Photo: Albert Roches, Health and Safety Manager at FORTIS Belize
by Orlando Pulido
SAN IGNACIO, Cayo District, Fri. Sept. 29, 2023
FORTIS Belize, formerly The Belize Electric Company Limited (BECOL), held an information session with community members at the San Ignacio and Santa Elena Town Council headquarters building in San Ignacio on Thursday night. Albert Roches, Health and Safety Manager at FORTIS, discussed mercury levels in, and water quality of, the Macal River.
According to Albert Roches, since 2016 the monitoring of mercury levels has been extended to other rivers in Belize. In 2019 the data showed a spike in mercury levels due to the forest fires in the Chalillo area, he said. He reported that most fish species studied in 2023 indicated an increase in the mercury levels. He went on to claim, however, that mercury in fish had been reported even before the dams were built.
Albert Roches also discussed water quality with data taken from 23 stations along the Macal River. He stated that in the Vaca area there are reports of a lot of resort developments leading to an increase in coliform levels. Additionally, there are some 10,000 heads of cattle near the Black Rock area.
John Bodden, Principal Health Inspector at the Ministry of Health, was present to reinforce the data given by Albert Roches. (The World Health Organization recommends only 0.5 milligrams of mercury per kilogram of fish as a safe limit). In the Macal River, the Butasi species of fish has four times more than the recommended safe levels of mercury; while in the same area, the Bay Snook has three times the recommended safe levels of mercury. Bodden reported that methyl mercury is toxic both to the central and peripheral nervous systems.
“It is dangerous for a pregnant woman to eat fish that is high in mercury,” he said.
FORTIS operates three hydroelectric facilities situated on the Macal River and stretching from the Mountain Pine Ridge down to the Vaca Reserve. Furthest upstream is the Chalillo Facility (2005), followed by the Mollejon (1995) and the Vaca (2010).
The Chalillo Hydroelectric Facility is 12 miles (19.3km) upstream from the Mollejon Hydroelectric Facility, 30 miles (48.3km) from Cristo Rey Village, and 32 miles (51.5km) from the twin towns of San Ignacio and Santa Elena. Cristo Rey is the nearest community along the river to the Facility site. The Chalillo is designed to generate 7.0 megawatts of power. Additionally, the Mollejon is 12 miles (19.3km) downstream of the Chalillo, 18 miles (30km) from Cristo Rey Village, and 20 miles (32.2km) from the twin towns of San Ignacio and Santa Elena. The Mollejon generates 25.2 megawatts of energy, while the Vaca Hydroelectric Facility, which is located 3 miles downstream from the Mollejon, 15 miles from Cristo Rey Village, and 17 miles from the twin towns of San Ignacio and Santa Elena, produces 19 megawatts of energy. All three dams jointly generate power that meets 40 to 45% of Belize’s energy needs.
John Bodden reminded community members on Thursday night of the dam failure in Libya. The recent catastrophic dam collapse in Libya occurred in the eastern city of Derna. The collapse was triggered by an extreme storm, known as Storm Daniel, which led to heavy flooding. The pressure of the water gathering behind the dams during the storm was too much for the structures to handle, causing them to give way.
The aftermath of the collapse was devastating. More than 11,000 people were killed and tens of thousands are missing. The United Nations estimated that at least 3,958 were killed by the floods that devastated eastern Libya.
There had been warnings that the dams may burst, but these went unheeded for years. Experts had long said that floods posed a significant danger to two dams meant to protect nearly 90,000 people in northeast Libya. They repeatedly called for immediate maintenance to the two structures, located just uphill from Derna.
In terms of the potential for dam breach, in January 2019, Gannett Fleming was commissioned by BECOL to prepare revised inundation mapping in the event of the failure of the Chalillo Dam and the subsequent cascading failures of Mollejon and Vaca dams. Fleming used state-of-the-art two-dimensional (2D) modelling and LiDAR terrain data. The scope of services included gathering and reviewing data, developing breach parameters, completing 2D hydraulic modelling, preparing inundation mapping and a dam break analysis report, and developing GIS deliverables and dam breach videos. The study reach extended downstream approximately 110 kilometers from the Chalillo Dam to the City of Belmopan, including reaches of the Macal, Mopan, and Belize rivers.
The Chalillo Dam has a drainage area of 883 square kilometers. The dam is a Roller Compacted Concrete (RCC) gravity structure with a design height of 47 meters. The dam consists of a 40-meter-wide central mass concrete ogee spillway, an 80-meter-wide RCC upper main spillway, and a 150-meter-wide auxiliary spillway. The combination of these three spillways provides the dam with significant flood control capability and necessary spill capacity.
