An unidentified big-box retailer could soon become part of the waterfront view staring back at Vancouver from the south shores of the Columbia River near Interstate five. Proposed as a $10.5 million substitute for the scorched remains of the Thunderbird on the River Hotel, the 125,000-square-foot retail store would be a single-story building with parking, according to an application submitted this month to the city of Portland. The proposal, entered by Portland-based architectural firm Baysinger Partners, did not include the name of the retail tenant planned for the tract. Stores that are out of the running so far include mega retailers Kirkland-based Costco, which said Friday it wasn’t looking at the site; and Bentonville, Ark.-based Wal-Mart, which just started building a new store off the next freeway exit south at Hayden Meadows. The proposed store also isn’t an expansion of Portland-based Fred Meyer or Minneapolis-based Target Corp., which recently opened a brand-new store at the Jantzen Beach mall across the street from the Thunderbird site.What about outdoor catalog-turned-superstore-chain Cabela’s? The company did not return calls, contributing to the mystery of the un-named project. Some say any development will be an improvement over the old Thunderbird, even if the vacant, 352-room hotel had not been burnt to a crisp in September. Over the last two months, backhoes have gingerly dismantled the structure and stacked the debris into piles at the site at 1401 N. Hayden Island Drive.The old hotel had been shuttered in 2005, unable to compete with an abundance of nearby accommodations. However, area retailers at the Jantzen Beach mall continue to favor the site as one that’s convenient to North Portland and Northeast Portland residents, and a huge attraction to Washington residents who aim to avoid the state sales tax, paid at a rate of 8.4 cents on the dollar in Vancouver.