Other Dredging Activities
There are a small number of other operators and facilities undertaking or proposing to undertake maintenance dredging within the study area, including Denton Wharf and Gravesend Canal Basin, but such new projects will be assessed separately and are presently excluded from this issue of the baseline document.
In addition, and in recognition of potential secondary impacts arising from maintenance dredging operations, consideration has been given to, particularly, the potential impacts arising from discharge from the two disposal lagoon facilities within the study area, namely Rainham and Cliffe Pools.
Rainham Pump Ashore Facility
Dredging is not undertaken at the site itself. However, the site is a receptor for material arising from maintenance dredging operations, as well as providing a resource within the Inner Thames Marshes SSSI. A management plan for the site is in preparation (January 2006) which will support the ongoing operation of the site to maintain the conservation status of the surrounding grassland and saltmarsh habitats.
The Waste Management Licence is currently under review, with an anticipated maximum annual reception capacity of 75,000 tonnes of deposited material (solids), excluding the water used to carry the material to the lagoons. The dredged material deposited at Rainham is used beneficially to create and maintain the habitats within the SSSI.
The ongoing operation of the site is an intrinsic element of the maintenance dredging strategy for the Thames, as well as continuing the management regime of the SSSI itself. The operations do not directly impact on the European sites and the discharge from the lagoons occurs outside the study area. No further examination of direct environmental impact has therefore been undertaken.
Cliffe Pools Pump Ashore Facility
The Cliffe site has operated as a dredging disposal site since 1960. It is located to the east of Gravesend, in Kent, and forms the western end of the Thames Estuary and Marshes SPA. Since 2001, the site has been owned by RSPB. In 2002, RSPB entered into a management contract for the lagoons with Westminster Dredging, and this arrangement is ongoing.
Dredging is not undertaken at the site itself. However, the site is a receptor for selected material arising from maintenance dredging operations in the Thames. The deposited materials are being used to manage and enhance the existing saline lagoon areas to reduce depths, provide beaches, and create island breeding and roost sites.
In 2004, Westminster applied (successfully) for a PPC Licence for the site (although Government has since removed the requirement for PPC at such sites). As part of that process, the applicant undertook a habitats risk assessment for the lagoons carried out under the Habitats Regulations. The evaluation considered:
- Toxic Contamination
- Nutrient Enrichment
- Habitat Loss
The assessment concluded that the ongoing operation of the lagoons, undertaken in accordance with the lagoon dredging plan established by RSPB and Westminster Dredging, with agreement of Natural England, as appended to the site management plan, does not adversely affect the integrity of the Thames Estuary and Marshes SPA.
The site has a potential capacity of 850,000 m3, with an annual ceiling of 150,000 m3. The site operates in support of dredging activity in the Thames, equating to quarterly periods of approximately three weeks duration. During these periods, the site is operational for up to 24 hours each day, with a daily ceiling of 10,000 m3 excluding the water used to flush material into the site from the discharging vessel. Water, from dredging and precipitation, is discharged from the site via a series of sluices leading to Cliffe Creek. These are operated by Westminster Dredging during operational periods and by RSPB during non-operational phases. The PLA are not aware of any water quality issues associated with this activity.
The RSPB, as landowner, is working in partnership with Westminster Dredging Plc to create at Cliffe Pools a flagship nature reserve and the focus for visitors to the RSPB's North Kent Marshes reserves.