The cars were lined up before 7am at Goulburn's Bourke Street COVID testing clinic on Wednesday.
Health authorities asked Capital Pathology to open the site earlier than usual, given Tuesday's notification of a positive COVID-19 case linked to Southern Meats abattoir.
The clinic has been operating at the former council depot since August.
Mr Cummins said 256 people had been tested by 11.30am Wednesday. On Tuesday, 145 people turned out. The clinic will also open at 7am Thursday to handle expected large numbers.
The Health District is working with Southern Meats to identify close and casual contacts of the positive case. The company was notified on Monday.
Southern Meats and WAMMCO chief executive Coll MacRury told The Post that operations at the export lamb abattoir had been suspended for the rest of this week as a precaution.
He confirmed the person who tested positive was working in an "ancillary" section and not in the main production area. The person had contracted the virus offsite and was now isolating. Three other associated workers subsequently tested negative.
"As soon as we found out we sent people for testing," Mr MacRury said.
"We won't be taking any risks this week. There will be no kills and hopefully we can start again next week."
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Mr MacRury said the abattoir had strict protocols in place, with workers tested before every shift.
He acknowledged suspension of operations would have a significant impact on the business. However it was fortunate it didn't occur in October and November when lamb numbers were expected to increase by one-third.
The facility employs 280 to 300 people but more will be engaged to handle the spring kill. Mr MacRury said the abattoir would likely rely on the Pacific Islander workforce as it could not engage the numbers needed locally.
The case follows another brush with COVID-19 at the facility in July. A delivery driver, who subsequently tested positive, had unloaded pallets at the abattoir on July 20 in an outside area. Two workers, who were considered casual and close contacts, tested negative. Production was not affected.
The industry has been affected elsewhere. In August, Fletchers beef abattoir closed for a week following community transmission of the Delta strain in Dubbo. The virus was not in the facility itself but some workers were casual and close contacts.
Mr MacRury said Southern Meats was not unlike any other business in grappling with the challenges.
"You'd prefer for it not to happen at all but you just have to deal with it when it does," he said.
Meantime, 125 people were tested for COVID-19 at Goulburn Base Hospital's clinic on Tuesday, the Southern NSW Local Health District confirmed.
In the past week, 631 tests were completed at the same site.
Yass has also reported large numbers after a Yass Public School student tested positive on Monday. The school was closed, deep-cleaned and reopened on Wednesday.
In addition, a COVID-19 positive child attended the Yass Pre-Kindergarten on Thursday and Friday, September 9 and 10. The kindergarten has been closed and close contacts have been informed and tested and are in isolation.
There are no venues of concern for any of these cases at this stage.
Mr Cummins said Capital Pathology tested 760 people at the Yass pop-up clinic at the Walker Sports Complex on Tuesday. His team was also onsite on Wednesday.
The provider has employed almost 30 extra workers this year to cope with demand.
It is also testing truck drivers at Marulan Checking Station and Yass Service Centre. At the former, collectors performed 1624 tests from September 6 to 14. Mr Cummins said numbers were higher at Yass.
In the week September 6 to 12, Yass Hospital undertook 266 tests, a Health District spokeswoman said. Crookwell Hospital completed 78 over the same period.
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