Exo Environmental were appointed by Brightlingsea Town Council and Brightlingsea Harbour Commissioners to conduct a Water Framework Directive (WFD) assessment, as part of a proposed project involving two significant access improvements across the Brightlingsea Creek.

The aim of the assessment was to identify relevant surface water bodies, understand current WFD classification (determined by the Environment Agency on a regular basis) and determine whether the project could cause deterioration in WFD classification or adversely affect the water body achieving good status in the future.

Firstly, the only water source identified for screening, based on the project location, was the Colne River. Knowing this, we identified its WFD classification (Moderate) and furthermore determined the River Colne does not fall within WFD mitigation measures. Therefore, the project will not impact any active mitigation strategies already implemented.

Exo used the WFD impact assessment matrix (below) to identify and assess how the project’s construction and operational phases could affect each WFD parameter used to discern water quality. These are Biological, Physio-chemical, Hydromorphological and Chemical criterion, and include receptors, such as fish, macroinvertebrates, river flow dynamics, dissolved oxygen, and many others.

Our analysis found that no change will be caused by the majority of activities associated with this project, falling under the ‘No Impact’ descriptor. The highest impacts observed from the analysis were identified as localised adverse effects, exclusively caused by the impact from piling on localised benthic sediment, with a temporally short impact period.

From our analysis Exo concluded that based on the current understanding of the project, the cumulative impacts will not significantly affect the various elements considered of the Colne Water Body. The project is very unlikely to impact the water body status or prevent the potential to achieve future good status.

A thorough GIS study of Blakeney Channel was requested to complement a recent aerial and topographic survey of the site, conducted by Exo Environmental. Comparing previous survey records with historical aerial photography, provided by the Historic England Archives, this work was to allow changes to the channel morphology and saltmarsh extent over the last 70 years to be identified.

Using our specialist GIS software, historic saltmarsh extents could be overlain with our recent high resolution Unmanned Aerial Vehicle (UAV) (drone) survey data, to locate and quantify losses and gains of this protected habitat. Of particular note, was the growth of approximately 0.5ha of saltmarsh following the rerouting of a drainage rill in the 1990’s, resulting in significant meandering of the Channel.

Channel cross-section datasets from previous survey efforts dating back to the early 1980’s were also digitised from paper drawings supplied, some of which contained limited, erroneous or inaccurate data. Two methods were employed to correct the historic data using: georeferencing, distances quoted on hand drawn maps, changes in saltmarsh extent and accurate topographic data obtained during our survey of the Channel.

Utilising these methods allowed us to maximise accuracy of the digitised datasets and facilitate future comparative studies and long-term management of the Channel.

Blakeney Channel is an important navigation channel that connects Blakeney Harbour to Blakeney Town and its iconic quayside on the north Norfolk Coast. The area is dynamic and has shown some significant morphological changes over recent decades, including; shifting sandbars, meandering of channel centres and both eroding and accreting saltmarsh.

As part of the ongoing monitoring of the Channel and to facilitate the long-term management of safe navigation channels within Blakeney Harbour, the Blakeney Channel Coastal Community Team (BCCCT) commissioned Exo Environmental to conduct an aerial and topographic survey, to compliment and allow direct comparison with historical data sets, to identify changes to the Channel’s morphology over recent decades.

To achieve this, a photogrammetric survey was undertaken using an aerial drone with a preprogrammed flight path and referenced to a series of ground control points placed over a range of altitudes across the study site.

To support the aerial survey, topographic GNSS equipment was used as a quality check and to obtain data from areas submerged at all states of the tide. The combined dataset was used to create an XYZ grid with <1cm accuracy and a resolution of approximately 2cm per pixel. The resolution of the resultant 3D model is far superior to historic aerial and satellite imagery and comparable to that of LIDAR data accessible from the Environment Agency.

A holistic understanding of the environment is critical for the sustainable development and maintenance of infrastructure. With regards to the beneficial use of dredged material (BUDM), particularly its application in habitat creation, restoration and enhancement projects, detailed knowledge of the local topography is fundamental. This allows volume and storage calculations, matching of sources and sinks and facilitating post-works monitoring of processes that typically occur over the medium- to long- term, such as consolidation of material and biological colonisation.

