5-foot soil cap

• Minimum safety factor for overturning and sliding

at the base of the concrete wall is 1.5

As shown concrete wall embedded to -10 ft or lower

to safety factor. This results in the total wall length of

30 feet.

OU2/OU4 Alternative 7 Common Elements – New Outfall (Phase 2)

New Outfall

OU2/OU4 Alternative 7 Common Elements – Final Cap (Phase 1 or Phase 2)

Cap footprint –

final grading will

change

Constructed at end of active remediation

Multi-layer cover: 60-mil HDPE geomembrane, cushion geotextile, overlain by 12

inches of drainage material, and 12 inches of topsoil.

Total area = 8.1 acres.

Stormwater collected and discharged to surface water through new outfall

OU2/OU4 Alternative 7 – Cost Estimate

Category Phase 1 Phase 2 Notes

Capital Costs

- Common Elements $51,773,000 Move shoreline bulkhead outboard ~ $16

million reduction

- Remedial Technology $29,538,000 $7,813,000

Present Value O&M/Periodic Costs

- NAPL Recovery $845,000 $0

- Hydraulic

Containment/GWTP

$3,940,000

(5 yrs)

$0

- EAB $1,692,000

(9 yrs)

$1,128,000

(6 yrs)

- Passive

discharge/treatment

$1,136,000

(4 years

$1,136,000

(4 years)

$4,260,000 (15 yrs) post functional and

operational not included

Thermal/GWTP $0 $15,127,000

Total $88,924,000 +24,574,000 ~$2.9 million decommissioning costs not

included in this total

15 Minute Break

OU2/OU4 Alternative 7

Phase 2 Trigger Criteria

OU2/OU4 Phase II Decision – Upper Aquifer Trigger Criteria

OU2/OU4 Phase II Decision – Lower Aquifer Trigger Criteria

OU2/OU4 Phase II Trigger Criteria Narrative

Upper Aquifer

− Recoverable NAPL present

− Passive treatment costs that are excessive

− Groundwater COC Conc Increasing and > Dilution Factor x PRGs

Lower Aquifer (applies to potable zone)

− Exceedance more likely to trigger a targeted action

Groundwater COC Conc Increasing?

Evaluate targeted treatment

Groundwater COC Plume expanding south?

Re-start hydraulic containment system

Evaluate targeted treatment

Groundwater COC Conc. Stable/Decreasing

Continue monitoring

OU2/OU4 Alternative 7 and OU1 Alternative 3

Phasing and Sequencing

OU2/OU4 Alternative 7 and OU1 Alternative 3 Sequencing

Break and Transition to OU1

OU1 – Remedial Action Objectives

#1 - Prevent risk to human health posed by direct contact with non-aqueous phase

liquid in shallow (10 cm) sediments in intertidal areas frequented by recreational

beach users.

#2 - Reduce to protective levels, risk to human health posed by dermal contact and

incidental ingestion of contaminated sediments in the top two feet of intertidal areas

frequented by shellfish harvesters and recreational beach users.

#3 - Reduce levels of contaminants of concern in the top 10 cm of sediments to

concentrations protective of benthic community health.

#4 - Reduce levels of contaminants of concern in shellfish tissue to concentrations

protective of tribal shellfish consumers, or reduce contaminant concentrations in

the top two feet of sediment to background concentrations.

#5 - Prevent risks from consumption of shellfish until protective levels are achieved.

OU1 – Intertidal July 31, 2015 Field Observations

East Beach

Existing Piles

NAPL Seep

OU1 – Definition of Target Area

OU1 Recommended Alternative 3 Cap Footprints

OU1 Recommended Alternative Discussion Points

Stay with Alternative 3?

Alternative 2 and Alternative 3 hybrid?

Is there any additional data to help inform the decision?

OU1 Alternative 2/Alternative 3 Long-term Monitoring

Draft OU1 FFS included the following O&M/Periodic allowances:

– $8,000 annual cost (years 1 to 30) for cap inspections and $45,000

5 year periodic cost (years 40 to 100)

– $446,000 5 year periodic cost (years 5 to 100) for comprehensive

assessment to inform 5YR. Typical activities included:

• Physical Stability/Visual Seep/Chemical Quality/Clam Tissue Monitoring

• SPME Portwater Monitoring/Surface Water Monitoring

• TarGOST Monitoring

– $1,200,000 10 year periodic cost (years 10, 20, 30, 40, and 50) for cap

repair

Previously discussed developing a tiered monitoring approach.

The following slides present a framework for tiered monitoring.

