Roundhill Park Formal EIA Scoping
Opinion
HYDROLOGY, DRAINAGE AND FLOOD RISK
An assessment of the potential effects on the water environment, to comprise surface
water (hydrology), groundwater (hydrogeology) and flood risk, within the vicinity of the
application site will be carried out by Weetwood Services Ltd (“Weetwood”).
Baseline Conditions
The site slopes and naturally drains from north-west to south-east towards Billing
Brook.
Billing Brook is a left bank tributary of the River Nene, which flows in a southwesterly direction along the eastern border of the proposed development. Billing Brook is
designated an ordinary watercourse within the vicinity of the site.
According to the Environment Agency (EA) Flood Map the site is located in Flood Zone
1 (low probability of flooding). However, land adjacent to either side of Billing Brook
from Cowpasture Spinney (approximately 600 m south-west of the application site)
towards the parish of Billing is located in Flood Zone 2 and 3 (medium to high
probability of flooding respectively).
Billing Brook (approximately 3.5 km downstream of the proposed development) is
included in the Water Framework Directive (WFD) Anglian River Basin Management
Plan (RBMP). The ecological status of Billing Brook has been assessed by the EA as
currently Moderate (and expected to remain Moderate by 2015).
There are known to be four small unnamed ponds within the application site and a
number of other ponds within the vicinity of the application site. The ponds to the
north-east and north-west of the proposed development are not located within the
catchment of Billing Brook and would not be expected to be affected by the proposed
development during either the construction or operational phases.
According to the EA Groundwater Vulnerability Map the site is underlain by a
Secondary A Bedrock Aquifer. The aquifer is referred to in the Anglian RBMP as the
Nene Mid Lower Jurassic Unit.
According to the RBMP, the quantitative and chemical status for the groundwater body
underlying the site is assessed as Good (and expected to remain Good by 2015).
EA data indicates the site is located within a Nitrate Vulnerable Zone (NVZ), i.e. land
draining to watercourses affected by nitrate pollution.
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Nathaniel Lichfield & Partners Limited is registered in England, no 2778116. Our registered office is 14 Regent’s Wharf, All Saints Street, London N1 9RL
According to the British Geological Survey (BGS) Groundwater Flooding Hazard Map the
susceptibility to groundwater flooding varies across the site from moderate to significant.
According to the Soilscapes maps produced by the National Soils Research Institute, the
site is underlain by loamy and clayey soils. For the most part, the soils have impeded
drainage. The exception is an area associated with loamy soils which are indicated to
the south of the proposed development which are indicated to be free draining.
The Kettering and Wellingborough Level 1 Strategic Flood Risk Assessment (SFRA) states
surface water flooding has occurred within the vicinity of the application site along
Holcot Lane in Sywell.
Potential Effects
Surface and sub-surface receptors potentially susceptible to environmental impact from
flooding and drainage issues associated with the proposed development have been
provisionally identified. This includes the assessment of construction and operational
impacts. These are subject to confirmation as the EIA is undertaken and baseline
conditions assessed.
The ‘importance’ of each receptor will be designated using professional judgment and by
reference to relevant guidance criteria, taking into account the quality and rarity of
each receptor.
In order to assess the impact significance of the proposed development on the identified
receptors, the characteristics of each identified impact at the construction and
operational stages have been considered.
Identified impacts may be significant at the level of importance defined for the receptor,
or at a lesser geographical scale. For example, limited impacts on a watercourse of
County value might be assessed as being significant at a District level.
Thus, the significance of effects will be determined from the importance of the receptor,
the magnitude of the impact and, where appropriate, the likelihood of the effect
occurring.
The likely receptors and their importance/scale to be assessed are listed in Table 1
below. All receptors and receptor importance will be confirmed as the EIA is
undertaken.
Table 1: Development Receptors – Preliminary Identification and Importance
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Nathaniel Lichfield & Partners Limited is registered in England, no 2778116. Our registered office is 14 Regent’s Wharf, All Saints Street, London N1 9RL
Receptor
Nature of Impact
Phase
Receptor
Importance
Billing Brook
Ponds
Water quality
Water
Construction and
Local to
Operational
District
Construction and
Local
quality/flood risk Operational
Aquifer
Water quality
Construction and
Regional
Operational
Residents of Billing
Flood risk
(adjacent to Billing Brook)
Construction and
Very high
Operational
Note: To be confirmed during the EIA
The potential unmitigated water environment effects considered significant to the
application site include:
Construction phase

A reduction in surface and ground water quality due to contamination of runoff
and/or changes to surface water drainage patterns and pathways from the surface
to the underlying aquifer;

Increased risk of flooding to people, plant and Holcot Lane due to an increase in
runoff due to soil compaction.
Operational phase

An increase in surface water runoff (volume and rate) due to an increase in
impermeable areas; leading to:
o
An increase in flow in Billing Brook and flood risk downstream;
o
An increase in volume of water in ponds;
o
A reduction in surface water runoff quality due to an increase in
impermeable areas and in traffic volumes. Contaminated surface runoff
could enter local water bodies;

