Mclinton, Raymond

From: Wangerud , Ken Sent: Thursday , Ju ly 03 , 2014 1 :41 PM To: David Abranovic Cc: Mark Ransom; R. David Gibby (dg ibby@usmagnes ium.com); Jus t in Burn ing; Kevin

Lundmark; Cather ine D. LeCours ; Dor thea L. Hoyt ; Wangerud , Ken Subject : Re Sal t -Cap Accumula t ion Tes t : EPA fo l low-up to ERM's Response to EPA Technica l

Comments on Sa l t Cap TM

David, etal:

Thank you for addressing EPA's June 11, 2014 comments on the Salt Accumulation Test Plan Technical Memorandum (Test Plan).

ERM's responses and suggested revisions for the next revision of the Test Plan are acceptable— with the following questions and clarifications. Please address the comments below as appropriate in your next revision/submittal of the Test Plan.

1. To clearly document the details of the salt cap accumulation test, please provide drawings or figures for the test pond and the associated monitoring devices. The drawings should be appropriately scaled to clearly delineate the following information: a. The final selected location of the test pond. Based on discussions with you, I understood that consideration has

been given to revising the location of the test pond from that shown on the figure included in the May 12, 2014 Test Plan (as we reviewed on-site on June 19).

b. Dimensions of the test pond and impoundment berm. c. Locations of the water inlet, staff gauges, and Piezometers. d. A cross-section of the test pond including the berms and monitoring devices. e. Details of the piezometers and berms.

2. Please explain and/or show on a drawing how the source water will be pumped or piped from Pond 1 North to the test pond.

3. The Test Plan will be revised to include additional monitoring; however, ERM does not believe it is practical or necessary to conduct monitoring after storm events. The EPA agrees that it may not be practical to inspect the salt cap after every, relatively minor, storm. However, dissolution of the accumulated salt from precipitation is important to understanding the overall salt accumulation dynamics and characteristics. Please include a discussion of how the salt cap will be inspected after a storm event that results in 1.5 inches of precipitation within a 24-hour period (approximately a 2-year, 24-hour storm event). The EPA recognizes that access may be difficult in muddy conditions, so the post-storm event inspection of the test pond may be conducted sometime within a 48 hour period after the storm.

4. The Test Plan will be revised to include additional monitoring to be conducted during the non-evaporation seasons (November through April). The addition of year-round monitoring is appreciated and should provide valuable information; however, it is not completely clear from ERM's responses to EPA's comments which monitoring will be conducted during the evaporation season (May to October) versus the non-evaporation season. Please include a table (example provided below) to clarity and summarize the monitoring elements and timing:

Monitoring

Evaporative Season Weekly

Monitoring

Non-evaporative Season

Monthly Monitoring

Water level measurements at all staff gauges and piezometers X X Detailed and consistent photographs documenting observations X X Inspection of berms for integrity, including indications of seepage or piping X X Inspection of accumulated salt for desiccation cracks, impacts from freeze/thaw cycles, or other cracks or dissolution features X X

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mailto:dgibby@usmagnesium.com

Monitoring

Evaporative Season Weekly

Monitoring

Non-evaporative Season Monthly

Monitoring Observation and documentation of detritus, dust, organic matter, or other impurities in the test pond X X

Collection of salt cores - 6 locations • Log and photograph core material • Measure thickness of salt cap • Evaluate homogeneity/heterogeneity and characteristics of accumulated salt • Inspect for layering, impurities, detritus dust, organic materials, or other

non-homogeneities • Classify precipitate material(s) as crystalline, microcrystalline, or

amorphous.

End of evaporation

season.

End of non-evaporative

season (prior to first pumping at

the start of evaporation

seasons 2 and 3)

5. ERM explains the berm construction method will be provided in the test pond as-built figures. While this is acceptable, the construction criteria for building the berms should be defined prior to construction to ensure that the berms are built of suitable integrity and consistency. Please revise the test plan and/or a drawing showing the test pond berm detail to specify the required construction criteria or method for the benn (e.g., density requirement or compaction method, lift thickness, moisture content) and to identify the material type and material source that will be used to construct the berms.

6. ERM explains that Shelby tube samples will be collected of the berm material for permeability testing by ASTM D2434 or D5084. The EPA agrees these tests will provide very useful information on the berms. Please confirm that a grain size analysis test per ASTM D422 will also be conducted to aid in determining which of the permeability/hydraulic conductivity tests is appropriate. In addition, ERM indicates that visual observations of the berm should be adequate for the salt accumulation test to indicate the presence of saturation or water flow through the berms. It is agreed that the monitoring proposed in the response is suitable for salt accumulation test. However, during the larger scale demonstration/treatability test, the EPA will require more thorough and quantitative monitoring of the berms and substrate for percolation, infiltration, and flow.

Please feel free to contact me or Catherine LeCours, PWT, if you have follow-up questions. EPA understands USM would like to get this test underway ASAP, and EPA supports that goal.

Ken Wangerud, Remedial Project Manager Superfund Remedial Program Office of Ecosystems Protection and Remediation USEPA Region 8 - EPR/SR 1595 Wynkoop, Denver CO 80202-1129

ofc. tel. 303-312-6703 fax 303-312-7151 wangerud.ken@epa.gov

From: David Abranovic [mai l to :David .Abranovic@erm.com] Sent: Tuesday , June 24 , 2014 5 :52 PM To: Wangerud , Ken Cc: Mark Ransom; R. David Gibby (dg ibby@usmagnes ium.com); Jus t in Burn ing; Kevin Lundmark Subject : RE: Response to EPA Technica l Comments on Sa l t Cap TM

Ken,

P lease f ind a t tached ERMs responses to your 11 June 2014 comment le t te r on the Sa l t Cap Accumula t ion TM submi t ted on 12 May 2014. Also p lease no te tha t g iven EPA's concern tha t the sa l t cap tes t a rea tha t we v is i ted on 19 June does no t s t r ic t ly adhere to the spec i f ica t ions in the draf t Sa l t Cap Accumula t ion TM, ERM and US Mag have dec ided to abandon tha t loca t ion and cons t ruc t a new tes t a rea . The new loca t ion wi l l have 'mud-f la t ' condi t ions s imi la r to those

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mailto:David.Abranovic@erm.commailto:dgibby@usmagnesium.com

within PRIs 5,6 and 7, and adhere to all specifications in the final Salt Cap Accumulation TM. Please feel free to contact me or Kevin Lundmark if you have any questions regarding the attached responses, we look forward to finalizing this TM as soon as possible and initiating the treatability study.

david -

David J. Abranovic P.E. Partner

ERM West, Inc. 7272 E. Indian School Road, Suite 100 Scottsdale, Arizona 85251 General: 480-998-2401 Direct: 480-455-6070 FAX: 480-998-2106 Cell: 602-284-4917 david.abranovic@erm.com www.erm.com

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