Restoration at Dogsthorpe Star Pit

Restoration at Dogsthorpe Star Pit

Dogsthorpe Star Pit by Tim Burke

The Anglian Water Flourishing Environment Fund has enabled habitat mangement at a nature reserve near Peterborough

Dogsthorpe Star Pit was a former clay pit and brick works to the north east of Peterborough - now a haven for wildlife - 63 species of water beetle have been found in the shallow pools. At this time of year damselflies and dragonflies are abundant along the edge of the water, kingfisher and heron hunt in the pools whilst snipe, shoveler and teal feed at the water’s edge. The reedbeds provide important habitat for birds; bittern are known to nest here.

Much work has taken place by staff, volunteers and contractors on a number of restoration projects across the 36 hectares site made possible by generous funding from the Anglian Water Flourishing Environment Fund, plus the Vera Joan Milhinch Charitable Trust, the Clark Bradbury Charitable Trust and the Wakefield Trust.

Work involved coppicing scrub and willow to maintain rich grassland on banks and pit floor, trimming hedges bordering path network and litter picking along the roadside to maintain the site visitor experience.
The creation of several new ponds across the pit floor has made homes for the aquatic invertebrates which thrive in the brackish waters that percolate up through the clay substrate. Waste material from the pond excavation was used to infill several pools which were overrun by Crassula helmsii (New Zealand pigmyweed, a non native invasive plant), which was swamping the area and preventing open water loving species. A specialist contractor cleared encroaching Phragmites reeds from the wetland swamp area using Truxor machines fitted with reciprocating blades and rakes. The tracked boats travel across the water surface thanks to the inbuilt buoyancy and remove the litter to vegetation stacks to dry and compost.

A major investment of contractor time and funding was used for the replacement of the pump house at the north-eastern corner of the site, involving serious groundworks to provide a long term solution. An excavator created a coffer dam, removing a compound floor and fencing, extracting the pump from its housing. An old brick wall was demolished and the loose spoil bank was  re-profiled to prevent subsidence, which had been pushing the concrete housing over for several years.

As expected in a complex project there were a few set backs (including working in snow on Friday the 13th). Sheet steel pilings intended to form the new pump housing refused to be driven deeply through the dense compacted clay which caused the site to be abandoned by the brick makers originally. These pilings had to be removed the following week after flooding and further bank collapses rendered this option unachievable.

The solution came with the creation of a thick concrete pad and bank revetments around three permeable 1.5m wide concrete culvert pipes set vertically onto the pad. The security compound was replaced and the coffer dam removed to allow the flow of water on site to the pump in its new housing. This was scheduled to take six days but eventually ran to 12 after the setbacks along the way and the restoration of the area near the pump house.