Shad Thames pumping station
First published as a supplement to GLIAS Newsletter 71, December 1980
Shad Thames Pumping Station stands on the north-west side of Maguire Street, Bermondsey, London SE1. One of several stations built to pump excess storm sewage into the Thames, it is of interest in retaining the original gas engines. This Report follows a GLIAS recording visit in June 1980. A fuller Report is to be deposited at John Harvard Library, Local History Section, Borough High Street and at the Museum of London Library.
The main drainage of London is a "combined" system, foul and surface drainage flowing into the same sewers. Commencing in 1858, the Metropolitan Board of Works built interceptor sewers to divert crude sewage, which previously discharged directly into the Thames, to new outfalls several miles downstream of London. These sewers were sized to take little more than the dry-weather flows. The much greater flows during heavy rain continued to pass to the river via the old system. This was, however, of insufficient capacity to prevent flooding, especially in low-lying areas. Accordingly, from 1879 the Metropolitan Board of Works and its successor, the London County Council, constructed "storm relief" sewers in various parts of London. The storm sewage, much more dilute than the mainly foul dry-weather sewage, spills over weirs into these storm relief sewers, which at other times are dry. They discharge directly into the Thames, by gravity where possible.
Severe rain storms, particularly in 1903, indicated the necessity for further storm relief sewers. Among these was the Southwark and Bermondsey Storm Relief Sewer which was constructed by the L.C.C. in 1906-8 to serve the low-lying areas of central-south London. It runs in tunnel for 1⅝ miles from near the Elephant and Castle, north-eastwards to Shad Thames. It is joined by an overflow from the Duffield Sewer just before reaching the pumping station, where the flow is lifted an average of 20 ft for discharge into the river nearby. The pumping station was initially provided with three pumps with combined capacity of 8,000 cu. ft (50,000 gallons) per minute, but it was built with provision for three more pumps to double the capacity and these were added in 1927-9.
Shad Thames Pumping Station from north-east 1980 (left); location of the Pumping Station (right)
This Report is the product of a joint effort by several GLIAS members. Contributors are: Andrew Bullivant, Bob Carr, Tony Freeman, Mike O'Connor, Sue Parker, Bet & John Parker, Ray Plassard, Philip Purkis, Alan Surry, David Thomas, David Thompson, Malcolm Tucker and Youla Yates.
GENERAL DESCRIPTION OF THE STATION
The station building occupies a slightly irregular oblong site surrounded on three sides by warehouses. A yard runs behind the station and a three-storey wing provides office and living accommodation. A house nearby at 25 Shad Thames provides further Staff accommodation. (The station is manned 24 hours a day.)
The station is faced externally with red glazed brick and terracotta and internally with white glazed brick. Mass concrete faced with brick is used extensively below ground. A slate roof with a clerestory is concealed by a parapet and gable ends. Ten steel roof trusses support timber purlins and diagonal close-boarding. Heavy wooden entrance doors are placed centrally in the street facade and a path to a side door at the north end serves the office and living accommodation above. The interior comprises a basement-level engine pit with a floor 8 ft. below Liverpool Ordnance Datum level (L.D.). An annexe at the rear of the engine pit, beneath the yard and office, houses auxiliary plant. The ground floor, 15 ft. above L.D., is limited to a continuous gallery, which cantilevers over the pit on its long sides. A staircase gives access to the pit at the north-east end, while there is a vertical ladder from a side gallery to one of the engine cat walks.
An overhead crane can be moved the length of the building on tracks mounted along the main walls at the level of the base of the window arches. The crane rails are supported by cast iron columns of back-to-back 'E' section enclosed within the brickwork of the walls.
The crane, by Thomas Smith's Steam & Electrical Crane Works, Rodley near Leeds, has a safe working load of 10 tons. Movement of the crane along the rails, the carriage across the building and of the hook is by manual operation of a pulley chain.
General view of interior looking NE
A dedicated, 12 in diameter, high pressure, gas main was laid in 1906-8 directly to the station from the gas works at Brunel Road, Rotherhithe. The station relied on gas for all lighting and for powering of the engines. Lighting is now by electric lights. It is not clear if coal stoves originally provided heating, but this is now taken from an oil-fired boiler. Fuel oil for this is held in a brick-enclosed tank in the yard. The yard also contains three cooling water tanks for the station's gas engines and a rain gauge.
