March Farmers – Whittlesey Washes Flood Storage Reservoir
The Brief
March Farmers is a 300-hectare holding within the Whittlesey Washes Flood Storage Reservoir, acquired by the RSPB in 2008 and converted from intensive arable to floodplain grazing marsh. The wider Nene Washes reserve holds Ramsar, SAC, SPA, and SSSI designations, with drainage channels supporting spined loach — a primary SAC qualifying species — and eels in the tidal River Nene.
Water level management is precise and time-critical. After winter flooding, the site drains by gravity to around 1.0m AOD before pumping draws levels down to 0.5m AOD — the specific depth needed to create viable nesting conditions for black-tailed godwits. The pump runs almost continuously and unattended between March and May, shifting approximately one million cubic metres across the season. The existing inlet headwall was a corroding sheet-piled structure no longer fit for purpose.
The Solution
ACE delivered the full MEICA package under a single contract — one scope, one point of accountability. At the heart of the station is a Pentair submersible fish-friendly pump, rated at 1,440 m³/h at 4.7 metres head, on a variable speed drive.
The pump is top-hung from the precast headwall with a submersible motor design allowing continued operation during site flooding, and is certified to NEN 8775 for fish and eel passage — non-negotiable on a site whose SAC designation rests partly on its spined loach populations.
ACE supplied a bespoke precast concrete pump sump designed and manufactured by JKH Ltd of Suffolk under an exclusive partnership. The sump arrived as a finished product and was craned into position in a single lift onto a prepared sub-base — no on-site formwork, no in-situ rebar, no curing time. On saturated fenland peat with restricted plant access, this eliminated the programme risk that in-situ construction would have introduced. JKH manufactures using ECO 1 concrete, reducing cement content by 46% and CO₂e by 12% without performance compromise.
The Result
The RSPB operates the station without dedicated engineering resource, so ACE’s single-contract approach — headwall, pump, controls, and valve specified and commissioned as one system — means one point of contact and one set of documentation. The pump control panel sits in a bespoke steel kiosk elevated to approximately 4.2m AOD, above the maximum potential flood level on a site that can fill rapidly via a 200-metre spillway. Control logic runs a variable speed drive with ultrasonic level monitoring across summer and winter operating ranges; a telemetry unit transmits alarms to mobile and email, keeping the station running unattended for weeks at a time.
Achievements
01
1,440 m³/h pump rated capacity at 4.7m head
02
1,000,000 m³ volume of water shifted over the pumping season
03
4.2m AOD control kiosk elevation above flood level
04
NEN 8775 fish and eel passage certification
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