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WRITTEN QUESTION TO THE MINISTER FOR TRANSPORT AND TECHNICAL SERVICES BY DEPUTY A.K.F. GREEN
ANSWER TO BE TABLED ON TUESDAY 24th MARCH 2009
Question
An application DP(B)2009/03/01 was published in the Jersey Gazette on 14th March 2009 for a permit to discharge "treated brackish water" arising from the Energy from Waste Plant excavation. Can the Minister give full details of this application, in particular –
- t h e chemical composition of the water before and after this "treatment," and how this chemical composition changes over time?
- th e natureof the treatment?
- h o w this brackishwater arose, thequantityinvolved,howthe situation wasdiscovered,and the likely duration ofthe discharge?
- w h ether theRamsarSecretariat will be informed of this potential discharge and their view sought? Answer
Application DP(B)2009/03/01 has been made by the Civil Engineering contractor for the Energy from Waste project Spie Batignolles Camerons (SBC) who are part of the main contractor consortium CNIM Spie Batignolles Camerons (CSBC Jersey Ltd). The application is to discharge water that will arise on the site during the construction of the plant. The water will come from the sea via ground infiltration, and from rainfall. In principal the water entering the site will be clean water from the sea or from rainfall. The application is to pump the sea water and rainwater out to sea if it gets on site. There is a risk that pollutants, for example hydrocarbons or silts, could be introduced to this water whilst on site and thus the contractor has made an application to the regulator for a discharge permit. This application gives details of the proposed treatment of the water prior to discharge.
- t h e chemical composition of the water before and after this "treatment," and how this chemical composition changes over time?
The water entering the site will be sea water and rain water. Any water leaving the site must comply with the limits set by the regulator. These limits will be set on the quality of water that can be discharged so as to protect the receiving water.
- th e natureof the treatment?
The proposed treatment process in the application is for a series of silt settlement tanks, pH adjustment (if necessary) and a hydrocarbon trap to be installed prior to discharge.
- h o w this brackishwater arose, thequantityinvolved,howthe situation wasdiscovered,and the likely duration ofthe discharge?
The brackish water will be predominantly sea water with some rainwater. In order to construct the waste bunker it is necessary to dig below the high water sea level. When the tide is high the water infiltrates through the porous ground and can enter the excavation pit until the permanent sealed concrete structure is in place. In order to construct the waste bunker the excavated pit must be dry so that the concrete can be safely and successfully cast.
In o r der to minimise the amount of sea water on site the contractors are constructing a sheet pile barrier
around the pit excavation. Whilst this should dramatically reduce the amount of water entering the excavation it is unrealistic to expect the sheet piles to prevent all water ingression.
It i s i ntended that the excess water is pumped through a treatment plant into the existing sea water culvert
to sea. In order to do this the application to discharge has been made. When the construction is complete there will no longer be a need to discharge water from the construction site so it is anticipated that the consent will be required until June 2010.
- w h ether theRamsarSecretariat will be informed of this potential discharge and their view sought?
The Regulator will not be consulting with the Ramsar secretariat as nothing will be consented that has the capacity to harm the ecology of the site.