A small workshop area occupies the north-east corner of the engine pit. It contains work benches, an electrically driven grinding wheel, a 6 in. Colchester lathe and a Denbigh K1 pillar drill. These facilities are necessary for maintenance and repair work on the station's equipment, much of which is now unique.
Storm sewage flows through the sewers — into the penstock chamber, thence through a gate (normally permanently open) to the three wells beneath the pumps. Whilst this happens, an indicator shows the level of this water and a buzzer alerts station staff. Auxiliary equipment is used to prepare the main pumps, which are started when they have been properly primed and valves are then opened to allow the water to be discharged through a short sewer pipe into the Thames. The number of pumps needed depends on the volume of water to be moved; all six can be started in a few minutes.
The individual items of equipment are now described in more detail.
General arrangement of the pumping station — plan and elevation
KEY (applies only to the above drawings)
1) Water tanks
2) Yard (auxiliary equipment below)
2A) Rain gauge
2B) Oil storage tank
3) Office & living accommodation
4) Main engines
5) Storm water pumps
6) Stairs (workshop area below)
7) Frontage line
8) Discharge sewer
9) Pipe for access & testing
11) Penstock chamber
12) Duffield Sewer overflow
13) Southwark & Bermondsey storm relief sewer
14) Float stand pipe
16) Discharge valve
17) Suction well
19) Engine floor
20) 8 ft. penstock gate
21) 6 ft. penstock gate
22) Liverpool Ordnance Datum Line (L.D.)
THE AUXILIARY EQUIPMENT (see plan below)
These items are located below the yard and office alongside the engine pit. They provide compressed air to start the main engines, hydraulic power to operate valves on the pumps' discharge pipes and penstock gates, vacuum to prime the storm water pumps and drainage pumping from sumps around the main engine beds. The function of each item is duplicated or can be performed by other means. Initially all these functions powered by gas engines, but some have been replaced by electric or diesel equipment.
1 Air compressor — gas engine
This is intact but now disused and is one of a former pair of water-cooled, single-acting, one-cylinder, horizontal gas engines. It is marked 'Campbell Gas Engine Co. Ltd.' It has a bore of 10¾in and a stroke of 18in. The compressor is similar but with a stroke of 12 in. The outlet gauge reads to 250 p.s.i.
Plan showing location of auxiliary equipment
1) Air compressor — gas engine
2) Air compressor — electric
2A) Starter for 2 above
3A, B, C & D) Four air receivers
4) Vacuum pump — electric
4A) Starter for 4 above
5A, B) Two hydraulic pumps & gas engines
6) Hydraulic accumulator
7) Sump pump — electric
8) Sump pump — diesel
9) Office/mess room
GM) Gas meter (disused)
2 Air Compressor — electric
This has taken over the work of both of the gas-engined air compressors. It is marked 'Reavell & Co. Ltd. Ipswich — type C.S.A.6E' and is a two-stage compressor with two vertical water-cooled cylinders. It runs at 750rpm, delivering up to a capacity of 180psi. An inter-cooler is fitted between the high and low pressure cylinders. Power is via a five-belt drive from a 'Crompton-Parkinson' electric 30hp motor.
2A Motor — starter (for item 2 above)
This is marked 'Allan West & Co. Ltd. — starter for slip-ring motor'.
3A, B, C & D Four Air Receivers
These vertical cylindrical receivers are arranged in two pairs, each approximately 10ft high by 3ft 3 in. internal diameter, of riveted plate construction, with a dial reading to 250psi (S.W.P. 190 psi). These receive compressed air from item 2 above and this is used to start all the gas engines. It appears that these vessels are kept permanently charged. (See photograph, p.5)
4 Vacuum Pump — electric
This is used to prime the storm water pumps and is not part of the original installation; the pumps were previously primed by an ejector worked off the compressed air system. Priming is also possible by allowing water to rise in the sewer. The pump is a 'Nash-Hytor W5295' by 'Nash Engineering, Croydon'. The vacuum gauge reads to 30 inches of mercury. The pump is directly coupled to a 12.5hp motor by 'English Electric'.
4A Motor Starter
For the above, mounted on a nearby pedestal.
