Waste waters must be managed with a recognition of the need for their treatment and disposal and the ability of the receiving waters to safely assimilate the discharge – balanced against the costs of treatment and public concern. Solutions must involve teamwork between our environmental scientists, wastewater engineers, regulators, stakeholders and our clients.

Assessments begin with the synthesis and evaluation of existing data. These results are used to design focussed field investigations of point and non-point pollution sources to understand existing conditions of water quality and ecological responses.

Dye-tracer studies, often supported by drone video footage, are used to assess plume trajectory, dilution and time of travel for use as input to water quality models.

We apply our experience and refined field study results to modelling techniques – using simpler mass balance models, more complex multidimensional models such as CORMIX and QUAL2K to assess dilution and assimilation in the near and far field and models linking phosphorus in lakes to oxygenated fish habitat.

We develop mass balance and export coefficient models of hydrology and phosphorus dynamics to quantify loadings from natural sources, storm water, agriculture and WWTP discharges and develop “no net increase” management plans in large and complex watersheds.

We stay abreast of current developments – assessment techniques, site specific water quality objectives, emerging contaminants of concern and the technologies to treat them and pollutant offset trading. We develop practical and protective water quality and effluent discharge objectives.

Finally, we explain our results in clear language and meet with stakeholders to understand their concerns, explain the assessment process and respond to their questions.

A solid assimilation study is built from coupling the need for regulatory approval to the challenge posed by the discharge, the feasible level of treatment and the assimilative ability of the receiver. We complete our work on time, document it clearly and respond promptly and effectively to concerns, such that the necessary approvals allow new or expanded discharges to proceed on schedule. Regulators trust our work.