STATE OF MINNESOTAPOLLUTION CONTROL AGENCY

\MINNESOTA DECISION DOCUMENT

Pursuant to the Minnesota Environmental Response and Liability Act (MERLA), Minn. Stat. ~~ 115B.01to .~O (2012)

SITE DESCRIPTION

Capri Beauty Salon, 15 4th Street Northwest, Byron, Olmsted County, MN

STATEMENT OF PURPOSE

This Minnesota Decision Document (MOD) presents the selected remedial action and cleanup levels forthe Capri Beauty Salon (Capri) Superfund site (Site), and summarizes the facts and determinations madeby the Minnesota Pollution Control Agency (MPCA) staff in approving the selected response actions. The,response actions are designed to:

• reduce the contaminant concentrations in the soils to levels that are protective of human healthand ecological risks

• remove contaminated soils that are a source(s) of vapor intrusion and groundwatercontamination •

• enhance natural attenuation to reduce contaminant concentrations in groundwater.

The Commissioner or his delegate has determined the response actions set forth in this MOD arereasonable and necessary to protect the public health and welfare and the environment from therelease and threatened release of hazardous substances and/or pollutants and contaminants from the

.Site.

DESCRIPTION OF PROBLEM

The former Capri Beauty Salon is located in the northwest quadrant of the intersection of 4th StreetNorthwest and Byron Avenue North, in Byron, Olmsted County, MN. A site map is shown in Figure 1. TheSite is located in a mixed commercial and residential area within the town of Byron. Primarily residentialproperty is to the north, east, and west and commercial property is to the south. The former Sette'sGarage facility (LEAK#8579) is located on the adjacent property to the west. The former Sette's Garageis currently occupied by commercial space on the first floor and residential apartments on the secondfloor. A school is located one block to the north of the Site.

The Capri Beauty Site consists of approximately 0.2-acres of land that has been improved with anapproximately of 3,800-square foot retail building. The building's construction is a two story wood framebuilding, with a stone foundation and dirt basement under the northern third of the building and a dirtfloor crawl space under the southern two-thirds of the building. A number of additional structuralsupports have been placed under the north end of the building to support the structure. Exteriorfeatures include a gravel parking area and landscaped grounds.

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The building was reportedly moved to the current location in approximately 1898. For the past 35 yearsthe building has been used as a hair salon (Capri Beauty Salon) and a pet grooming business. Previouslythe building was used as the Byron Lodge No. 135 of the Independent Order of Odd Fellows, arestaurant, grocery store, and leather salon. It is also reported that the building was previously used as alaundry.

During the petroleum release investigation at the former Sette's Garage, adjacent to the property,chlorinated Volatile Organic Compounds (cVOCs) were detected, and it was determined that the sourceof the cVOC release was the Capri Beauty Site. The primary Contaminant of Concern (COC) isTetrachloroethlene (PCE)and its breakdown compound Trichloroethlene (TCE). The cVOCs appear tohave been released to the ground surface on the northern side of the Site building. PCEhas migrateddownward through the clay soils at the Site to a depth of approximately 15 feet below ground surface.The horizontal extent of the cVOC soil contamination is primarily below the north end of the buildingand to the north of the building. The extent of the cVOC groundwater contamination is from thenorthern third of the building and offsite to the north. The soil gas PCEcloud extends approximately375-feet northeast, 250 feet southeast, and 300-feet west of the Site. The PCEsoil-gas cloud hasimpacted the indoor air quality in the Capri Beauty Salon.

REGULATORY HISTORY

The primary COC for this site is PCEpresent in the soil and groundwater, which has been above the .Minnesota Department of Health's Health Risk limits (HRLs) and above the vapor Intrusion ScreeningValues (ISVs). PCEis a solvent that has been used in the dry-cleaning industry.

The property is connected to the Byron Municipal water supply system so there is not a completedpathway from ingestion of contaminated groundwater. Because PCEis very volatile, there is a potentialfor contaminants in soil gas to enter buildings through foundations to complete a risk pathway.

