On 20 October 2026, the Lesotho Highlands Development Authority said it would refer suspected pollution at a Lesotho Highlands Water Project construction site near the Sekoai River in Mokhotlong for inspection and testing, following observations of foamy water and continuous wastewater discharge. The contractor had previously been suspended over acidic and oily wastewater discharges. allAfrica.com
Key takeaways
- The Lesotho Highlands Development Authority will refer evidence of suspected pollution collected near the Sekoai River to the project engineer for inspection and testing. allAfrica.com
- Residents of Tloha-re-Buoe reported seeing foamy water in the Sekoai River on 7 September near the tunnel access area. allAfrica.com
- The contractor’s suspension followed findings that its wastewater-treatment systems were non-compliant, including missing effluent test results, high pH levels and oil contamination. allAfrica.com
- Work resumed on 25 May after upgrades were inspected and independent laboratory results confirmed that treated effluent met required standards, according to LHDA spokesperson Mpho Brown. allAfrica.com
What happened
Concern has centred on a tunnel boring machine access adit at Polihali, where wastewater was observed discharging from an outlet pipe onto land about ten metres from the Sekoai River before reaching the watercourse. allAfrica.com
Residents of Tloha-re-Buoe reported foamy water in the Sekoai River on 7 September in the same tunnel access area. allAfrica.com
Responding for Kopano Ke Matla, Brown said the observed outlet was the treatment plant’s designated discharge point and that only treated effluent was released through the approved and monitored system. He added that the authority had received no complaints or reports of foaming, discolouration or pollution linked to the works, while confirming that inspection and tests had not yet been carried out. allAfrica.com
Brown said the discharge would be stopped immediately if testing identified non-compliant effluent quality, and Kopano Ke Matla would be required to correct the cause before discharge resumed. allAfrica.com
Earlier suspension and treatment upgrades
In May 2025, Kopano Ke Matla, which is building the Polihali transfer tunnel, was suspended for discharging oily and acidic wastewater into nearby rivers and the Katse reservoir, a reservoir that supplies drinking water to South Africa. allAfrica.com
A suspension letter dated 5 May 2025 said the contractor had addressed only three of 26 identified non-compliance issues. Concerns included missing effluent test results, a malfunctioning sulphuric acid dosing pump, high pH levels in treated water and evidence of oil contamination. allAfrica.com
Work resumed on 25 May after the project engineer inspected the upgrades and independent laboratory results confirmed that the treated effluent met required standards, Brown said. allAfrica.com
The contractor was required to add settling capacity and pH correction, revise operating procedures and appoint a qualified process specialist. Its revised method statement included additional clarifier capacity for primary settlement, a pH-correction stage before final discharge and specialist supervision, and the engineer approved that statement. allAfrica.com
Brown said the earlier suspension was “a precautionary and corrective step, taken to address identified shortcomings in wastewater treatment before they could result in harm.” allAfrica.com
Specification read
The reported scale was a M42-billion tunnel project between Lesotho and South Africa, but the source did not report the wastewater plant’s design flow in m³/day, its population equivalent, or influent and effluent BOD and COD concentrations. Those inputs therefore cannot be converted into a treatment capacity or loading rate without inventing figures. allAfrica.com
For a construction wastewater plant of this type, the treatment train would ordinarily progress from screening and equalisation through primary settlement to biological treatment, followed by tertiary treatment or disinfection where required. The reported deficiencies point most directly to primary settling, chemical dosing, pH correction, oil control and final discharge monitoring—the stages between collection and the permitted outlet. allAfrica.com
If your plant has construction flow in m³/day, BOD and COD in mg/L, acidic or oily influent, and pressure to demonstrate compliant final discharge, this event shows why clarifier capacity, pH-control integrity, specialist operation and documented effluent testing need to be specified together rather than treated as separate issues. allAfrica.com
Operators handling oily wastewater should specify the appropriate oil-control process, while sites requiring dissolved-air flotation can evaluate Daf flotation systems and associated water-purification equipment. allAfrica.com
FAQ
What treatment stages need review for acidic and oily construction wastewater?
The reported deficiencies involved missing effluent test results, a malfunctioning sulphuric acid dosing pump, high pH in treated water, oil contamination and inadequate primary settling capacity. A plant review should therefore cover oil control, acid dosing, pH correction, primary clarification, specialist supervision and discharge monitoring as an integrated chain. allAfrica.com
What information is needed to price a wastewater-treatment upgrade?
The source did not report design flow, population equivalent, BOD, COD, oil concentration or the required treatment capacity, so a defensible budget cannot be calculated from the available facts. A supplier would first need those operating data, the current equipment condition, discharge limits and the required project lead time. allAfrica.com
How should a buyer select a supplier for a temporary construction wastewater plant?
The reported corrective programme combined added settling capacity, a pH-correction stage, revised operating procedures, specialist supervision and approved discharge controls. A buyer should ask bidders to demonstrate how each requirement will be delivered, how treatment will be monitored and what evidence will demonstrate compliance before discharge resumes. allAfrica.com
What happens if discharge fails to meet the required standard?
Brown said discharge would stop immediately if non-compliant effluent quality were identified and that Kopano Ke Matla would need to correct the cause before discharge resumed. At the time of the report, inspection and testing had not yet been carried out. allAfrica.com
