Who bossed the slaves Mrs. Adams saw?

Judging from the records, the commissioners finally addressed the problem of rubbish in September on the Capitol Square first. There a Captain Coyle was filling Capt. Elisha Williams shoes by overseeing the overseers, in this case just one overseer. Smallwood‘s first replacement didn‘t last long. Capt. Coyle needed a new one and the commissioners hired a Mr. Tippett who they hoped would do. They warned Coyle “it will be absolutely necessary that some industrious active man should be employed to push on the work,” and ordered him “to increase the number of laborers to twenty and the Carts to eight or ten at least.” On November 11, a few days before the First Lady arrived and two weeks before she wrote her letter quoted above, the commissioners wrote to Stoddert that they would have "an Overseer and twenty good Laborers" available to clean up the White House yard in "a few days."

Quote from Slave Labor in the Capital, page 157 

In another post I quote the letter in which First Lady Abigail Adams sneered at the overseer of the slave laborers working in her yard http://capitalslaves.blogspot.com/2015/03/abigail-adams-amused-by-slaves-working.html. In the commissioners' letter below I think I found the name of that overseer, Mr. Tippett. In other records I've seen a Dyson Tippett listed.

I first thought these laborers were pavers, but since that work was done by contractors, I don't think that first impression was accurate. They were likely the crew cleaning up the grounds around the public buildings.

The description by Mrs. Adams and this letter allow us to draw some other conclusions. The commissioners referred to "laborers" and the First Lady saw only "slaves." That suggest that in 1800 white laborers could get better pay elsewhere, preparing the grounds for the Navy Yard for example.

Also, Tippett, the overseer, was himself overseen by a Captain Coyle. In 1799 the commissioners laid off Captain Elisha Williams the man who previously oversaw the overseers. Williams oversaw three overseers, maybe four at time, who, in turn, oversaw up to 120 laborers, at least 90 of them hired slaves. What Mrs. Adams saw was a shadow of the force the commissioners once commanded yet the note they sent to Captain Coyle seems more officious than anything they ever sent to Williams.