DOCUMENTS REVIEWED

The MPCA based its remedial action decision on the documents listed below. These documents describethe Site characteristics, evaluate selected alternatives, and describe the effectiveness and cost analysisof various response actions for the Site:

Phase I Environmental Assessment, Terracon - January 2006

limited Phase II Investigation Updated, Terracon - December 2007

Vapor Mitigation Report, Terracon - June 2008

Additional Site Assessment Report, Terracon - June 2011

Focused Feasibility Study, Terrcon - November 2011

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DESCRIPTION OF RESPONSE ACTIONS ALREADY COMPLETED

A temporary membrane active depressurization system was installed above the basement floor in 2008to mitigate the potential for vapor intrusion into the eapri Beauty Salon building. Follow-up indoor airmonitoring has indicated limited effectiveness of the vapor mitigation system. No other remedialactivities have been completed at the Site to date.,

Because of the limited long term effectiveness of the vapor mitigation system, alternative measureswere examined in the November 2011 Focused Feasibility Study to manage the long term vaporintrusion risks.(

SUMMARY OF RESPONSE ACTION ALTERNATIVES

\ The November 2011 Focused Feasibility Study identified and evaluated alternatives that could be usedto remediate threats and/or potential threats posed by the site to human health and the environment ifconcentrations in indoor air remained above the ISVs.These alternatives were developed to address thepreviously elevated chlorinated voes in the soil gas samples. The Focused Feasibility Study whichevaluates these alternatives has been placed into the administrative record for the site.

Response action alternatives evaluated were based on the following primary scenarios:.

1. Install a permanent vapor mitigation system in the basement.

This alternative was rejected because the condition of the building's basement and crawl spacewould make it difficult to implement. The barrier would be susceptible to damage and could becompromised. Therefore, it would not provide a permanent solution to vapor risk on-site andongoing vapor monitoring at the site would be needed. Also, it would not provide a long-termsolution to the groundwater contamination at the site, which could potentially causechlorinated voe vapor intrusion impacts at adjacent properties. An institutional control wouldbe needed, describing the contamination on the site and limiting future use of the site.

2. Seal the first level floor of the building to limit the vapors that enter the building.

This alternative would provide a greater chance of mitigating vapor intrusion into the building,but was rejected because it would not provide a permanent solution to vapor risk on-site andongoing vapor monitoring at the site would be required. Additionally, it would not provide along-term solution to the groundwater contamination at the site, which could potentially causechlorinated voe vapor intrusion impacts at adjacent properties. An institutional contr61 wouldbe needed, describing the contamination on the site and limiting future use of the site.

3. Seal the earthen floor and crawlspace, such as coating the soil floor and foundation with cellularconcrete.

This alternative was rejected because of the difficulty in implementation and uncertainty of thelong -term effectiveness. Ongoing vapor monitoring would be required at the site. It would notprovide a long-term solution to the groundwater contamination at the site, which couldpotentially cause chlorinated voe vapor intrusion impacts at adjacent properties.

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An institutional control would be needed, describing the contamination on the site and limitingfuture use of the site.

4. Purchase the property so that the site building may either be removed or demolished. Impactedsoils in the source area would be left in place. The basement would be backfilled with clean fill.

This alternative would eliminate the pathway for chlorinated VOC vapor intrusion into thebuilding that is located on the site, but was rejected because the chlorinated VOC contaminationin the source area would be left in place. It would not provide a long-term solution to thegroundwater contamination at the site, which could potentially cause chlorinated VOC vaporintrusion impacts at adjacent properties. An institutional control would be needed, describingthe contamination on the site .and limiting future use of the site.

5. Temporarily support the north end of the building so the impacted soil may be excavated anddisposed of at an approved landfill. Place an institutional control on the property, limitingproperty use, becau'se of soil and groundwater contamination remaining outside the sourcearea.

