The document summarizes the ongoing groundwater contamination issue in Hinkley, California. Pacific Gas and Electric operated a compressor station that contaminated the local groundwater with chromium. This led to a major lawsuit and settlement. The contamination plume has since expanded and five options are being considered for cleaning it up. The options involve different combinations of extracting, treating, and containing the groundwater to reduce chromium levels. They involve tradeoffs between speed of cleanup, costs, and environmental impacts. A thorough analysis is needed to evaluate the social and health costs and benefits to determine the best approach.

1. Hinkley Groundwater
Contamination
It’s not over: it’s just the beginning….
Masahiro Yagi
Environmental Economics (ECON 360.01)
Prof. Diya Mazumder

2. Erin Brockovich
• Erin Brockovich (2000),
successfully highlighted the
issue of environmental
conflict by depicting the case
of Hinkley Groundwater
Contamination.
• http://abcnews.go.com/US/eri
n-brockovich-fighting-
neighbors-toxic-drinking-
water/story?id=15120603#.U
LxMUYNQVnc

3. History of Hinkley Groundwater Contamination
• Pacific Gas & Electric (PG&E)
operates a compressor station in the
town of Hinkley in San Bernardino
County, California
• An underground plume of a chemical
called Chromium(VI )
• Lawsuit led by a lawyer Erin
Brockovich to represent 600 Hinkley
residents against the PG&E
• In 1996, PG&E agreed to pay $333
million to those who claimed health
issues due to the contamination,
which was the largest settlement in
the history of the U.S.

4. The case has not ended yet!
• The area of chromium(VI) contaminations has expanded in recent years.
• Currently, Hinkley residents have been offered 5 final cleaning up options.
• Regional water board and residents are expected to choose a clean-up option by
January 2013.
“What is the best clean-up option for the Hinkley?”

5. No Project 4B 4C-2 4C-3 4C-4 4C-5
Years to 50 ppb Cr6 6 6 6 4 3 20
Years to 3.1 ppb Cr6 Not Estimated 40 39 36 29 50
Years to 1.2 ppb Cr6 Not Estimated 95 90 85 75 95
Maximum Agricultural Units* (acres) 182 446 575 575 1394 575
Maximum groundwater pumping
rate (gallons per minute, annual
average)
1100 2395 3167 4388 4388 3167
Subsurface (in-situ) treatment? Yes Yes Yes Yes Yes Yes
Avobe-ground (ex-situ) treatment? Not currently No No Yes, 2 locations
plume core and
northern area
No Yes, 1 location
near plume core
Key features PG&E continues
existing cleanup
without
expansion.
(Alternative
required by
CEQA). Doesn’t
address full
extent of plume.
Expands AUs and
in-situ zones
over No Project.
Groundwater
extraction is not
year-round.
Up to 9 AUs, year-
round
groundwater
extraction using
AUs with winter
crops added.
Similar to 4C-2,
but year-round
groundwater
extraction using
2 aboveground
treatment
facilities instead
of AUs in winter.
Up to 25 AUs for
year-round
groundwater
extraction Most
extensive plume
capture zone,
fastest cleanup,
but most aquifer
drawdown.
Aboveground
treatment in
plume core
(instead of in-
situ). Number of
AUs similar to 4C-
2. Removes all
forms of
chromium from
the high
concentration
plume area.
Feasibility Study Estemiated Costs
($million)
N/A 84.9 118 276 173 171
Impact Level (1 is low, 6 is high)
Groundwater Drawdown 1 2 4 5 6 3
Aquifer Compaction 1 2 4 5 6 3
Plume Bulge 1 2 3 5 6 3
TDS/Uranium byproducts 1 2 3 5 6 3
Mn, As, Fe byproducts 1 4 4 3 4 2
Nitrate byproducts 1 2 3 4 4 3
Wildlife habitat ot loss 1 2 3 5 6 4
EIR Alternative
Element

6. Groundwater extraction
contaminated groundwater is pumped from the
subsurface (also called the aquifer) to contain
the groundwater plume from further migration
and is used in one or more of the following
ways:

7. Agricultural treatment
(land treatment or agricultural units)
• extracted groundwater is used to irrigate
livestock forage crops, such as alfalfa. Cr(VI) in
the extracted groundwater is hanged to solid
trivalent chromium as it infiltrates through the
soil. Cr(VI) is the toxic form of chromium, while
Cr(III) has very low toxicity.

