THE STATE’S Mines and Geology Division (MGD) has joined the discourse on the suitability of Jack’s Hill in St Andrew for multifamily housing developments, describing the area as “highly prone to a number of geo-hazards”.
Much of the hill, according to the MGD’s landslide susceptibility/hazard map, is characterised by moderate to very steep slopes.
Tavistock Terrace and Harriman Close, where four housing developments are either ongoing or in the beginning phase, fall within the poor suitability zone.
This means that the zone is characterised by moderate to steep slopes, high landslide susceptibility, moderate to high erodibility, and poor to very poor rock mass rating.
The zone is not recommended for urban/suburban occupation and, therefore, engineering construction is not desirable in this area, the MGD said.
Still, months after work on one of the developments caused the collapse of Tavistock Terrace and a second triggered a landslide blocking another section, the National Environment and Planning Agency (NEPA) has remained silent on the approval processes for both.
Several requests by The Gleaner for information surrounding the permits for housing developments on the “problematic” hillside have not been met by the Peter Knight-led agency even as residents expressed concerns about the safety of multifamily dwellings.
The Robert Hill-led Kingston and St Andrew Municipal Corporation has also not responded to similar requests despite several Gleaner requests.
The two state agencies have not said, among other things, what were the terms/conditions for building under which permits, if any, were granted. Additionally, if the country’s hillside development policy and the Town and Country Planning Development Order were being adhered to.
According to the MGD, there are areas in Jack’s Hill that may be favourable for leisure activities, green spaces, limited infrastructure works, and public utilities where alteration of the natural environment will be minimal.
In a Gleaner interview on Tuesday, Director of Research Canute Ricketts said four applications for housing developments between Jack’s Hill and Norbrook were denied in the last year.
He explained that if the slope of the hill is greater than 30 degrees, an equivalent of 58 per cent, the division would not support requests for residential development.
He said multifamily developments are supported for slopes up to 26 degrees, but if the area is geologically sensitive (exposure to geo-hazards), the limit is 18 degrees.
“So we have a number of stipulations, including those that speak to the density at which you develop in certain areas,” Ricketts said.
He continued: “So if it’s a gently sloping terrain that is not highly prone to geological hazards, we will allow for developments to proceed at a density of 30 habitable rooms per acre.”
However, Ricketts said as the likelihood for geo-hazards increases, a much lower density is recommended of 20 habitable rooms per acre.
He said that this is recommended to limit disturbance across the site.
Ricketts, who authored the engineering geology and landslide susceptibility maps for Jack’s Hill, confirmed that the area is “highly prone to a number of geo hazards”.
He noted that it is heavily faulted and undermined by colluvium, which is old landslide deposits.
He warned that this is not to be misconstrued for alluvium, which are river-borne deposits found along coast lines and plains. Alluvium is more compact when compared to colluvium, which is loose.
“So once you try to build in this area, once you start to modify areas that comprise colluvium, it tends to fail because it has very low shale strength, especially when exposed to high moisture content. With excessive rainfall, it really tends to easily fail,” he said.
“So yes. Jack’s Hill is highly prone to the occurrence of landslides, and historically, you can see that,” Ricketts said, pointing to the Skyline main road, which failed following the passage of a tropical storm in 2008.
Last week, The Gleaner reported the concerns of residents in Jack’s Hill over infrastructure and potential housing damage amid the construction of the multifamily developments in the upper St Andrew community.
Tariq Malik, Peter Azar, Kirk Holbrooke, and Arthur Von Strolley are the developers behind projects in the community.
Government minister Daryl Vaz, who has denied any involvement in the multifamily development commissioned by Von Strolley, said he and his brothers transferred land as part of a joint venture in 2019.
“I will receive my compensation for land input at the end of the development,” he said.