This alternative would mitigate the contamination in the source area and would eliminate thevapor intrusion pathway. However, it was rejected because of the difficulty and potential hazardassociated with excavating the impacted soil beneath the building without endangering thestructure of the building. An institutional control still would have been needed, describing thecontamination on the site and limiting future use of the site. However, the institutional controlwould have been less restrictive because the contamination in the source area would be\removed.

6. Purchase the property so the site building may be moved or demolished. The impacted soils inthe source area would be excavated and disposed of at an approved landfill. Place aninstitutional control on the property, limiting property use, because of potential soil andgroundwater contamination remaining outside the source area.

This alternative, with the building demolished and impacted soil beneath the building excavatedand removed from the site, will have a high long-term effectiveness by removing the source ofcontamination to the groundwater and the source ofthe chlorinated VOC vapors. This willeliminate the vapor-intrusion risks on site and reduce the risks to adjacent properties. Aninstitutional control will be placed on the property to control future activities on the site tomitigate the risk associated with any residual contamination after the response actions havebeen completed. However, the control will be less restrictive because the contamination in thesource area will be removed.

7. Purchase the property so the site building may be moved or demolished. Impacted soils in thesource area would be excavated, treated onsite and returned to the excavation. Place aninstitutional control on the property, limiting property' use, because of soil and groundwatercontamination remaining outside of the source area.

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This alternative would mitigate the contamination in the source area and would eliminate thevapor intrusion pathway, but was rejected because the high cost of implem,entation, andbecause the effectiveness of treating the soils on-site is uncertain. If the alternative worked asdesigned, it would provide a long term solution by removing the source of contamination to thegroundwater, and eliminate the source of chlorinated voe vapors. However, an institutionalcontrol would be placed on the property to contro'l future activities on the site to mitigate therisk associated with any residual contamination after the response actions have beencompleted.

Summary of Remedial Action Alternatives:

Remedial Action AlternativeLong-term Ease of

CostEffectiveness Implementation

1. Vapor mitigation system Low Medium Low

2. Vapor floor barrier Medium High Low

3. Basement vapor barrier Low Low Low ')

, Low to4. Remove site building Medium Highmedium

5. Support building, conduct excavationHigh Low Mediumcleanup, and construct new basement

6. Remove building and conduct excavationHigh High Mediumcleanup (the selected alternative)

7. Remove building, conduct excavation and on-Medium Low High. ,

site soil treatment

'The remedy selected was Alternative six, purchase the property so the site building may be moved ordemolished. The impacted soils in the source area would be excavated and disposed of at an approvedlandfill. The excavation will be backfilled with clean soil. An institutional control will be placed on theproperty, limiting property use, because of potential soil and groundwater contamination remainingoutside the source area. '

This remedy provides an immediate and cost effective solution by removing the vapor receptors and byremoving the impacted soils in the source area. Removing the contaminated soils will reduce the long-erm vapor intrusion risk by removing the source of the cvoe vapors and remove the source of cvoe

• contamination to the groundwater. It is anticipated that the groundwater quality will improve aftersource materials are removed because the cvoe contamination will no longer leach into thegroundwater. In addition, the excavation will be backfilled with a layer of zero valent iron amended sandto enhance the degradation of the remaining contamination in the groundwater after source removal.Groundwater mol1itoring will be necessary to insure that the residual groundwater cvoe contaminationis being remediated. The fill area will be paved.

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This remedy was also chosen because: removal of the source area contamination has been proven to beeffective at other sites with tight soils; it will provide a permanent solution to the risk associated withthe contaminated soil and vapor intrusion; and it can be implemented and completed relatively rapidly.Given the geology at the Site, other methods of remediation, including in-situ remediation techniquessuch as multiphas~ extraction and enhanced bioremediation, have been less consistently effective andwould typically require a longer time period to complete the remediation. For this Site the costs couldbe equal or greater than the source removal alternative, and vapor mitigation may still be required it:"the buildings adjacent to the Site in order to reduce the risk to the building occupants.

After construction, vapor monitoring will be conducted at the apartment building (former Sette'sGarage) and at the County Museum to ensure these adjacent properties are not being impacted.

