A desk top model has been developed for "user-friendly" application in personal computers to simulate watershed response to a rainfall event in terms of runoff generation and to estimate nonpoint source pollutant loadings associated with the storm event. The algorithms utilize the SCS TR - 55 method for calculating runoff hydrographs for a single storm event. A methodology has been adapted to generate pollutographs which combines the SCS Type II rainfall distribution with the standard pollutant washoff equations. In addition, this model allows for the design, evaluation, and cost effectiveness analysis of various best management practice (BMP) measures as tools to manage stormwater quantity and quality. / M.S.

Thesis (MEng)--Stellenbosch University, 1994. / ENGLISH ABSTRACT: Various aspects affecting the inlet capacities of modified stormwater kerb inlets were investigated. Investigations centred on the influence of effective inlet length, ratios of upstream transition section length to inlet section length and road crossfall. The suitability of existing design curves for use in the design of modified kerb inlets was verified and new more "user-friendly" design curves were developed. Attempts were made to develop a sound theoretical model to predict inlet capacities for stormwater kerb inlets as the lack of such a model had previously been identified as a major shortcoming in the design of stormwater kerb inlets. A detailed study of relevant literature and of various full scale model test results confirmed the fact that the effective inlet length is the most important variable affecting the inlet capacity at stormwater kerb inlets. Model studies on various combinations of transition section lengths and inlet section lengths have indicated that in the case of supercritical flow the inlet capacity of stormwater kerb inlets is not sensitive to changes in the ratio between the inlet section length and the upstream transition section length. Furthermore no marked effect on the inlet capacity of a modified stormwater kerb inlet was detected when the road crossfall was increased from 2% to 3%. The inlet capacities predicted by the existing design curves were found to be consistent, although on the conservative side, when compared to the inlet capacities obtained from the full scale model tests. New design curves derived from the existing design curves were developed to provide a less cumbersome procedure in the design of stormwater kerb inlets. The development of an improved comprehensive theoretical model based on pure hydraulic principles was not possible due to the extremely complex nature of flow conditions at stormwater kerb inlets. The most important findings emanating from this research project are: - The confirmation of the "effective inlet length” concept, whereby a part of the expensive inlet section is replaced by an equivalent length of inexpensive transition section upstream of the kerb inlet. which does not affect the inlet capacity of the kerb inlet negatively and thereby results in a substantial saving in the cost of stormwater kerb inlets. - Model tests revealed that for supercritical flows the upstream transition section can be made up to 6 times longer than the inlet section with a maximum length of 6m. without any negative effect on the inlet capacity of the kerb inlet. Similarly an analysis of previous research results has indicated that even in cases of subcritical flow the upstream transition section can be made twice the length of the inlet section. - The full scale model tests also indicated that an upward adjustment of 30% in the inlet capacities as predicted by the existing design curves was justified. The modified design curves proved to be suitable for the design of conventional stormwater kerb inlets as well as for modified stormwater kerb inlets where part of the inlet section is replaced by a transition section. A new set of "easy to use" design curves was developed specifically for urban applications. - Guidelines for determining upstream transition section lengths were drawn up for use in conjunction with the existing and new design curves for the design of stormwater kerb inlets. / AFRIKAANSE OPSOMMING: Verskeie aspekte wat die inlaatkapasiteit van verbeterde randsteeninlate belnvloed is ondersook. Die belangrikste aspekte wat ondersoek is, was die invlood van effektiewe inlaatlengte en die moontlike verhouding van die stroomop oorgangslengte tot die werklike inlaatlengte sowel as dwarshelling. Die ontwerpgrafieke wat tans gebruik word om randsteeninlaatlengtes te bepaal is ook ondersoek aan die hand van modeltoetse op volskaalse modelle om die grafieke se akkuraatheid te toots. Meer gebruikersvriendelike ontwerpgrafieke is ook ontwikkel. 'n Belangrike tekortkoming tot op datum, naamlik 'n geskikte teoretiese model om die inlaatkapasiteit van randsteeninlate te beskryf, is aangespreek. 