ATHENS, Ga. — Georgia offensive tackle Kolton Houston remains ineligible because he continues to test positive for an anabolic steroid he was given for shoulder surgery more than two years ago.

If eligible, Houston would have been Georgia's No. 1 right tackle for Thursday's opening day of practice. Instead, coach Mark Richt said Georgia must prepare to be without the third-year sophomore.

Richt said Georgia's medical staff hopes the banned substance, 19-norandrosterone, will eventually leave Houston's system.

"Over time you assume that substance would leave your body," Richt said. "We've been waiting for that moment and it hasn't come. It's been two and a half years and this thing has not for whatever reason gotten out of there.

"He's been tested probably more times than anybody in the history of college football. We're 100 percent certain he has not continued to take this thing, but it's just never gotten far enough out of his system for him to be declared eligible to play."

Georgia released documents Thursday that included an email it received Tuesday from NCAA President Mark Emmert, who denied Georgia athletic director Greg McGarity's request for a special exemption for Houston.

Emmert said he understood Georgia's "empathy for Kolton's situation" but added he was surprised the school would ask for the exemption.

"That surprise stems in part from the fact that Kolton tested positive in subsequent drug tests after his initial sanction, and the Drug Test Appeals Subcommittee did not impose additional sanctions for those positive tests due to the 'declining value' argument that supported the conclusion that there was no new use of the banned substance," Emmert said.

The drug test policy "is not something that can be waived or appealed because doing so would undermine the purpose of the drug testing program," Emmert said, adding that Houston will remain ineligible until the presence of the substance "drops to an appropriate threshold."

Richt remains hopeful a successful test for Houston "could happen anytime, really."

Georgia associate athletic director for sports medicine Ron Courson said he has evidence that "can show without a doubt in two and a half years there has been no re-use."

Houston, from Buford, Ga., had the shoulder surgery before enrolling at Georgia before the 2010 season.

"We fully admit a mistake was made prior to his enrollment here," Courson said. "He's paid his due. Let's let him return."

Courson would not say if the banned substance was given as an injection or as a cream.

Speaking of cases in general, Courson said injections can become trapped in fatty tissue and then can be released into the system during massage therapy. In his communication with the NCAA, Courson said he believed massage therapy administered at Georgia could have affected Houston's drug tests.

The NCAA's drug policy calls for a lifetime ban if a student-athlete has a second positive drug test. Courson said Georgia successfully appealed to have that ban lifted when the NCAA's second test showed the substance was still in Houston's system.

Courson said Georgia is giving Houston weekly tests. When his level of the substance reaches a level low enough to meet the NCAA standard, Courson said he will ask the NCAA to give Houston its own test.

Richt said sophomore Watts Dantzler, who played in three games last season, moves up as the starting right tackle for the beginning of practice.

Georgia lost three starters, Justin Anderson, Cordy Glenn and Ben Jones, making the offensive line a top concern for preseason drills.

"One of our bigger challenges in camp is to put together our starting five and then anybody else who is capable of playing SEC football, we've got to find out who they are," Richt said.

"We've got to get the starting five as soon as we can because they need to be a cohesive unit."

NOTE: Georgia spokesman Claude Felton confirmed LB Chase Vasser has been suspended for the first two games of the season following his DUI arrest in Atlanta on May 11. Vasser, a junior, started three games last season and began preseason drills listed as a starter. Richt previously announced a two-game suspension for CB Sanders Commings following Commings' arrest in January on a domestic violence charge.