More than a million concrete electricity columns could be used to cushion waves and prevent coastal erosion

To prevent coastal erosion, Bang Khunthian district has come up with a novel idea to use electricity poles to protect the coast. Courtesy of Bang Khunthian district

Having removed 800 electricity poles from Bangkok's roads, City Hall has hit on the idea of turning these no longer needed concrete columns into an ideal solution to one of its major problems -- coastal erosion.

The Metropolitan Electricity Authority (MEA) has already taken the uprooted poles to a coastal area in Bang Khunthian district to form a number of structures designed to curb the erosion.

Coastal erosion in Bang Khunthain is a headache the city has struggled to cope with and has worsened to an alarming extent in recent decades.

The average rate of erosion has reached 7 metres per year and the coastline stretching 4.7 kilometres in the district has been eaten away over the years by between 900m to 1.2km, according to Prasert Chaweeint, director of Bang Khunthian district office.

"Over the past decade, the Bangkok Metropolitan Administration [BMA] has invested a great deal of money in buying close to 100,000 bamboo trees for use in forming a barrier to cushion the impact of waves.

"However, bamboo trees last three years at most before they need to be replaced, while those concrete utility poles should be able to do the same job and last up to 30 years," he said.

After discussing his idea of using the utility columns as a tool to mitigate coastal erosion with affected residents in Bang Khunthian, he then proposed the idea to Bangkok governor Aswin Kwanmuang who approached the MEA to donate the poles.

The MEA agreed and sent the first batch of 800 poles, removed from roads such as Sukhumvit, to Bang Khunthian district. The construction of the barrier has been carefully planned as the BMA does not want to cause further ecological problems. In the past, other concrete seawall projects have tended to crumble and become ineffective or ended up diverting waves into unprotected areas of nearby coastal land.

To make sure the structure is ecologically sound, the BMA has worked together with King Mongkut's University of Technology Thonburi to design a structure that is capable of cushioning the impact of waves without adversely affecting the local environment.

The final design of the barriers is a triangular line of the 12m long utility poles that are wedged 7m deep into the sea about 200m off the coast.

With the 800 poles used so far, the structures, placed about 50m apart from one another, now cover 200m along the 4.7km of eroded coastline.

"We aim to add more of the same to cover the entire area even though this may take several more years to complete," said Mr Prasert.

The MEA's project to improve the efficiency of its power grid by removing utility poles and electricital wires from the streets and replacing them with a new underground network began in 1984, said MEA governor Chaiyong Puapongsakorn.

Power lines in Bangkok have long been an eyesore and the subject of safety concerns. The Metropolitan Electricity Authority since 1984 has been working in Nonthaburi and Samut Prakan to remove them and place them underground. Pattarapong Chatpattarasill

So far, the project has been implemented in three provinces under the MEA's care -- Bangkok, Nonthaburi and Samut Prakan.

There are about 1.6 million such poles in these provinces and so far about 1,100 of them have been removed, he said, adding that the poles can then be sold at about 21 baht per metre.

Before the BMA's request, the MEA had already responded to a similar request from Samut Prakan province which wanted a number of poles to help mitigate coastal erosion in the area adjacent to the Phra Chulachomklao Fort in Phra Samut Chedi district of the province, said Mr Chaiyong.

Sometimes, the MEA has received requests from Buddhist temples that wanted to construct floodwalls or communities wanting materials to create makeshift bridges, said Mr Chaiyong.

Even though the poles were given to these projects free of charge, the MEA must still inspect them all before they can be handed over to ensure they are in good condition and suitable for use, he said.

In a previous bid to resolve coastal erosion in Bang Khunthian, the BMA hired two private companies in 2005 to serve as consultants on a project investigating potential solutions to the problem, said Narong Ruangsri, deputy director of Department of Drainage and Sewerage of the BMA.

After the study, the consultants came up with three recommendations for implementing coastal defences in the area -- hard, T-Groyne and soft structures, he said.

A project was then initiated, but has long been stalled by a lengthy environmental impact assessment (EIA) study, which has had to be ordered to be amended on four separate occasions. The fourth revision is set to be concluded in February next year.

The concrete poles donated by the MEA are being used to form T-Groyne sections.

When the EIA study is finally approved, the implementation of the rest of the project will require about 1.5 billion baht in funding, plus 35 million baht more to cover the cost of hiring a construction consultant that will work with the BMA for the 30 months during which the rest of the coastal erosion defences are put in place, said Mr Narong.