Institutional Controls will be placed on the Capri Beauty Salon property to restrict future groundwaterusage, to require a vapor mitigation system on any structures constructed on the Site, and to identifyonsite areas that have had impacted soils removed and/or areas that may still have some contaminationremaining.

ESTABLISHMENT OF RESPONSE ACTION OBJECTIVES AND CLEANUP LEVELS

The remedial action objective is to eliminate the risk associated with vapor intrusion due to the soil,groundwater and soil-gas impacts in the inferred source area this will be accomplished by eliminatingeither the source or the pathway for vapor intrusion into the Capri Beauty Salon, or any other buildinglocated on the site or on adjacent properties that are above the soil-gas plume. The remedial action willprovide a long-term solution to vapor intrusion of the COCs.

RESPONSIVENESS SUMMARY

Pursuant to Minn. Stat. 9 115B.17, subd. 2b (2002), the MPCA issued a public notice (see Attachment 1)describing the recommended response action. The notice was published in Rochester newspaper andsent to the local TV and radio stations. The press release stated that the MPCA would present itsProposed Cleanup Plan at the Byron City Council meeting at 6 p.m. on February 27,2013. The meetingwas held at Byron City Hall, located at 680 Byron Main Court, Northeast, in Byron. The press releasealso stated that the Agency would take public comments on all alternatives and on the information thatsupports the alternatives until March 13, 2013.

At the Byron City Council meeting: Members of the Byron City Council were concerned as to how thesite would be left foll.owing removal of the contaminated soils.

One resident of the City spoke and indicated that he believed that in-situ treatment would be a betteroption for the site and that more cqncern should be given to potential vapor issues to surroundingbuildings and to contamination to the south. The resident also expressed concern about the PetroleumRemediation Cleanup at the adjacent Sette's Garage Leak Site.

The resident submitted written comments on March 12, 2013. This was the only written commentsreceived by the MPCA. The letter, copy attached, restated the concerns expressed at the Byron CityCouncil Meeting.

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On April 2, 2013, the MPCA responded to the resident's concerns and indicated that in-situ remediationwould:

• take longer to reach completion• would require long term follow up

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based on past experience with remediation efforts in similar soil conditions in-situ remediation was notas consistently effective as expressed in the comments received. In response to the Byron City Council.concerns regarding the site conditions following the remedial action, the site will be left with pavementover most of the excavated area and grass over the remaining area.

STATUTORY DETERMINATIONS

The selected response actions are consistent with MERLA, Minn. Stat. 99 l1SB.01 to .20 (2012), and arenot inconsistent with the Federal Comprehensive Environmental Response, Compensation, and LiabilityAct, 42 U.S.c. 9 9601 et seq and the National Contingency Plan, 40 C.F.R. Part 300. I have determined theselected response actions are protective of public health and welfare and the environment.

1{~-IcUKathryn J. SatherDivision Director

KJS/NF:csa

Attachments: Figure 1, Public Notice Letter from Pinnacle Response, Letter to Pinnacle

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IeFor release: Feb. 19, 2013

Contact: Alexis Donath, 651-757-2312

s Minnesota PollutionControl Agency

MPCA proposes cleanup plan for contaminated site in Olmsted County

St. Paul, Minn. -- The Minnesota Pollution Control Agency (MPCA) has finished its investigation ofsoil and groundwater contamination at a property in Byron, Minn. "the contaminated site, located atthe intersection of Fourth Street and Byron Avenue, is currently home to the Capri Beauty Salon.

Agency representatives will present options for cleaning up the contamination at a meeting of theByron City Council on Feb. 27, 2013, at 6 p.m. The meeting will be held at Byron City Hall, located at680 Byron Main Court, N.E., in Byron.

According to the MPCA, the pollutant of greatest concern at the site is tetrachloroethene, also knownas PCE, a solvent that has been used in the dry-cleaning industry. The PCE contamination isbelieved to have occurred over 40 years ago, before the building was occupied by the beauty salon.The contaminant was released at ground level on the northern side of the building, where it migratedthrough the soils to a depth of about 15 feet. PCE has been detected in groundwater at the site atlevels that exceed Minnesota Department of Health standards. Vapors from the contaminated soilhave also affected indoor air quality in the Capri Beauty Salon.

