WRRC Special Reports

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Now showing 1 - 10 of 36
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    WRRCSR No. 97-02 Technologies and Strategies Used in Okinawa: Third Symposium on Hawiai/Okinawa Water Resources
    (Water Resources Research Center, University of Hawaii at Manoa, 1997-08)
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    WRRCSR No. 96-01 Assessment of Groundwater Models: 1994
    (Water Resources Research Center, University of Hawaii at Manoa, 1995-07)
    Assessment of groundwater models was the focus of the Pacific Northwest/Oceania conference held on March 21-23, 1994, at the Turtle Bay Hilton, Oahu, Hawaii. This conference differed from other modeling meetings by focusing on critical assessment-to what extent models have been adequate to address water, land, and environmental problems and have been able to advance scientific understanding of groundwater systems. These needs have been made acute by the very popular use and sometimes misuse of computational (numerical) models in recent years. Consequently, the crucial issue is, what is needed in the next generation of models in light of the critiques?
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    WRRCSR No. 9:23:83 Rainfall Frequency Study for Oahu: Option 1--Preparation of Rainfall Frequency Maps
    (Water Resources Research Center, University of Hawaii at Manoa, 1983-09) Giambelluca, Thomas W. ; Lau, L. Stephen ; Fok, Yu-Si ; Schroeder, Thomas A.
    Annual maximum rainfall series at 157 gages were used to evaluate extreme value rainfall. Daily fixed-interval data were adjusted by a factor of 1.143 to represent true maxima. Records of short-term stations were extrapolated by regional analysis. Gumbel extreme value, log-Pearson Type III, and log-normal distributions were tested for applicability and found to have approximately equal goodness-of-fit. The Gumbel distribution was used, fitted by the method of moments. A topographically based interstation interpolation model was developed as an aid in mapping maximum rainfall for durations of 1-, 6-, and 24-hr and return periods of 2-, 10-, 50-, and 100 years.
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    WRRCSR No. 9:19:86 Rotating Biological Contactor Pilot Study: Fort Kamehameha Wastewater Treatment Plant, Pearl Harbor, Hawaii
    (Water Resources Research Center, University of Hawaii at Manoa, 1986-09) Dugan, Gordon L. ; Takiguchi, Dean K.
    A self-contained pilot unit (including primary and secondary sedimentation) complete with electric motor driven plastic discs (surface area approximately 500 ft2), located at the U.S. Navy's 7.5 mgd Fort Kamehameha Wastewater Treatment Plant (WWTP) at Pearl Harbor, O‘ahu, Hawaii, was operated from July 1985 to July 1986 at four different operating modes: hydraulic loadings of 1.5, 3.0, and 5.0 gpd/ft2 (flat disc area) with discs exposed; and 5.0 gpd/ft2 with discs covered. The influent for the RBC unit was primary clarifier effluent, which was very brackish for wastewater (4000-5000 mg/l chloride). In addition, wastewater from industrial-type operations that use and discharge controlled/treated concentrations of heavy metals were received at the WWTP. The median effluent BCDs concentrations for the first two hydraulic loading rates (1.5 and 3.0 gpd/ft2) were respectively 2.0 and 8.0 mg/l, with corresponding respective median suspended solids values of 8.0 and 7.5 mg/l. These values were comparable with the present WWTP operation utilizing the activated sludge process. Hydraulic loadings at 5.0 gpd/ft2 provided median effluent BOD5 concentrations in the 30 to 35 mg/l range. Heavy metal concentrations in the wastewater flows of the WWTP and RBC unit were considerably below the level of concern, while some accumulation of heavy metals was noted for the higher concentrations of suspended and settled solids--the mixed liquor suspended solids and the raw and digested sludge. Replacing the existing activated sludge component with an RBC component being hydraulically loaded at 3.0 gpd/ft2 would require an estimated capital cost of approximately $2,500,000, which would require nearly 20 years to repay in electrical cost savings, based on a 10¢/kWh electrical cost, that increases in cost at an annual rate of 5%, and an interest rate of 8% compounded annually.
