Drawdown operation

Service: Monitoring

Abstract: The Client is the manager of an artificial dam on the Corfino stream. He committed us to prepare a Special drawdown operation plan (POp) in compliance with the Reservoir Management Project (PdG) and to implement the environmental monitoring (water and fish fauna) during the ante-operam, works and post-operam of the drawdown activities.

Client: Energy Sector (renewable)

Period: 2019 – 2020.


Initial Client situation

On the indications of the Ministry of Infrastructure and Transport – Dams General Management (MIT), the company, as manager of the reservoir, has found the need to empty the hydroelectric basin and to produce a project for the complete disposal of the dam or, alternatively, to carry out interventions to improve the structural safety of the dam.
To comply with the MIT prescription, therefore in order to carry out the complete emptying of the hydroelectric basin, the manager had to prepare an update of the Reservoir Management Project (PdG) pursuant to DM 30/06/04 and Legislative Decree 152/06, as well as the preparation of a specific drawdown Operational Plan (POp).

Both in PdG and in the consequent Pop are recalled the environmental monitoring operations that must be carried out, in agreement with the competent authorities, aimed at monitoring over time the evolution of the potential effects of the operation itself.


SHELTER activities

Having supported the manager in the revision of the PdG and in the drafting of the POp as well as in the dialogue with the Competent Authorities, we have been called to carry out all the environmental monitoring activities as reported in the specific Monitoring Plan.

The monitoring activities involved several phases: pre-flushing, during flushing and post-flusching. For each of these phases, a series of investigations have been carried out to evaluate the quality of the environmental sector over time.
Specifically, the following were implemented:

  • Biological monitoring, through surveys on the macrobenthic communities and on the fish communities along the Corfino stream pursuant to Ministerial Decree 260/10, to be carried out before and after flushing operations.
  • Operations for the recovery of the fish fauna in the stretch of the Corfino stream downstream of the dam and upstream of its entering into the hydroelectric basin below.
  • Operations for the recovery of the fish fauna present in the basin during the emptying phase.
  • Operations for the recovery of potentially suffering fish fauna in the underlying hydroelectric basin due to the turbidity of the waters coming from the Corfino stream.
  • Execution of the "continuous" monitoring operations of the drawdown operations, along the Corfino stream, and "spots" ones along the Serchio river, through the activation of a system to control the quantity of suspended solids and active turbidity until the end of the operations themselves (real-time detection of suspended solid parameters, turbidity and dissolved oxygen).