OU1 Alternative 3- Intertidal Long-term Monitoring

RAO

Monitoring Activity-

Tier 1

Monitoring Activity –

Tier II Remedial Response Activity

1- Prevent risk

to human

health posed

by direct

contact with

NAPL in

shallow (10

cm) sediments

in intertidal

areas

frequented by

recreational

beach users.

Visually inspect

intertidal beach area for

evidence of NAPL on

beach surface; if no

evidence of NAPL, no

direct contact.

If visual evidence of NAPL

present, institute

temporary IC to restrict

access to beach while

investigations conducted.

Investigations would

include inspection of seep

with tidal cycles to see if

recurring.

Under Alt 3, a recurring seep

present within a cap footprint

would be evidence of

breakthrough or bypass requiring

repair/replacement.

If present within MNR area,

would need to be assessed for

potential cap installation.


RAO Monitoring Activity- Tier 1


Tier II

Remedial Response

Activity

2-Reduce to

protective levels,

risk to human

health posed by

dermal contact and

incidental ingestion

of contaminated

sediments in the

top two feet of

intertidal areas

frequented by

shellfish harvesters

and recreational

beach users.

Visually inspect intertidal

area for habitat suitable for

shellfish and establish

locations where sediment

microcores can be collected

and analyzed over time

(composite full depth).

Use 3 year interval

consistent with current clam

tissue program.

Compare data assess

trends/progress to protective

levels. Maintain IC until

protective levels attained.

If no downward trend

established and

sediment

concentrations remain

above protective levels,

perform subsequent

TarGOST to determine

distribution of

potentially mobile

NAPL.

Suggest 10-year period

be allowed (10 yrs

consistent with current

ROD) to demonstrate

downward trend (3

observation events).

Under Alt 3, the top 30 to

42 inches of sand will be

removed across the cap

footprint, which includes

most of the intertidal area

frequented by beach users.

The re-emergence of NAPL

in this area would indicate

that NAPL has moved

through or around the cap

and signal evidence

breakthrough or bypass

requiring repair or

emergence of a new seep.

OU1 Alternative 3- Intertidal and Subtidal Long-term Monitoring

RAO


Tier 1


Tier II

Remedial Response

Activity

3- Reduce levels of

contaminants of

concern in the top 10

cm of sediments to

concentrations

protective of benthic

community health.

Deploy SPME samplers in

gridded network across the

affected area; remove and

analyze in like areas on

established frequency;

suggest 3 year interval

consistent with above.

Suggest benthic community

study be performed to

monitor community

abundance and diversity.

Suggest pore water be

collected near locations

where historic clam tissue

collection has occurred to

use tissue concentrations as

indicator of benthic

community health.

If no downward trend can

be established, and

sediment concentrations

remain above protective

levels, but benthic

community analysis

demonstrates

improvement; keep

monitoring. If the latter

benchmark shows no

recovery, perform

subsequent TarGOST.

Suggest a 10-year period

be allowed to demonstrate

trends and TarGOST not

be performed in fewer

than 10 years.

Under Alt 3, the elevated

pore water

concentrations over the

cap target area would be

an indication of a local

cap failure requiring

repair or presence of

new seeps/seep

transport pathways.


RAO


Tier 1


Tier II

Remedial Response

Activity

4 - Reduce levels of

contaminants of

concern in shellfish

tissue to

concentrations

protective of tribal

shellfish consumers,

or reduce

contaminant

concentrations in

the top two feet of

sediment to

background

concentrations.

Collect shellfish samples

consistent with the 2002

OMMP Addendum which

includes sampling and

analysis of clam tissue

every 3 years from the

intertidal zone of the East

Beach and North Shoal

areas. Use sample size

consistent with the

USACE program - Tribal

leaders have approved

the sampling approach.

Use data to show a

reduction of contaminant

levels in the shellfish

tissue. Maintain IC until

levels are attained.

If data do not support

tissue concentration

reduction to

concentrations

protective of tribal

shellfish consumers,

maintain IC and

continue monitoring.

Compare results with

additional data on

benthic community

and sediment cores to

determine if other

indicators are

showing alternate

trends. Suggest a 10-

year period be

allowed to

demonstrate trends.

Under Alt 3, with the entire

impact area being capped

and surficial media

replaced, it is likely that

clam tissue concentrations

would decrease over time; if

downward trend is not

demonstrated then shellfish

exposure to NAPL is not

directly related to Site.


RAO

Monitoring Activity- Tier

1


Tier II

Remedial Response

Activity

5 - Prevent risks from

consumption of

shellfish until

protective levels are

achieved.

Maintain IC and

monitoring to confirm

effectiveness. Remove

when protective levels are

achieved.

N/A N/A

Questions and Action Items

redacted summary of technical team meeting on ...boots can significantly reduce direct contact risk....

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