The Vancouver-based company has received results from two further drill holes, which returned 19.89 grams per tonne over 32.2m, including an interval of 51.5g/t over 8.2m, and 5.88g/t over 20.1m.
The latest intercepts follow earlier hits of 15.15g/t over 19.4m, 12.64g/t over 7.7m and 13.72g/t over 12m.
Sabina said this week the results continued to support its thesis on the continuity of a high-grade "corridor" extending from the high-grade Vault zone at depth to the lower limits of the current Umwelt openpit design. Further drilling at this target is underway with results expected soon.
CEO Bruce McLeod said the results were among the best encountered at the project in terms of grade and thickness.
"The intercept results we are now getting in the upper portions of the Umwelt high-grade corridor are over twice the grade of the Umwelt underground resource. The tenor and robustness of gold mineralisation we see in this area just below the proposed Umwelt pit are very similar to the intercepts from Vault, approximately 600m down plunge," he said.
McLeod suggested more drilling could result in the company's modelling to unlock higher-grade material for processing earlier in the mine life.
Back River is shovel-ready after successfully navigating federal and territorial permitting processes.
A 2015 feasibility study, based on US$1,150/oz gold, outlined 200,000oz of gold production per annum over an 11-year mine life. It had calculated an after-tax (5% discount) IRR of 24.2% with an NPV of $480.3 million, with a 2.9-year payback.
The company said the capex component, pegged in 2015 at C$415 million, had escalated in step with the gold price, which would it would address in an updated feasibility study slated for publication in the first half next year.
Shares in the company (TSX:SBB) are up 55% since the New Year, and gained 39% in the past 12 months to $2.97. Sabina has a market capitalisation of $967.5 million (US$736 million).