The MPCA is accepting public comments on all cleanup alternatives and the it:lformation that supportsthe alternatives until March 13, 2013.\

A fact sheet, Proposed cleanup plan for Capri Beauty Salon Site, is available on the MPCA's website.

For additional details or to review files about the site, contact Nile Fellows, site manager (651.-757-2352, nile.fellows@state.mn.us).

Broadcast version:

The Minnesota Pollution Control Agency has finished its investigation of soil and groundwatercontamination at the Capri Beauty Salon Site in Byron.

The site is polluted with a dry-cleaning chemical, which has been detected in groundwater at the siteat levels that exceed Minnesota Department of Health standards. Vapors from the contaminated soilhave also affected indoor air quality in the beauty salon.

M-P-C-A staff will discuss' cleanup alternatives at a meeting of the Byron City Council on Wednesday,February 27. The meeting will be held at Byron City Hall at 6:00 P-M. .

A fact sheet about the proposed cleanup plan for the Capri Beauty Salon Site is available on theMinnesota Pollution Control Agency website.

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The mission of the MPCA is to work with Minnesotans to protect, conserve and improve ourenvironment and enhance our quality of life.

st. Paul • Brainerd • Detroit Lakes • Duluth • Mankato • Marshall • Rochester • Willmarwww.pca.state.mn.us • Toll-free and TOO 800-657-3864

PinnacleEngineering.

Owning Challenges. Winning Trust.

March 12,2013

Mr. Nile FellowsProject ManagerMinnesota Pollution Control Agency520 Lafayette Road NorthSt. Paul, Minnesota 55155-4194

7389 Airport View Dr. SW. Suite 400

Rochester, MN 55902Tel: 507-280-5966

Fax: 507-280-5984

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RE: Comments on Proposed Cleanup Plan for Capri Beauty Salon Site in Byron, MN

Dear Mr. Fellow:

This correspondence is in regards to the former Capri Beauty Salon site located in the northwestquadrant of the intersection of Fourth Street NW and Byron Avenue North in Byron, Minnesota ...I am an interested party that has resided in Byron, Minnesota for over 6 years and currentlyliving at 749 12th Street NW, Byron, Minnesota ..

The MPCA released a fact sheet outlining a summary of proposed alternatives to remediatethreats and/or -potential. threats posed by the site to human health and the environment if. concentrations remairi above the Intrusion Screening Values (ISVs). The .fact sheet alsoreferenced a November .20 II Focused Feasibility Study (FFS) that detailed the sampling andproposed alternatives that were evaluated for remediation at the site. I have the followingcomments regarding the proposed alternatives outlined. .

It does appear that the MPCA did have a subcontractor (Terracon) investigate chemical oxidation(chern-ox) options, but not in/-situbioremediation or enhanced reductive chlorination (ERD). Inthe FFS, treatability test (Appendix D) was conducted for 5 different chern-ox methods (AAsodium persulfate, H202 activated sodium persulfate, VTX persulfate,. sodium permangariate,and modified fenton's). Chern-ox, like in-situ bio involves injection. However, the rule of_thumb with chern-ox is "contact, contact, contact". Chern-ox requires that the a~endmentremains in contact with the contaminant in the subsurface for an extended period of time. In lowflow systems, this is difficult due to getting the chemicals in contact with the contaminants in thefirst place. Then the amendments must remain in place for a long period of time for the reactionsto occur. Another big pitfall is that chern-ox amendments interact\affect the media; and then theoxidant is used up (Le., permanganate oxidizes organic carbon in soils, and in outwash\tilllike in.. . .