8. Above-ground treatment
(ex-situ treatment)
• Where the extracted groundwater is
processed through a water treatment plant to
remove all forms of chromium (trivalent and
hexavalent), which is transported off-site for
disposal.

9. Subsurface treatment
(in-situ treatment)
• food-grade carbon substances, such as
ethanol, are injected into the groundwater
within the aquifer to turn the hexavalent
chromium into trivalent chromium which is
left in solid form at the water table.

10. Subsurface freshwater injection
• this method creates barriers of freshwater
within the aquifer to deflect the contaminated
groundwater towards another direction.

11. Combinations

12. Impacts
Water Supply:
• Drawdown - aggressive groundwater
extraction to contain and clean up plume lowers
groundwater levels
• Compaction - loss of aquifer water storage
capacity due to groundwater drawdown

13. Impacts (continued)
Water Quality:
•Cr plume “bulge” – injection or irrigation
causes temporary bulge during remediation
•Byproduct formation - increased in-situ
treatment increases manganese, arsenic, iron in
groundwater

14. Impacts (continued)
Biological Resources:
• Restricted tortoise movement - AUs may limit
desert tortoise movement through valley
• Loss of wildlife - could be disturbed, killed
during construction/operation

15. Benefit-Cost Analysis
• Benefit
– Agricultural benefit
– Health benefit Cr[6]
• Cost
– Engineering Cost
– Social Cost
• Health (Nitrate, Uranium)
– Worst case scenario

16. Focus: Health Risk
• Health risk of Cr 6
- Lung cancer
- Allergic dermatitis
- Oral cavity, and intestine tumors
• Health risk of bi-products by clean-up
– Nitrate
– Uranium
– Total Dissolved Solids(TDS)  Not available
– Manganese Not significant
– Arsenic  Not significant
– Iron Not significant
High Blood Pressure, Diabetes, non-Hodgkin’s
lymphoma, Birth defects
 Bone cancer, Kidney damage
Social
Benefit
Social Cost

17. Social Benefit
Cancer Risk
• Current Cr[VI] in Hinkley: 7.8ppb
• Objective: 1.2ppb
• 1.2ppb = 2 in 1 million has a cancer risk if
he/she drinks 2 liters of water that contains
this level of Cr[VI] for 70 years.
1-2ppb
7.8ppb/0.06ppb…
130 in 1 million have cancer
risk (when Cr[VI] = 7.8ppb)
1.2ppb = 2 in 1 million have a
cancer risk
 130 – 2 = 128 people are
saved
Social Benefit = costs of cancer
treatment x 128

18. Social Benefit
• extracted groundwater is used to irrigate
livestock forage crops, such as alfalfa
• Benefit
-profit for the local farming community and using
the resource for its current highest productive use
-potentially reducing the import of potable water
for agriculture
-job opportunities for local farmers

19. • Uranium
- Increase from 4ppb to app. 80.5ppb (Worst
Case Scenario)
• Nitrate
- Increase from 10ppm to 10.5ppm
Social Cost
Bone Cancer + Kidney damage = Social Cost
2.683 in 1 million
= cancer / kidney damage risk
1.5 in 1 million have
health risks
High blood pressure + diabetes + non-Hodgkin’s
lymphoma = Social Cost

20. Conclusion
No Project 4B 4C-2 4C-3 4C-4 4C-5
agricultural profit 7,382,437 18,091,026 23,323,633 23,323,633 56,544,598 23,323,633
health benefit (cr6) N/A 2,815 2,864 2,913 3,015 2,815
total benefit 7,382,437 18,093,841 23,326,497 23,326,546 56,547,613 23,326,448
engineering costs N/A 84,900,000 118,000,000 276,000,000 173,000,000 171,000,000
health cost (uranium
and nitrogen) 342 410 478 613 680 477
total costs 342 84,900,410 118,000,478 276,000,613 173,000,680 171,000,477
benefit-cost (7,382,095) -66,806,569 -94,673,981 -252,674,067 -116,453,067 -147,674,029

21. Discussion
• People’s perception toward risk
• Influence of media
• Politics(Regional water association, PG&E)
• Different preference for the clean-up option

22. Reflection upon research
• Difficulty of monetizing social and
environmental cost/benefit
• Uncertainty