Project experience Ponds
Work expertise Dredging / silt pumping
Client Harlow Town Council
 
 

Context

Netteswell Pond is a large body of water located off 2nd Avenue in the centre of the town of Harlow. It is fed predominately from an incoming stream but also potentially from an underground spring located somewhere deep below. The pond is maintained under a joint venture with Harlow Town Council and the Stort Angling Society.

Requirement

Pond restoration work required the removal of an invasive species of reed and deep deposits of silt which were contributing to a drop in water oxygen levels.

Challenge

The project had various phases and many challenges were overcome to get the job complete.

The first problem encountered was the draining of the lake for the resident fish to be caught and temporarily removed while the works were carried out. When the project started the area was hit by unseasonably heavy rains, this meant as fast as the lake was being pumped out it was quickly refilling by surface run off and the incoming stream. To counter this two six inch silent pumps were bought in order to empty the lake, when the level was sufficiently drained a single pump was kept running in order to maintain the water at a satisfactory level for the works to be carried out.

Another challenge was to drain the lake sufficiently so that fish could be removed by netting or electro stunning under guidance from the Environment Agency and Framlingham Fisheries, the company tasked with catching the fish.

Solution

With the heavy rains encountered during the project the decision was made to bring in low ground pressure machinery by the way of tracked dumpers in order to minimise bankside damage and with a higher ride height enabled them to enter the lake to be loaded. Coupled with a large long reach excavator plus two 14 tonne 360 machines it enabled the materials to be removed.

Excavated materials were to be deposited in three locations in the vicinity of the pond behind an earth bund to contain the silt and mud. These three areas were quickly identified as not having the capacity to store all the excavated materials, so another spoilt site had to be sought.

After negotiations from Harlow Town Council and a local farmer a much larger site was found for the material to be deposited. This however brought its own set of challenges as the materials would have to be transported off site. Using a local agricultural contractor, materials were moved using large tractors and trailers to the tipping area and a local road sweeping firm to ensured the highways were kept safe for motorists.

Once all materials were removed the site was made good using the existing machinery and fish released back into the pond once the water levels had reached a suitable level. Silt deposit areas were fenced off and signs placed warning of the dangers of the wet materials.


Context

Netteswell Pond is a large body of water located off 2nd Avenue in the centre of the town of Harlow. It is fed predominately from an incoming stream but also potentially from an underground spring located somewhere deep below. The pond is maintained under a joint venture with Harlow Town Council and the Stort Angling Society.

Requirement

Pond restoration work required the removal of an invasive species of reed and deep deposits of silt which were contributing to a drop in water oxygen levels.

Challenge

The project had various phases and many challenges were overcome to get the job complete.

The first problem encountered was the draining of the lake for the resident fish to be caught and temporarily removed while the works were carried out. When the project started the area was hit by unseasonably heavy rains, this meant as fast as the lake was being pumped out it was quickly refilling by surface run off and the incoming stream. To counter this two six inch silent pumps were bought in order to empty the lake, when the level was sufficiently drained a single pump was kept running in order to maintain the water at a satisfactory level for the works to be carried out.

Another challenge was to drain the lake sufficiently so that fish could be removed by netting or electro stunning under guidance from the Environment Agency and Framlingham Fisheries, the company tasked with catching the fish.

Solution

With the heavy rains encountered during the project the decision was made to bring in low ground pressure machinery by the way of tracked dumpers in order to minimise bankside damage and with a higher ride height enabled them to enter the lake to be loaded. Coupled with a large long reach excavator plus two 14 tonne 360 machines it enabled the materials to be removed.

Excavated materials were to be deposited in three locations in the vicinity of the pond behind an earth bund to contain the silt and mud. These three areas were quickly identified as not having the capacity to store all the excavated materials, so another spoilt site had to be sought.

After negotiations from Harlow Town Council and a local farmer a much larger site was found for the material to be deposited. This however brought its own set of challenges as the materials would have to be transported off site. Using a local agricultural contractor, materials were moved using large tractors and trailers to the tipping area and a local road sweeping firm to ensured the highways were kept safe for motorists.

Once all materials were removed the site was made good using the existing machinery and fish released back into the pond once the water levels had reached a suitable level. Silt deposit areas were fenced off and signs placed warning of the dangers of the wet materials.


 
 
 
Downloads
  • Hugh Pearl Nettleswell Pond Case Study
    Hugh Pearl Nettleswell Pond Case Study
    2pp 292.82KB
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Hugh Pearl (Land Drainage) Ltd
New Farm
New House Lane
Bobbingworth
Ongar
CM5 0DJ
Tel: 01277 890274
Fax: 01277 890322
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