You could try one or all of these (same authors):
Edidin, Dan; Graham, William, Algebraic cycles and completions of equivariant $K$-theory, Duke Math. J. 144, No. 3, 489-524 (2008). Zbl 1148.14007.
Edidin, Dan; Graham, William, Riemann-Roch for equivariant Chow groups, Duke Math. J. 102, No. 3, 567-594 (2000). Zbl 0997.14002.
Edidin, Dan; Graham, William, Equivariant intersection theory, Invent. Math. 131, No. 3, 595-644 (1998). Zbl 0940.14003.
