Geology and Hydrogeology

of the

Marchbank Syncline

of

Kings County, N.B.

2010 Revision

Quality of Life Initiative

 Note: This document is the result of research by

The Quality of Life Initiative.

Those seeking a professional geological/hydrogeological evaluation

should consult those registered professionals. 

For QLI visit: www.the-quality-of-life-initiative.info

Geological / Hydrogeological Summary

Safe underground salt cavern gas storage requires:

1.      Ability to contain pressurized gas within the halite (rock salt) cavity.

2.      A secure geological site without features which would permit movement of escaping gas to the surface:

·         faults

·         boreholes

·         old mine workings

·         wet rockhead

Corporate responsibility requires that industrial processes respect the natural and human environments, particularly protection of the individual, protection of the environment, and protection of the local water supply.

Corridor Resources’ proposed project at Cassidy Lake violates all of these requirements:

1.      The Cassidy Lake area is home to a minimum of 3 significant faults in close proximity to the proposed Corridor site. The largest and closest (Clover Hill Fault) is a complex fault system less than one km away.

2.      The proposed Corridor site is near the center of a geological section of the Marchbank Syncline known as the North Block, characterized by government and private geologists as “highly disturbed” and “extensively suberoded”.

3.      The rock strata in the Cassidy Lake area, including the salt body, have been pierced by borehole drilling in 25 different locations since the 1970’s alone.

4.      The Cassidy Lake Mine, abandoned because of flooding in 1998, reaches to within 1.1 km of the proposed Corridor site. Their depths differ by only 177 meters.

5.      Wet rockhead conditions (water eroding the top of the salt deposit) in the Cassidy Lake area have been described repeatedly by geologists since the 1970’s. Wet rockhead has been described at the IMC4 site itself.

6.      Wet rockhead conditions were identified as the major contributor to the flooding and closing of the Cassidy Lake Mine.

7.      Daily pumping of up to six million liters of water from the Cassidy Lake Mine, prior to 1998, was associated with damage to domestic water supplies up to 5 km away.

8.      Corridor proposes to pump ten million liters of water daily from the Cassidy Lake water supply over a total period of several years.

9.      Corridor was warned, through its own consultants, in 2005, about the potential for deep water extraction to contaminate freshwater supplies.

10.  Corridor has no means to dispose of the brine it intends to create.

Based upon the available geological and hydrological data, the Quality of Life Initiative concludes that the Cassidy Lake area is not a suitable site for underground salt cavern gas storage.

Geology and Hydrogeology

of the

Marchbank Syncline

of

Kings County, N.B.

Geology

The Marchbank Syncline is a trough-shaped, geological structure stretching 38 km, north-easterly, roughly from French Village to Markhamville. It is best to think of it as an underground valley, now filled with salts and sediments. The syncline, near Cassidy Lake, is the site of the proposed Corridor Resources underground salt cavern gas storage facility.

On the surface, the Marchbank Syncline is a valley with a maximum width of 7 km. The ridges on either side of the syncline are approximately 420 feet higher (140 m.) than the valley floor. (Bloomfield Ridge to the north, Upham Mountain to the south)

The Marchbank Syncline is bounded, on the north and west, by the Clover Hill Intrusive, a massive block of harder, crystalline rock, 3,000 feet thick (1,000 m.), moving upward and eastward. The intrusive leans into the Marchbank Syncline below it (a ‘reverse fault’). To the east and south, the Marchbank syncline runs up against the Caledonian Highlands, the last remnants of ancient fold mountains.

The rock strata of the Marchbank Syncline, greatly simplified, may be characterized as young rocks (the Hopewell Formation), older rocks (the Windsor Formation), and very old rocks (the Moncton Formation).

In the 1970’s, 23 boreholes were drilled into the Marchbank Syncline to investigate its valuable potash deposits; all stopped at the edge of the Moncton Group, at depth of approximately 3,300 feet (1000 m.). (Most of these holes are designated as IMC in reference to the International Minerals and Chemical Corporation (ex. IMC4). Two additional boreholes, PMC1 and PMC2, were drilled in 1997 within the property of the Cassidy Lake Mine. A great deal is known about underground structures within the Marchbank Syncline as a result of the rock samples from these boreholes.

Salt and potash are found within the Windsor Formation in a lense-shaped, layered deposit known as the Cassidy Lake Formation. This formation begins 1,829 ft. (557 m) below the proposed Corridor site at IMC4.¹ IMC4 is located near the thickest part of the salt deposit. The top half  of the deposit (1200 ft /369 m) at IMC4 is so-called ‘dirty salt’² (randomly alternating layers of thin bedded salt, claystone and potash); the bottom half (1137 ft/ 347 m) is relatively pure rock salt (halite). 

