10 Biggest Mistakes Groundwater Remediation R1

2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com

GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTSGROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS

AVOIDING THE 10 BIGGEST MISTAKES

IN GROUND-WATER REMEDIATION

The Nielsen Environmental Field School, Inc.

2012 North American Environmental Field Conference & Exposition

John Scripter, Technical Sales

JohnS@GeotechEnv.com

800.228.2310

www.GeotechEnv.com

…a world leader in environmental technology,

manufacturing and product training since 1978.

Geotech Corporate HeadquartersDenver, Colorado USA

� an environmental industry

products leader since 1978

� partners with federal, state,

local and international

government agencies

� over 20,000 private sector

clients worldwide

� distribution in 72 countries

� provides products and product

training to colleges, universities

and technical schools around the globe

Audience Introductions

• Name

• Company name

• Experience with groundwater remediation

Defining the Problem

“If I had one hour to save

the world I would spend

fifty-five minutes defining

the problem and only five

minutes finding the

solution.”

#10: Mineral Build-up

• Builds up on air stripper

components and pipes

• Builds up on electrodes

in pump controllers

– Shuts off the system

– Inhibits conduction

Managing Mineral Build-Up

• Laboratory analysis of soil chemistry

• Laboratory analysis of water chemistry

• Minimize aeration of liquids. Where build-up is anticipated, build in cleanouts for easy maintenance. Cannot really prevent.

• Plan system maintenance

• Add clean outs

• May need to change technology

• May need to add a sequestering agent to process flow

Case History/Example

• Low Profile Air Stripper systems experience

frequent fouling of the bubble plates due to

high iron/inorganics. This causes a lower

stripping efficiency due to lower air flow from

the blower. The addition of a sequestering

agent helps to keep the inorganics in

suspension until after the air stripper.

#9: Temperature

• Temperature affects Henry’s Law (vapor phase) because it makes contaminants more likely to volatilize.

• pH probes will freeze and break when too cold

• Pumps will freeze and break when too cold

• If water sampling equipment is not completely purged and dried it can freeze and break

• PID lamps fog up when moved from warm to cold

• FID’s have problems lighting in cold or windy environments

• Heat can also be problematic, causing equipment to overheat, fail and even be ruined

Temperature Issue Prevention

• Understand your site characteristics, including temperature

• Store equipment in a heated area, not in a vehicle or shed

• Check the operating temperature specifications on your equipment if you feel there may be an issue

• Install below frost line and micro seeps for frost protection above ground

• Don’t leave meters or pumps in sheds or work vehicles if freezing is likely to occur overnight.

• Heat trace water discharge lines where possible.

• Ship “do not freeze” or empty water from cavities if possible.

• Dual pumping system at a refinery in

northeast was pulled from the well for

maintenance. Pumps were left out of the well

for a period of time, water was not drained

therefore froze, expanded and cracked/split

the SST water jackets and reservoirs.

#8: Viscosity

• Product characteristics not considered in equipment purchase

• Seasonal variability with product recovery

• Product too thick for remediation system to pump/sparge

• Using in-situ heat enhancement excludes electric pumps

• Product viscosity tested at room temperature or worse, at surface temperature in sun– Much less viscous than at groundwater temperature

Viscosity

• Determine vapor pressure of contaminant to

establish best possible equipment for the job

• Be sure to approximate actual conditions on-

• Bunker C, #6 Fuel, Creosote are typically too

viscous for most pumping systems to operate

consistently. Sensors get coated and then can

no longer differentiate between

water/product.

#7: Air Flow (CFM)

• Product not reaching surface

• Altitude not considered

Example Tampa vs. Denver

• Denver calculated at 5,280’

– Temp 68° F

– Air pressure 12.2 PSI (.00005 PSI / foot elevation)

– 82 ACFM (actual CFM)

– 100 SCFM (big difference)

• Standard Tampa calculated at Sea Level

– Temp 68° F

– Air pressure 14.7 PSI (sea level)

– 100 ACFM (actual CFM)

– 100 SCFM (standard CFM same as actual at standard conditions)

CFM: Very Basically

• If SCFM at sea level is 68°F at 36% relative

humidity.