'n Voorvereiste vir so 'n model was dat die model gebaseer moes word op suiwer hidrouliese beginsels. Die bestudering van vorige navorsing asook die uitvoering van verskeie modelstudies op volskaalse randsteeninlate het die effektiewe inlaatlengte as die belangrikste veranderlike wat die inlaatkapasiteit van randsteeninlate bepaal geYdentifiseer. Tydens tootse uitgevoer op volskaalse modelle onder superkritiese vlooitoostande met verskillende kombinasies van oorgangslengtes en inlaatlengtes, vir die dieselfde totale lengte het dit geblyk dat die inlaatkapasiteit grootliks onatbanklik is van die verhouding van die oorgangslengte tot die inlaatlengte. Vit die modeltootse het dit oak geblyk dat paddwarsval 'n baie beperkte invlood op die inlaatkapasiteit van ransteeninlate gehad het toe die paddwarsval verander is van 2%na 3%. Die resultate wat verkry is uit die modeltoetse het ook aangetoon dat die bestaande ontwerpgrafieke konserwatief is in hul voorspelling van inlaatkapasieit van randsteeninlate. Die bestaande ontwerpgrafieke is voorts gebruik om nuwe meer gebruikersvriendelike ontwerpgrafieke te ontwikkel. Die ontwikkeling van 'n teoretiese model am inlaatkapasiteite volledig te voorspel was egter nie moontlik nie vanwee die uiters komplekse aard van die vloei by randsteeninlate. Die belangrikste bevindinge van hierdie studie kan soos volg opgesom word: - Afdoende bewyse is gevind dat die "effektiewe inlaatlengte" konsep, waarvolgens 'n gedeelte van die duur inlaatgedeelte met 'n goedkoper oorgangsstuk van dieselfde Iengte vervang kan word sonder om inlaatkapasiteit in te boet, weI suksesvol aangewend kan word om kostes in die ontwerp van stOlIDwater randsteeninlate te bespaar. - Afdoende bewyse is gevind dat die "effektiewe inlaatlengte" konsep, waarvolgens 'n gedeelte van die duur inlaatgedeelte met 'n goedkoper oorgangsstuk van dieselfde Iengte vervang kan word sonder om inlaatkapasiteit in te boet, weI suksesvol aangewend kan word om kostes in die ontwerp van stOlIDwater randsteeninlate te bespaar. - Afdoende bewyse is gevind dat die "effektiewe inlaatlengte" konsep, waarvolgens 'n gedeelte van die duur inlaatgedeelte met 'n goedkoper oorgangsstuk van dieselfde Iengte vervang kan word sonder om inlaatkapasiteit in te boet, weI suksesvol aangewend kan word om kostes in die ontwerp van stOlIDwater randsteeninlate te bespaar. - Riglyne is ook ontwikkel vir die bepaling van stroomop oorgangslengtes. Die riglyne kan saam met die bestaande en die nuwe ontwerpgrafieke gebruik word by die ontwerp van stormwater nmdsteeninlate.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: This thesis deals with understanding and quantifying the components that make up sewage base flows (SBF). SBF is a steady flow that is ubiquitous in sewers, and is clearly seen when measuring the flow rate in the sewer between 03:00 and 04:00. The components of SBF are: ● return flow from residential night use, ● return flow from leaking plumbing, ● groundwater infiltration, ● stormwater inflow. By understanding each component of SBF, this research can answer the burning question as to how much of the SBF was due to plumbing leaks on residential properties. While previous work on SBF had been done, the work focused on groundwater ingress and stormwater inflows, and thus not much had been said about plumbing leaks. Furthermore, previous work focused on SBF as an isolated sewer related topic, whereas this research integrated SBF as both a sewer related topic and water conservation and demand management (WCDM) topic. Due to the high variability in each of the SBF components, a method of quantifying each component was developed using residential end-use modelling and Monte Carlo simulations. The author constructed the Leakage, Infiltration and Inflow Technique Model (LIFT Model). This stochastic model was built in MS Excel using the @Risk software add-on. The LIFT Model uses probability distributions to model the inflow variability. The results of the stochastic model were analysed and the findings discussed. This research can be used by water utilities as a tool to better understand the SBF in networks. Armed with this knowledge, water utilities could make informed decisions about how to best reduce the high SBF encountered in networks. / AFRIKAANSE OPSOMMING: Hierdie verhandeling bespreek die begrip en berekening van die komponente van riool nagvloei. Die nagvloei was duidelik wanneer die vloei in die rioolstelsel tussen 03:00 en 04:00 gemeet is. Die verskillende komponente van die nagvloei is: ● huishoudelike gebruik, ● lekkende krane en toilette, ● grondwaterinfiltrasie, en ● stormwaterinvloei. ’n Begrip van die komponente van nagvloei kan die brandende vraag van hoeveel nagvloei die gevolg van lekkende krane en toilette is, na aanleiding van die navorsing beantwoord. Vorige werk het op beter begrip van die grondwaterinfiltrasie en stormwaterinvloei gefokus en lekke het nie veel aandag geniet nie. Vorige werk het net op nagvloei as geïsoleerde rioolonderwerp gefokus, terwyl hierdie navorsing nagvloei as ’n onderwerp wat met riool verband hou, sowel as ’n waterverbruik- en behoeftebestuursonderwerp, ondersoek. As gevolg van die groot verskil tussen elk van die komponente van die nagvloei, is ’n metode ontwikkel wat elke komponent kwantifiseer deur gebruik te maak van eindgebruik-modelle en Monte Carlo-simulasies. Die outeur het die Leakage Infiltration and Inflow Technique Model (LIFT-Model) gebou. Hierdie stogastiese model is in MS Excel, met behulp van die @Risk sagtewarebyvoeging gebou. Die LIFT-Model gebruik waarskynlikheidverspreidings om invloeivariasie te modelleer. Die resultate van die stogastiese model is ontleed en die bevindinge bespreek. Hierdie navorsing mag moontlik deur watervoorsieningsmaatskapye as instrument gebruik word om nagvloei in rioolstelsels beter te verstaan. Hierdie nuwe kennis kan watervoorsieningsmaatskapye in staat stel om ingeligte besluite te neem rakende die beste metodes om te volg om nagvloei te verminder.

