Petersham Hole
| The Petersham Hole | |
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 Location of The Petersham Hole in Greater London
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| Location | A307 road, Petersham |
| Coordinates | 51°26′44″N 0°18′11″W / 51.445678°N 0.303154°WCoordinates: 51°26′44″N 0°18′11″W / 51.445678°N 0.303154°W |
The Petersham Hole was a sink hole caused by subsidence of a sewer which forced the total closure of the A307 road in Petersham in the London Borough of Richmond upon Thames in 1979–80.
The affected area comprised elements of the culverted 'Sudbrook' stream, a minor tributary of the Thames, with a catchment extending south to Kingston, and foul sewer serving much of the Petersham area including four nearby schools. The culvert dated from 1920–22 and the foul sewer from 1890.
An initial collapse occurred in June 1978 in a section of outfall pipe in River Lane (51°26′47″N 0°18′13″W / 51.446405°N 0.3036°W), off the main A307. The lane is prone to tidal flooding and the outfall is protected by a flap valve. The damage proved to be sufficiently extensive to justify a temporary repair and letting a contract for permanent replacement of a long section.
In February 1979, a further collapse occurred 100 metres upstream to the south, in the busy A307 carriageway. On excavation, an area of cracked pipe was found, but, due to heavy rainfall and imminent spring tides the damaged section was set into rapid-hardening concrete and the hole refilled. Subsequent video inspection indicated the pipework to be in reasonable condition. However, a few weeks later, at the end of March, a further collapse occurred at the same site and a large cavity was found. It was clear that the whole section of sewer had to be replaced, and urgently.
The hole and subsequent repair work forced a total road closure of the main arterial route between Richmond and Kingston upon Thames. The impact was exacerbated by the narrowness of the road at and near the collapse site. Long diversions resulted via Twickenham to the west or Roehampton to the south-east causing additional congestion. Bus services 65 and 71 were forced to terminate either side of the hole and passengers and crew walk around the site to continue their journeys. To help relieve the transport pressure, exceptionally, nearby Richmond Park remained open to vehicular traffic overnight between Richmond, Ham, and Kingston gates. The park road was widened at Ham Cross near Ham Gate to accommodate temporary traffic lights to facilitate the additional traffic flow. This additional and unusual traffic resulted in the deaths of 84 deer in the park whilst the diversion was in operation.
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