The Environment Agency is progressing its work on the £30 million Flood Alleviation Scheme and continuing to work on the final design for the scheme, which aims to protect the communities in Coggeshall, Feering and Kelvedon from further flooding.

Image: Coggeshall flooding in 2001

In October 2001 Coggeshall, Feering and Kelvedon suffered from significant flooding. Since then, in May 2012 and February 2014 the villages experienced further flooding. Due to changing weather patterns the villages are expected to experience more frequent, more damaging flooding in the future

Local residents and parish councils will then be able to make further comment on the plans as part of the formal planning review process.

In 2006 the EA commissioned a study to explore whether a scheme would be viable for the villages. The study demonstrated that the cost-benefit ratio for this area was low, resulting in options being too expensive to fund through the Agency’s Flood Defence Grant in Aid (FDGiA) money.

Completion of work in 2013 on a hydrological model of Robin’s Brook, a “Main River”allowed the EA to carry out further investigation.

Out of the 8 options consulted upon in 2015, the scheme that received the greatest public support was that of providing flood storage within the River Blackwater.

However the option could not go forward for the following reasons:

• Firstly the costs were estimated to be in excess of £6 million, with no corresponding funding source available.
• Secondly it failed to achieve the required levels of flood protection because there is insufficient storage capacity within the Blackwater Valley.

In 2015 we approached Blackwater Aggregates to ask for their support in developing a low impact and sustainable flood alleviation scheme within the Blackwater Valley that could provide the necessary 1 in 100 year flood storage across land under their control.

The flood alleviation scheme and next steps

The scheme has continued to develop, arriving at a final design which will provide flood protection to the villages of Coggeshall, Feering and Kelvedon through an “on-line” dam and the creation of an extended flood storage area to manage and accommodate flood flows.

The overall principles of the scheme and required level of flood protection for the 203 houses (some of which are important heritage assets) and 15 local businesses located within Coggeshall, Feering and Kelvedon are:

• 3.02 million m3 storage capacity required to create a long-term significant improvement to the flood protection for three communities
• The dam location and finished height remains the same (and will avoid upstream impacts)
• The extension to the floodplain provided by the quarrying activity is still a major factor in the scheme’s design, without which the scheme would not be feasible
• Contributions by Blackwater Aggregates and the commercial viability of the project remain a key part of the partnership delivery

The extended floodplain has been designed to provide bio-diverse habitats connected to the existing floodplain . Additional areas of broad leaf woodland will be created across the site which will connect existing habitats with the flood alleviation scheme

The dam itself has been made wider at its base following further analysis of the structure and local ground conditions which has resulted in changes to the dam and realigned section of the river

Project funding

The project has received £1 million from central government (via the Environment Agency), and up to £8 million in direct funding contributions through the Blackwater Aggregates partnership.

Project costs in more detail, excluding the cost of aggregate removal are:

• Blackwater Aggregates: Over-dig of clay – up to £6 million
• Blackwater Aggregates: Dam construction – up to £1.5 million
• Blackwater Aggregates: Planning process – up to £0.5 million
• Environment Agency: Project delivery - £1 million

Blackwater Aggregates’ normal quarrying operations across the site will ultimately support in the delivery of a flood alleviation scheme that would otherwise mean the public purse would need to contribute in excess of a further £25 million.

The existing floodplain will be extended into the southern side of the Blackwater valley to create a flood storage area upstream of Coggeshall, Feering and Kelvedon through Blackwater Aggregates’ normal quarrying and restoration operations.

The extended floodplain will be developed within the base of the proposed quarry which will be located to west of Coggeshall across large open fields that are currently farmed under a commercial farm tenancy contract agreement.

It is proposed that Blackwater Aggregates’ quarrying operations would progress across the southern side of the Blackwater valley, in a phased and systematic manner, to create the extended floodplain adjacent to the River Blackwater over a period of approximately 20 years.

Once the design stage is complete a planning application and supporting Environmental Impact Assessment (EIA) will be submitted to Essex County Council for their consideration and approval following their formal process, which may vary based on the current and future response to Covid-19.