Several faults characterize this area. The Clover Hill Fault is a complex fault system³ where the granite of the Clover Hill Intrusive crushes into the westerly side of the Marchbank Syncline. The Clover Hill Fault is 3000 feet deep, and affects a zone 500 to 1500 feet in width because of its major horizontal displacement^{4 5} .

A second fault, unnamed, runs the length of the salt deposit, roughly through its center⁶, and parallel to the Clover Hill Fault. This steep reverse fault divides the salt deposit into  two sections, the North Block or “Window Area”⁷, and the South Block. The two sides of this fault are vertically displaced by 400 to 500 feet.⁸

The North Block is described as “highly disturbed” compared to the “relatively placid South Block”⁹. Department of Natural Resources geologists describe this north block as characterized by “extensively suberoded”¹⁰ areas where moving water has penetrated deep underground dissolving salt and potash, in ‘salt windows.’ The crest of the salt body, near the Corridor site, is one such area.¹¹

The supposedly placid south block contains the flooded, and now abandoned PCS Cassidy Lake Mine (depth approximately 2,700 ft/823 m.). The second fault skirts the north-western edges of the mine. A third, near-vertical fault, with a major vertical displacement, has been described closer to the heart of the mine, near IMC12 .¹²

The proposed Corridor Resources site and IMC4 are located at the heart of this much disturbed window area, between the Clover Hill Fault (0.9 km north) and the second fault (1142 ft/ 348 m south). The Corridor site is 1.1 km north of the nearest  tunnel of the flooded Potash Corporation of Saskatchewan (PCS) Cassidy Lake mine. The proposed cavern begins a mere 177 m lower than those tunnels.

There exists another geological structure, called the Dunsinane Synclinorium, 25 km to the northeast at Penobsquis. Except for a slightly thicker salt bed (1000 m. vs. 750 m.), its Windsor Formation rock structure is virtually identical to that of the Marchbank Syncline. Its present and potential difficulties are also strikingly similar to those of the Cassidy Lake area (see below).

Hydrogeology

An aquifer is a layer of permeable rock able to store significant quantities of water, through which groundwater moves.

The Marchbank Syncline contains two layers of rock within the Hopewell Formation which act as aquifers. These are located at depths of 500 to 600 feet (150 to 180 m). (Poodiac and Wannamaker Formations)

Cracks and fractures in the rock offer the highest volume of water flow, more so than the sponge-like formations of porous rocks in other kinds of aquifers. The Marchbank Syncline abounds in such faults and fractures.

Corridor Resources proposes to exploit aquifers at the 500 to 600 ft depth^{13 14}. Domestic wells for drinking water in the Cassidy Lake area access much more shallow sources of water (averaging 37 m); none exceed depths of 77 m.

Consultants to Corridor Resources¹⁵ note that such fractures, originating at the Clover Hill Fault, may be responsible for the flooding of the Cassidy Lake mine 2 km away.

Dr. John. Gale, Hydrogeologist, reporting to the United Steelworkers union in 1997, concluded that, “The higher flows are assumed to reflect connection to a fault/fracture zone(s) or an aquifer that has much higher transmissibility than the regularly fractured bedrock.¹⁶” The faults running through the salt deposit may be some of these.

The IMC4 site was chosen by Corridor Resources precisely because of its proximity to the Clover Hill Fault and the water-filled fractures expected to be found there. Corridor proposes to extract 10,000 cubic meters of water daily (10,000,000 litres per day) in order to dissolve each of its 7 proposed caverns. (This amount is more than twice the daily drinking water requirements of the towns of Hampton, Sussex and Sussex Corner combined.) The construction will take 15 months for each cavern, or nearly nine years.

Wet rockhead is created when water penetrates down to the top of the salt body, dissolving it and causing collapse of the overlying mudstones¹⁷. Collapse breccias, dissolution windows and other evidence of suberosion are the chief characteristics of the North Block. Such areas can be subject to rapid degradation¹⁸.

Recharge refers to the ability of an aquifer to renew itself by means of rainwater  seeping into the ground. Most rainwater is lost to runoff or evaporation. Total recharge rates  for the Moncton Basin are on the order of 14%¹⁹; the vast majority seeping into the most shallow aquifers within days or months. Very little rainfall makes its way to deep aquifers, which recharge at a rate of less than 1% per year²⁰and can take millennia²¹ to do so.

