Mr Dempster’s response to EARA

I write in response to the petition to development control committee on 27th June 2019 which invites the council to –

‘Defer making the decision regarding the application by Brett Aggregates to quarry on Ellenbrook Fields until information is provided to the Committee is current and up to date. We expect that an informed decision should be made on relevant information that has been collated and gathered recently, including but not limited to, up to date traffic surveys, current studies of air pollution, and a study undertaken on the cumulative impact of this and other plans submitted or proposed in the surrounding areas on these issues and local residents and frequenters of this area’.

Your presentation referred to the need to provide up-to-date traffic and air quality surveys, and flood risk and health impact assessments that take account of existing and proposed developments since January 2017, including the housing developments at Sandpit Lane, Beaumont School, Ellenbrook Meadows, Comet Hotel student accommodation, as well as the commercial developments at Hatfield Business Park, Glinwells Nursery, Pearce Recycling and Hatfield Quarry.

Health Impact Assessment

The Environmental Statement includes individual assessments of noise and air quality. There is no policy requirement for planning applications to include a human health impact assessment.Hertfordshire Public Health advised there is no requirement for a separate health impact assessment to be submitted with the application because the individual noise and air quality assessments provide sufficient information to assess the potential human health impacts.

Air Quality

The site is not within an air quality monitoring area indicating there is no significant degradation of local air quality. Welwyn Hatfield Environmental Health department requested continuous air quality monitoring be put in place prior to mineral extraction. The monitoring locations have been agreed with EH officers. The draft planning conditions require monitoring equipment to remain in place throughout the development to assess the impact of the mineral working on local air quality. The conditions include measures to avoid adverse impacts during operations. Similar conditions are in place for the approved developments at Hatfield Quarry to avoid any degradation of local air quality.


The impact of additional HGV traffic on the HGV has been assessed by the Highway Authority as being within the existing daily fluctuation of traffic using the A1057. The proportion of HGV traffic from the development site, in combination with Hatfield Quarry traffic, is less than 10% of total traffic using the road. The Highway Authority considers this level of additional traffic would not have a severe impact on the road network. The development provides the necessary local infrastructure improvements and financial contributions. A comparison of traffic survey data between 2015 and 2019 indicates the levels of traffic using this section of the A1057 has not increased significantly between the two dates.

Impact of other approved developments

The other housing developments mentioned are Oaklands College [348 homes], Beaumont School [75 homes], Jove Gardens [22 homes], the former Radio Nursery site [28 homes], and the equivalent of 272 units of student accommodation at the former Comet hotel site. The student accommodation relates to the adjacent University campus and is not expected to generate significant additional car journeys. The other housing developments are within St Albans district at distances of 2.5km, 2.3km and 0.5km from the proposed quarry site entrance. There are various options to access these housing developments that do not involve using the section of A1057 in the vicinity of the quarry entrance. The pattern of traffic movement generated by the housing developments is expected to be dispersed across the network. Each development provides the necessary highway infrastructure and appropriate contributions to mitigate the highway impact. The Highway Authority considers the impact of these developments to be acceptable.

In terms of the commercial developments; the Hatfield Business Park developments do not exceed the maximum levels of traffic modelled as part of the overall Hatfield Aerodrome development; the additional glasshouse development at the Glinwells site is not expected to generate significant additional levels of HGV traffic; the traffic generated by the Smallford farm shop will be dispersed over four local roads. The Pearce Recycling site is within the built-up area of St Albans over 1km west of the quarry entrance. The majority of HGV movements are unlikely to pass the quarry access. The traffic surveys will include the Pearce Recycling HGV movements passing the quarry entrance. In terms of the combined quarry HGV movements, the proposed development together with the operation of Hatfield Quarry would represent less than 10% of total traffic using this section of the A1057. At this level the Highway Authority is satisfied there would be no severe impact on the local highway network.


The presence of Bromate contamination in groundwater is unrelated to mineral working. The extent of the Bromate plume does not affect the proposed mineral extraction area. The level of Bromate concentration in groundwater has been monitored by the applicant over an extended period from 2010 leading up to the submission of the planning application. This has involved the applicant working with the Environment Agency to ensure that the proposed method of working will have no significant impact on Bromate contaminations at the site level. The Environment Agency has no objection to the proposed development and advises that a Groundwater Monitoring Plan condition will provide satisfactory mitigation. Affinity Water share that view. The proposed precautionary method of working is designed to minimise the risk of further contamination; this includes working the mineral deposit in small parcels in wet conditions with only essential limited dewatering. In parallel it is proposed to infill each of small parcel using inert waste to avoid large voids being exposed. The working will be lined with a geological barrier to prevent cross contamination of groundwater in the upper and lower mineral layers.

Surface Water

The individual developments on the Hatfield Business Park provide appropriate sustainable urban drainage at the green field run-off rate. The Lead Local Flood Authority has been consulted on all major developments within the business park since 2015 and have accepted the proposed discharge rates in all cases. The quarry application proposes to manage groundwater and surface water within the site using two infiltration lagoons. Working the lower mineral in wet conditions reduces the need for dewatering. An exceedance route (backdrain) is proposed to Ellenbrook to avoid the possibility of uncontrolled flooding from the site. The infiltration lagoons provide sufficient water storage so that controlled discharge to Ellenbrook would only occur in exceptional circumstances.

I trust that this response addresses the points you raised. If you require any further response I would be grateful if you would write to me prior to committee on 24 July 2019.

Yours sincerely

Chay Dempster
Principal Planning Officer - 
Development Management
Spatial Planning & Economy,
Environment Department CHN216
Hertfordshire County Council
County Hall Pegs Lane