Employer: Union Miniere Pirdop Med AD
Designer and contractor: Geotechmin OOD
Project implementation period: 1998 – 1999

Description of the project

In the past the Small Lagoons 1 and 2 were used for disposal of the sludge generated by the industrial wastewater treatment plant of MDK–UMPC. The lagoons were partially cleaned of the slime in 1997.

The conceptual design provided by Geotechmin for capacity enlargement of the Small Lagoons was based on a preliminary study performed by SEGES-Belgium as well as on additional hydrogeological investigations. It was approved in October 1998.

From an environmental perspective, the project aims to prevent water and soil contmination with arsenic and heavy metals by ensuring the smooth operation of the temporary wastewater treatment facility for a period of 3 years.

Conducted works:

• cleaning of residual arsenic slime – 6,000 cub.m.
• demolition and transportation of old reinforced concrete structures – 320 cub.m.
• excavation and backfilling works – 18,000 cub.m.
• PVC pipe drainage system (diameter 110-160 mm) – 1,400 m
• HDPE liner (2 mm thick, protected with geotextile) – 17,200 sq.m.
• construction of a road past the surrounding walls, two unloading platforms and an approach ramp
• reinforced concrete coverings

internal and external drainage systems and two shaft pump stations for return of cached drain and rain water