During the summer season at a busy National Park, we were asked to give assistance with a blocked soakaway drain. Due to the location and the time of year the soakaway had to be treated rapidly and with the minimum of disturbance. Then drain received combined effluent from a busy restaurant (which had not been maintained) and a large septic tank that served several public toilets.
The pipe feeding the soakaway was clear for the majority of its length. The overlying topsoil was removed to expose the aggregate, which was found to be white with congealed fats, oils and greases (FOG). To facilitate the continued running of the treatment area and to cater for the recent increase in loadings, it was decided to construct a new soak-away adjacent to and abutting the existing one, to serve the system whist the existing soak-away was allowed to repair by bio-remediation.
On day 1, a trial depression was scratched into the surface of the aggregate to expose the slotted feed pipe, which was found to be dry, and 100ml of EU60 was poured onto the stones. By the morning of day 4 wastewater from the slotted feed pipe was flowing readily through the aggregate and spilling over into the new trench. The stones had been de-contaminated sufficiently to prevent them coagulating as the picture indicates. This picture also shows a marked reduction in the white FOG scum that had previously been coating the stones.
Based upon the success of this trial portion, the entire length of the old soak-away was treated following the placement of the aggregate in the new soak-away; this being done to avoid distortion of the existing unit as the EU60 degraded the FOG that had been binding it solid. Regular maintenance dosing has prevented reoccurrence and reduced bad odours.