Report on Foul Water Sewerage & Wastewater
Total Page:16
File Type:pdf, Size:1020Kb
REPORT ON FOUL WATER SEWERAGE & WASTEWATER TREATMENT FOR DEVELOPMENTS AT NORTH FAMBRIDGE Introduction This report, prepared at the request of North Fambridge Parish Council, considers the foul water sewerage and wastewater treatment aspects of applications to Maldon District Council for approval of reserved matters for two developments at North Fambridge. Outline planning consent for these was granted in 2016. Site A B Brief Description Up To 75 market and affordable dwellings, A Up to 30 dwellings Village Centre of up to 1,000 sq m of flexible commercial and community floorspace and a 1.8Ha Village Green and Public Open Space. To avoid confusion the identification letters (A) and (B) are consistent with the titles used in Drainage Statements produced on behalf of the developer, even though the initial application for Site (B) preceded that for Site (A). The planning history has been complex, including in regard to Site (B) an appeal to the Planning Inspectorate in relation to Maldon DC's original decision, and is summarised in the Appendix. For ease of reference the following table lists the relevant application numbers for the planning applications: Site A Site B Original application OUT/MAL/14/00186 OUT/MAL/13/00473 Resubmitted application OUT/MAL/14/01016 OUT/MAL/14/01018 Reserved Matters application RES/MAL/17/00776 RES/MAL/17/00766 Compliance with conditions 17/05154/DET 17/05142/DET application At present foul water sewage is pumped via a rising main to Latchingdon Water Recycling Centre for treatment with a discharge ultimately into the Blackwater Estuary. Joint Position Statement There was concern over the adequacy of drainage infrastructure to cope with development at North Fambridge. This resulted in a Joint Position Statement prepared by Anglian Water, the Environment Agency and Essex County Council being issued in January 2014 to assist Maldon District Council in their decision making on development in North Fambridge. As far as my report is concerned the relevant sections of the statement are the capacity of the foul water sewerage network and the availability of sewage treatment facilities. The statement confirmed that the village is served by a foul only sewerage network with two pumping stations located at The Avenue and Franklin Road. The statement said that the current network did not have the capacity to accept the further growth indicated, presumably referring to the 75 units included in the Local Development Plan, but possibly referring the total of 105 units from the two current applications plus a further 37 units from another application that might have gone to appeal at that time. It did not unfortunately say how much, if any, growth below that value could be accommodated. The Position Statement made it clear that both Anglian Water, as operator, and the Environment Agency, as the body responsible for issuing the discharge consent from that Centre, considered that the Latchingdon Water Recycling Centre was already operating at flow capacity. There was a recognition within the statement that, following a review, the consented dry weather flow needed to be increased but it was specifically stated that this was to take account of seasonal variation and that any further increase in loading would be unlikely to be looked on favourably if it led to increased nutrient levels in the Blackwater estuary. Hence process improvements would be required at Latchingdon WRC if it had to accommodate the planned growth. As a preferred alternative it was identified that South Woodham Ferrers WRC had sufficient capacity. Moreover the cost of providing a new sewerage system to pump the foul sewage to the latter location was estimated to be less than that of enhancing the system to Latchingdon, but still would be of the order of £2 million. Conditions placed on the Outline Permissions in Respect of Foul Water The outline permissions granted contained the following conditions with respect to collection and treatment of foul water: Site A 31. No development shall commence until a detailed wastewater strategy has been submitted to and approved in writing by the local planning authority. The development shall be carried out in complete accordance with the approved details and retained as such thereafter. 32. Pursuant to condition 31 above, no dwelling hereby approved, or approved as part of the reserved matters referred to in condition 1 of this permission, shall be occupied until the wastewater strategy has been carried out in complete accordance with the approved details. 33. No development shall commence until a foul water strategy has been submitted to and approved in writing by the Local Planning Authority. The development shall be carried out in complete accordance with the approved details and retained as such thereafter 34. Pursuant to condition 33, no dwelling hereby approved, or approved as part of the reserved matters referred to in condition 1 of this permission, shall be occupied until the foul water strategy has been carried out in complete accordance with the approved details. Site B 16. No development shall commence until a foul water strategy has been submitted to and approved in writing by the Local Planning Authority. The development shall be carried out in complete accordance with the approved details and retained as such thereafter. 17. Pursuant to condition 16, no dwelling hereby approved, or approved as part of the reserved matters referred to in condition 1 of this permission, shall be occupied until the foul water strategy has been carried out in complete accordance with the approved details. It can be seen that for both sites the conditions reflect the concerns over the ability of the foul water sewerage system to cope with additional load. However only the Site A condition gives consideration to the capacity of the Water Recycling Centre. Consideration of wastewater elements of application for Approval of Reserved Matters General The applicants have submitted Drainage Statements produced by their consultants RSK for both sites. As Appendix B to both these they have included the 2014 Joint Position Statement. RSK state that the Joint Position Statement was produced in response to a consultation from Maldon DC concerning the availability of infrastructure capacity in the Latchingdon Waste Water Treatment Works catchment to serve 800 new homes. However nowhere within the Joint Statement is such a figure mentioned as the context for its production. The only figures that are mentioned are the allocation of 75 units in the Local Plan (represented by Site A), the 30 units at Site B and another refused application for 37 units. The figure of 800 homes quoted by RSK as the context for the production of the Joint Position Statement gives the incorrect impression that the present applications are minor compared to the limited capacity of the sewerage and waste water treatment facilities. Foul Water Sewerage The RSK reports includes as their Appendix C an Anglian Water Development Impact Assessment dated 16th December 2015, but misleadingly referred to by RSK as being from January 2015. The Development Impact Report itself states that It should be read in conjunction with the pre-planning report dated 15 January 2015. Unfortunately a copy of that pre-planning report does not seem to have been submitted to Maldon DC. The Development Impact Report includes a spreadsheet calculation of the additional Dry Weather Flow anticipated from the residential dwellings in the two proposed developments. I note that a value of 131 litres/head/day has been used. This seems a little on the low side: the average UK water consumption is 150 litres/head/day and for billing purposes Anglian Water assume 90% of this is returned to the sewer. This would give a slightly higher value of 135 litres/head/day input to the sewer. I also see that no allowance has been made for flows from the commercial and community development within Site A. The Development Impact Report concludes that without mitigating measures the combined effects of the developments would result in increased foul water flood risk downstream of the proposed connection points. The solution proposed by Anglian Water, and by implication now forming part of the Applicant's submission, is to allow the Site B properties to connect by gravity to the sewerage system, to increase storage capacity at the existing The Avenue Pumping Station by 33 cubic metres and provide 68 cubic metres of storage within Site A (i.e. a total additional storage of 102 cubic metres) An on-site pumping station would be situated within Site A with real time control to prevent its operation when there is excessive build up at The Avenue Pumping Station. Using the Anglian Water flow figures, the anticipated daily output of foul water from the two sites would be 40 cubic metres under average conditions and 77 cubic metres if peak flow conditions were maintained. From this it would appear that, once all the storage had been provided, the proposal could provide storage for at least a day's input from the two sites. Anglian Water's calculations in the Development Impact Report assume that the two developments take place at the same time. They do however state that If the southern site [Site B] starts first then the full 30 dwellings may be connected prior to mitigation, on the proviso that the northern site will still be going ahead at the same time. However the full mitigation will need to be in place prior to any connections from the northern site being made. They have not given any justification for the first italicised sentence and I consider that sufficient mitigation measures must be in place before any of the Site B properties are occupied. An appropriate way of achieving this would be to require the increased storage at The Avenue Pumping Station to be in place prior to occupation of the Site B properties.