Lower Macungie Township's newest shopping center is one step closer to reality.

All variances requested for the Hamilton Crossings shopping center were approved by the Lower Macungie Township Zoning Hearing Board Tuesday night.

That approval gives the development team a big green light to proceed with detailed planning for the 63-acre shopping center, which will include a Costco, a Target and as many as 28 other stores, restaurants, banks and gas stations on both sides of Krocks Road between Hamilton Boulevard and the Route 222 bypass in Lehigh County.

Those land development plans will be reviewed by the township, as well as by the state Departments of Transportation and Environmental Protection. The developers hope to get all final project approvals within a year.

They anticipate construction beginning immediately after final approval and that Hamilton Crossings will be completed by late 2014 or early 2015.

“It will be a special shopping center, much better than other shopping centers in Lower Macungie Township,” promised developer Tim Harrison.

While the hearing lasted nearly four hours, and focused solely on Hamilton Crossings, it took the three zoners only a few minutes to unanimously approve all the variances and hammer out the language of their approval.

Both the township commissioners and Lower Macungie’s planning commission had recommended the zoning hearing board approve those variances.

Two of the three zoners conducted a previous hearing on Hamilton Crossings in January 2011 and approved all requested variances in February of that year.

But Harrison said the project approved last year cannot be built.

The developers had to go back to the drawing boards to completely redesign the shopping center, then return to the zoning hearing board Tuesday, because they discovered a major new problem on the site: deposits of mine wash were found as deep as more than 24 feet underground.

From the 1850s until the 1930s, iron ore was mined from open pits on the property, said Harrison, who added those pits later were filled in with mine wash, which is sediment separated from the iron ore using water.

“We knew something about the mining past of this site when I was here before you in January 2011,” Harrison told zoners. “But we’ve done much more extensive testing in 2012 and the problem is much, much worse than anybody ever dreamed.”

Harrison said 333,000 tons of the saturated material, which he compared to wet sand, must be removed from the ground, dried and stabilized with crushed concrete or stone, then compacted back into the ground. Even after that mine wash is remediated, “we can only park on it. We can’t build buildings on it.”

The deepest mine wash deposits are on the southern side of the property, east of Krocks Road, exactly where many of the large stores were going to be built.

“The principal reason we’re here tonight, asking basically for the variance relief we asked for many months ago, is because the buildings had to be moved off this material,” said Harrison. “The whole shopping center had to be reconfigured.”

He said discovery of the mine wash deposits was an unhappy surprise, but led to the creation of a much better project, in cooperation with the township.

“We are on our 150th concept plan,” Harrison told zoners. He has been working on the project since 2009.

Some new information about Hamilton Crossings emerged during the hearing:

• Harrison said Costco has been looking for a site in the Lehigh Valley for seven or eight years. “They are very selective. They are only going to do one site in the Lehigh Valley. This is it. They feel this is the best site to serve the Lehigh Valley, because of the combination of visibility, location, transportation infrastructure and the size of the site.”

• While not the first Target in the Lehigh Valley, the Hamilton Crossings store will be one of only 20 new stores Target is planning to build in the United States, said Harrison. He said Target has reviewed hundreds of sites, adding: “They have picked this as one of their top 20.”

• A proposed service road will parallel eastbound lanes of Route 222, so eastbound vehicles heading to Hamilton Crossings can access the shopping center from more points than just the Krocks Road/Route 222 intersection.

• “A well-defined interior boulevard,” informally called Costco Boulevard, will wrap around the property to serve Hamilton Crossing’s parking areas and link Krocks Road and the Costco. The southern end of that boulevard will intersect with Hamilton Boulevard, requiring traffic lights at that new intersection, opposite the Ethan Allen furniture store.

Two hours after the hearing began with a detailed overview of the project, Harrison laid out 13 variance requests for the shopping center. He said they were very similar to variances granted by the zoning hearing board early in 2011.

The only new variance request had to do with the minimum width of spaces in parking lots. Harrison said the township requires parking spaces be at least 10 feet wide. He got approval for spaces that will be 9.5 feet wide. Each actually will be 8.5 feet wide, not including six-inch-wide double striping on each side.