Fidelia N. Nnadi

Performance reconnaissance of stormwater proprietary best management practices

This paper presents a study to investigate the relative pollutant removal effectiveness of three proprietary end-of-pipe Best Management Practices (BMPs), namely, Baysaver, CDS, and Stormceptor. In this study, controlled conditions were used in order to provide documentation for the performance of the BMPs. For that purpose, a prototype facility was constructed at the University of Central Florida. For each BMP, five tests were conducted with five different flow rates: 1.6, 1.28, 0.96, 0.64, and 0.32 cfs. The monitored pollutants were sediments, nutrients, metals, and litters such as organic leaves, soda cans, plastic bottles, and cigarette butts and boxes. The results showed that some of the pollutants decreased in concentration while others increased between the influent and the effluent of the units. TSS load reductions for Baysaver, CDS and Stormceptor were 62.2%, 71.2%, and 83%, respectively. The performances of the studied BMPs for the pollutants were different. All the studied BMPs had good performance in removing the large sediment particles and litter. However, CDS had lower average inflow velocities in all tests than Baysaver and Stormceptor, causing sediment accumulation in the CDS inlet pipe. This study also showed that there was an increase in the total nitrogen concentration in Stormceptor while the nitrate/nitrite concentration increased in Baysaver and CDS. Other factors that should be considered in BMP evaluation are also presented in this paper.

Factors influencing groundwater sources under the direct influence of surface waters

Abstract The objective of this study was to identify preliminary and other factors that could be used to screen surface waters before embarking on the expensive laboratory procedure. In order to determine which public water systems that are groundwater under the direct influence (GWUDI), a total of 62 wells at public water supplies suspected of being GWUDI were investigated. The wells sampled were distributed across seven counties in the Central Florida region. Water samples were collected and analyzed at the Department of Health Laboratory in Tampa, Florida using the Microscopic Particulate Analysis (MPA). The study investigated the well and hydrogeologic characteristics, and land use within the vicinity of the well locations. The results showed that 13% of the wells sampled were in the high‐risk range while 29% and 58% of the wells sampled were within the moderate and low risk ranges, respectively. It was also observed that some well characteristics and the hydrogeology of an area generally influence th...

Evaluation of techniques for control of disinfection by-products: a pilot study.

Abstract The purpose of this study was to evaluate the effects of various treatment processes as they relate to the development of disinfection by-products (DBPs). At an existing municipal water supply, several tests were performed, including: air-stripping, potassium permanganate (KMnO4) addition, pH adjustment, evaluation of corrosion control inhibitors, final disinfection, and granular activated carbon (GAC) filtration. Several HAAs were shown to increase at higher pH. The use of air stripping greatly reduced the required amount of chlorine disinfectant. Air stripping, permanganate addition, and chloramination reduced DBPs below 20 µg/L. Stiles-Kem 7840 addition effectively controlled lead and copper concentrations in the distribution system. The use of chloramination as a secondary disinfectant is recommended to meet stage 1 of the disinfection by-product rule.

Assessment of groundwater under direct influence of surface water.

ABSTRACT Waterborne pathogens are known to reside in surface water systems throughout the U.S. Cryptosporidium outbreaks over recent years are the result of drinking water supplied from such sources. Contamination of aquifers has also led to several reported cases from drinking water wells. With high resistance to typical groundwater treatment procedures, aquifer infiltration by Cryptosporidium poses a serious threat. As groundwater wells are the main source of drinking water supply in the State of Florida, understanding factors that affect the presence of Cryptosporidium would prevent future outbreaks. This study examines karst geology, land use, and hydrogeology in the State of Florida as they influence the risk of groundwater contamination. Microscopic Particulate Analysis (MPA) sampling was performed on 719 wells distributed across Florida. The results of the sampling described each well as having high, moderate, or low risk to surface water influence. The results of this study indicated that the hydrogeology of an area tends to influence the MPA Risk Index (RI) of a well. Certain geologic formations were present for the majority of the high risk wells. Residential land use contained nearly half of the wells sampled. The results also suggested that areas more prone to sinkhole development are likely to contain wells with a positive RI.

Side-by-Side Evaluation of Stormwater Proprietary BMPs

This paper presents a side-by-side study to determine the relative pollutant removal effectiveness of three proprietary end-of-pipe BMPs, namely, Baysaver, CDS, and Stormceptor. In this study, a controlled laboratory conditions were used in order to provide documentation of the performance of the BMPs. For that purpose, a lab facility was constructed at the University of Central Florida (UCF). The setup of the facility has the ability to pump flows required to replicate runoff events. Using this type of setup enables the relatively rapid testing of BMPs to evaluate their performance, under repeatable and consistent conditions for multiple flow rates, different constituents, particle sizes, and sediment concentrations. In this study, five tests were conducted with five different flow rates: 1.6, 1.28, 0.96, 0.64, and 0.32 cfs. The studied pollutants were sediments (TSS, TDS, and Bed load), nutrients (nitrogen and phosphorous), Metals (Fe, Cu, Zn, Cr, Ni, Cd), and litters such as organic leaves, soda cans, plastic bottles, and cigarette butts and boxes. The results showed that some of the pollutants decreased in concentration while others increased between the influent and the effluent of the units. The results also showed that the performances of the studied BMPs for the pollutants varied. Baysaver had the lowest TSS removal efficiency. Even though TSS removal efficiencies of CDS and Stomceptor were higher than Baysaver, they were still relatively low. All the units had good performance in removing the large sediment particles and litter. The results also suggested that nitrogen was produced in the Stormceptor unit during the testing program. Other than removal efficiencies, the paper also presents some factors that should be considered in BMP evaluation. The review engineer will need to decide which factors to include in an evaluation and their respective importance to the user.

Non-Point Source Nutrient Loading in an Urban Watershed

The United States Environmental Protection Agency (EPA) passed the Federal Clean Water Act (CWA) in 1972 which set the framework for the water quality standards for the entire United States. As a result of the CWA many point sources were eliminated, but in the process it became apparent that non-point source loads represented even more of a threat. To further study the physical and chemical characteristics of urban runoff the Nationwide Urban Runoff Program (NURP) was established in 1978. This lead to series of management options, named Best Management Practices (BMPs) which proposed various structural and non-structural methods to reduce nutrient loads. The present study attempts to generate accurate and effective water quality and quantity data that future stormwater management decisions can be based upon. The main objective of this study is to determine the nutrient loadings into the tributaries of Lake Tohopekaliga, using automatic monitoring sites established throughout the City of Kissimmee, Florida. These monitoring sites were located to monitor subbasins within the watershed such that inflows from outside the city limits can be isolated and external pollutant loads quantified. Additional internal monitoring sites were established to determine the pollutant loads of sections within the city.

Estimating phosphorus removal in lakes using marsh wetlands

Abstract The objective of this study was to develop a modified simplest seasonal model that predicts phosphorus removal efficiency for lakes using marsh wetland system using lake waters. The proposed model calculates the wetland removal efficiency and total outflow phosphorus (TPout) concentration as a function of the soluble and nonsoluble reactive phosphorus (SRP and NSRP respectively) while considering the accumulation mechanisms. The observed and predicted TPoutconcentrations compared reasonably which suggest that empirical models can be adapted to estimate the phosphorus removal efficiency of the marsh wetlands. The results also indicate that TPout concentrations decreased exponentially with time through the wetland and decreasing the surface hydraulic loading rate of the system would increase the removal efficiency of phosphorus. It was observed that about 78% of the total phosphorus and 77% of the soluble phosphorus content within the water column was removed with about 19% of the total phosphorus ...