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    WRRCSR No. 7:85 Subsurface Water and Soil Quality Data Base for State of Hawai'i, Part 1
    (Water Resources Research Center, University of Hawaii at Manoa, 1985-07) Oki, Delwyn S. ; Giambelluca, Thomas W.
    In recent years, various chemical contaminants have been detected in Hawai'i’s groundwater sources. Several agencies in Hawai'i have been monitoring the groundwater quality for the contaminants, dibromochloropropane (DBCP), ethylene dibromide (EDB), and trichloropropane (TCP). In addition, several agencies have investigated the movement of these compounds in the soil at various sites on O'ahu and Maui. The Data Base which accompanies this report represents an effort to compile all available results from these agencies and to organize than into a uniform, computer-readable system in order to facilitate research on the extent, movement, and persistence of contaminants in the soil and groundwater of Hawai'i. Results from analyses performed on water samples taken from wells, springs, and from points within various water distribution systems throughout the state, as well as results from analyses performed on soil samples taken at sites on O'ahu and Maui are included herein. The primary emphasis of the Data Base is on the compounds DBCP, EDB, and TCP, but other pertinent compounds are also included. A data summary table of the maximum concentrations of these three compounds present in well and spring water samples is included as a part of this report.
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    WRRCSR No. 07:21:87 Aquifer Recharge by Irrigation with Primary Effluent: Field Experiments with California Grass and Sugarcane
    (Water Resources Research Center, University of Hawaii at Manoa, 1987-07) Lau, L. Stephen
    The 'Ewa caprock aquifer has been a long-standing water source for southern Oahu, but the freshwater viability of the aquifer is being threatened with a gradual increase in the salinity level of pumped aquifer water in recent years. Concern over enhancing the freshwater quantity and quality of the 'Ewa caprock aquifer prompted a consortium of six agencies to sponsor a demonstration “Groundwater Recharge with Treated Wastewater Effluent” project.
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    WRRCSR No. 7.5:85 Drilling Program and Pesticide Analysis of Core Samples from Pineapple Fields in Central O'ahu
    (Water Resources Research Center, University of Hawaii at Manoa, 1985-11) Peterson, Frank L. ; Green, Kim R. ; Green, Richard E. ; Ogata, Janice N.
    As part of the ongoing research of the WRRC Subsurface Water Quality Project, a drilling program was begun in October 1985 to collect soil and saprolite core samples from sites located in central O‘ahu pineapple fields. Samples were analyzed for concentrations of fumigant pesticides used in pineapple cultivation. These included EDB (ethylene dibromide), DBCP (dibromochloropropane), and TCP (trichloropropane) which originated in the pesticide Shell DD applied over 30 years ago. Results from the analyses are expected to provide current information on the subsurface movement of these toxic organic compounds. Thus far, pesticide analyses have been completed for five test boreholes in Dole fields (D-4201A, D-4201B, D-4213B, D-4111W, D-4101), in which residual pesticides have been detected in the first three. None were detected in boreholes D-4111W and D-4101. Additional core samples were collected and preserved intact from the same boreholes for physical, hydraulic, and mineralogical measurements to be performed at a later time. These intact or "undisturbed" core samples can be used to characterize and relate the structural and mineralogical properties of the samples and to determine the importance of such properties on the deep percolation of water and the associated transport of residual pesticides.
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    WRRCSR No. 7.4:85 Deep Percolation of Water from Pineapple Fields
    (Water Resources Research Center, University of Hawaii at Manoa, 1985-11) Giambelluca, Thomas W. ; Oki, Delwyn S.