As part of the Brightlingsea Dredging and Restoration project, Exo conducted dual-frequency bathymetric and unmanned aerial vehicle (UAV) (drone) photogrammetric surveys throughout the site, during high and low water spring tides respectively. The high resolution datasets were then merged across the overlapping intertidal zone (an approximate tidal range of 5m) using specialist software, to provide a comprehensive map of levels throughout the Creek.

Applying the clients requested target depths for each dredge area, accurate dredge volumes can be calculated and used to match with the storage volumes of restoration sites selected following the comparison of historic and current saltmarsh extents. In addition to project design, the data obtained also supports project planning through the identification of priority areas, provides baseline data for continued environmental monitoring and assists in the formulation of a long-term management plan for the Brightlingsea Harbour Authority.

The combination of these survey techniques provides excellent data coverage for logistically challenging sites located at the landwater boundary such as the intertidal zone.

In June 2021, Exo Environmental were commissioned to carry out sediment sampling along the River Trent at Flixborough.

The sampling involved the deployment of our Trimble VRS now RTK corrected GPS system, to locate the pre-determined spot sampling sites.

Using our Exo Surveyor dell quay dory, we navigated our way to the pre agreed sampling locations. Once in the correct location, we anchored in place, recorded our actual sampling GPS position, and the Van Veen sampler was lowered overboard.

Due to the strong currents on site, mud weights were fitted to the benthic grab, to ensure straight line descent to the bed.

Once on the bed the sampler was closed shut by pulling the attached lever and pulled to the surface. The benthic sediment was then emptied and stored in double bagged plastic liners and placed in cold storage.

In total 12 samples were collected, each weighing roughly 1.5kg. After demobilisation and transport back to the office the samples were sieved at 0.5mm and all organisms and debris collected was stored and sent to our Ecologist for benthic species assessment.

This assessment helped the client determine the health of the water body and sediment in this stretch of the River Trent and inform future management techniques for maintaining or improving the water quality.

In the summer of 2021 Exo Environmental were appointed by Duration Brewing, West Acre, Norfolk, to conduct a water sampling campaign from its Bioreactor and Klargester outflows.

The purpose of the sampling campaign was to ensure water quality met with environmental standards as set out by the Environment Agency concerning discharge.

An initial sampling campaign was designed by Exo and implemented in July 2021.

Several samples were collected from each source, using special sterilised 1000ml plastic bottles and glass jars and 40ml vials. The reason we have different sampling receptacles is that each will be tested for different determinands. For example, glass jars and glass vials are typically used for Total Petroleum Hydrocarbons (TPH) and plastic bottles are used for a general environmental suite, which measures a number of parameters including Biochemical oxygen Demand (BOD), and pH.

Following initial sampling, Exo adopted a project management role, developing a long term sampling strategy, organising laboratory testing of monthly samples from the brewery and collating all the data into a final report, helping the brewery to understand the impact of operational changes on water quality and their compliance with EA regulations.

Beccles Yacht Station and Boat Dyke has silted up over the years due to run off related sources from the main river and the main town drain. The accumulated silt had to be removed to allow for safe navigation as well improve conveyance of the drainage system. Exo were appointed to design and manage the desilting works, including site investigations (Preliminary ecological survey, bathymetric survey and sediment sampling followed by analysis), licence applications (MMO, EA, BA and NE), facilitate a tender and project manage the project throughout. The project was successfully completed in November 2021, and included dredging under D1 licence (EA), Marine licence (MMO) and Broads Works permit with a bank side long reach excavator. The dredged material was dewatered in temporary lagoons before it was transported to a spreading site under a SR2010 No.4 Landspreading licence (EA). The spread and cultivated dredged material will be sown in as a wildflower meadow to improve biodiversity of the the grass swards.

Exo worked with a private client in Sandwich to assess the impact of a development project (Scoping) on a local water system. The area under consideration is protected under various environmental designations including SSSI. Our investigation included an initial desktop study followed by a site visit and field work including a topographic survey, Valeport flow measurements, water quality assessment with a multiparameter sonde, and sample analysis at a laboratory. We furthermore worked closely with the local IDB and EA to understand the hydrological regime and concluded that the development could not affect the water body status or jeopardise the water body achieving good status because the water bodies were not directly interconnected. Furthermore dilution of any upstream impacts of the development by the significant quality of water, would leave any contaminants entering the water course untraceable. It needs to be stressed that the development was very small scale and no serious contaminants were under consideration.