Byron, you have to sometimes add 2 to 3 or even up to ten times more chern-ox compounds thanthe stoichiometry requires for the chemistry to qestroy the contaminants). This is called Soil-Oxidant Demand, and this is one of the major drawbacks of chern-ox outside permeable soils likeclean sands and gravels. -

Corporate: 11541 95th Avenue North, Minneapolis, M N 55369800-366-3406 . Main> 763-315-4501 . Fax: 763-315-4507

Minneapolis, MN . Rochester, MN . Omaha, NE . Minot, NOwww.pineng.com

24 Hr. Emergency Res~onse: 1-866-658-8883

Mr. Nile Fellows - MPCACapri Beauty Salon Proposed CleanupMarch 12,2013Page 2 of4

On the other hand, the rule of thumb with in-situ bioremediation, and ERD in this case, is"environment, environment, environment". The ERD amendments do not require contact withthe contaminant. The purpose with this method is to engineer the environment (this is a hugedifference with chern-ox) to be either anaerobic (no oxygen) or aerobic (enhancing oxygen)conditions, and maybe having to add other nutrients [nitrogen, sulfate sugars, etc]' In the Byroncase (PCE contamination), the goal would be engineering the subsurface to enhancemicroorganisms' growth for the bugs that utilize the contaminants (PCE) as a food source byadding a carbohydrate (i.e., emulsified vegetable oil [EVO]) and as a secondary amendmentnano-scaled zero valent iron (nZVI)~ When properly designed for the microorganism colonies togrow (in numbers, not size), the microorganisms have no choice but to 'eat' the contaminants fortheir carbon source.

Regarding the specific site conditions (from data collected) at the Byron site, the site soil profileis a till, making it more difficult, but ERD has been successfully implemented in a lot tighter soilmaterial than detailed at the Byron site .. In Appendix E, there are ample boring logs. and severalgrain size analysis (around pages 191 of the 201 in the FFS) showing the glacial materialcontains ample sands and courser material (all the GSD curves show >80% sand size and up) foran in-situ bioremediation (ERD) injection program. Since, unfortunately, it doesn't appear thatthe MPCA looked at ERD, it also appears that the site data for Byron was not reviewed in thatcontext. Almost all the boring logs iildicate the VOCs are concentrated in the courser materialand the immediate zone above this (e.g. the vapor migration).

From the review of the FFS, Isee no impediments to an in-situ injection program. In-situ chem-ox applications can last from weeks to months, whereas, ERD applications can last from monthsto years and even decades. There are examples of ERD systems in place in Geneva, NY for 5-years in a tighter formation than located in Byron.

During the proposed cleanup plan presentation at the Byron City Council meeting on February27,2013, the MPCA staff stated that the soils are so tight that in-shu remediation methods wouldnot work at this site. If the tills are so tight (impermeable), then how did the contaminants getinto the groundwater system in the first place? This is another indicator that in-situbioremediation methods could work at this site.

Also, during the presentation to the Byron City Council, comments were also made by theMPCA stating that they didn't believe that the Byron municipal water supply was affected bythis contaminated site due to.the location of the aquifer. I think it is a little hard for the MPCA toassert this without specific data to support this statement. All waters are connected, either byhead or flow system. Changes in any head pressure will affect the entire system. It is just a.matter of time and magnitude. Has there been,any specific testing completed on the municipalwater supply to determine if it has been impacted or could potentially be impacted in the future?

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Mr. Nile Fellows - MPCACapri Beauty Salon Proposed CleanupMarch 12,2013Page 3 of4

Additional specific issues of note or comment for the Byron, MN .site:

1. For the proposed MPCA preferred remediation method, the outer limits of the excavationleave in place significant, and at some locations, the highest VOCs left in the contaminatedground .. For example, there were very high VOC levels in the -20' bgs interval at P-98 onthe east, at the -25' bgs interval at P-69 on the west, and high concentrations at P-I 00 in thepermeable sand layer below the vertical limits of the excavation. Post-excavation, thesevapors will migrate into the more permeable fill theyput into the excavation, and then we'reback at square I with soil contamination of the clean fill. This issue has not been addressedby the MPCA.

