|The Rushden Echo, 16th June 1911, transcribed by Gill Hollis
Rushden Urban District Council
Visits To Luton And St. Albans
At a meeting of this Council on Wednesday evening the following report was presented by the Surveyor:-
The following members of the Special Sewage Disposal Committee, viz., Messrs. J. Claridge. G. Miller, C. Bates, and T. Swindall, together with the Surveyor, paid a visit to the sewage works of the Luton Corporation and the St. Albans City Council on Tuesday, the 23rd May.
Proceeding first to Luton the committees were met at the Town Hall by Mr. J. W. Tomlinson, the borough engineer and surveyor, who kindly accompanied and showed us over the works. He explained that the new works were in course of construction (about half finished) and the committee would see the works in its various stages, all being carried out by direct labour.
The sewage, which is strong, with a with a fairly large quantity of dye water, is pumped from the old works near the refuse destructor in Luton, to land in the parish of Stopsley, where the new works are in course of construction. The dry weather flow is about 1½ million gallons per day, and the system of sewage disposal is entirely on bacteriological lines, viz., that of sedimentation and double filtration.
First, we inspected the two sedimentation tanks (which are the patent of Dr. Travis and known as “Hydrolytic Tanks”). These tanks (which are of reinforced concrete construction of the indented bar patent) are circular and divided into compartments each 65 feet 2 inches diameter and 30 feet deep. They have a capacity of 520,000 gallons, being equal to eight hours’ dry weather flow. They are worked on the continuous flow principle. The type of tank is designed so that by opening the valves controlling the various sections into which the tank is divided, the sludge falls to the centre and thence gravitates to a sludge chamber, from which it is forced by compressed air on to the high land into thin channels after the principal the committee saw at Kettering and which appears to be a very good system of dealing with the sludge. After leaving the tanks the sewage flows through a supply main from which it is passed on to ten circular percolating filters 100 feet diameter by 6 feet deep, filled with clinker. The revolving distributors are of the sprinkler type. The filters are built entirely above ground level and without walls, large lumps of uncrushed clinker being set up at a suitable batter to hold the medium, this simplifies the aeration of the beds and where the levels permit appears to be very satisfactory. The filtering medium is gas works clinker from London Gas Works. After passing through the primary filters the sewage will be collected and passed through another tank (which was in course of construction) of similar design to those first mentioned but smaller, being 42 feet 2inches diameter and a capacity of 95,000 gallons. The sediment from this tank is dealt with in the same manner and worked from the same air compressing station as deals with the sludge from the first tanks.
The effluent from the intermediates tank will be passed over six similar filters to those already described, but the filtering medium will be much finer and the effluent will pass first through a lagoon and from thence through a culvert to the watercourse a mile away without further treatment.
As previously remarked, the works are in course of construction, and your committee were much interested in inspecting the various stages of the work and exceedingly well pleased with all they saw. The two sedimentation tanks receiving the crude sewage and most of the course filters were completed and in use and the remaining portion of the works were well in hand. The Local Government Board enquiry was in November, 1909, and the amount of the estimate was £25,000.
St. Albans Sewage Works
After the inspection of the works at Luton the committee proceeded to St. Albans to inspect the sewage disposal works of the City. These works are situated near the village of Park Street, some two miles from the City, and on arriving there we were met by Mr. A. Eade, who most courteously showed us over the works and gave every information concerning them.
Some 30 years ago the sewage was dealt with by irrigation on about 30 acres of land. The land after a few years becoming “sewage sick,” it was decided in 1893 to put down three tanks and sludge-pressing plant and deal with the sewage by chemical precipitation. In 1902 the tanks were converted into coarse contact beds supplemented by five new ones. Eight fine contact beds were also laid down at a higher level and plant provided for pumping the effluent from the course beds to the fine beds. The rapid sludging up of these beds, however, produced difficulties with the effluent and attendant nuisance. Septic tanks followed, but by 1907 the works again required serious attention, and the effluent was adversely reported upon by the Thames Conservancy. The Corporation thereupon called in further advice and the works as we saw them have been entirely re-modelled.
The average dry weather flow is about 325,000 gallons per day or equal to about 18 gallons per head of the population. The outfall sewer is about 21 inches diameter with a fall of 1 in 1760 and upon reaching the works is rough screened and passed through one of the duplicate grit tanks in which are three finer screens and thence to a new sedimentation tank of a modified Dortmund type and with a capacity of 15,000 gallons, which, added to the two old septic tanks, gave a total capacity of about 325,000 gallons or one day’s dry weather flow. The sludge is removed daily from the sedimentation tank. A Helical Scraper gathers the sludge into the centre, and on opening a valve the natural head of water forces it up a 9 inch pipe into a steel tank receiver of a capacity of 950 gallons. When this is filled the sludge is forced by air pressure into trenches through a 4 inch cast iron main and immediately covered in with soil. This is similar to that proposed for Luton. The area of land reserved for sludge is 6¾ acres. The sewage is drained off by floating arms into a channel to the septic tanks. From the septic tanks the effluent flows to any of the ten contact beds which have an area of 4462 square yards and an average depth of 4 feet 2 inches, and with three fillings a day a capacity of three and one third times the dry weather flow. The effluent from contact beds is lifted through a 12 inch main to the high level channel which communicates with the cast iron trough to the percolating filters. The eight old fine contact beds have been converted into percolating filters, their area is 3454 square yards and depth 5½ feet, and they are well ventilated. The filtering medium is from refuse destructors, large material at bottom and ¾ inch gauge at top. The distributors are of the Fiddian patent water wheel type to suit the rectangular plan of the beds. They are automatic in action and appeared to give very satisfactory results. A boarded wind screen has been erected at the south end of these filters, with beneficial results. The effluent from these filters is either led to the 16 acres of land or in dry weather to the storm water beds to arrest the colloidal matter and finally passes into the River Ver about a mile away.
The effluent shown was exceedingly clear, and, we were informed, entirely satisfactory to the Thames Conservancy. Seeing the present works have largely had to be modelled out of old ones, they appear to have been exceedingly successful and the management to be in very capable hands.
The committee highly appreciate the facilities shown them in being privileged to visit the works of other authorities. The information gained is thoroughly practical and cannot fail to be of the greatest use to them in connection with the important question of sewage disposal now before them.
In a conversation which took place with regard to the question of visiting other places, Mr. Miller said he thought they were doing all they could to meet the requirements of the County Council.
In reply to a suggestion that the special committee had not yet spent their £80.
Mr. Knight said it was not decided that they should spend that amount.
Mr. Bates: And we are not likely to so long as we pay our own expenses.
Mr. Knight said the visits paid by the Kettering Council did cost £80 or £90, but the Kettering Council regarded that expenditure as one of the best investments they ever made.
It was resolved to visit Nuneaton and Tamworth, and, on the motion of the Chairman, seconded by Mr. Miller, a very cordial vote of thanks was accorded to the authorities of the districts visited for their courteous treatment of the committee.