Floods call drainage system into question

Wed, Oct 5th 2011, 11:14 AM

As thousands of people took to the streets yesterday for the morning commute, many had to contend with more than just gridlock. Great seas stood in the way as the city's drainage system once again struggled to keep up with the demand.
Cars plowed through the flooding, sending wakes high into the air. Some motorists were stranded in the middle of the road from stalled engines.
Dionisio D'Aguilar, president of Superwash, feels the solution is simple - build the wells properly, and maintain them.
As evidenced by the streets, there is clearly a problem, he said.
"The government needs to assess their wells and see if they're sufficient," he said.
"Either they are not deep enough, clean enough or there aren't enough of them. This is a reoccurring problem."
In the laundromat business, he added that Superwash maintains more than 20 wells to ensure effective drainage. These disposal units need to go down 200 to 300 feet in order to properly drain the water and must be cleaned out frequently.
When asked about the depth of the city wells, Colin Higgs, the permanent secretary at the Ministry of Public Works and Transport, estimated they were approximately 150 feet.
Maintenance, he added, is handled by five private companies which are assigned to five areas of New Providence.
Their contracts, Higgs said, are renewed annually, and will be coming up again for consideration soon.
Higgs admitted that it's the job of these private companies to ensure the drains are clear of dirt and debris, as these obstructions cause the system to back up and create flooding.
When asked for the names of the private companies, he could not recall them.
Overall, Higgs felt there isn't much the government can do. "There is no way you can avoid flooding when you have exceptional rain," he said.
"The way the system is designed, is when you have that type of rain, the runoff period can be as long as eight hours."
That said, he pointed out "we are looking at a number of things that can be done to improve drainage".
The main problem, he felt, which is mostly unavoidable, are low-laying land. When you go down Blue Hill Road, he pointed out, the water table is one or two feet below the surface, and that's why the roads have been built up in those areas.
Other areas aren't so lucky, such as stretches along Thompson Boulevard.
Higgs said engineers are looking at drainage in low-lying areas in the middle of the island, but to solve the problem, "it's an expensive network of drainage systems and retaining ponds".
"We have deep wells in there, but that's a low-lying area and you get a lot of debris.
"Once the baskets that keep them clear fill up, it slows down the drainage process and you have to make sure they are cleaned. People throw a lot of garbage around and it can cause unexpected problems. Road conditions can change quickly."
D'Aguilar explained that streets that were built more than 10 years ago tend to have a problem, often because the slope and gradient weren't properly taken into consideration.
Although it would be too expensive to dig up the roads and replace them, more wells can be constructed, they can be deepened and these private companies can be made accountable for maintenance.
In at least two locations of Superwash, D'Aguilar said he has been forced to "deal with it ourselves" when it comes to flooding.
This means either hiring a drilling company to come in and extend the depth or create a new site entirely. Sometimes, it just needs a good cleaning. "I could not wait for the government to solve it," he said.
"You couldn't get into the parking lot. That's what you have to do, otherwise it could take years. When it's impeding your ability to make money and do business, you can't wait."

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