1. This proposed development site is on a flood plain Figure 1. This is not an optimum development site and would be better utilised as a flood water retention zone for the downstream urban conurbation. The site has a natural tendency to flood during peak storms and could retain much more water if developed as a City Flood Retention Area as part of the Climate Emergency Measures. A new reservoir would also be much more beneficial for biodiversity off-setting impact elsewhere.
2. The surface water run-off from this development will compound the existing flood levels in the downstream urban conurbation, Figure 2. Yazor Widemarsh and Eign Brooks will flood the City. This excess run-off could result in considerable increased liabilities for City residents and businesses.
3. The proposed development site surrounds a Conservation Area, best conserved for the residents of the City as a Historical Hamlet in an area of natural beauty. This brook and surrounds are noted for the rich array of wildlife using the brook as a corridor to migrate through from the country into the City and back. This is currently refuge and habitat for many fish, birds, bats insects and mammals including badgers and otters.
4. The proposed development is over a vulnerable commercial aquifer (Figure 3) with a complex, near surface, geological boundary of intermixed clay and gravels. Site not suitable for development. Reports on the complex geology by WYG expose the risks of breaking into perched water tables or releasing near surface secondary aquifers into the site and downstream into the City. The term superficial aquifer means it is hosted by superficial deposits. It is far from superficial in its importance to the region.
5. Hereford City has two major industries, employers and taxpayers who depend on the commercial aquifer that underlies this proposed site. Excavations for footings and drainage of houses, roads and ponds could contaminate commercial groundwater. The main commercial aquifer is below and upstream of proposed developments and layouts have already changed to reflect the complexity and risk of contaminating the ground waters. Why risk such a great loss to the City and County for just 350 houses?
6. The aquifer boundary Source Protection Zone 2 is poorly defined (Figure 4) given investigation by WYG and Groundsure shows greater than 10m of groundwater below the proposed site and recharge from the west and north. The proposed development site straddles the boundary, but the boundary does not cover the full extend of the water source. Detailed investigation showed extensive groundwater extends north under the site. In the light of evidence presented by WYG the Environment Agency should revisit the poorly defined SP2 zone and extend it further North.
7. Future liabilities for the proposed development will be passed on to the householders via a company to administer the site specific but who will be responsible for future issues arising from floods and contamination downstream? We will all pay more council tax.
The probability of a risk occurring has been reviewed by a hydrogeologist and adjustments made based on professional judgement, to take account of specific local circumstances relevant to the site.’ Tetra Tech Hydrological Risk Assessment Report
This is the key statement from the hydrological risk assessment conclusions. It states adjustments were made based on professional judgement to take account of specific local circumstances relevant to the site. This raises several RED FLAGS
8. The Tetra Tech risk assessment report is based on the author's conceptualisation of the current ground conditions and assumption that they will largely remain the same between the time of this assessment and the commencement of development, but ground conditions have already changed. Tetra Tech and the Environment Agency did not locate the underground water course that now runs permanently above ground as a stream South through the middle of the proposed development site, west of the Beeches Business Park under the Roman Road along the small valley and down to the highly sensitive area around the Yazor Brook. The intention to cover low lying areas with clays removed from higher areas risks breaking secondary perched water tables, generating saturated unstable ground and pollution of the vulnerable commercial aquifer.
9. Why roll the dice with reserved matters for outline planning permission when a geophysical survey could clearly assess the risk of failure more accurately by measuring the depth of clay cover over the Yazor gravels and vulnerable aquifer gravels. The presented maps of clay thickness for staged site construction are based on sparse sampling and exhibit a typical naive ‘fried egg pattern’ expected from a poor data set. A geophysical survey could identify precisely how thick the cover is in between the sparse sample points. The clay layer over the gravel above the aquifer is, in part, less than 0.5m thick according to Environment Agency observations in its response. Given the strongly worded disclaimer in the WYG desk study, used to inform the Tetra Tech risk analysis, the Council is exposed to significant risk due to the unknown geological variables. A detailed survey would enhance the current modelling assumptions and may negate key geological and hydrological assumptions used in the development proposal.
10. Why is the local knowledge of the connectivity between brooks and abstraction rates not considered as part of the professional judgement. The observations of groundwater levels from just two boreholes compared with water levels in the Yazor Brook are stated as evidence that the surface flows are not connected to the aquifer. City residents know the Brooks can rise and fall irrespective of rainfall in the catchment, clearly pointing to variable abstraction rates. Licensed boreholes give Heineken and Avara (formerly Sun Valley) rights to pump over 4.38 Olympic swimming pools a day from the gravels (10.98 million litres daily) and the average abstraction is 1.75 Olympic swimming pools a day (4.38 million litres daily).
11. Tetra Tech noted that building on a floodplain requires bigger drainage and flood retention tanks to protect the downstream environment. Surely this statement is enough to rule out any long-term major housing developments across the floodplain so why start developing it? It is proposed to provide increased flood storage by undertaking excavation. The excavation constraints limit the storage volume that can be provided within above ground SuDS. It is expected that additional below ground storage will be required within the areas of public open space to the south of the Site to provide the storage volume required. It frequently floods immediately south of the site and the City can’t afford to keep its existing underground sumps and drainage systems clear of blockages.
12. The risk to this County of failure in developments over a vulnerable commercial aquifer have not been spelt out to the public. Breach of the surface gravels and pollution of the aquifer could result in loss in jobs and quality of life for generations in Hereford City. Why has the professional judgement based on local knowledge not laid out the full risks of proposed excavations in plain English. Is it inherent bias in this technical reporting that errs towards development when professional judgement sweeps the detailed risk of failure into the small print of an appendix? The presentation for public relations is a glossy brochure but the inherent risk to the City and County is buried in the appendices.
13. The Environment Agency stated, in December 2021, it was adjusting the boundaries of the Source Protection Zones around onsite boreholes. The current SPZ merged data set on the National system has not changed. The boundary of aquifer source protection zones relates to proximity of boreholes and the time it takes for water to travel in the aquifer to the borehole. The on-site boreholes, shown as A and B in Groundsure report sect 5.6, could be re-designated SPZ1 and prohibit any development in the South-eastern portion within 100m radius. SPZ2 is technically defined as 400 days of flow away from or 250-500m away from the nearest abstraction points. The new SPZ2 boundary for the active on-site boreholes should extend further north and east by 250m-500m reducing the proposed development area. The new Source Protection Zones 1 and 2 boundaries should envelop a wider area of the proposed development site given the strict technical definitions. This does not appear to be taken into the design of the latest development plans which closely follow the original SPZ2 boundary. THIS IS A BIG RED FLAG
Impact on development of the redefined Source Protection Zones
a. A 250m radius around Borehole A takes out all proposed housing south of the Huntington Lane roughly 20-25% of development and
b. a 500m radius takes out all proposed housing north of the Huntington Lane and between Beeches Business Park and the Farm, say 40-50% of development
14. How can we as the public be expected to make informed comment before the Environment Agency has published its new source protection zones which should negate 25% to 50% of the proposed development site?
The current published SPZ boundaries for Hereford are on the National system. They do not yet reflect and enlarged protection area around the on-site abstraction boreholes, close to the intersection of Bakers Lane and Three Elms Road.
https://environment.data.gov.uk/arcgis/rest/services/EA/SourceProtectionZonesMerged/FeatureServer
Background notes and comments
DEFRA/Environment Agency response with reference to SPZ designation dated December 2021
