Pulles Howard & De Lange
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PULLES HOWARD & DE LANGE INC.
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RIVER BASIN MANAGEMENT AND AQUATIC ECOLOGY
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Blesbokspruit Catchment Study : Status Quo Analysis

The purpose of the study, undertaken for the Department of Water Affairs and Forestry, was to provide the information and tools required to develop an integrated Water Management Plan (WMP) for the Blesbokspruit catchment. This WMP takes into account all the needs of the interested and affected parties, located both within the immediate study catchment area, as well as further downstream. All the traditional components contained within a WMP were addressed.

The environmental impact of the Johannesburg Southern Sewage Treatment Works on the Klip River.

This two year project, in association with Stewart Scott Inc., assessed the impact of the Johannesburg Southern Sewage Treatment Works on the Klip River in terms of bacteria, ammonia and phosphates. A detailed monitoring programme was developed to quantify all pollution sources in the area and a river model was developed and calibrated for nutrients and coliforms. The breakdown in infrastructure in Soweto was clearly identified as a significant source of bacterial contamination. Detailed evaluations were made regarding users of the river, their water quality needs and objectives for the river were set. Detailed modelling of the river system was done as well as testing of various scenarios to quantify future pollution loads.

Preliminary situation analysis of the Vaal Barrage catchment, with a focus on the impact of gold mining activities

A study was undertaken, together with Stewart Scott Inc. to determine the impact of operational and defunct gold mines in the Witwatersrand on the Vaal Barrage catchment. A preliminary water and salt balance was developed for the catchment and point and diffuse source pollution sources and abstractions were identified. A basic model was developed to estimate the beneficial impacts of different water management strategies on catchment water quality and impacts on water users. The scope of further detailed studies which would be required for a catchment water management plan were defined.

Development of a water management plan for the Free State goldfields and lower Vet River catchment

This project developed a water management plan for the whole catchment and was undertaken together with Stewart Scott Inc. The project addressed all aspects of water management within the catchment such as pollution sources, water users and their quality and quantity requirements, legislative and regulatory frameworks, hydrology, land use, future development planning, monitoring and data management requirements, etc. A water management plan was provided which sets clear in-stream water quality objectives at different points in the catchment, apportions waste loads to the different polluters and establishes structures, procedures and timetables for the implementation, management and review of the plan.


A catchment management plan for the Kalabas River and Klipspruit, for Durban Navigation Colliery

A scoping catchment management plan which takes into account the potential impact on downstream users, and identifies their minimum water quality requirements, was developed. Based on this information and discussions with the interested and affected parties in the catchment, preliminary in-stream water quality objectives were set. This enabled the mine to develop management strategies which are aimed specifically at achieving the set objectives. A second phase of the project will incorporate a detailed catchment management plan for implementation.


Vaal River Barrage catchment water quality management plan - Phase 1 & 2

Phase 1 was a reconnaissance and scoping study to characterise the catchment by identifying the key elements and questions that need to be addressed in Phase 2, all current water quality objectives, statutory requirements, statutory authorities, their functions and related legalities, all interested and affected parties within the catchment, their forums and the best means for their involvement in the project. In Phase 1 the available relevant information was found, where it was held and its accessibility. Critical issues where interim measures were necessary were identified and prioritised, and the motivation and terms of reference for Phase 2 of the study were set out.

A catchment management plan for the Mooi River

The first phase of the catchment management plan for the Mooi River – the situation assessment - is currently being undertaken for the Department of Water Affairs and Forestry. This catchment covers a large percentage of the active South African gold mining industry from Krugersdorp in the east through to Potchefstroom in the west. The study includes assimilation of all data relevent to sources of pollution, water users, water quality requirements, catchment development and land use, hydrological and water quality modelling.

Economic and technical evaluation of regional treatment options for point source gold mine effluents entering the Vaal Barrage catchment

The project evaluates the strategies that could cost effectively be employed to manage/treat point source gold mine effluents, to confirm the current contribution of these point sources discharges to the salt load entering the Vaal Barrage catchment and to predict the future discharges. The costs to users of the Vaal River between the Vaal Dam and Balkfontein will be estimated, for the purpose of comparison with costs of management or treatment options.

Evaluation of the current situation of water quality of the Centurion Lake

PHD undertook to take an objective holistic approach to the water quality status in the Centurion Lake, Verwoerdburgstad after numerous contradicting reports were published inlocal newspapers. The objective approach provided the Centurion Town Council and the public with an accurate and unbiased indiaction of the current situation. Water samples were taken at ten strategic points along the Hennops River, from Temibisa to Centurion. The water samples were analysed for microbiological populations as well as various chemical constituents.

Improving the trophic and aesthetic status of Zoo Lake.

A detailed investigation was undertaken in association with Stewart Scott Inc. to determine the factors that cause highly eutrophic conditions to develop, resulting in dense algal blooms occurring which, on decay, cause odour and aesthetic problems within the lake. Remedial actions to address these problems were also developed.

Research on the future management of urban impoundments.

This three year project developed guidelines for the management of urban impoundments. These guidelines will assist those persons responsible for management in identifying their problem, assessing the scale of the problem and then adopting applicable strategies. A national survey was undertaken to prepare a register of urban impoundments. Some 50 impoundments were identified. Of these 10 impoundments with good water quality information were selected for detailed assessment. Although a desk-top study, each impoundment was evaluated to identify water quality problems, and to determine whether any existing management strategies were in place. A two year monitoring programme has been implemented at three of these impoundments to investigate in detail the limnology of the impoundments and the associated changes to their limnology as a result of management strategies in place.

Management and control of aquatic macrophyte infestations in Wemmer Pan, Johannesburg.

The infestation of this popular recreational area with Potomogeton pectinatus led to impaired use for rowers, canoers and sailors. An evaluation of water quality parameters and available options for control resulted in the management of the weed using Chinese grass carp.

OTHER RELEVANT PROJECTS UNDERTAKEN BY PULLES HOWARD & DE LANGE DIRECTORS