A cloud is forming in West Des Moines, where city leaders hope others will form.

In this case, the cloud will exist in a cluster of modular servers at the Microsoft Corp. data center. That’s where documents, images, music and more digital data will be stored and delivered, possibly to Greater Des Moines, possibly to a business in India.

The first of six modular units that are planned for the data center was to be delivered March 1. By late spring, all six will be connected by a structure called a spine, with another connection to a 40,000-square-foot administration building. The spine is in place, as is the framework of the administration center.

Also on site at the $100 million project are eight backup power generators.

When completed, the data center will employ about 25 people at an average annual salary of $31,000.

Microsoft announced last year that it would proceed with the project, which was first announced in August 2008 and originally conceived on a much grander, $600 million scale. Current construction at the 41-acre site at South 88th Street and Grand Avenue allows for future additions.

The data center will be an anchor for other high-tech businesses along what the city calls the Grand Technology Gateway (a name the city has trademarked), which will stretch from the Des Moines Area Community College (DMACC) technology campus west to 105th Street.

West Des Moines is spending $8 million to extend Grand from the DMACC campus to South 88th, pave the street between Raccoon River Drive and Booneville Road, lay conduit for fiber-optic lines, and install water mains and storm and wastewater sewer lines.

Left-turn lanes from the eastbound portion of Grand must be completed, along with through lanes at the intersection of Grand and South 88th.

Some paving work remains for South 88th.

To recoup those costs, the city and Microsoft agreed to a minimum property assessment of $15 million. If the valuation exceeds $18 million, the city will use tax increment financing to return the excess property taxes to Microsoft. The agreement expires in 19 years or when West Des Moines recovers its development costs.

The city has completed about 90 percent of the paving, grading and underground work on the project. Work has included relocation of a 30-inch water main, construction of culverts and installation of a new Iowa Interstate Railroad train crossing.