Gunnison City and The Environment

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Lance Hess, M.S., P.G. , Certified UST Consultant

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Gunnison City Protecting Human Health and the Environment

You can download many documents filed with DEQ regarding the gasoline release at:  

www.deq.utah.gov/Issues/Gunnison_TopStop/index.htm

·         Update: February 22, 2010

Air Quality:

I have reviewed indoor air and sub-slab air quality data collected to date by RMEC.  After a cursory review of the database, recent trends generally show improvements in most areas of the City.  However, I did have a couple of concerns and I therefore posed some questions to Wasatch and RMEC regarding a few of the sample results at both businesses and residential homes.  There is on-going dialogue regarding some locales with other potential sources of petroleum.  To the best of my knowledge, a more detailed back-ground indoor air quality study has not been done.

Handheld organic vapor meter (PID) emission data have been collected from the smaller ventilators by Wasatch.  As of December 23, 2009, there has been a steady downward trend in concentrations since data collection began.  On December 23, 2009 no detectable concentrations were reported at the ventilators tested.

Ground Water:

Three (3) new ground water wells have been installed at the southwest portion of the plume near the intersection of 200 South and 100 West.  One of the three (3) wells contained 26 parts per billion (ppb) benzene, above the regulatory limit of five (5) ppb.  However, the other two (2) wells were below the regulatory limits for benzene.  Therefore, the ground water plume appears to be characterized near the southwest, leading edge of the contaminant ground water plume.  Of course this can change because ground water concentrations typically change with seasonal fluctuations in water table elevations.

However, monitoring well MW-27, located at the north side of 100 South and near approximately 28 West, continues to be highly contaminated with 22,000 parts per  billion (ppb) benzene.  This is up from 13,000 ppb benzene in August.  The regulatory limit is 5 ppb.  So, there is still some instability inside the plume.  This “slug” or concentrated zone of contamination has either “run the gauntlet” of trenches; or the trenches were installed after the slug passed by. 

SVE Remedial Progress:

As of December 23, 2009, Wasatch reported 12,954 gallons of fuel removed by the SVE units with little change to no change since the last report.  Whereas the water levels have dropped somewhat since the last quarterly monitoring report, the water table seems to be approximately 0.5 to 1.0 feet higher over all than last year.  Given the severity of the last couple of winters this is not surprising. What this means is that even though the water levels have dropped since the last monitoring event, they have not dropped enough allow the SVE units to extract gasoline vapors to the extent we would prefer.  

Alternative Remediation Technologies

Wasatch is working on alternative remedial technologies to help expedite ground water remediation.   They will be testing some nutrient amendments to the ground water to enhance, if possible, biodegradation of the hydrocarbons.  They have invited me to be present for initial test injections. In the event this test is not successful, then I expect other alternative means will be explored.   

Ground Water Plume Maps 

I have attached the November 2009 benzene plume map which was prepared by Wasatch and submitted to DEQ (in mg/l or parts per million).  I have also developed two (2) ground water plume maps: One depicts benzene concentrations as well and the other depicts total petroleum hydrocarbons as gasoline range organics (TPH gro)  in parts per billion.  Typically, we “expect” benzene to be at the leading edge or, in this case, at the southwest edge of the plume.  The maps show the potential for two plumes or at least two release events based on the two areas of concentrated benzene levels, especially at MW-20 and MW-27.  Also given the “slug” or mass of petroleum at MW-27, the maps suggest that the plume does not and has not moved as fast as one might assume.

If you have questions regarding the locale of your home or business relative to the ground water plume, please feel free to call anytime. 

Age of the Ground Water Plume – Historical Releases

Based on some factors including the November 9, 2010 plume maps, in our opinion it is possible that the fuel releases started as early as 2005.  We reserve the right to modify this observation as additional data come available.

Amount of Fuel Released

Based on several factors, the amount of fuel released appears to be approximately 22,000 to 25,000 gallons.  We reserve the right to modify this observation as additional data come available.

·         Update: as of June 9, 2009

The June 9, 2009 report from Wasatch showed the amount of fuel removed was 11,484 gallons or approximately 243 gallons since October of 2008.  This amount does not include fuel removed from the small ventilator systems attached to several residences and businesses.    

Six (6) new ground water wells have been installed around the plume and are designated MW32 – MW37.  Of the six wells, only MW37, which is located near 100 West and 200 South, contained regulated levels of contaminants including 670 parts per billion (ppb) benzene.  The target clean up level for benzene is 5 ppb.   Therefore, the southwest edge of the plume, or areas down gradient from MW37 still require some characterization.

However, MW-17 has been non-detect for benzene during two (2) sampling events in 2009 again corresponding to a drop in water table elevations during 2009.    Ultimately what this means is that ground water monitoring at MW-17 will continue until concentrations achieve clean-up objectives over several sampling events.

MW-27, which is located along 100 South at approximately 28 West persists as the hottest spot in the ground water plume with benzene levels at 13,000 ppb.  In February of 2009 the levels were at 35,000 ppb.