In cities, storm runoff is usually collected in the streets and conveyed to underground storm drains through inlets located at street level. Construction and maintenance of storm drain systems is always expensive. In semiarid regions with a very low frequency of storm occurrence, most cities use streets as the drainage route even though their primary function is for the movement of traffic. As a result, the shape of a runoff hydrograph at the outlet of an urban watershed will vary with the pattern of street arrangement within the watershed. The objective of this study is to investigate tradeoffs between alternative street patterns with respect to urban drainage. The study area is confined to residential subdivisions where the subdivision boundary is assumed to be the watershed boundary. Three street patterns, namely, rectangular, curvilinear and dendritic, are considered in this study. The cost-effectiveness technique is employed to give an objective evaluation for these three alternative patterns. The effectiveness is measured by three kinds of evaluators. The first evaluator is the flow depth at certain points on the streets; the second evaluator is the total time during which the streets are occupied by a certain depth of water; the third evaluator is the total cost associated with the construction of a street pattern. A framework of a distributed system model has been constructed for simulating the runoff hydrographs and flow depths at certain points on the streets. A parcel of land near Willcox, Arizona, is selected to illustrate how the model could be used. Possible subdivisions of the land for each of the three different types of street patterns are shown, and the runoff hydrographs and flow depths from each of the patterns are examined. It is found that the peak flow rate resulting from the rectangular pattern is 13 percent higher than that from the curvilinear pattern and 29 percent higher than that from the dendritic pattern. The dendritic pattern has the smallest percentage of street intersections occupied by water during a storm. Time of occupation of high water stages at street intersections is much shorter in the dendritic pattern than that in the rectangular and curvilinear patterns. The development cost for the dendritic pattern is the lowest among these three patterns. Therefore, the dendritic pattern appears to be the best type of street arrangement in terms of urban drainage.

