Horsham District Local Plan Wastewater Treatment

Letter published in West Sussex County Times, 11 January 2024

Dear Sir,

Horsham District Local Plan – Wastewater Treatment

Under the Water Industry Act, developers have the automatic right to connect to sewer networks, hence the essential requirements stipulated in the Horsham District Local Plan 2023 – 40 (HDLP), Strategic Policy HA2: Land West of Ifield, that

‘Close liaison with water treatment companies must be undertaken, including clear agreements on the phasing of development, to ensure that a new or expanded Wastewater Treatment Works (WwTW) is provided to provide timely additional capacity for the sewerage network’.

The omission of these essential requirements from HDLP Strategic Policies HA3: Land North West of Southwater (1000 homes) and HA4: Land East of Billingshurst (650 homes) is cause for concern.

According to the HDLP Sustainability Appraisal Update, December 2023, large scale development East of Billingshurst (as well as West of Ifield) ‘could have implications’ for the capacity of existing WwTW infrastructure.

In other words, timely additional capacity for the sewerage network will be needed at Billingshurst as well as West of Ifield.

The Appraisal makes no mention, however, of Strategic Policy HA3, which is surprising, considering Southern Water’s letter, dated 17/01/2023, to HDC, re DC/22/1916: Land North West of Southwater.

This letter advised that sewerage flows from the proposed development may lead to an increased risk of foul water flooding, and a need for the sewer network to be reinforced in consequence.

Furthermore, DC/22/1916 identified the Barns Green WwTW as ‘the nearest point where capacity is currently available for reception of flows from the proposed development’ but omitted to mention that storm overflows from the WwTW discharged into the adjacent Parsons Brook, 40 times/252 hours in 2021, and 43 times/410.85 hours in 2022.

Parsons Brook is a tributary of the River Adur, and the Adur West Water Body catchment has a ‘poor ecological status’, apparently due in large part to pollution from wastewater/sewage discharge.

Treating sewage from development North West of Southwater could add to overflows from the Barns Green WwTW, and worsen the Adur’s existing pollution problem to the detriment of the Adur River Project – one of only 22 nationwide projects to receive funding (£500,000) from Defra.

Clearly, the essential requirement for close liaison with water treatment companies and clear agreements on the phasing of development to ensure timely in-place provision of additional sewerage-network capacity for West of Ifield should also be stipulated in the Strategic Policies for Land East of Billingshurst and Land North West of Southwater.

Yours faithfully,

Dr R F Smith

Trustee CPRE Sussex