If P = Periodic payments done quarterly (that is, four time in a year) = $5,200, n = number of years (5), R = Annual interest rate = 8% = 0.08, and A = Amount to be set aside today, then
A = P [1-(1+R/4)^4n]/(R/4) = 5200 [1-(1+0.08/4)^4*5]/(0.08/4) = $85,027.45
Therefore, Valdez construction should set aside $85,027.44 now to satisfy the capital requirement.