There is no publicly available information about the recharge capability of the aquifers of the Marchbank Syncline. What is certain is that if water is withdrawn from an aquifer in greater amounts than it can recharge, the aquifer will be depleted. Corridor’s consultants warned in 2005 that such may be expected from the proposed project: “…there is a potential for interference with domestic wells at the proposed sustained high pumping rates….”²²

Given the trough shape of the Marchbank Syncline, the local recharge zones for its aquifers are assumed to be on the highlands to either side of the syncline, or in the Clover Hill Fault itself.²³ Given that the ‘trough’ is slightly up-tilted, recharge on a regional scale is assumed to come from the north-east.²⁴

No data is publicly available about the presence of salt-laden, non-potable water at greater depth in the Moncton Formation. No boreholes have penetrated the Moncton formation to date. Corridor has stated that it is also seriously considering drawing upon such sources of deep saline water. There is no precedent for such activity in New Brunswick, and its safety is unknown; however,  saltwater contamination of  freshwater supplies is a well known phenomenon, particularly in coastal areas.²⁵ Corridor’s consultants were warned, in 2005, by a Department of the Environment hydrogeologist, about the potential for just this sort of freshwater contamination.²⁶

A great deal is known about the impact of underground water removal from the  Marchbank Syncline. In the early 1980’s, the first Denison-Potacan exploration shaft (4.9 m in diameter) “experienced difficult water conditions associated with fracturing and faulting”²⁷ in the Hopewell Formation. By 1986, the new owners of the mine, PCS  Inc. – Cassidy Lake Division, had constructed a pipeline to the Bay of Fundy, and was pumping over 4 million litres of salt-saturated water daily out of the mine and into the bay. (This figure was to increase to its current value of  over 6 million litres per day.)

During the time that the mine was attempting to pump out the incoming water, effects were noted in the Cassidy Lake underground water supply. Residents up to 5 km away  reported changes in water levels, while domestic wells within 2.5 km of the mine reported lower than normal water levels. In 1998, PCS abandoned the mine and allowed it to flood completely. Water levels then returned to normal. ²⁸

There are parallels today in Penobsquis, the geological sister-site to Cassidy Lake. The Penobsquis potash mine operated by PCS in the Dunsinane Synclinorium is currently flooding. PCS spent $1 million per month to truck in-flooding water to their Cassidy Lake facility for disposal in the Bay of Fundy. A multi-million dollar pipeline to the Cassidy Lake facility now performs this task. The mine is scheduled to be abandoned in 2012.²⁹ A new, ‘Piccadilly’ mine is scheduled to open within sight of the Penobsquis mine.

Since 2004, complaints have been lodged with the New Brunswick Dept of the Environment by approximately 50 households in the Penobsquis area. Complaints there include cloudy water, diminished water supply, dry wells, and ground level lowering.³⁰ Domestic wells nearest the mine are no longer functional; drinking water is now piped in from Sussex Corner. Both Penobsquis and Cassidy Lake are parts of the same geological structure known as the Moncton Sub-Basin.

Saving the Water Supply

Effectively addressing Corridor Resources’ proposal has proven a difficult task for the community because Corridor presents a moving target. What Corridor intends to do seems to change without warning. To date, there are two versions of Corridor’s underground salt cavern storage scheme:

May 2008 – Corridor held an open house at a local church in Southfield. 75

                     residents attend the meeting. Corridor planned to do the following:

·         construct a 2-4 billion cubic foot underground storage cavern near Cassidy Lake for natural gas storage

·         follow this with up to 6 additional caverns over 10 years

·         excavate these caverns using 10 million litres per day of fresh water

·         water is to be taken from 10 wells drilled to a depth of about 180 m. (600 feet)

·         pump the resulting brine to the Bay of Fundy via the existing PCS pipeline facilities

·         water with salt content greater than 30% cannot be used

·         water from sources more than 8 km away is not economically viable

February 2009 – Corridor attended a public forum sponsored by The Quality of

Life Initiative in Hampton. 300 people attended. Corridor now  

 plans to do the following:

·         construct one cavern of 2-4 billion cubic metre capacity cavern for storage of natural gas, liquid petroleum gas (LPG), crude oil, or carbon dioxide dumping

·         excavate this cavern using 10 million litres per day of non-potable water

·         water is to be taken from the Bay of Fundy (18 km away; salt content 3.0%) or from deep wells

·         no mention that PSC is on record as saying that there will be no joint use of their brine disposal facilities with Corridor Resources³¹