Some real estate developers are drilling storm water drain wells less than a quarter of the required depth.
Minister of Works Arden McLean said the discovery was made by the National Roads Authority recently when it began using its new vacuum truck to clear clogged drains.
‘An interesting thing has been discovered,’ Mr. McLean said. ‘Some developers do not drill the wells as deep as they’re supposed to go.
‘Some are only 10 to 20 feet deep, so they’re cheating on us.’
Developers must have an approved storm water management plan. The National Roads Authority is in charge of approving those plans and inspecting drain wells.
Mr. McLean said that from now on, when the NRA goes to inspect drain wells, it will measure their depth.
‘Those who get caught cheating will just have to drill the wells over,’ he said
NRA Acting Managing Director Edward Howard said that drain wells were generally required to be 100 feet deep. The NRA drills its wells that deep.
However, some developers can do tests to determine the depth needed. At The Ritz-Carlton, Grand Cayman, for example, tests showed that wells drilled to 75 feet drained water at the same rate as wells drilled to 100 feet, Mr. Howard said. Given the evidence provided, the NRA allowed the Ritz development to drill its wells to 75 feet.
However, wells drilled to shallow depths would likely have little effect in draining off storm water.
Drain wells are charged by the linear foot of depth. One prominent drilling company charges $16.50 per foot, so a 10-foot well would cost $165 while a 100-foot well would cost $1,650.
Mr. Howard said the NRA has already measured some drain wells that have been drilled too shallow and refused to approve them.
‘We’ve spotted a few on some of the more recent developments,’ he said, adding that the NRA found the problem primarily in industrial and commercial developments.
The drain wells are required to keep roads from flooding, and to keep neighbouring properties from flooding.
Mr. Howard said that as George Town in particular has continued to develop, there is less and less permeable land for water to drain on. The addition of large areas of roofing also increases rain water at specific spots.
‘With the rapid developing, there’s nowhere for the water to go,’ Mr. Howard said.
Although the drain wells are vital for draining accumulating storm water, the Water Authority has taken issue with all of the 100-foot wells because it feels the fresh water lenses could be negatively impacted, Mr. Howard said. There are proposals to resolve the issue.
The vacuum truck now being used by the NRA changes the way it used to clear clogged drain wells. Mr. McLean spoke about the new piece of equipment in Finance Committee.
‘We’re using the vacuum truck to clear the drains out rather than blowing them out and then having them just getting clogged again,’ Mr. McLean said.
Mr. Howard explained that when compressed air was used to blow out the drains, all of the water and debris, including silt, would just came out of the hole onto the surrounding property. Subsequent rains would simply put all of the silt and debris right back into the hole.
The vacuum truck on the other hand has a 4,000 gallon holding tank, which sucks up the water and silt, creating much less mess and a more lasting solution to the clogged drain.
The vacuum truck was temporarily being emptied at the sewage treatment plant, but a new place has to be found, Mr. Howard said.
The NRA is working with the Department of Environmental Health to find a permanent place to dump the vacuum trucks at a site in the landfill.