Master of Science

A study was undertaken to evaluate the effectiveness of alum coagulation, permanganate and chlorine dioxide preoxidation, and powdered activated carbon pretreatment for the removal of trihalomethane (THM) precursors from the Po River, the Ni River and the Ni River Reservoir waters in eastern Virginia. The effects of temperature and storage were also studied. Samples were collected on two occasions and were analyzed for total organic carbon (TOC), THM-formation potential (THMFP), color, UV-absorbance and pH. Samples were then treated in a manner similar to that ina typical water treatment plant by bench-scale jar tests and reanalyzed for TOC, THMFP, color and UV-absorbance. The results indicate that the THMFPs of both Po and Ni River waters were high. Alum coagulation at pH 6.0 reduced TOC by as much as 48 percent while THMFP reductions averaged 63 percent. Permanganate preoxidation at dosages as high as 2.0 mg/L reduced THM precursors by less than 14 percent. Powdered activated carbon at 10 to 20 mg/L reduced THM precursors by less than four percent. Application of 2 mg/L chlorine dioxide reduced THM<-precursors by eight percent over what could be achieved by alum coagulation alone. A major conclusion was that treatment of the Po River by conventional measures to meet existing and future drinking water standards for THMs would be difficult, if not impossible. / Master of Science

The conclusions of this survey should be considered with the fact in mind that it was in the nature of a preliminary or reconnaisance rather than a final survey. While the authors feel that the conclusions drawn are justified by their test results it should be realized that the data is not comprehensive or complete enough to draw any final conclusions regarding the overall sanitary condition of the lake. Considering the test results, the following conclusions and recommendations are presented: 1. There is evidence of pollution throughout the portions of the lake tested, during the extent of the sampling season. 2. The pollution at Sections 1, 2, and 3 showed a tendency of being localized in relatively narrow well defined channels, while that at Section 4 seemed to be dispersed throughout the cross section. 3. The water in the vicinity of the V.P.I. property and the upstream part of the state park property would, in general, meet the various bacteriological requirements of health departments for bathing areas. 4. The water just below the proposed bathing area at the downstream part of the state park showed evidence of pollution in amounts which might make the use of this area questionable unless careful control is maintained by frequent bacteriological tests. 5. There was no evidence of a trend or fluctuation in pollution during the period of study. 6. In general, there was no correlation between the results of the bacteriological tests and the chemical and physical results. / M.S.

Study of two sections of a stream associated with highways of different traffic densities and a third section used as a reference area demonstrated that concentrations of lead, nickel, cadmium, and zinc in sediments, benthic macroinvertebrates, and fish were highly correlated to the amount of traffic associated with the respective sampling site. Highest sediment concentrations of lead, nickel, and zinc occurred in spring, most likely due to accumulation and subsequent runoff in snow. Accumulation of these metals in invertebrates and fish is probably a more· time-dependent process. Concentrations in these organisms were related to physiological and ecological factors as well as the relative availability of each metal at each study site. The major physiological factor influencing accumulation of heavy metals in stream organisms seemed to be the relative amount of tissue with a high affinity for these metals in each organism. The major ecological factor influencing accumulation of heavy metals seemed to be the relative amount of sediment association characteristic of each species. Invertebrates contained the highest levels of each metal, followed by bottom-oriented fish with a small proportion of muscle, while species of fish with a large percentage of muscle inhabiting the upper water column contained the lowest concentrations. Biomagnification of these four metals was not demonstrated. Significant bioaccumulation of lead, nickel, and cadmium in bone; and cadmium in the kidneys of fish was found to occur. Major biological uptake of lead, nickel, cadmium, and zinc in these organisms was via water and/ or sediment-water interaction. / Master of Science

M.S.

Motorboat activity can adversely effect the water quality of a reservoir. The potential impacts of motorboat activity on the Occoquan Reservoir's water and sediments were evaluated. Thirty-one sites, both marina and nonmarina, along the reservoir were selected. Sediment and water samples were collected in 1990, during peak boating activity, and in October, during low boating activity. The objectives of this research were to determine the concentrations of polyaromatic hydrocarbons (PAHs) in water and sediment samples and to determine if their presence was related to boating activity. The presence of other non-PAH organics was also determined. Contours of total PAH concentrations, boxplots and ANOVA analyses between marina and nonmarina sites were generated from gathered data in order to meet these objectives. PAHs were present in the water during peak boating activity and not detected during low boating activity, while PAHS were detected in the sediments during both sampling periods. The aqueous and sediment PAH concentrations were at or below the method detection limits. The PAH ratios of unalkylated PAHs confirmed PAH contamination to be of a combustion source. Boating was shown to be a PAH source to the water column, during peak boating activity, throughout the entire Occoquan Reservoir. An ANOVA between marina and nonmarina sites for the aqueous total PAH concentrations did not show a significant difference in June. This implied that boating did not cause any localized impacts to the water column and that there was another PAH source. There was a significant difference for total PAH concentrations between the marina and nonmarina sites for the sediment samples in June, showing localized impacts at marina areas due to boating activity. PAH profiles showed urban runoff as another major contributor to the PAH concentration in the water and sediments. The urbanization of Hooes Run and the hydrology of the reservoir caused urban runoff to impact localized areas. Finally, atmospheric deposition was also a source of PAHs to the sediments throughout the entire reservoir. Non-PAH organics found in a few of the water and sediment samples were the pesticides atrazine and p,p'-DDD, alkyl phosphates, alcohols and C₈ to C₁₂ hydrocarbons. / Master of Science

The possibility of the existence of an iron-organic interaction in Harwood's Mill Reservoir contributing to a problem with floe formation after chlorinating filter-applied water was investigated. Shortened filtration-cycle times resulted when the filter-applied water contained the floc. The effects of varying pH, temperature, alum dosage, and oxidant addition on organic and meta.ls removals were examined with jar tests. Ultrafiltration analyses were performed to determine with which molecular size range of organic matter the iron may have been associated. Particle-size analysis was used to further examine the chlorination phenomenon. The low iron concentrations in the raw water were removed easily under any experimental condition. Organic removal, however, was optimized by alum coagulation ( 50 mg/L) at pH 5. 5 and a preoxidant dose of 2 mg/L. Improvements in organics removal over that of the WTP suggested that poor organic removal contributed to the floe-formation problem. / M.S.

The objective of this study was to develop a comprehensive, basin-wide, water-quality-planning model using system dynamics methodology. Later, the model was to be interfaced with a more conventional system dynamics model: one simulating social, technological, economic, and political interactions. By doing so, it is envisioned that such management policies as zoning, abatement facilities, and best management practices may be simulated together. / Master of Science