Hanningfield Water Joint Management Committee

HWJMC was created to provide additional supplies for summer demand and water was shared between the Southend and South Essex Companies
Following the severe drought of 1933-1935 the combined flow of the Rivers Blackwater, Chelmer and Ter fell to 3.5 mgd for several weeks. Flow information gathered from 1927 indicated an average available flow of 21.5 mgd from the existing 8 mgd already abstracted at Langford.
In 1950 the Southend Waterworks Company was authorised under the Hanningfield Water Order of 1950 to enter into a joint agreement with the neighbouring South Essex Water Company to form the Hanningfield Water Joint Management Committee. Up to 43 mgd could be abstracted from the Rivers, Blackwater and Chelmer at Langford. With the construction and management of the Hanningfield Reservoir of 5,968 million gallons, and Treatment works.

Up to 35 mgd of river water abstracted at Langford was pumped via a 48in main, nine miles to Hanningfield Reservoir covering almost 1000 acres.
The main dam 6850 ft long, has a core of puddled clay topped with concrete slabs to prevent wave erosion. An initial volume of 8.6 mill gallons a day of treated water being supplied to both Companies, from August 1956. to the Basildon and Brentwood areas.

The original 1956 treatment plant comprised of 4 Accelators as above, previously trialled at Langford Treatment works

Hanningfield Treatment Plant circa 1980

Water demand having steadily increased, the Hanningfield works was extended with the addition of Vertical flow softening tanks during 1970 -1973. This increased the output from 80 to 150 Ml /day. A further extension of the filters in 1983 increased the output to 200 Ml/day with an ultimate capacity of 270 Ml/day if required. Vertical flow tanks being found preferable to Accelators.

Water from Hanningfield supplied to the Southend Company was predominantly pumped via Downham to Basildon and boosted to Langdon Hills. Also via Nevendon booster to Thundersley and Southend. With the closure of the Vange treatment works also via Vange to Pitsea, Rayleigh, South Benfleet and Canvey Island.

Water supplied to the South Essex area was fed via the trunk mains from Danbury to Herongate Reservoirs.

Water treatment included softening to comply with the requirement to supply Southend with softened water, although not required for South Essex.
High river nitrate levels are not a problem  with water treatment at Hanningfield, as initially they are diluted within the reservoir, followed by natural biological nitrate reduction. They can result however in prolific algal growth, resulting in algal blooms  such as the blue green algae microcystis, which can be fatal if consumed by animals, and cause rashes in humans.  A monitoring station  “The Iron Lady”  was constructed to compare meteorological data and reservoir conditions to establish optimum conditions for algal proliferation. This was stationed where the reservoir was at its deepest at 16 mtrs. Water conditions were measured at 1 metre intervals from the surface and transmitted to the Laboratory Computer system.

                                             Hanningfield Reservoir Nitrate Reduction                                                Average annual Nitrate Nitogen levels mg/lt

 

River Blackwater                                          10.0                                                                           River Chelmer                                                 9.8                                                                      Reservoir                                                         4.3

            

Algae commonly found in Reservoirs

The Launch of the Iron Lady (DNW Photo)

The Iron Lady Monitoring station (DNW Photo)

Due to a manufacturing defect, the Iron Lady unfortunately sank below the waves, only to be salvaged by the Police Diving Team to ride the waves again.

The Iron Lady beneath the Waves  (DNW Photo)

The Iron Lady Rising from the Deep (DNW Photo)

The Iron Lady was eventually decommissioned, the cabin removed, and the base used as a platform for breeding terns.