The Royal Ordnance Factory
Bridgend South Wales
  The Task Ahead
  The End of War

The disposal of waste water

The disposal of waste water from filling bombs with Yellow Phosphorus - a synopsis of reference document AY 2/446

The Treatment and Disposal of Waste Waters

In a factory complex the size of the Bridgend Royal Ordnance Factory water management is a major activity.

The factories used two to three hundred thousand gallons of water per day for drinking, heating, plus sewerage and process applications

The primary source of water was obtained from Cartesian wells sunk on the site with the balance being supplied from the local water utility company.

Water was an expensive resource costing the ROF over £9000 per annum in 1942 (£ 257,580 when scaled to 2002 values), so every effort was made to use it effectively.

However, disposal of waste water was a major problem, the sites were constructed on flat marshland with poor drainage, the streams fed into the local river Ogmore and it’s tributaries, pollution of these would cause serious problems for the local populous.

Equally, many of the streams fed the underground lake that the sites were built over and it’s pollution would certainly find its way back into the human population as many farms used wells as their only source of fresh water.

Sewerage was the initial water treatment problem and increased steadily as the work force increased from 1000 or so construction workers in 1937 to the 40,000 work force of 1942.

To overcome this the decision was taken early in 1940 to increase the size of the sewerage main from the site pump house to the discharge point; this was increased to a 17-inch diameter main. It was also decided to extend this main from the mouth of the river Ogmore to the Tusker Rocks well beyond the low water mark of the Bristol Channel.

With this in place the problem of sewerage disposal was overcome, however, the disposal of wastewater that arise from the filling of bombs was another matter.

In May 1943 the Ministry of Supply commissioned a secret research program to be conducted by the Department of Scientific and Industrial Research Water Pollution Research Board.

The advice of the Water Pollution Research Laboratory was sought and on the 9 th of March 1943 Mr C. Hammerton of the Ministry of Supply and Dr B.A. Southgate of the Water Pollution Research Laboratory visited Bridgend ROF.

For evaluation purposes water samples were obtain from Messers. S.S. Tomkinson at Kidderminster, where a similar process of filling bombs with phosphorus was in operation. The Ministry of Supply had decided to conduct this activity at the Brackla Hill site of the Bridgend ROF so the information gathered from this evaluation would be of great value in the management of its waste water.

The were a few disposal options open to the Bridgend ROF management and these were:

1. Discharge the effluent into the local ditches.

2. Pipe it into the Bridgend sewerage disposal works.

3. Or to discharge the waste waters into the underground natural lake beneath the site.

All three were considered the ditches were problematical as they ran for a considerable distance through the fields in which cattle grazed, before joining a larger stream.

The sewerage works at Bridgend consisted of tanks in which the sewerage was retained for discharge during the ebb tide into the river Ogmore Estuary.

Whilst the underground natural lake is a cavern in the limestone strata, unfortunately no information was available on the course of the river/s flowing into and out from the cavern.

Handling phosphorus is difficult in small quantities in a laboratory environment in volume in a factory making bombs it is a nightmare.

Delivery and Handling.

The phosphorus was delivered in welded steel containers with the phosphorus covered under a layer of water to prevent spontaneous combustion when exposed to air. These containers were lowered into specially constructed water filled tanks the containers were then opened and steam was injected into the container which melted the phosphorus.

The phosphorus was extracted from the container using another pipe where it was distributed through steam heated pipes to points in the factory where the bombs were filled.

During this process some of the phosphorus entered the water filled receiving tanks in which the transport containers were delivered. When a fresh container was immersed into the receiving tank it displaced an equivalent volume of water, which flowed from this tank into open channel in the factory floor.

This water contained some of the phosphorus which solidified in the open channels which were fed with cold water to ensure that the leakage was always water covered, this contaminated water was discharged into the disposal system.

Bomb Filling.

Empty Bomb cases consisted of two compartments one for the phosphorus the other for the bursting charge. The rear compartment contained the phosphorus; to fill the bomb it was first filled with water and held in a vertical position under water in a lead lined tank.

Molten phosphorus was fed into the bomb case from the steam-heated pipe that displaced the water in the rear compartment. When the bomb was full the stream of molten phosphorus was turned off, and a metal rod inserted to displace a certain amount of the chemical to allow for expansion of the remaining fill. A screw plug was inserted into the filling hole at the bomb rear. This plug was coated with a mixture of Red lead, litharge, and glycerine. Later, the bomb tail fin would be screwed onto this plug.

As a result of these operations the filling tank water contained phosphorus, red lead, litharge, and glycerine washed from the plugs. There was a continuous flow of contaminated water from the filling tanks, caused partly by condensation of steam, and partly by the water displaced from each bomb casing when it was filled with phosphorus.

The waste waters overflowed into open channels under the floor of the shop, the spilled phosphorus was recovered each shift and reused.

The bombs were thoroughly washed following the filling process with the waste waters flowing into the under floor channels.

Testing the Bombs.

After the bombs had been filled and washed they were immersed in a shallow water filled tank. The water was then heated to 70ºC and maintained at this temperature for about 30 minutes in order to melt the phosphorus inside the bomb casing. If there was a leak round the plug in the bomb phosphorus would escape. The water contained this phosphorus in suspension, and this was run off into the water filled channels.

Phosphorus escaping through leaks round the plugs burns and this allowed leaking bombs to be separated from the batch. Leaking bombs were emptied in the lead-lined tank and these bomb cases were either refilled or rejected.

Removal of Grease from Plugs.

The screw plugs that were used to seal the bombs were cleaned by first immersing them in a solution of trisodium phosphate, and then washed in running water. The solution was discharged frequently into the waste water channels.


Treatment of Waste Waters.

The concentration of pollutants based on tests conducted at the Water Pollution Research Laboratory using waste water from the S.S. Tomkinson plant showed a high concentration of Red lead and phosphorus .(See references AY2/446 and DSIR 13/524)

The method of treatment at the Kidderminster works was considered inadequate for the proposed facility at Bridgend. Massive tanks would be needed to allow for sedimentation to have the desired effect of reducing Red Lead and phosphorus pollution to an acceptable level where the waste-waters could be discharged into the local ditches and streams.

However, the levels of lead were still considered too high to allow discharge of the waste waters into either the streams or underground lake.

The Water Pollution Research Laboratory therefore recommended that the waste waters should be conveyed through a pipe to the sewerage disposal works at Bridgend for discharge to the Ogmore estuary.


Authors Note:


There is no record of the implementation of The Water Pollution Research Laboratory’s recommendation, but there is documentation contained within the records held by the Glamorgan Records Office files that the matter of sewerage and water pollution was raised by the then Bridgend Urban District Council.

What begs the question is; that it is known that the filling of bombs began in 1940 so how were the waste waters treated before 1943, and was the Bridgend Urban District Council made aware of the problem?


19 September 2023

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