Centers for e-fulfillment need to be designed from the ground up, says consultant Don Derewecki, Gross & Associates (732-636-2666, www.grossassociates.com). All the systems for materials flow and for information flow must support efficient order taking, picking, packing and shipping. All systems must be integrated too, he adds.

Due to customers' high expectations, the time from receipt of a Web order and when it's picked and shipped must be minimal. "In many cases, only hours should elapse," Derewecki maintains.

Indeed, "a lot of stuff stacks up at the cutoff hour for e-commerce orders," observes Jim Apple, consultant and co-founder, The Progress Group (770-804-9920, www.theprogressgroup.com). "That puts the screws to the distribution center's operating window to ship to customers." In other words, timing is everything!

DC design must also accommodate the peaks and valleys faced by so many e-fulfillment operations. Worse yet, these variations occur with a high degree of unpredictability.

So among other design fundamentals, says Derewecki, are that e-fulfillment operations must be flexible and scaleable. Capacity must be ready for peak throughputs tied to buying spikes for holiday gift-giving, seasonal needs for clothing, sports gear, or back-to-school supplies. Then sales can fall sharply. And so does the need for capacity.

Somehow, adds consultant Geoffrey Sisko, Gross & Associates, these facilities must find the scaleability that permits them to run efficiently and cost-effectively over a range of capacity utilization.

"Design to smooth out the order peaks," suggests consultant Kevin Hume, eSYNC International (www.esync.com, 831-722-0402). For a typical, seasonal retail business with high, last-quarter sales, one searches for ways to make distribution efficient in the remaining three quarters of the year.

Go slow making system investments, but proceed wisely, is one path to achieving scaleability. Patrick Sedlak of Sedlak Management Consultants (www.jasedlak.com, 330-908-2100) advises his e-fulfillment clients "to start with relatively manual handling processes. But put in place the means to evolve to a more mechanized, more automated facility when increased business warrants that evolution."

Designing flexibility in systems and then cross-training the workforce manning them is a tactic to cope with peaks and valleys. Consultant Drew Hale, The Progress Group, explains how this strategy works for one client, the e-fulfillment operation at a major apparel retailer.

Orders peak just before the Christmas holidays, then they fall. Weeks later, this retailer then sees peak volumes of returns, a common problem in soft goods bought on-line. Sizes or colors may be wrong, for example.

Systems were designed and laid out so that the retailer's DC has the two functional areas for packing orders and for processing returns co-located (see graphic at right). The retailer's associates can be crosstrained in both packing and processing returns, moreover.

When seasonal business surges, says Hale, the packing operation can be augmented by as many as 40 additional stations from the returns area. When the outbound flow of orders later reverses and the numbers climb for returned goods, associates at packing stations can be used to support reverse logistics, if needed.