How To Object
Summary of Preliminary Observations Regarding NI Water’s Response to LCCC
This letter highlights concerns regarding NI Water’s adherence to the British Water’s Code of Practice for sewage treatment systems specifically at Drumbeg Waste Water Treatment Works (WWTW).
Key points include:
- Deviation from Code of Practice: NI Water is not following the established guidelines that use the number of bedrooms in a dwelling to determine required treatment capacity, raising questions about their methodology.
- Settlement Occupancy Rates: NI Water calculated population equivalent (PE) using settlement occupancy rates from the 2021 Census, deviating from NISRA’s more widely accepted average household size approach.
- Contradictory Capacity Claims: NI Water previously acknowledged capacity issues at Drumbeg WWTW, yet has now reported finding 226 available PEs, suggesting a misrepresentation of actual conditions.
- Need for Further Investigation: These inconsistencies necessitate further inquiry into NI Water’s assessment methods to ensure alignment with established practices and accurate reflection of operational realities.
Overall, there is a pressing need to address these issues to ensure effective and safe management of Drumbeg WWTW. Further comments will follow as additional information is reviewed.
Letter sent to LCCC Planners and subsequently uploaded to the planning portal.
Dear Planners,
These are preliminary observations in relation to one aspect of NI Water’s response to LCCC’s recent questions posted to the planning portal which we consider need to be interrogated further with NI Water.
1. Adherence to British Water’s Code of Practice Flows and Loads – Sizing Criteria, Treatment Capacity for Sewage Treatment Systems
CODE OF PRACTICE
British Water’s Code of Practice for Flow and Load guides practice in Northern Ireland as evident from the following: ‘The Environment Agency, the Northern Ireland Environment Agency and the Scottish Environment Protection Agency support the use of this code of practice,’ (Page 1).
The Code of Practice uses the number of bedrooms in a domestic dwelling to determine population in relation to the treatment system; as evident from the following extract from Page 4:
‘Domestic housing
• A treatment system for a single house with up to and including 3 bedrooms shall be designed for a minimum population (P) of 5 people.
• The size of a treatment system for a single house with more than 3 bedrooms shall be designed by adding 1 P for each additional bedroom to the minimum single house value of 5 P, eg:
– house with 3 bedrooms = minimum 5 P system
– house with 4 bedrooms = minimum 6 P system (5+1)
– house with 6 bedrooms = minimum 8 P system (5+3).
• For groups of small 1 and 2 bedroom houses or flats
– flat with 1 bedroom = allow 3 P
– flat with 2 bedrooms = allow 4 P
• A treatment system serving a group of houses shall be designed by adding together the P values for each house calculated
independently, eg:
– for a group of two houses (3 and 4 bedrooms, respectively) the system shall be for a minimum of 11 P (5+6)’ (Page 4 Code of Practice Flows and Loads – Sizing Criteria, Treatment Capacity for Sewage Treatment Systems).
It is unclear why NI Water is deviating from the Code of Practice when assessing capacity at Drumbeg WwTw, this is a matter which requires to be addressed with NI Water before accepting its new measure described at 2 below.
2. NISRA use of average household size as a measure within the Census
In its response NI Water states: ‘By dividing the number of households into the number of residents for each settlement, the respective settlement occupancy rates were calculated. Based on using the 2021 NI Census population data, the Actual PE within Drumbeg WWTW catchment has been calculated to be 1693. As the Design PE is 1919, the theoretical headroom as determined by these updated PE calculations is 226.’
No explanation is provided for the use of ‘settlement occupancy rates’ by NI Water nor its deviation from the Code of Practice cited at 1 above.
It is noteworthy that NISRA does not use occupancy rates but rather average household size which given that it is a Province wide measure is likely to be accurate at a regional level. In the 2021 Census NISRA reported on a Northern Ireland wide basis that: ‘the population grew by 5% from 2011 to 2021 while the number of households grew by 9% over the same time period, meaning that the average household size has fallen from 2.54 in 2011 to 2.44 in 2021.’ That measure would only hold true for Drumbeg WwTw if population growth and household growth equated to the Northern Ireland position.
NISRA sets out known limitations to data in respect of using average household size for planning purposes. What are the limitations associated with using ‘settlement occupancy rates’?
NI Water has consistently informed MLAs and the public that Drumbeg WwTw is at capacity. Examples include:
(a) In answer to an Assembly Question in November 2014 NI Water identified capacity issues at Drumbeg WwTw. Details are available at NI Assembly deposited assets
(b) In 2019 NI Water again highlighted issues at Drumbeg WwTw confirmed in June 2023 when NI Water identified network issues at the facility.
(c) Correspondence between NI Water and Mrs Emma Little-Pengelly MLA and David Honeyford MLA in December 2022 and February 2023 stated: ‘that Drumbeg WwTw is currently operating at capacity. As a result, any new planning applications received by NI Water for consultation will receive a negative response, with a recommendation for the planning authority to disapprove the application, except for those with extant planning permission’. (Highlighting added) The content of the letter to Mr Honeyford is consistent with NI Water’s response to Mrs Emma Little-Pengelly in December 2022.
Now, however, NI Water has miraculously found 226 available PEs at Drumbeg WwTw. This finding suggests that the ‘occupancy settlement rates’ measure is seriously misrepresenting the known, and well documented, capacity issues at Drumbeg WwTw.
Concluding preliminary observations
The NI Water answer, posted on the Planning Portal on 4 October 2024, ( see the application and the questions they asked NIW here) in response to questions posed by LCCC uses occupancy calculations which are likely to be particularly sensitive to the fact that the Census occurred at a specific point in time (21 March 2021). The findings resulting from this measure also are contradicted by long standing information relating to capacity issues at Drumbeg WwTw, examples of which are provided at 2 above.
The reason for NI Water moving away from the Code of Practice on Flows and Loads – Sizing Criteria, Treatment Capacity for Sewage Treatment Systems which uses the number of bedrooms to determine the required treatment system size is not explained; this requires to be interrogated further with NI Water.
The above are preliminary comments on this one topic. We shall be considering the rest of the response from NI Water and may comment further.