Corrosion of concrete sewer crowns will cost the County Sanitation Districts of Los Angeles County approximately $150 million for repairs to their deteriorating sewage system. Other parts of the country are experiencing similar problems. Crown corrosion is induced by microbial oxidation of reduced sulfur to sulfuric acid, which attacks the concrete. Bacteria, of the genus Thiobacillus are generally responsible for catalyzing these reactions. Thiobacillicollected from sewers were used to establish stoichiometry and biochemical aspects of sulfide oxidation. Metals inhibition was studied among the same cultures. Thiobacilli collected from extremely corroded sewers possess a greater tolerance for metals than those from lightly corroded areas. Acidophilic isolates grow at greater rates and oxidize sulfide more efficiently than non-acidophiles. Chemical inhibitor studies indicated that S(-II) oxidation is tightly linked to respiration by T. thiooxidans. It is doubtful that initial steps in bacterially catalyzed S(-II) oxidation are linked to oxidative phosphorylation.

Chemical inhibition of acid production by acidophilic thiobacilli was tested using a variety of metals and chelators (alone and in combination) including Hg(II), Ag(I), Co(II), Mo(VI), Cu(II), Zn(II), Cd(II), EDTA and NTA. When tested individually, Hg(II) and Ag(I) showed toxic effects at concentrations of 10-5 M and below; Cd(II), Zn(II) and NTA were noninhibitory at millimolar concentrations. Combination experiments showed both synergistic and antagonistic effects on chemical toxicities. Antagonism was apparent in experiments involving Cu(II)-EDTA, Cu(II)-Fe(III) and Cu(II)-Co(II). Synergism was apparent in experiments involving simultaneous addition of Mo(VI), Cu(II), Co(II) and Zn(II). In general, inhibitors either completely blocked or delayed the onset of acid production. In those cases where delayed reactions were observed, acid production began following an acclimation period on the order of days to weeks. Acclimation and metals speciation experiments suggest that adaptation events are due to biologically dependent changes in inhibitor speciation.

This research investigate and analysis 77 kinds of volatile organic compounds (VOCs) in the sewage system of a southern urban area (A, B, C, D, E and F). The 77 kinds of VOCs will be divided into BTEX, chlorine-containing hydrocarbons and non-chlorine-containing hydrocarbons, and to estimate the emission of 27 kinds of hazardous air pollutants (HAPs). Cancer risk within 12 kinds of HAPs will also be part of the investigation by using Risk Assessment. In terms of consistency, except A1, D5 and E, VOCs are required mainly of non-chlorine-containing hydrocarbons at other areas, and main contribution species are ethylene, acetylene and ethane. There are 55.05 % of BTEX (1298.2 £gg/m3) and 35.51 % of non-chlorine-containing hydrocarbons (837.6 £gg/m3) in A1, but the main contribution are toluene, m-xylene and p-xylene. In D5, there is 76.39 % of BTEX (3744.7 £gg/m3) and the main contribution are m-xylene, p-xylene and toluene. In E, there is 80.02 % of chlorine-containing hydrocarbons (4807.1 £gg/m3) and the main contribution are chloromethane and toluene. Results show that the most emissions of total HAPs is D5 (12195.3 mg/hr), followed by B2 (4602.9 mg/hr), E (2659.4 mg/hr), A4 (2043.7 mg/hr) and A1 (1526.2 mg/hr). BTEX represent the largest proportion of the emissions of total HAPs in D5, A4 and A1. Chloroethene represents the largest proportion of the emissions of total HAPs in B2, followed by trichloroethene and tetrachloroethene. Chloromethane represents the largest proportion of the emissions of total HAPs in E. The most cumulative cancer risk in the sewage space is B2, followed by C2 and A3. The main contribution of the average cancer risk (not include B2) in a southern urban area are 1,1,2-trichloroethane, 1,2-dichloroethane and 1,4-dichlorobenzene.

Thesis (Ph.D.)--Murdoch University, 2001. / Thesis submitted to the Division of Science and Engineering. Bibliography: leaves 205-222.

Thesis (M.Env.Sc.)--University of Wollongong, 2005. / Typescript. Includes bibliographical references: leaf 81-84.

Thesis (Ph.D.)--Edith Cowan University, 2006. / Submitted to the Faculty of Computing, Health and Science. Includes bibliographical references.