2. VOC impacted soils (and groundwater) extend far to the south, outside the proposed area ofexcavation, which are not addressed. Therefore, this area will continue to act as a vapor trapfor the VOCs left in place (the benzene, ethyl benzene, and xylene concentrations at P-I04beneath the foundation) and will continue to supply ample vapors into the structure or areapost-excavation.

3. The excavation certainly would have to extend south and east past P-I02, which wouldplace the municipal building to the east at risk if the excavation sidewalls are compieted asdrawn. The municipal building to the east will be less than 10' away with a near verticalslope.

4. The property owners to the south at boring P-79 and P-80 should be concerned as well forpotential vapor migration in any sub-street utilities (sanitary sewer) as noted by the resultsofP-14.

5. There are high levels of MTBE, assuredly there is groundwater contamination .. MTBE willact as a co-solvent for the other chlorinated and petroleum hydrocarbons.. This may allowthose pollutants to travel even faster than the ground water. Delineation of impactedgroundwater needs to occur if it hasn't been done already. This is an issue of communityconcern.

,6. The closest boring to the muniCipal building (P-75 and P-76} contains unacceptable levels ofsubsurface VOCs. At a minimum, each occupied building shown on the FFS'Site Map(Figure 2a) should have a sub-slab soil vapor sample collected simultaneously with anindoor air sample, analyzed for TO-15 parameters, methane; carbon dioxide, and 02.

7. The Soil Vapor Point data was not collected sub-slab, which is where the data needs to becollected for a better utilization of the two air models referenced in the FFS. Specifically,'the benzene impacts adjacent to the grocery store are unsettling, but it is the acetone andMEK results near this structure (arid building '14 to the west) which are alarming. In fact,the subsurface vapors concentrations exceed the MPCA screening values far to the south atKJ's Cafe, more than 200' east of CBS, more than 300' to the north at SVP-54, and 300' NWat SVP-60. This clearly has the potential to be a much larger soil vapor intrusion (SVI)issue than just the Capri Beauty Salon site.

Mr. Nile Fellows - MPCACapri Beauty Salon Proposed CleanupMarch 12,2013Page 4 of4

It is likely that the most appropriate way to immediately reduce the potential threats posed by thesite to human health is demolition of the building above the contaminated soil to remove thethreat of vapor intrusion exposure to building occupants. However, I believe that the MPCAneeds to evaluate and consider in-situ bioremediation methods prior to moving forward withexcavation and. back fill of .C1ean materials. In addition, I believe that the MPCA needs toevaluate the subsurface vacs of the nearby municipal building by taking sub-slab soil vaporsamples in conjunction with indoor air samples to ensure that the vapor intrusion is adequatelyaddress on this property. The last major concern involves the city water supply and additionalevaluations or assurances that this hasn't or won't be impacted in the future due to thecontamination in and surrounding the site (from both the Capri Beauty Salon Site and formerSette's Garage Site).

If you have question. regarding my comments,. I can be reached at 507-269-2034,mayres@pineng.com, or at the following address: 7_4912th Street NW, Byron, MN 55920.

Sincerely,PINNACLE ENGINEERING, INC.

Marley Ayres, JDPrincipal Scientist

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Ce. Marley Ayres - Pinnacle Eng.

Enclosures

..Minnesota Pollution Control Agency520 lafayette Road North I St.Paul,MN55155-4194 I 651-296-6300 I 800-657-3864 I 651-282-5332 m I W1I'JW.paI.state.mn.us

. April 1, 2013

Mr. Marley AyresPinnacle Engineering7389 Airport View DriveSuite 400Rochester, MN 55902

Dear Mr. Ayres:

This letter is in response to your comment letter regarding the former.Capri Beauty Salon site (Site), datedMarch 12,2013, and comments at the Byron city council meeting-on February "l.7i 2013. We appreciateyour comments and will attempt to address the issues in our response.