In the event of a dam breach, the potentially impacted downstream area would include multiple road crossings and several developed communities, including Black Rock, Negroman, Cristo Rey, San Ignacio, Bullet Tree Falls, Unitedville, Ontario Village, Teakettle, and Belmopan.
With a release of the large storage from the three dams (Chalillo, Mollejon, and Vaca dams), high flow velocities and flow momentum changes are anticipated as the breach wave travels downstream. Further downstream along the Macal River where the river reaches the town of San Ignacio and confluences with the Mopan River (before forming into the Belize River), the terrain flattens and has significant floodplain storage. Due to the flat nature of the floodplain terrain in this area, and the anticipated high level of flooding from any possible dam breach, multidirectional flow spreading would occur in the floodplain near the river confluence. The multidirectional flow spreading at the confluence would have a significant impact on the attenuation of the flood wave. Breach flows would flow upstream into the Mopan River as a backwater, create complex flow dynamics upstream of the confluence of Macal and Mopan rivers, and flow back downstream into the Belize River.
Several residential structures in and near the communities of Black Rock, Negroman, Cristo Rey, San Ignacio, Bullet Tree Falls, Santa Familia, and Mount Hope would be impacted by the breach outflows. Due to the significantly steep nature of the stream reach along with a characteristic narrow river valley for the portion of the Macal River between Chalillo Dam and the upstream end of the town of San Ignacio, outflows from a dam breach would have fast travel times in the range of 3 to 10 meters per second. The breach flood wave is anticipated to reach the town of San Ignacio within 4 hours after a breach, allowing limited time for warning and evacuation./
Downstream of San Ignacio, the terrain flattens and has a large floodplain that attenuates and reduces the speed of the flood wave. Water levels in the downstream rivers and water bodies are estimated to reach their peak and recede back to normal levels within 48 hours from the time of breach. The flood wave from the breach, once it reached the confluence of the Macal and Mopan rivers, is anticipated to cause backwater into the Mopan River to a location approximately 3 km upstream of Bullet Tree Falls. Flooding from this backwater would impact a number of structures in the town of Bullet Tree Falls. By the time the flood wave would reach the town of Ontario Village located approximately 80 km downstream of Chalillo Dam, it is estimated that breach outflows from a Sunny Day breach would be channelized and contained within the banks of the Belize River.
But what are FORTIS’s measures in place in the event of a dam breach? A dam is a concrete wall built across a river. As a result, measures have been put in place should the dam become compromised. Evacuation routes have also been mapped, should there be a dam breach. It would take an estimated three to four hours for San Ignacio to become affected, should there be a dam breach.
Howard Cabral, who is in charge of dam safety at FORTIS, says that the company conducts annual mock drills in coordination with the National Emergency Management Organization (NEMO) and the Department of the Environment (DOE). The last one was held on August 30, 2023. Additionally, FORTIS has a dam safety review done by an engineering firm every seven years.
The Dam Safety Emergency Preparedness Plan (EPP) is a key component of FORTIS’s Dam Safety Management System (DSMS). FORTIS has developed this EPP in accordance with the requirements of the Consolidated Environmental Compliance Plan (ECP). The EPP is designed to deal with any crisis experienced with the Chalillo, Mollejon, or Vaca dam structures. The plan is developed in conjunction with relevant authoritative bodies responsible for activities during natural disasters in the area, in the interest of public safety.
According to Howard Cabral, FORTIS has seven sirens along the Macal River connected via VHF Radios. Some 21 more audible alarms will be installed in 2024 to reflect the increased population in the area.
FORTIS inspects, maintains, and tests the siren network on a monthly basis in order to ensure its functionality. Early Warning System maintenance and testing are recorded, documented, and filed by FORTIS for safekeeping. Copies of these records are also disseminated to the Department of Environment and National Emergency Management Organization in a timely manner.
Dam activity can have a direct effect on dissolved oxygen, temperature, and total suspended solids in the water. Those parameters can in turn influence the behaviour of others which can affect the entire river system. There is also the potential for the accumulation of substances over time, which could be released during instances of spillage or flushing.
Queries with FORTIS can be made at [email protected] or by calling 501-824-3016. A Department of Environment official confirmed on Thursday night that the information exchange between FORTIS and the DOE occurs on a continuous basis.