DES administers the state's Tier II program and requires E-Plan for every submission -- either entering data directly or importing a Tier2 Submit file into the system. No other reporting method is accepted.
Who has to file, and when
Standard federal thresholds -- 10,000 pounds for hazardous chemicals, 500 pounds or the TPQ for extremely hazardous substances.40 CFR 370.10 Deadline is March 1st, covering the previous calendar year.
The good news on cost, and the catch
South Carolina's own guidance states plainly that the state doesn't charge Tier II reporting fees -- a genuine contrast to Florida, Georgia, and North Carolina, its E-Plan-using neighbors, all of which do. But that's specifically the state level. Your county LEPC and local fire department may have their own fees and their own specific reporting preferences, and DES directs facilities to check with each of them separately rather than assuming "no state fee" means "no fee anywhere."
E-Plan's Submission Validation Report has to come back clean before you're able to submit at all -- the system won't let incomplete or inconsistent data through, which catches errors before they become a filing problem rather than after.
Where HazRecord fits
HazRecord keeps your inventory validated and current throughout the year, so the data going into E-Plan is clean before you ever hit submit, and your county-level LEPC and fire department requirements are tracked as their own item rather than assumed away.