A number of the comments in the letter were in regards topetroleum related Volatile Organic Compounds(VOCs) at the Former Sette's Garage Site (MPCA Site ID LEAK#8579), therefore the Minnesota PolI~tionControl Agency (MPCA) staff in the Petroleum Remediation Program (PRP) were forwarded your commentletter; This MPCA response letter will contain the PRPresponse to petroleum issues and the MPCASuperfund Pro~ram response to the non petroleum issues regarding investigations and remediation at thesites located near the intersection of Fourth Street Northwest arid Byron Avenue,No'rth in Byron, "Minnesota.

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The proposed remedy for t,he Capri Beauty Shop as presented by the MPCA Superfund Program is to 'remove the existing building and then remove contaminated soils in a defined area~ Clean soils would thenbe brought in to fill in the excavated areas. Institutional Controlswould be placed on the property to i~sureproper notification for any future site o~ners that groundwater is contaniinateda~d that some 'contaminated 'soils remain bnsite.

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"The Petroleum Remediatio~ Program (PRP)completed ~orrective action at the Sette's Garage S'ite .(Leak 8579) 'that included the removal and disposal of petroleum impacte~ soil and the lining of the sanitarysewer 'system in the vicinity of the site along fourth street Northwest sanitary 'sewer line. The decision to

.complete this corrective action was made after a petroleum release investigation was completed.

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In your letter you indicated that you believed that in situ remediation with bioremediation or enhancedeductivechlorinatio~ would be a better remedy for this site: And that you had concerns about the vapors.entering the buildings next to the Capri BeautY shop; that the city municipal water needs to be protected

. and that the contamination goes further to the South and that the current plans would not address theseissues.

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fv1r. Marley AyresApril 1, 2013Page 2

The MPCA Superfund Program selected the current remedy being proposed because of the past history ofsuccess we have had with removing source material. The extent of the chlorinated VOCs has been welldefined. Removing the majority of the VOC contamination in the sourc~ area will allow natural attenuationto take place in the remaining.soil that has lower contaminant concentrations. This will remove the sourceof the vapors and remove the source of contamination to the groundwater. This work can be accomplishedin a short time period and will greatly reduce the site contamination.

As you are aware, bench scale testing of possible in situ reagents did not identify one that seemed to workwell ..MPCAstaffs past experience with enhanced bioremediation has had mixed results, which aredependent on site conditions. This site has clay soils. In staffs experience, the clay binds and shields thecontaminants from the reagent which reduces the effectiveness of the treatment. As a resul~ multipleinjections are typically required which drives up costs and.or as pointed out in your letter, extensive time isrequired to see if these processes could work. Staff has also noted the generation of potentially dangerouslevels of methane at or near buildings where bioremediation has been utilized Bioremediation is often.utilized for groundwater treatment whereas the site has significant impacts in the soils above thegroundwater table. Often bioremediation is used in conjunction with other remedial actions such as source.relTloval, soil vapor extraction or multiphase extraction. In additiqnj bioremediationrequires a longer timeperiod to achieve the desired results. During remediation, vapor mitigation would still be required in theCapri" building because of the elevated chlorinated VOCs in the soil and groundwater and because of thepotential for generation of methane gas during the enhanced bioremediation proc~ss.The FFSindicates.that installing a vapor mitigation system that will be effective for the long term will be expensiveanddifficult because of issues with the condition of the building.

The MPCA is not aware of anyone drinking contaminated water. The groundwater that is contaminated is inthe surficial aquifer. The municipal well in the adjacent well house has been abandoned. And the wells that

", .' .the city uses for water supply are not located in the immediate area .

. Once contaminated.soils have been removed from the site some additional soil vapor sampling wiil be .conducted to determine if there are any vapor concerns; Additional groundwater testing is planned toevaluate how. the groundwater rea~ts once source material is removed.

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if you .have any additional questions, feel free to contact Nile Fellows, at 651-757-2352.

S;?4;f~Nile R. Fellows ..project LeaderSite Remediation Division and Redevelopment SectionRemediation Division

NF:csa

cc: Mary Blair-Hoeft, City Administrator, City of ByronKatherine Serier, Petroleum Remediation, MPCA

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