Appeal 6004315

The appeal is dismissed.

Following the refusal of planning permission on drainage grounds, the appellant has submitted a revised [name] (DSR), Drainage Strategy Plan (DSP), and [name] as part of the appeal.

I have considered the additional drainage information in consideration of the Holborn Studios Ltd v The Council of the London Borough of Hackney [2017] EWHC 2823 judgement. The DSR, DSP and hydraulic calculations provide further supporting information regarding the drainage of the site but do not amend the proposal. As such, I have considered whether accepting the information would cause procedural unfairness to interested parties. The Council has provided comment on the revised DSR, DSP and the calculations.

As the DSR does not amend the proposed development from that seen within the application, this evidence does not make a substantive change to the proposal, and no objections have been received in relation to the proposal. As a result, the acceptance of the DSR, DSP and calculations would not unfairly deprive those entitled to be consulted on the application, the opportunity to make a representation. Whilst my decision has therefore taken the DSR, DSP and calculations into consideration, no drainage statement that evaluates this technical evidence has been submitted to assist me in understanding the implications of this data.

Whilst on site I observed that the appeal site has been subject to development undertaken that is not shown on the proposed layout plan. A caravan has been provided (number 9) adjacent to number 26, and two concrete pads have been laid, one of which is adjacent to number 23 and the other is adjacent to the new caravan at number 9. These fall within the red line boundary of the appeal site and would appear to prevent the development being laid out as proposed on the site layout (drawing number 0172_P_300E). Nonetheless, I have assessed the proposal based on the plans before me.

The main issue is whether the site can be adequately drained for both foul and surface water.

Policy ER11 of the Telford and Wrekin Local Plan (2011-2031) (TWLP) addresses sewerage systems and water quality and requires that the development demonstrates that it can be drained appropriately for both foul and surface water against a set of five criteria. TWLP Policy ER12 covers flood risk management and requires development to comply, where applicable, with a set of ten criteria relating to flood risk and surface water management.

The application form states that foul water would be discharged to the mains sewer with no change to the existing public sewer connection. The site has a private sewer network that connects to [name] network. Several drainage surveys have been undertaken which have failed to identify a connection point to the [name] network. I note the evidence of a connection to the public sewer network following the submission of a [name] bill for one of the existing properties on the [site address] site.

The DSR has identified that a foul water drain runs alongside the existing units at numbers 10, 11 and 13 [site address] which feed into a combined foul and surface water drain adjacent to number 26 [site address] . This combined sewer appears to connect to the public sewer adjacent to number [address], at the rear of the [site address] site. However, this does not appear to concur with the plan of the sewer/drain network within the evidence from [name]. The DSR also identifies that parts of the private on-site drainage network are in a poor condition and require remedial works or replacement.

As a result and given that the connection to the public sewer network was not found as part of the survey work, I am unable to conclude with reasonable certainty that a foul water connection for the appeal site is available and that the existing drainage network on site is serviceable to allow for the further expansion of [site address] . Whilst a planning condition could be imposed that requires confirmation of a connection agreement with [name], without further information to ascertain that it can be achieved, this would not be reasonable.

The DSP has amended the proposed attenuation basin to reduce the permanent water level that would remain within the attenuation basin. The Lead Local Flood Authority (LLFA) has identified that the despite the amendment, a level of stagnant water would remain within the basin that could become a health hazard and would hinder the biodiversity of the site. I also acknowledge the LLFA’s concerns regarding the storage capacity of the basin in relation to the 1 in 100 year +45% CC and whether this would be sufficient without using the ‘freeboard’ of the basin. As no further commentary has been provided by the appellant as to why the basin cannot be dry except during periods where the basin is required for the storage of surface water or regarding its storage capability, I am not satisfied that the attenuation basin has been appropriately designed and calculated to accommodate the surface water requirements of the appeal site.

The submitted water management statement identifies that surface water would be addressed using soakaways, for new roof and hard surfaced areas. These appear to drain into the proposed attenuation basin where water would then be pumped into the private drainage system in the wider [site address] .

The Council’s Sustainable Drainage Systems (SuDs) Handbook 2019 [name] (the [name]) identifies that the pumping of surface water for new development will not be permitted. It goes on to advise that development should be directed to where the discharge of surface water via gravity can be achieved. I acknowledge that infiltration of surface water is not allowed on the site due to the presence of shallow mine works and a mine shaft. However, no evidence is before me regarding alternative sustainable drainage solutions, or confirmation provided, that demonstrates that the pumped solution is the only viable surface water management scheme for the site.

Overland exceedance surface water flows, as indicated on drawing number LM25017-XX-DR-C-520 P01, appear to fall towards the wooded area to the west of the appeal site. Due to the site topography, the surface water would appear to flow down towards the B4373 [site address] Way. Consequently, should the proposed pumped system fail and/or the storage capacity of the basin not be sufficient, the proposal could lead to a surface water flood risk on and off site, including onto the B4373. On this basis, I am unable to conclude with reasonable certainty that the proposed development has adequately calculated and accommodated surface water drainage and management within the proposal. I also note that the Council considers that the SuDs proposed are not of a suitable quality for adoption.

Whilst a sustainable drainage condition could be imposed, this would not be reasonable where doubt remains as to whether an appropriate drainage system can be accommodated on site. The evidence provides no alternatives or reasoning for the drainage solution before me. Accordingly, I am unable to conclude that both an appropriate foul and surface water drainage system can be achieved on site. Therefore, a condition that may not be capable of being complied with would not be reasonable.

Accordingly, for the reasons given above, the proposal would conflict with Policies ER11 and ER12 of the TWLP. These policies, amongst other things, require development to demonstrate how foul flows produced by the development will be drained and the identification of the agreed point of connection to the public foul sewerage network. They also require development to include appropriate sustainable drainage systems to manage surface water appropriate to the hydrological setting of the site and that a management and maintenance plan is in place that includes arrangements for adoption by a public authority or statutory undertaker. The proposed development also fails to accord with the Council’s SuDs Handbook.

The proposed development would provide nine residential units that would contribute to the Government’s objective to significantly boost the supply of homes. The units would also provide housing for a wide range of the population, including older people. These factors attract only modest weight in favour of the scheme.

Whilst the proposal would provide nine additional residential units, these do not outweigh the requirement for the site to be adequately and appropriately drained. For the reasons given above the appeal should be dismissed.