The large number of people visiting and employed at the proposed development
will increase the risk of watercourses becoming blocked due to tipping of rubbish
etc, leading to change in flood flow dynamics and an increase in downstream
flood risk;

Foul water from the developed site could pollute receptor water bodies; and

The proposed development for the north-east portion of the application site is for
naturalistic parkland and proposed woodland. As such, the impact to these ponds
is considered to be minimal.
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Nathaniel Lichfield & Partners Limited is registered in England, no 2778116. Our registered office is 14 Regent’s Wharf, All Saints Street, London N1 9RL
Cumulative Impacts
The ES chapter will include a consideration of the cumulative impacts arising from the
development of sites at:

Roundhill Park (Phase 2)

Overstone Leys
Both sites drain in a south-easterly direction towards Billing Brook, the same drainage
receptor as the application site. These could potentially impact upon the same
environmental receptors (with the exception of ponds) as those identified for the
application site.
It is envisaged that these proposed developments will implement appropriate mitigation
measures, including a surface water drainage system that restricts peak runoff rates to
Greenfield rates (in accordance with national and local policy), and a foul water
drainage strategy in consultation with Anglian Water and the EA, resulting in no
significant cumulative effects.
We do not propose including the following applications and proposals:

Northampton Lane

Land North of Boughton Road (DWH Site)

Land South of Boughton Road (Hallam Land Site)

Land North of Boughton Road (Salisbury Landscapes Site)

Marsh Spinney

Moulton Heights (Phase 1)

Moulton Heights (Phase 2)
These sites will not be included in the cumulative assessment because of their distance
from the application site and also because these sites naturally drain (it is believed)
towards the unnamed watercourse that flows into the Malton Arm of the Brampton
Branch catchment, and are therefore located within a different catchment area to the
application site.
Method of Assessment of Impact
The assessment will consider the potential effects on the water environment (both
surface and sub-surface) and local hydrology. It will consider the capability of
available water resources and supply networks to service the proposed development, in
addition to an assessment of the location and capacity of the existing sewerage
infrastructure including wastewater treatment works.
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Nathaniel Lichfield & Partners Limited is registered in England, no 2778116. Our registered office is 14 Regent’s Wharf, All Saints Street, London N1 9RL
The assessment will be informed by a Flood Risk Assessment (FRA) based on the
requirements of the National Planning Policy Framework and its Technical Guidance.
The FRA will include:

Details of historic flooding events;

Identification of potential sources of flooding;

An appraisal of the scope of possible measures to reduce the risk of flooding to and
from the proposed development;

A surface water drainage scheme based on sustainable drainage principles
highlighting how sustainable drainage measures can be utilised to mitigate the
impact of the proposed development on the water environment.
Baseline information considering water quality, flooding and drainage, ground
conditions, and topography will be based on a desktop study, site visits, stakeholder
consultations, and relevant guidance and legislation.
The methodology for carrying out baseline research includes the following:

Review currently available data and information, including information on water
resources (abstractions, designations etc) and on surface and sub-surface water
quality, at and within the vicinity of the application site;

Review international and national legislation and regulations relevant to the
assessment of potential impacts to hydrology and drainage. In addition, review
guidance and policy documents including, yet not exclusively, those published by
the Department of Communities and Local Government, DEFRA, the EA, CIRIA
and by relevant regional and local authorities including SFRA’s and Catchment
Management Plans;

Consult with the EA and Northampton County Council (NCC) (the Local Lead
Flood Authority) regarding flood risk and drainage issues;

Consult with NCC and the Borough Council of Wellingborough regarding highways
flooding and flooding of ordinary watercourses; and

Review the potential impact of the development on the quality of groundwater and
amount of groundwater recharge, the British Geological Survey groundwater
flooding maps, and the impact of the proposed development and associated SuDS
scheme on the quality and quantity of surface water infiltration.
Potential mitigation
It is envisaged that the potential impacts on the water environment from the proposed
development will be mitigated through a series of measures during both the construction
and operational phases of the proposed development.
Construction phase
These may include:
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Nathaniel Lichfield & Partners Limited is registered in England, no 2778116. Our registered office is 14 Regent’s Wharf, All Saints Street, London N1 9RL

Implementation of a Construction Environmental Management Plan;

Best construction practices; and

Sealed storage vessels to contain foul water from temporary staff welfare facilities
and disposed of off-site.
Operational phase
These may include:

Implementation of a surface water drainage scheme based on sustainable drainage
principles;

Implementation of a maintenance and management regime to prevent build up of
debris and/or rubbish in water bodies on site; and

Development of a foul water drainage strategy through consultation with Anglian
Water and the EA to ensure foul water from the proposed development is
sustainably managed.
Consultation
Consultation will be undertaken with the relevant statutory and non-statutory bodies,
including:

EA – regarding flood risk and drainage issues;

NCC – regarding flood risk, drainage issues, highways flooding and flooding of
ordinary watercourses;

Borough Council of Wellingborough – as NCC; and

Anglian Water – regarding water supply and foul water drainage.
5807161v1
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Nathaniel Lichfield & Partners Limited is registered in England, no 2778116. Our registered office is 14 Regent’s Wharf, All Saints Street, London N1 9RL