The system carries effluent — a mixture of water from the large boilers, trace amounts of fuel and other contaminants — from the powerhouse building, down through filtration points, running to collection basins, for final treatment, testing and release.
The drainage system has 136 metres of associated underground piping, valves, grease traps and oil-water separators, all meant to contain and remove contaminants.
“In recent years, damaged sections of pipe, pipe blockages and inoperable valves have resulted in the premature leakage of effluent into the environment,” noted Newfoundland and Labrador Hydro’s 2017 capital budget plan.
Filed with the Public Utilities Board, it goes on to request approval of $923,100 in spending for repair and replacement work, to be recovered from ratepayers.
No one was available at Hydro to speak to the subject Friday, but a statement was provided in response to questions.
“There have been minor leaks in the underground lines involving boiler water waste — which were investigated and reported to the regulator —which is normally fairly clean and presents a low environmental risk,” said a spokeswoman.
“These leaks were not significant enough to cease plant operations or enforce immediate mitigation measures.”
She said the planned project is really meant to prevent future challenges, particularly in the case of a large leak or oil spill that needs to be handled by this drainage system.
The application used much stronger language in regards to the existing leaks in the system. They were confirmed after an engineering study was approved under Hydro’s 2014 capital budget.
“This premature release of effluent is an environmental non-compliance and a direct violation of the regulations. Failure to address this non-compliance could result in penalties, fines or an order to cease plant operations pending remediation of the deficiencies,” Hydro states.
The regulations referenced are the provincial Environmental Control Water and Sewage Regulations of 2003. The provincial Environment department did not respond before press time Friday. In an email received Saturday morning, the department stated it's monitoring the effluent treatment process at Holyrood. The email referred to already-existing requirement for Hydro to test and report on effluent quality just prior to final discharge. It remains unclear if there is any understanding of the extent of possible soil contamination as a result of the pipe leaks.
Meanwhile, Environment and Climate Change Canada made no comment on monitoring of Holyrood, directing questions to provincial officials.
Underground drainage systems typically have a service life of 45 years, according to the PUB filing. The system at Holyrood was installed in 1991.
Hydro proposes replacement of 100 out of 136 metres of underground piping, all existing valves, installation of additional valves, one oil-water separator replacement and removal of any contaminated soil around the existing piping.
“The plant’s underground drainage system is an integral component of the plant’s operation and is vital to ensuring that provincial regulatory requirements are satisfied. The proposed upgrades are required to restore the integrity of the drainage system,” Hydro has stated.
Investigations in 2014 showed blockages and structures not matching existing design specs (eg. use of asbestos cement concrete piping, versus PVC or regular concrete), complicating the work.
In the five years up to and including 2015, a total of $19,500 worth of maintenance work was performed on the drainage system.
The Public Utilities Board will now decide if the $923,100 refurbishment (including contingency) can be passed on to ratepayers, as part of the Hydro’s $271.4-million capital budget.
Tenders for the replacement of the underground system are scheduled to go out March to May of 2017, with the bulk of on-site work undertaken in August and September, wrapping up commissioning and any loose ends by October, ahead of the winter of 2017-18.
(NOTE: Updated Sunday morning, Aug. 7, to include notes from email response from Department of Environment, sent Saturday.)
