The Blashford groundwater appeal has been dismissed, blocking 140 proposed homes near Ringwood in Hampshire despite the site being allocated for housing. Inspector John Longmuir rejected Gladman Developments’ scheme on 4 November 2026 after finding that the evidence did not reliably establish how groundwater would behave or whether residents would be safe from flooding.
The proposal concerned land at Snails Lane, Blashford, in New Forest District. It included 70 affordable homes, open space, sustainable drainage, highway works and ecological mitigation. The appeal followed the council’s failure to determine application 25/10114, although the authority subsequently identified ten potential reasons for refusal.
The Blashford groundwater appeal is significant because almost all of those issues were resolved before the inquiry concluded. The allocated site, severe shortage of housing and substantial public benefits were not in dispute, yet uncertainty about a single fundamental drainage question remained enough to defeat the entire development.
Why the Blashford groundwater appeal failed
The majority of the site lies within Strategic Site 15 in the adopted New Forest local plan, an allocation for at least 100 dwellings. All 140 proposed homes would have stood inside the allocation boundary, with a northern parcel outside it needed to support delivery. Both main parties agreed that development was acceptable in principle.
Ahead of the September 2026 inquiry, the council stopped contesting highway safety and pedestrian access. A legal agreement dated 1 October secured matters including affordable housing, air quality, ecology, alternative recreational greenspace, education, highways and monitoring. The Inspector therefore concentrated on groundwater and flood risk, rather than treating the proposal as an unacceptable location for housing.
Flood Zone 1 did not mean groundwater safety was proved
The proposed homes were in Flood Zone 1, although a portion of the wider site lay in Flood Zone 3b. The council accepted that the sequential test had been satisfied and that no exception test was required. The Environment Agency raised no objection on river flooding, but specifically left groundwater and surface water assessment to the relevant lead local flood authority.
The Blashford groundwater appeal turned on a more local problem: a depression in the former sand and gravel workings had held standing water. Drone footage from February 2025 showed substantial ponding. The site had been worked and then backfilled with materials whose properties were incompletely recorded, making the direction and speed of water movement harder to predict.
Gladman’s position was that shallow perched water sat above less permeable infill, while a separate deeper groundwater system lay around 1.5 metres below ground level. The drainage strategy proposed to intercept water before it pooled. However, the Inspector found that the two-system explanation had not been demonstrated with sufficient reliability to establish the safety of the detailed scheme.
Extensive surveys still left crucial gaps
The evidence was not sparse in numerical terms. The inquiry considered 74 exploratory holes, 24 monitoring wells and 170 groundwater dip results across 26 monitoring dates. But not all boreholes had been properly sealed, and the central depression, where water gathered, had not been investigated with boreholes.
There was also no continuous autumn-to-spring recording to capture seasonal changes reliably. Monthly rainfall averages could not explain individual periods of heavy rainfall, the water depth in the depression had not been measured, and winter levels in neighbouring lakes were unknown. An existing pipe found near the depression was not surveyed, leaving its route and condition uncertain.
The Inspector warned that there is a real risk that the drainage system will not work
if the assumed groundwater model proved wrong. That is the practical heart of the Blashford groundwater appeal: even a technically elaborate flood assessment cannot compensate for missing measurements at the precise location where uncertainty matters most.
Seventy affordable homes and a serious housing shortage
The housing need evidence strongly favoured permission. The Inspector recorded a 1.53-year housing land supply, a shortfall of 7,524 dwellings and a Housing Delivery Test result of just 48%. The scheme offered 70 affordable homes, alongside private housing and construction spending. The Inspector accepted the overall benefits were substantial.
Other concerns did not change the outcome. The Inspector accepted the proposed habitat mitigation and found no unacceptable effects on ecological designations, the New Forest National Park’s setting or landscape character. There would be some harm to the nearby listed Waggon Wheelhouse and a non-designated farmhouse, but the Inspector decided the substantial public benefits outweighed the heritage harm.
That balancing exercise did not rescue the development from the flood risk objection. The Blashford groundwater appeal demonstrates that a housing allocation and acute need do not remove the requirement to show that residents can occupy the proposed development safely.
Why a planning condition could not fix the problem
One earlier suggested condition would have required further flood-risk review after permission, with mitigation to follow. The Inspector rejected that approach because new findings might require changes to a detailed layout that would already have planning permission. Later suggested drainage and maintenance conditions did not resolve the underlying uncertainty about the groundwater model.
The decision applied national Framework policy F7 alongside local policies STR1 and CCC1. The Inspector identified flood safety as an issue that had to be established before permission, rather than deferred until construction. The case concerned a full planning application, which makes the proposed layout and finished levels particularly important.
For promoters of allocated sites, the lesson from the Blashford groundwater appeal is to interrogate the weakest parts of the hydrological model before finalising a scheme. Our flood risk assessment guide explains why flood zones do not capture every source of flooding and when groundwater and surface-water evidence may also be needed.
Appeal decision and sources
Inspector John Longmuir dismissed appeal 6009295 on 4 November 2026, following an inquiry held on 9, 10, 11, 15 and 16 September. The appeal decision is also available on AppealBase. The quotation is from the Inspector’s published decision under the Open Government Licence.
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