·         Corrective Action Public Comment Period – Ended June 19

The Corrective Action Summary letter has been filed with the State.   Two copies are kept at the Library.

You can download this or many other documents from the State website at this link:

            www.deq.utah.gov/Issues/Gunnison_TopStop/index.htm

·         Update on the Second Hole Theory Letter (see link below)

After I submitted the Second Hole Theory Letter, Wasatch found the tank. It had not been crushed yet and Wasatch invited me to visit the tank on February 12, 2008.  There were not two (2) holes in the tank but four (4) holes. However, the situation is more complicated than that….

Wasatch showed me several photographs of the tank, which were taken when it was removed from the ground.  They also showed me photos they took just days prior to my tank visit.  I can confirm only one (1) hole in the tank removal photos.   We can see only two (2) holes in one welded seam in the photos taken a few days prior to my visit.  This seam had three (3) holes when I finally got to the tank. One other seam had one more hole for a total of four (4) holes.   

This, of course, means one of two things. First, perhaps one cannot clearly see the holes in the photos; or the highly corroded “rust plugs” popped out when the tank was being moved around.   Furthermore, these four (4) holes were clearly on the bottom of the tank, not on the sides.  However, at the time of the tank visit, the tank was laying on the side so I could not see either side.  The tank is eight (8) feet wide (“tall”) and 32 feet long. I was under strict orders from all attorneys not to touch or roll the tank.    

All of the holes we found were along the welded seams of the tank and located within the bottom-section of the tank.  I would say the bottom 1/5 or 1/6 of the tank had extensive corrosion and numerous pitted spots.  

·         Other Updates: 

Wasatch previously issued a Subsurface Investigation Report.  You can obtain a copy by going the DEQ link at the end of this web page.   They identified a second, older release near the dispenser island.

The small residential SVE Units have been reasonably effective at controlling vapors given the difficult conditions. However, one unintended consequence of the residential ventilation units is that they seem to give us an additional way to monitor the plume dynamics as these units are located along the plume.  We have seen concentrations both increase and decrease at some of the units.   Please bear with us as the spring run-off approaches.  Hopefully I am wrong, but I suspect the water table will try to complicate things for us all.

If you have a Residential SVE Unit, these are designed to run continuously and have a very low failure rate, less than 0.5% chance of failure.  The contractor has seen only 2 in 500 fail.  

An SVE Flame Oxidizer (“flame-ox”) is now located south of 100 South.  An SVE flame oxidizer has a maximum of four (4) times the maximum capacity of a catalytic oxidizer (“cat-ox”) to burn vapors.   The flame ox was started on March 4 and has the capacity to remove 50 to 60 or more gallons per day.   Wasatch has several contaminant-rich trenches ready to feed into the Flame-ox.  Regardless, Wasatch is taking care to run the Flame-Ox at moderated capacities so if a “slug” of contamination comes through, it can handle the momentary bumps without shutting down.  Wasatch has installed an extra cat-ox next to the flame-ox to help increase the remedial capacity in this highly contaminated area.

Side-note:  These systems, including the Flame-Ox,  are efficient in that they are capable of gradually switching over and running off of the very vapors they pull from the subsurface, up to 100%!. 

Background Air Quality Levels of Benzene:   Thus far back ground, or ambient, outdoor air quality levels outside the plume area in Gunnison range from under 1 ug/m³ up to 2.6 ug/m³ benzene.   

·         Target Clean up Levels: The State of Utah Leaking Underground Storage Tank (LUST) Program uses three (3) methods to determine clean-up levels, which are:

1.     The Initial Screening Level (ISL):  The ISLs are the most stringent levels established for the State (see link below). 

2.     Tier 1 Screening Level: If a contractor wants to leave the contamination in place with no further action whatsoever, several restrictions apply.  This risk-based approach is restricted to situations where no buildings, property boundaries or utility lines are within 30 feet of contamination that exceeds the ISLs and are under the Tier 1 levels.  The contamination must remain on-site. 

3.     Tier 2 Screening Level: The Tier-2 risk-based assessment process involves sophisticated modeling to calculate site specific clean-up levels if Tier 1 levels fail. 

Wasatch, in one of their subsurface investigation reports, is invoking ISLs for off-site contamination; and Tier 1 clean up levels at Top Stop.  However, considering that ISLs are the targeted goals just across the Top Stop property boundary, it is easy to imagine that much of the Top Stop site should be cleaned up to ISLs. 

• Natural Gas odor vs Gasoline Odors:    Most people can distinguish gasoline from natural gas.  However, to review, gasoline has a “sweet” or “aromatic” odor.  Natural gas has a “rotten egg” odor.  The rotten egg odor actually comes from an additive put there by the natural gas company.  The natural gas companies typically use a meter that detects natural gas down to 50 ppm.  Most people smell the additive in natural gas down to 1-4 ppm, the “odor threshold.”

So when you call Questar, they may say there is no problem but you still smell gas.  The communication breaks down because most Questar personnel do not know the odor threshold.  It would be helpful at this point if the technician would say, “Our meter does not detect gas at this level, it is not explosive or anything, but you may still have a leak.”  The bottom line is that if Questar leaves and the odor persists near an appliance; call the appropriate repair company for that appliance.   If needed, we can help “sort out” these issues.   