    Efforts are being made to identify the sources, concentrations, spatial extent, movements, and rates of degradation of recently detected groundwater contaminants in Hawai'i. A spatially detailed evaluation of the time series of water percolation is required so that leaching from the top soil, downward transport through the profile, and eventual movement of the pesticides within the basal groundwater may be estimated. Using the water balance method, the 1946 through 1983 sequence of downward percolating water will be estimated for each present and former pineapple grating area of central O'ahu. Thus far, work on this project has focused on land-use identification, parameter evaluation, and data gathering. Results obtained using the same model in a previous study indicate that ET-suppression by pineapple causes percolation to be significantly higher than that experienced under a natural vegetative cover. This may account for the unexpected movement of these chemicals through the great thickness separating the pineapple fields from the basal water table.
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    WRRCSR No. 7.3:85 Spatial and Temporal Distribution of Contaminated Basal Water in Southern and Central O'ahu Aquifers
    (Water Resources Research Center, University of Hawaii at Manoa, 1985-11) Oki, Delwyn S. ; Giambelluca, Thomas W.
    In recent years, several pesticide-related contaminants have been detected in the basal waters of southern and central O'ahu aquifers. Dibromochloropropane (DBCP) and ethylene dibromide (EDB), two soil fumigants which were previously used by pineapple growers in southern and central O'ahu, have been discovered in several wells in the area. A third contaminant, trichloropropane (TCP), which is an impurity of the soil fumigant DD, has also been detected in a number of wells. DBCP, EDB, and TCP are of particular concern to state public health officials due to the known and possible unknown health effects associated with these compounds. This is especially true for the Pearl Harbor Aquifer, which is the major potable water source for Honolulu. Thus, it is imperative to have an understanding of the extent and movement of the contamination. The locations of the contaminated well sites appear to be correlated with the areas of past and present pineapple cultivation when the ambient groundwater flow pattern is taken into consideration. In addition, several significant pipeline leaks of petroleum products (aviation fuels) in the vicinity may have contributed to the EDB contamination. An analysis of the temporal variation of contamination in selected wells indicates no significant fluctuation in contaminant levels over a one-year study period from 1 September 1983 to 1 September 1984.
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    WRRCSR No. 7.2:85 Exploratory Study Using Water Disinfectants to Remove EDB from Clean Water
    (Water Resources Research Center, University of Hawaii at Manoa, 1985-11) Fujioka, Roger S. ; Narikawa, Owen T. ; Yoneyama, Bunnie S.
    A reliable and practical method is required to reduce the concentrations of hazardous chemicals (EDB, DBCP, TCP) which have been detected in some of the groundwaters used for drinking on O'ahu. This study evaluates the feasibility of using high concentrations of water disinfectants to oxidize (reduce) the concentrations of EDB in water. Water seeded with 100 ppt to 20 ppb of EDB were treated with various doses of disinfectants (chlorine, chlorine dioxide, hydrogen peroxide, ultraviolet light, ultraviolet light plus hydrogen peroxide). The concentrations of ED3 in water samples before and after treatment with these disinfectants were determined using liquid-liquid partitioning to extract the EDB and gas chromatography to measure the concentrations of EDB. The results of this study indicated that 5 to 5,000 mg/l of chlorine and 2 to 50 mg/l of chlorine dioxide are incapable of reducing the concentrations of EDB in water. The ability of 3 and 10% hydrogen peroxide to reduce the concentrations of EDB in water was erratic. In some experiments, no reduction of EDB was observed while in other experiments up to 45% of the EDB was apparently oxidized. Ultraviolet (UV) light alone removed only 10% of the EDB. The most promising system was the use of UV light plus 3 or 10% hydrogen peroxide. When this system was used, 33 to 75% of the EDB in the water was reduced. Thus, further studies assessing the feasibility of using UV light and hydrogen peroxide to remove and other toxic chemicals in water is recommended. However, hydrogen peroxide is available in a liquid state at 30% and therefore it is impractical to treat large volumes of water with high concentrations of hydrogen peroxide. In this regard, ozone is chemically similar to hydrogen peroxide but is more reactive. Ozone can also be generated as a concentrated gas and apparatus for the treatment of large volumes of water with UV light and ozone is commercially available. It is therefore recommended that further studies be done to determine the feasibility of using UV light and ozone to remove the concentrations of EDB in water.