Ash Dam Drainage and Piezometer Repair

Eskom Holdings SOC Ltd, through Matla Power Station near Kriel in Mpumalanga, has issued an open tender (Ref. E2933GXMPMAT) for the repair of ash dam filter drains and the installation of piezometers to improve the stability of the Ash Dam Facility. The Ash Dam is registered with the Dam Safety Office as a Category III facility. A recent stability analysis found that the eastern side of the dam does not meet the required factors of safety, and the condition is deteriorating. The primary cause is excess water retention, with phreatic levels raised and walls persistently saturated, which has led to cracking and sliding. The works are therefore time-critical and carry significant safety implications.

The scope is delivered under an NEC3 Engineering and Construction Contract (ECC) using Option A (priced contract with activity schedule), with secondary options for delay damages, low performance damages, and key performance damages. The work is divided into four sections: preliminaries and general requirements (site establishment, safety file, SHEQ compliance, staff transport, accommodation, and management over 16 months); piezometer provision and connection; a trial installation of 12 horizontal drains; and, subject to a successful pilot, the phased implementation of the remaining 48 drains. Drains consist of perforated 110mm HDPE pipes with geotextile filter surrounds, installed by horizontal directional drilling at a minimum 3-degree slope, with connection to collector systems discharging into the existing solution trench. Vibrating wire piezometers must be supplied with a data logger, wireless gateway, and web-based software, and the contractor must design the drainage system and provide drawings signed by an ECSA-registered civil engineer.

Compliance requirements are substantial. Bidders must hold a CIDB CE Level 6 or higher grading and be CSD-registered. Mandatory returnables include a valid COIDA letter of good standing, an OHS plan and baseline risk assessment, detailed OHS costing, three years of safety statistics, an environmental management system aligned with ISO 14001, a quality control plan, and a draft contract quality plan. Functionality is scored at 100% with a 70% threshold, and points are allocated 90/10 or 80/20 under PPPFA. Eskom's standard payment terms apply, and the contract carries a 5% retention and a 52-week defects period. Tender validity is 84 days (12 weeks). A non-compulsory clarification meeting was held on 8 June 2026. Note that the source documents contain some internal inconsistencies, including the closing date, the tender number suffix, and references to gravel road work in the technical evaluation criteria, so bidders should confirm all details with the Eskom Representative before submitting.