– Pressure ↓ SCFM ↑– Pressure ↑ SCFM ↓

Establish CFM

• CFM

• Standard Cubic Feet per Minute (SCFM): determines the weight of air to fixed or “Standard” conditions

– At sea level

– 14,696 pounds per square Inch (psia)

– 60 degrees Fahrenheit (°F)

– 0% relative humidity

• Actual Cubic Feet per Minute (ACFM):– Depends on

• Pressure

• Temperature

• Humidity

• Inlet Cubic Feet per Minute (ICFM):– When air passes through the filter there will be a pressure drop.

• With an SVE or Sparge system, if altitude is

not taken into consideration, blowers may be

undersized and will not provide flow, vacuum,

pressure required.

#6: Total Dynamic Head

• Sample is a trickle of what is necessary

• Need to replace pump sooner than expected

Total Dynamic Head

• Calculate trunk line (psi issue)

• Calculate length of tube, not a direct

measurement to the sampling location, must

consider the ups and downs of elevation

• Calculate friction of bends

• Calculate friction of tubing vs. hard pipe

Total Dynamic Head Calculation

• A site where a pump was trying to produce 20

GPM, but only had a ¾” discharge line to the

treatment system. Due to the head losses, we

could only get 12-13 GPM. Increasing the

discharge line to 1.5” solved the problem

#5: Water Table Fluctuation

• Volatile and trace metal contaminants are removed from the well when high-flow pumping methods purge the wells dry and highly aerate water samples.

• Pumping saltwater or water not just product

• SVE system is sucking water

• Costs are increased due to treating accumulated water

• Product layer typically disappears at high water levels – Air exposure to smear zones can reduce product recharge

rate when bio growth and heavy oil sludge build up collects on open screen interval

Water Table Fluctuation

• Tidal influences– Floating intake range of travel is insufficient for tidal fluctuations

• Seasonal– Rain events

– Drought

– May have to move from liquid to vapor phase remediation

• Periodic purging or chemical cleaning of smear zone may be required.

• More regular maintenance– Smear zone and additional salt crust deposits reduce product recovery

recharge rate

• Dual Pump system at a site with water table fluctuations. Water pump was allowed to cycle on/off based on hi/lo probe that had 1 foot of travel. Reset the pump in the well so the desired water drawdown was in middle of probe travel. Set the discharge valve so that the pump rate matched the recharge rate. This kept the water table at a steady drawdown allowing more product to enter the well and be recovered.

#4: Salt Water Intrusion

• Inconclusive results from sample findings occur when the pumping test is not of a long enough time period to result in true results of water migration into the well bore from a close proximity body of salt water.

• Brackish water can lead to corrosion of equipment that is not designed for salt water applications

Salt Water Intrusion

• Good hydrogeology analysis is worth the expense and time to avoid wrong assumptions of long term results

• Thorough pump test over several days can help determine the extent of any salt water intrusion into the well

• Introduction of salt water from a nearby body of salt water (salt water intrusion) into a normally fresh water extraction well caused corrosion of a hydrocarbon recovery pumping system designed for a fresh water environment. If a salt water, or brackish water environment was taken into consideration, the equipment could have been purchased with the correct material of construction thus avoiding additional equipment and maintenance costs

#3: Well Construction/Placement

• Locations are incorrect to detect groundwater contamination

• Assumptions made on topography instead of subterranean geology

• Water table column is inaccurate because wells are drilled too shallow to discern true extent of aquifer

• Too few monitoring wells in place in a remediation plan resulting in too little data and too many assumptions

Monitoring Well Placement

• Properly located wells are necessary to

determine extent of plume

• Can be used as a guideline for placement of

recovery wells

• Use of down hole cameras allow for more

accurate representation of groundwater flow

and direction (Boroscope)

Recovery Well Diameter

• Expectations too high for what can be achieved in 2” well.– Pump tests can be limited

– Not designed for long-term applications (sampling only)

