10 Biggest Mistakes Groundwater Remediation R1

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

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


The Nielsen Environmental Field School, Inc.
2012 North American Environmental Field Conference & Exposition

AVOIDING THE 10 BIGGEST MISTAKES
IN GROUND-WATER REMEDIATION



John Scripter, Technical Sales

JohnS@GeotechEnv.com
800.228.2310



Geotech Corporate Headquarters
Denver, Colorado USA

…a world leader in environmental technology,
manufacturing and product training since 1978.
www.GeotechEnv.com


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-
site



• 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
• Standard Tampa • Denver calculated at
calculated at Sea Level 5,280’
– Temp 68° F – Temp 68° F
– Air pressure 14.7 PSI (sea – Air pressure 12.2 PSI
level) (.00005 PSI / foot
elevation)
– 100 ACFM (actual CFM) – 82 ACFM (actual CFM)
– 100 SCFM (standard CFM – 100 SCFM (big difference)
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.


10 Biggest Mistakes Groundwater Remediation R1

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