D.C. Mun. Regs. tit. 27, r. 27-2305
Construction contracts may authorize a variation in estimated quantities of unit-priced items.
When the variation between the estimated quantity and the actual quantity of a unit-priced item is more than plus or minus fifteen percent (15%), an equitable adjustment in the contract price shall be made upon demand of either the contracting officer or the contractor. The contracting officer shall base the adjustment on the increase or decrease in the contractor's costs due to the variation in quantity.
The contractor may request an extension of time if the quantity variation will increase the time necessary for completion of the contract. The contractor shall ensure that the contracting officer receives the request no later than ten (10) days after the beginning of the period of delay.
Pursuant to a request in accordance with § 2305.3, the contracting officer may extend the time limit based on a determination that an extension would be in the best interests of the District.
D.C. Mun. Regs. tit. 27, r. 27-2305