• Monitor wells typically not designed and developed for use as remediation groundwater extraction and or hydrocarbon recovery wells

• Remediation equipment options are limited

• Cannot reach the deep water table because what fits in a small well won’t pump at high enough capacity

• Larger remediation wells to allow for:

– More flow into the well

– More tolerance to well screen clogging

– Adequate space for proper pumping/remediation

equipment

– Allows for monitoring of the well without having

to pull out equipment

• Should be rule of thumb:

– If free phase product is found, consider drilling larger wells designed for groundwater remediation

– Properly screened and developed wells enhance groundwater extraction/hydrocarbon recovery

– Drilling a 2” well saves money now, which must be invested later in larger wells or longer O&M, monitoring costs. Longer time to closure

– 2” wells are designed for monitoring and limit the effectiveness of remediation. “Penny Wise-Pound Foolish”

Improperly designed and installed

wells cause:

• Contaminant migration from the surface into a water-bearing zone or between water-bearing

zones if improperly installed

• Chemical alteration of samples due to well casing and well screen materials that are not

compatible with the hydrogeological environment or the anticipated contaminants

• Well sedimentation and turbid samples due to nonstandard well screen or screen slot sizing

• Acquisition of water-level or water quality data from discrete zones is impossible due to

improper length and placement of the well screen

• Alteration of sample chemical ability or damage to the well as a result of inadequate surface

protection measures

• Detection of contaminants and collection of reliable data are prevented because drilling

method contaminated well

Well Design and Installation Tips

• Monitoring wells should be designed & placed

depending on the hydrogeological, geographical

and contaminant-related conditions.

• Use appropriate well screen and materials for

geology and contaminant characteristics

• Drill large enough wells to allow for future

remediation options ( pay now or pay later)

• Client with a 2” monitoring well looking for a pump to deliver 3 GPM at 75 feet TDH. Because of the size and depth of the well, we are limited to a pneumatic submersible that can only produce just under 2GPM at that depth. If the well was 4” or larger then there are several options that can be considered for this application.

#2 Pilot Tests – Lack thereof

• Require assumptions made based on similar

sites which may or may not be valid

• Too short of a duration can lead to

inconclusive, inaccurate or improper data

Pilot Testing

• Properly conducted pilot tests are essential in

gathering data for:

-Determining ROI for any potential remediation technology

-Air flow requirements for SVE & Sparge Blowers

-Water recharge rate for sizing groundwater extraction pumps

-Product recharge rate for sizing and determining type of

product recovery systems

-Sizing and designing solar powered remediation equipment

- Bench test for Bio assay when Insitu bio-remedaition is

considered. Same concept when considering Insitu Chem-OX

• Recently supplied a product recovery system

for a client. They called to report that the

system was not pumping product into the

recovery tank. After some discussions and

tests to determine functionability of the

system, we found that there was no product in

the well for the system to recover.

#1 Site Characterization

• Budget restrictions are probably the biggest factor in limiting proper site characterization

• Proper analysis – the right test for the right contaminants of concern (COC)

• Full Lab Analysis of water and soil(organics and inorganics)

• Viscosity tests for free phase hydrocarbons

• Delineation of Contaminant Plume = Amount of contaminant expected to be remediated

• Product recharge rates calculated based on pump test on entire well, not just on product layer thickness. Separate hydrocarbon bail down test required to determine recharge of product only when a ground water extraction pump is utilized to enhance product recovery

Site Characterization

• Proper site characterization leads to:

-Determining the correct type of remediation technology

-Speeds up site closure

-Saves money

-Determines economic & technological feasibility of any

remediation technology

• Product recharge rates calculated based on

pump test on entire well, not just on product

layer thickness. Separate hydrocarbon bail

down test required to determine recharge of

product only when a ground water

extraction pump is utilized to enhance

product recovery

Summary

• Planning will save money in the long-run

• Be prepared to change your plans based on

accumulating site data. Don’t write yourself

into a corner.

John Scripter, Technical Sales

JohnS@GeotechEnv.com

800.228.2310

10 Biggest Mistakes Groundwater Remediation R1

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