At a time the district was facing job losses, including up to 80 at Summit Wool Spinners, the plant proposed by Holcim (New Zealand) Ltd could eventually create 241 new jobs and boost the Waitaki district economy by up to $14.2 million a year when it was in full production.
There would be even greater benefits while the plant was being constructed, from next year to 2012 at the earliest, with 458 extra jobs created in the district and an additional $24.5 million a year injected into the district economy.
Mr Copeland said the cement plant would diversify the local economy, making it more resilient to fluctuating agricultural prices.
Of the $500 million latest estimate for the plant, quarries, new ships, shipping, transport and other facilities, about $177 million would be spent in the Waitaki district.
The average plant workforce during construction would be about 290 employees, with wages and salaries averaging $16 million a year.
Once operational, the plant would continue to have a significant direct and indirect impact on the district's economy.
In its first year of operation it would employ 110 people, rising to 125 when at full capacity by 2030.
Wages and salaries would rise from $8 million a year to $9.2 million at full capacity.
There would be flow-on effects creating further jobs in the district.
Including jobs at the plant, the number of new jobs created would rise from 196 initially to 241 by 2030, increasing household income by $11.8 million in the first year to $14.2 million by 2030, Mr Copeland said.
Other benefits included increased profitability for local businesses, the possibility of lower prices for consumers, an improvement in services (including health and education), new employees and management supplementing the "potential leaders" in the community and Holcim supporting activities and organisations as "a good corporate citizen", he said.
Dunedin archaeologist Peter Petchey said heritage features and places associated with the agricultural, pastoral and quarrying history of the area were widespread and would be affected by the visual impact of a cement plant.
An accidental discovery protocol in place during initial earthmoving and quarrying would address any effects on potential archaeological sites.
Work would stop if anything was found, allowing archaeological excavation and recording to be carried out, he said.
Key points
Holcim (New Zealand) Ltd
•A $300 million cement plant, coal mine, limestone and sand quarries in the Waiareka Valley, 2.5km from Weston.
•The Otago Regional and Waitaki District Councils granted 46 resource consents for the plant in February 2008.
•Consents appealed to the Environment Court by Holcim, the Waiareka Valley Preservation Society and Andrew Renalson, with interested parties Waitaha Waitaki Trust Board and Waitaha Maata Waka, and respondents the Otago Regional and Waitaki District Councils.
•Being heard by Judge Gordon Whiting, commissioner Charles Manning and deputy commissioner Dr Bruce Gollop.
•Hearing ran from March 9 to 11, then from March 30 until completed.