5A, 5B Hydraulic Pumps & Gas Engines
Two, three-throw, hydraulic pumps, each powered by a horizontal gas engine, are connected to a hydraulic accumulator, the hydraulic power being used to operate valves on the discharge pipes of the main pumps and, though rarely needed, the penstock chamber gates. Each gas engine is by Campbell and is similar to item 1 above, but is much smaller, with a bore of 5½in. and a stroke of 9in. A hand-operated clutch links the gas engine shaft to gears with a ratio of approximately 10:1 which in turn drive a crank shaft operating a three-throw hydraulic pump with plungers 2 in. in diameter with a 2¾ in. stroke.
Engine 5A formerly also powered the sump pump adjacent (7 on plan), but that pump has now been converted to electric power.
6 Hydraulic Accumulator
The hydraulic accumulator, marked 'Mather and Platt — Manchester', has 11 cast iron weights 4ft.9in. square with a total height of 7ft.4in.. They rest on a central vertical piston set in a cylinder and rise within guide rails to near ceiling height at which level there is a small header tank. The pressure gauge reads up to a pressure of 1,200psi, but it is assumed that about half this is employed. The accumulator is charged only when needed.
The illustration shows the accumulator (left) and one of the air receivers (right).
7 Sump Pump — electric (not illustrated)
Sumps around each of the six main storm water pumping engines are connected to suction pipes.
By these, residues (vacuum pump sealing water drains and waste cooling water from the main pumps' exhaust valves) can be pumped either between these sumps or into the station's drains. This item is a centrifugal pump which appears to be part of the original installation, having once had a belt drive from one of the hydraulic pump gas engines, (item 5A), but has since been converted to electric power. A D.C. starting resistor, adapted to A.C., is used.
8 Sump Pump — diesel
A Lister diesel-powered Sykes Unival centrifugal pump of recent installation is now used in preference to the electric sump pump, as it is much more powerful.
Note — There is no way of pumping out the wells below the storm water pumps other than by use of a portable pump, although appropriate pipework is shown on original plans for the station.
THE MAIN STORM WATER PUMPING ENGINES
All six of the station's main engines are three-cylinder, vertical, single-acting, four-stroke, totally enclosed gas engines, made by Campbell Gas Engine Co. Ltd, Halifax, England. The original three, dated 1907, are of 350hp. The later three, installed twenty years later, are rated at 250hp. One of these latter (which is basically the same as those of 1907) is described in some detail.
It is mounted on a plinth 12 ft 10 in. long, 8 ft 1 in. wide and 2 ft 3 in. high. It measures 10 ft 6 in. from the York Stone slab floor to the control platform and a further 8 ft to the top of the air intake filter. The bore is 19 in. and the stroke is 24 in.
The flywheel is cast-iron, 9 ft 1in diameter. It has six straight spokes, a split hub and a rim rather over 1 sq. ft in cross-sectional area, with barring teeth in an outer edge.
Lubrication of the main bearings on the 6 in. crankshaft is from a pair of 3½ in. stroke eccentric-driven pumps, immersed in a tank of oil, with a system gauge reading 0-30 p.s.i. Upper cylinder lubrication is effected by a six-cylinder pump with as many sight feeds and then via copper pipes to the cylinders. Other bearings are fitted with Snowden lubricators, or with oil boxes or cups and trimmings.
The fuel gas enters the engine via a 4 in. pipe, a filter, an 'antifluctuator' and the starting valve and on to the combustion chambers via the governor throttle and the inlet valves.
Ignition is by rotary magneto, labelled 'Scintilla, Switzerland', driven off an auxiliary shaft on top of the engine. There is also, on this engine only, a disused 'trip' magneto and its associated drive.
Exhaust flows from the combustion chambers, via water-cooled exhaust valves, into an exhaust trunk and then, via an 8 in. pipe, to the silencers outside the station. The governor is driven off the auxiliary shaft. It consists of a thick horizontal disc fly-wheel, with two cylindrical weights sliding out on the opposite ends of a diameter and connected by linkage to the throttle in the gas pipe.
Cooling is by a 3 in. engine-mounted centrifugal pump, circulating water from the station system and supplying cylinders, cylinder heads and exhaust valves. These last are connected-up by short lengths of hose. The hot water from the exhaust valves runs to waste in the engine sump well. Other cooling water is returned by pipes to three steel water tanks in the yard, each being 10 ft in diameter and 21 ft 6 in. high. It was the initial intention to provide more tanks once the second batch of engines was installed. This was thwarted by inability to gain access to the enclosed yard; the tanks consequently can become 'overheated and cold water has to' be introduced from the mains.