• Wasatch Locates Free Phase Product:  Wasatch Environmental located free phase product floating on the water table on or about January 10, 2008 south of 100 South.  Free Phase Product is also known as light, non-aqueous phase liquid (LNAPL).   It just means that straight gasoline has been found floating on the water table.   This area contains huge volumes of gasoline floating on the water table.   The Flame-ox is up and running (see above).

• Gunnison Valley Bank:  On January 7, 2008 we placed a SUMMA in the upstairs office area workroom or “fireplace room” above a furnace vent.  We removed the SUMMA on January 8, 2008.  The lab measured 1.9 ug/m³  benzene in the upstairs office workplace area.  As of August 11, 2008 data showed the levels of benzene have decreased to 1.1 ug/m³.

• The State of Utah DEQ in a letter dated January 7, 2008 issued a series of directives to Top Stop which we summarize as follows: 

1.     Find the leading edge of the plume and adjust maps accordingly.

2.     Assess the potential for contamination to impact the San Pitch River.

3.     Provide a comprehensive ground water data table with lab analyses.

4.     Provide a soil data table with lab analyses.

5.     Estimate how much petroleum has been removed and provide supporting documentation.

6.     Provide geologic cross sections which show subsurface features that might be affecting how the contamination migrates (A cross section is a drawing that shows what the ground might look like under the surface; not unlike driving through a “road-cut” in the mountain and being able to “see” horizontally through the side of the mountain).

7.     Provide daily inventory records of the underground gasoline storage tank for a period of 24-months prior to the tank removal.

·         The San Pitch River and the Ground Water Plume:  I hand drilled next to the San Pitch to about five (5) to (6) feet below the bottom of the river.  The soil was very moist as I punched through the subsurface but I did not hit ground water.  Furthermore, surveying efforts by Wasatch corroborate the bore-hole findings.   In addition, several residents have informed me that the river dries up annually.  Therefore, all data show that this is a “losing” stream meaning water discharges from the river and flows down into the groundwater.  This provides hydraulic separation from the ground water contaminant plume.

      ________________________________________

Understanding Benzene:  

·         Benzene is one of hundreds of compounds found in gasoline.

·         It evaporates very quickly. This is what we call “volatility.” 

·         It is one of the odors you smell when you pump gas into your car; hence the name aromatic hydrocarbon.  

·         And it causes a variety of health concerns depending on exposure. 

·         It is six carbons connected together in a ring.  A picture of benzene is usually drawn as a six sided shape, not unlike the shape of a “stop-sign” with a circle in the middle to depict the bonding between the carbons.   

·         Because of its volatility, it vaporizes into soil pore spaces, the air, and unfortunately, living spaces.

·         Benzene is biodegradable and has led to a whole area of remediation referred to as “bio-remediation.

·         It is one of the more soluble or more easily dissolved components of gasoline.  As such we commonly find it at the leading edge of many ground water contamination plumes.  What this means is that it usually travels faster than the other components of gasoline away from the source of the spill.

·         As a general rule of thumb (though there are exceptions), older gasoline spills have a lower percentage of benzene and more recent spills have relatively more benzene.

·         Wasatch Environmental is using the property of high volatility against benzene by using vacuum systems to remove it from the subsurface.   In fact, most components of gasoline respond well to this approach. 

What do my lab data mean? 

·         If you have air quality data from the laboratory, you should also have an explanation letter.  If not, you can get a copy of the explanation letter from the link below.    The main component to look at is benzene.  We are now using micrograms per cubic meter or ug/m³ to discuss and understand concentrations.  A microgram is one millionth of a gram.  The unit concentration- ug/m³ - is the amount of contaminant mass contained in a cube of “air” one meter tall, by one meter wide, by one meter deep.   The national average background-or baseline level-ranges from 3.25 ug/m³ to over 21 ug/m³.

How big is the plume?

·         Recent plume maps by Wasatch and Remedy are included as a link.   

Vapors: 

·         If you want me or someone from Wasatch to come by and check your home be sure to snuff out all candles, remove all air fresheners, ensure no cigarette smoke is in the house, try not to bring dry cleaning home, make sure water trap drains are full of water by running water in the drains, do not spray cleaners like pledge, do not use home fresheners, try not to work in the garage or pump gas the day you call etc..

If you have legal questions regarding this issue, or if you feel your real estate equity has been impacted please contact the Gunnison City Attorney, Stirba and Associates:

(Mr. Bret Rawson can be reached at (801) 364-8300)

Useful Links:

Useful Links:

Remedy, Inc. Website  www.remedyinc.net

Letter_Webapage_update_Feb 2010

PDF Wasatch_1241-026A Quarterly GW Benzene Monitor Map_Nov 2009

PDF_Gunnison_Nov 2009 _GW_benzene_rev2 Model (1)

PDF_Gunnison_Nov 2009_GW_GRO_rev2 Model (1)

Tier 1 Clean Up Levels

Suspected Second Hole in Tank