ACCOUNTS RECEIVABLE (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jul. 28, 2012	Jul. 30, 2011	Jul. 31, 2010
Accounts Receivable [Abstract]
Contract billings	$ 136,610	$ 136,371
Retainage and other receivables	5,448	2,549
Total	142,058	138,920
Less: allowance for doubtful accounts	(270)	(368)
Trade acccounts receivable and costs in excess of billings	141,788	138,552
Movement in Valuation Allowances and Reserves [Roll Forward]
Allowance for doubtful accounts at beginning of period	368
Bad debt expense (recovery), net	186	(23)	198
Amounts charged against the allowance	(284)	(168)
Allowance for doubtful accounts at end of period	270	368
Allowance for Doubtful Accounts [Member]
Accounts Receivable [Abstract]
Less: allowance for doubtful accounts		(368)	(559)
Movement in Valuation Allowances and Reserves [Roll Forward]
Allowance for doubtful accounts at end of period		$ 368	$ 559