Sewerage systems still under par

Several of the worst performing private sewerage systems in Grand Cayman have not been re-checked by the Water Authority since tests taken in 2008 revealed many fell far below the legally required standard of quality.

In June last year, the Caymanian Compass revealed the 18 worst waste management systems in private estates and retail sites in Cayman. At the time, tests showed that one site was almost 275 times over the legal limit of total suspended solids, which are supposed to be broken down by the wastewater treatment plant.

Wastewater systems are assessed in terms of their biochemical oxygen demand and total suspended solids. Under the Water Authority Law, sewerage treatment systems must be below 30 parts per million of BOD and TSS.

While some of the sites have shown a marked improvement, most of the 18 still do not meet the legal standard, according to data released following a Freedom of Information request.

No re-sampling by the Water Authority has been done at seven of the sites – Walkers South Apartments; Stone Haven Apartments; Templeton Apartments; Windsor Lakes; Grand Palm; Cayman Crossing and government housing at Windsor Park – to establish if they have been repaired.

In a written response to the Compass, the Water Authority stated it had contacted the relevant stratas and business owners about the problems. It had also notified the housing ministry of the problem at Windsor Park – where the BOD is 859.5 and the TSS is 1,071.2 – but had not received a response as of mid-December.

The Water Authority’s Information Officer Anita Fausett-Khan said: ‘No legal action has been undertaken against any owner/operator of a wastewater treatment plant.’

Sampling done by the Water Authority at 186 sites throughout Grand Cayman between April 2008 and February 2009 revealed that two thirds did not meet the legal standard.

Worst site improved

However, the site that had been performing the worst, Georgian Court Villas, at Ithmar Circle, has seen a massive improvement since the earlier report, although its level of biochemical oxygen demand, which is the amount of oxygen used by microorganisms that decompose organic waste matter in water, is still more than double the legal limit.

In September 2008, when it was sampled, its BOD was 3,144 and its TSS was 8,240 parts per million. After its system was repaired, the Water Authority re-tested the site and found its BOD was reduced to 70.9 and its TSS to 13.6.

In an earlier interview with the Compass, Water Authority director Gelia Frederick-van Genderen said re-sampling would only be done once repairs had been carried out on the relevant systems.

High levels of total suspended solids and biochemical oxygen demand accounts for unpleasant odours from sewerage systems and also can pose a threat to the environment if improperly treated wastewater gets into waterways.

But Ms Frederick-van Genderen has said it is unlikely that high BOD and TSS levels from private sewerage treatment systems would find its way into the sea or affect fish, adding that BOD discharges would be very diluted before reaching Cayman’s near shore waters, and would therefore be unlikely to attract fish.

‘The concentration of TSS discharged via a well would be even more diluted as the settleable solids would be entrapped in the substrate,’ she said.

‘Effluent is indirectly discharged to near shore waters after passing through the substrate 40 – 100 feet below the surface,’ the director said.

Re-sampling

The Water Authority has revisited nine of the 18 sites to take samples, including the ones at Coco, Sunset, Garden and Mystic Retreats which has been repaired and now meets legal standards.

L’Ambience measured well below the minimum quality standard in May 2008. It was re-sampled in October 2009 and had improved dramatically – down to 88.18 BOD and 97.5 TSS – but was still above the legal limit of 30 parts per million.

Samples taken from Walkers South Apartment in May 2008 registered a BOD of 510. The service provider has since visited the site, but by mid-December, the Water Authority had not done a re-sampled to check the levels of pollutants.

Stone Haven Apartments registered 1,410 BOD in May 2008 and has not been re-sampled.

In May 2008, Templeton Apartments showed a BOD of 449.5 and a TSS of 530. The Water Authority issued the property with a notice of violation on 30 June last year after it was determined the system was beyond repair.

Three systems servicing Windsor Lakes were all found not to meet legal minimum standards in the original report. That system has also not been re-sampled.

Original reports from the Water Authority showed tests taken at the Mirco Centre, Elizabethan Square and CUC, fell below the minimum standard, but those results were discarded because of an error in how the samples were taken. Subsequent re-sampling showed none were as bad as the original samples had indicated, but all three sites still failed to meet the minimum required standard.

Other sites which are awaiting re-sampling include Grand Palms of the Caribbean and Cayman Crossing.

The Countryside Shopping Centre in Savannah originally showed a BOD of 855 in November 2008. Testing a year later showed this had dropped to 404.9, while its TSS, which had been 115, had dropped to the legally acceptable limit of 24.7 by November 2009.

The Water Authority said it had originally erroneously listed the Countryside results as those of AL Thompson Home Depot store in its original report.

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