Skelton Flood Gate
Case study
Skelton Flood Gate
Flood gate and cofferdam works at Skelton
Scope
operated directly from the road under an Phase 1 — to reduce criticality of the situation by the emergency road closure. All necessary permits and installation of a long term cofferdam to reduce flood statutory obligations were fulfilled and consultation risk to Howden and surrounding properties and with the local residents/business were carried out businesses and 3D Cloud Point Surveys throughout the duration of the workings. Other obligations regarding utilities, access, diversions,
Phase 2 — to install new wooden penstock valves
school transport, council run services and full traffic and install replacement new flood gates forming management system to Chapter 8 regulations. outlet to tidal River Ouse
Community liaison in post and person also formed
Flood gates prevent tidal and/or flood waters part of our remit. flowing back inland into low lying agricultural,
We also were challenged by the client to make an
residential and commercial areas with potential for allowance for the cofferdam to allow some water to significant flooding damage. be able to run by gravity through the temporary The river at this location is 268m wide with varying cofferdam. We achieved this by using a steel frame tidal depths from 0.0m up to 5.29m and infrequent in the base and fixing 6 x450mm diameter non- surges topping 7.4m. Obviously, any works return flap valves. This element did add cost but involving tidal/flood gates generate considerable allowed for greater capacity during wet times when concerns for local residents and companies. the doors would normally be operating along side a pump station, This also had a cost saving to the
Key Aspects
client over the duration of the long project as it has
Design had less electricity consumption to power the pump
The state of the existing wooden door structure was station. surveyed and was deemed to be in a critical state.
Urgently working with our designers, we developed
a large scale cofferdam that could be used to mitigate all flood risk posed by the damaged doors for a long duration. With the time line of the project being across 12 months we had to ensure that the top of the cofferdam reached at least the height of the existing flood embankment making the cofferdam 6.18m tall. A lot of structural calculations had to be conducted to ensure the temporary cofferdam structure could withstand such a huge head of water pressure.
Speed
The urgency of the first phase meant that we had to
respond exceptionally quickly, taking a lot of
Project Images
Challenges
structure, the River Ouse bottom is a very difficult environment to keep clean and dry and posed
Flood risk
significant risks to the health and safety of our By far the biggest issue and key at every stage; a workforce. In order to maintain safe working lot of consideration and design work for temporary practices, it was necessary to excavate silt and works had to be put in place before removing any debris and boulder rock to create a level platform to existing infrastructure to ensure that we did not work from. A concrete foundation was cast in situ to cause any flooding. Large volumes of water coming build the new cofferdam on. To initially keep the through the drainage network had to temporarily workings dry had to over pumped with a 4” high dammed off to make the workings dry. This was pressure pump. managed with 3 pumps one 8” and two 6” to cope
Public Interest
with the volume of water that needed to be over pumped for the duration of the works 24/7. Works of this nature typically engage both public interest and concern particularly from residents and
Tides
businesses that are affected by flood gate removal The tidal nature of the River Ouse meant that works works and possible flooding. had to be planned and executed at key windows of
A great deal of time went into communicating with
opportunity around the best tide which meant some local residents, parish council and East Riding of night working. We overcome this with portable site
Yorkshire Council throughout the duration of the
lighting but due to the proximity of residential works to alleviate concerns regarding the weather, properties, screening was necessary to deflect light anticipated flooding, lengths of work, progress and away from the residential properties and only the difficulties and inevitably frustration at road quietest of tasks was undertaken during the night to closures. minimise noise disturbance. A lot of consultation was carried out with 3 residential properties A fully Chapter 8 compliant traffic management specifically. programme was implemented and adapted to differing layouts throughout the project to
Health & Safety
accommodate weight and height restrictions on Working in the base of the existing culvert ancillary lanes and roads.
Planning a watercourse or environmental project?
Speak to Sweeting Bros about practical land drainage, water management, environmental and civil engineering works.