The tachometer consists of an 'Orbit' rev. counter, by Budenberg, Broadheath, Manchester, which is driven off the engine shaft between the flywheel and coupling and reads from 60 to 300rpm The engine runs at 200rpm
The engine is started by first turning over by compressed air, with the gas throttle being opened once speed has been achieved. On this engine the mix is admitted to all three cylinders via a common valve, but on the older engines each cylinder can be induced separately.
THE STORM WATER PUMPS
The engine is directly-coupled to a 30 in. outlet centrifugal pump, with double-sided inlet from the well. It is by the Lilleshall Co, Oakengates, Shropshire and is dated 1925. The pump has a maximum horizontal diameter of 9 ft 7 in. with a 4½ in. shaft and stands on a base 9 ft 5 in. wide and 6 ft long. The impeller, seen as a spare elsewhere in the station, is 5 ft 8 in. in diameter, 16 in. thick across the hub and has a 5 in delivery throat at the periphery. Lubrication is by both oil cups and a pair of built-in 'grease guns'.
To prime the pump, the vacuum pump is used to exhaust the air from the pump casing, allowing the storm water to rise; the exhausting pipe enters the top of the casing via a sight glass by Dewrance.
Once the pump is primed and the engine started, a hydraulic lifting gate valve on the discharge pipe is raised to allow discharge of the storm water. There is a gauge glass, by Dewrance, on the full diameter of the discharge pipe, which appears to be made from standard boiler water gauge fittings.
Note — Impellor blades of the 1925 pumps differ from those of 1907, which were manufactured by Cochrane.
In the south-east alcove is equipment for obtaining samples of pumped effluent. A pipe joins the discharge pipes to a settling tank; taps can be opened and a peristaltic pump operated to draw water from any of the discharge pipes. A pump is used to withdraw a small amount of water from just below the tank surface and transfer it to a suitable container so that the relative volumes of untreated sewage and 'clean' storm water that is discharged into the river can be analysed. The apparatus can be drained into the adjacent float stand pipe.
The station was equipped with one gas meter for each main engine and one, somewhat smaller, (shown in photograph) for the auxiliary equipment. The earlier four, of 1907, were by Parkinson Cowan and the later three by James Milne of Leeds. All but one remain in situ (see CM on auxiliaries location plan) although superseded by a single meter in 1942. They were wet sealed, rotary drum type meters, being 76 in. in diameter and 70 in. long. It has not been possible to see inside one, but a typical design contains a pair of coaxial drums, with ends, the space between being divided into four equal sections by shaped vanes. There are rows of holes, or slots, at the positions shown, in both drums on the horizontal axis. Gas is fed in at one end of the inner drum, via a hollow axle and leaves the outer casing well above the centre line. The pressure difference causes the internal assembly to revolve, counters count the revolutions and thus the volume of gas used is shown.
This is a large board on the south-west wall of the engine pit. It has two main functions: to show the level of storm water in the penstock chamber and to show the positions of the two gates to that chamber. All three are by vertically moving pointers.
The water level indicator is actuated by a cable attached to a float in a stand pipe above a recess off the penstock chamber. As well as having a lamp bulb for ease of sighting, its movements activate a warning buzzer when the water has risen to the level when the station's pumps need to be used; they are normally started when this is at a depth of 3 ft 6 in.
The two penstock gates are operated by the station's hydraulic system, although they are rarely moved. One gate, normally open, allows the flow of storm water into the pump wells. The other, normally closed, can in emergency allow access via the penstock chamber (itself reached by vertical ladder from a manhole) to the discharge sewer.
The station will change considerably within the next few years, as the Thames Water Authority is well advanced with plans to replace the main engines and pumps with modern automatically-operated equipment. The station will then be unmanned. It is possible that the hydraulic system will be retained to operate the penstock gates.
GLIAS would like to thank the Thames Water Authority for granting access to the station and particularly Mr. Bulley, the Group Manager at Deptford, Mr. Smith and Mr. Bugg at T.W.A, H.W, who allowed us to peruse original plans and, not least, the station's staff who cheerfully accepted our intrusion.
© GLIAS, 1980