Department of Water Supply
"By Water All Things Find Life"
Hamakuapoko Wells

History of the Wells Filtration Water Quality Data Other Information

Read the Ordinance banning the use of the Hamakuapoko Wells for human consumption.

History of the Hamakuapoko Wells

Hamakuapoko Wells #1 and #2 were drilled in 1992. The wells were the first of six phases in the long-range project to develop 16 million gallons per day of water in the East Maui area for the Central system. According to the September 1992 East Maui Water Development Plan, "Phase 1: Develop 2 MGD (million gallons per day) water in the Hamakuapoko area and a transmission system to Paia. Changes in the existing water system will allow gravity flow of water toward Kahului."

The wells were first used in 1999 as an additional source during times of drought emergency for the Upcountry water system. They have been used intermittently between 1999 and 2004 for drought emergency Upcountry.

In December 2003 a consent decree settled the lawsuit between "The Coalition to Protect East Maui Water Resources and the Board of Water Supply." The decree limited the East Maui Plan to the two Hamakuapoko wells, the treatment facilities, and the transmission line to Paia. This resolved the need for an environmental assessment (EA) for use of the water in the Central system.

Funding for the EA to send the water Upcountry is included in the Fiscal Year 2006 budget.

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Granular Activated Carbon Filtration

The filtration system at the site is Granular Activated Carbon (GAC), which is considered the best available technology for DBCP removal.

GAC is used in many areas: California - Fresno, Ceres, Modesto, Reedley, Ripon, Turlock, Upland; Oahu - Mililani, Waipahu, Kunia, Haleiwa; and on Maui - Maunaolu, Kaanapali, Napili Well "A" and Hamakuapoko.

There are two GAC filters at Hamakuapoko. The water flows through both filters in series - one after the other - before going into the storage tank. Each filter has sampling points at four different locations to insure DBCP, EDB and TCP are removed to non-detectable levels (ND). Note that current science does not allow measurements to "zero." The closest to "zero" is "non-detectable."

All of the treatment and disinfection processes follow the federal government's Environmental Protection Agency (EPA) rules. The Hawaii State Department of Health enforces these rules.

How does it work?
Untreated well water passes through activated carbon on to which the contaminants adhere - a process known as adsorption. Treatment involves passing water through two beds of activated carbon.

The carbon has been specially treated so that it attracts contaminant molecules, similar to how iron particles are attracted to, and held by, a magnet.

The carbon has an incredibly large surface area for contaminants to collect. The contaminants in water are adsorbed (or held) to the surface of carbon by surface attractive forces similar to gravitational forces.

Water contaminants adsorb because the attraction of the carbon surface for them is stronger than the attractive forces that keep them dissolved in solution.

How do is the water quality monitored?
Water samples are taken from nine different points in the treatment process.
1. before filtration
2. GAC #1 at 25% of the carbon
3. GAC #1 at 50%
4. GAC #1 at 75%
5. GAC #1 at 100%
6. GAC #2 at 25%
7. GAC #2 at 50%
8. GAC #2 at 75%
9. GAC #2 at 100%
This way trends can be monitored for water quality and the DWS can make plans to replace the carbon as soon as we detect any contaminants at the 50% level of the first GAC unit. By doing this we can ensure that contaminants are not detected in the finished water.

Keep in mind the water goes through BOTH GAC units!

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Water Quality Data

DBCP or 1,2dibromo-3-chloropropane has been found in the wells. It is a synthetic organic chemical. DBCP is a carcinogen that caused sterility and infertility in male workers at the manufacturing plants and is a cancer risk to consumers of produce with DBCP residues. DBCP was used in Hawaii until 1984.

DBCP has been detected in wells in throughout the country - California, Florida, Alabama, South Carolina, Kentucky, Arizona, New York, Illinois, North Carolina, Indiana, and New Jersey.

The other chemicals that were used on the pineapple fields and are now found in the wells are EDB (ethylene dibromide) and TCP (1,2,3trichloropropane).

Nitrates are also found in the wells and range between 3 milligrams to 6 milligrams per liter. The maximum allowable level is 10. GAC does not remove nitrates. The DWS will install a continuous nitrate monitor prior to use.

Water Quality data collected October 2004

Data H'poko 1
pre-treatment		 H'poko 2
pre-treatment		 GAC
50% bed depth		 GAC
75% bed depth		 GAC
#1 effluent		 GAC
#2 effluent		 GAC
combined effluent		 Kamole WTF
Haliimaile
Date: October 6, 2004
Nitrate+Nitrite as N 3.5 mg/L 3.5 mg/L
1.6 mg/L
pH 8.08 7.87
EDB ND ND ND ND ND ND ND ND
DBCP ND 0.17 ug/L ND ND ND ND ND ND
TCP 0.34 ug/L 0.30 ug/L ND ND ND ND ND ND
Date: October 25, 2004
Nitrate+Nitrite as N 3.8 mg/L 5.2 mg/L
pH 8.1 7.86

Hamakuapoko Wells
Water Quality Levels for EDB, DBCP, TCP and Nitrate
Criterion Concentration (parts per billion)

Chemical Federal MCL (1) State MCL (2) Long-term goal (3) GAC Effluent (4)
EDB 0.05 ug/L 0.04 ug/L 0.002 ug/L ND
DBCP 0.20 ug/L 0.04 ug/L 0.04 ug/L ND
TCP none 0.60 ug/L 0.80 ug/L ND
Nitrate 10.00 mg/L 10.00 mg/L 10.00 mg/L 4-6 mg/L

EDB = ethylene dibromide (1,2-dibromoethane), a chemical formerly used to fumigate the soil in pineapple fields
DBCP = 1,2-dibromo-3-chloropropane, a chemical formerly used to fumigate the soil in pineapple fields
TCP = 1,2,3-trichloropropane, a chemical structurally related to DBCP, used to fumigate the soil in pineapple fields
Nitrate (measured as Nitrogen), used as a fertilizer for row crops

(1) Federal MCL - US EPA Maximum Contaminant Level. The highest level allowed in drinking water
(2) State MCL - State of Hawaii Department of Health Maximum Contaminant Level. State MCL's can be equal to or stricter than federal standards
(3) Long-Term Goal - This concentration represents a desirable level at which lifetime exposure is without significant risk, that is, a virtually safe dose (Tardiff and Turnbull, December 1985)
(4) Levels measured after filtration

ug/L = micrograms per liter or parts per billion
mg/L = milligrams per liter or parts per million
ND = not detected

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Other Information

Read the letter from the Mayor to the Council regarding pending prohibition on use of Hamakuapoko wells.

For more information on contaminants, go to the Environmental Working Group National Tap Water Quality Database