On a consolidated basis, operating earnings for the year-to-date period increased 19% and EBITDA rose 10% compared to 2019 results.
In addition, we generated over $188 million of cash flow from operations, which is a 93% increase from 2019.
They're very near to achieving 1 million exposure hours with no lost time safety incidents.
For the quarter, production volumes were 53% ahead of third quarter 2019 results, while the cost to produce these tons declined 24%.
On a year-to-date basis, production tons have increased 28% from 2019 levels and production costs are down 11%.
Keep in mind that we typically move more than 12 million tons of bulk materials using multiple transportation modalities each year.
These efforts were largely responsible for the 8% year-over-year increase achieved for consumer and industrial average selling prices this quarter.
Given the mild weather during last winter, it came as no surprise that the bid season was competitive, as we noted in our second quarter call, with total bid tenders down roughly 15%.
We've essentially completed all bidding activity and have achieved 4% growth in our contracted bid volumes with a price decline of 11% compared to prior bid season results.
Consequently, these bid season results along with slightly elevated customer inventories had us trailing our full year salt volume guidance by about 250,000 tons for 2020.
After draining those ponds, we then spent 10 months harvesting, which is essentially scooping up the material from dry pond beds and transporting the material to the production plant.
Currently, under this new equipment setup, we're delivering 28% more tons per load for SOP and about 14% more for salt.
Just to level set a bit, we entered the year with a strong expectation for around 20% EBITDA growth using the midpoint of our guidance provided in February.
We now estimate a combined negative impact of this original forecast of about $45 million from several factors, which were largely outside of our control.
Salt segment sales volumes are down just 9% on a year-to-date basis, which is more than explained by the weak winter weather we experienced during the first quarter of 2020.
As a reminder, first quarter 2020 snow events were 24% below the 10-year average and 30% below 2019 levels.
On a year-to-date basis, Plant Nutrition North America sales volumes are up 20% versus the 2019 period, which you may recall with very challenging due to the excessive rainfall in our served markets.
Our Plant Nutrition South America segment generated a 5% year-over-year increase in sales volume on a year-to-date basis as strong and early demand for plant nutrients in the first half of the year offset third quarter sluggishness.
Despite the challenges we faced, we delivered double-digit consolidated earnings growth as well as strong free cash flow of $126 million through the first nine months of 2020.
Third quarter revenue declined 11% compared to the prior year on a 13% drop in sales volume, slightly offset by a 1% increase in average selling prices.
Average salt selling prices in the third quarter of 2020 increased 1% compared to third quarter 2019 results.
A shift in sales mix toward lower price chemical sales pushed highway deicing pricing down 8%, while consumer and industrial average selling prices increased 8%, largely due to strategic price increases implemented as a result of our enterprisewide optimization effort.
On a net price basis, we actually achieved a 5% improvement in average selling price versus third quarter 2019 results, with highway deicing average net price flat to prior year results and consumer and industrial net price up 8%.
Improved production and logistics costs in the 2020 third quarter more than offset lower revenue and resulted in year-over-year increases of 21% for operating earnings and 17% for adjusted EBITDA.
These efforts contributed to the expansion of the Salt segment EBITDA margins of 30% compared to 23% in the third quarter of 2019.
We reported a 21% year-over-year decline in revenue on a 22% decline in sales volumes and a 2% higher average selling prices.
This segment delivered a 5% year-over-year increase in third quarter 2020 revenue in local currency, driven by increases in average selling prices for both agriculture products and chemical solutions products.
In local currency, third quarter 2020 operating earnings and EBITDA declined 9% and 7% respectively, which was mostly attributable to lower volumes in our B2B business compared to the prior year quarter and continued aggressive investment in our direct-to-grower sales force.
In an average winter scenario, we're expecting highway deicing average selling prices to decline about 8% compared to prior year and the Salt segment overall is expected to see a price decline of around 5%.
In local currency, however, we expect to deliver 20% to 25% EBITDA growth compared to prior year.
Excluding the inventory adjustment, we are now expecting to deliver $330 million to $345 million of adjusted EBITDA for the full year 2020.
We are very pleased to report that we still expect strong free cash flow generation of around $125 million for the full year despite the headwinds Kevin and I have discussed today.
Our net debt to adjusted EBITDA ratio is expected to end the year below 4 times as we continue to make progress improving our balance sheet and maintaining a very strong liquidity position.

Summary:
Excluding the inventory adjustment, we are now expecting to deliver $330 million to $345 million of adjusted EBITDA for the full year 2020.