I assume that’s because it hadn’t leaked yet, and they didn’t want it to. When we converted our house from heating oil to natural gas, that tank was a pretty big liability. We ended up filling it with foam rather than removing it, but for the same purpose.
It’s likely that there has to be additional environmental cleanup before that lot can be reused. Gas tanks can leak, which is why they immediately removed the old tank, but there may be previous leakage that has to be cleaned up. That probably makes it too expensive for most prospective clients.
Do you have a cool spongy bounce pad in your backyard now?! 
Yep. For some businesses, this is their business model. Lowe’s always opens near a Home Depot. CVS has a policy to only build near Walgreen’s.
Sometimes it’s all the time, sometimes it varies. For example, Hardee’s is usually near a McDonald’s around here, but I see standalone Hardees occasionally. I’ve never seen a CVS that wasn’t right across the street from a Walgreen’s though.
They could just repurpose the tank to hold House Blend. Already tastes enough like motor fuel of some kind anyway.
More seriously, Starbucks will sometimes open stores on or near opposite corners of a busy intersection, so people don’t have to walk that far.
And just the possibility that a tank has leaked and it will be discovered in the future is a tremendous liability. Often the costs of cleaning up an unknown leak have already been assigned to the previous owner but it’s still a disincentive to get involved. Even if the previous owner would be responsible for the clean up the site would have to be torn up and possibly shut down altogether while the work is done. That affects properties adjacent to gas stations also. Gas stations are the haunted Indian burial grounds of commercial real estate.
It was mentioned in passing by a couple of people, but it deserves to be emphasized that certain businesses pay a lot of attention to locating on the “going to work” side of the road or the “going home” side of the road. Donut stores want to be on the morning side, of course. When there was such a thing, video stores wanted to be on the going home side. Liquor stores prefer the going home side, too, but people will actually cross the road to buy liquor.
It is very common to have two gas stations on opposite corners of busy intersections to serve the morning and afternoon demand segments; sometimes it’s even the same brand. Most people don’t want to cross over to get gas, they would rather pull in and then out on the right side. The best quadrant is on the right before the intersection, which means the best two quadrants are diagonal across the intersection.
So, to the OP, are the two existing stations on opposite corners? Is one of them old and obsolete?
As mentioned, most stations have had to replace their tanks in recent years, so that could be a factor.
I live near town with under 10K in population, which seems too small to justify even one Subway, but we have two. Across the street from each other.
I see Subway restaurants in towns one-tenth that size. Subway has very loose franchisee restrictions, and low financial requirements.
Still, I agree that it seems odd that two would be across the street from each other.
The existing ones are on the NW and SW corners, the new one is going in on the SE corner.
One of the existing ones is pretty old and run-down (SW), the other is newer with a good-sized store that in addition to the typical convenience stuff has fresh produce, a butcher counter, etc. catering mostly to Mexican-American customers.
In addition to the the resistance of people to get gas on the opposite side of the street, there could be other things going on as well. I remember an intersection that had gas stations on two corners , a tire shop on the third and a transmission shop on the last. So you’ve got a little bit of the " this is the car-related intersection" going on. But the gas station were both owned by the same guy. One had a large convenience store, the first 24 hour one in thee neighborhood and a couple of bays for oil changes, etc. The other one had a full repair shop in addition to the gas pumps. The gas pumps were really just a convenience to the customers- the mechanic shop and the convenience store were where the money was made.
At one point virtually every gas station was attached to a repair shop. If you look at an older one that’s since been converted to a convenience store, you can still see the remnants in the architecture. Here, for instance, is the convenience store/former service station on a Connecticut parkway.
It tells you something about how much more reliable cars are in recent years that very few gas stations do any sort of repair service.
I can see a new station opening up hoping to drive an existing station out of business, but that doesn’t seem to happen all that often.
E.g., there’s a Quickie Mart near us that has two really big (upgraded) gas stations nearby offering cheaper gas. And it’s off the main road unlike the other two.
I have no idea how it’s still in business after all this time.
(Around here the doubling ups are Waffle Houses. Two at an interchange so you don’t have to cross the freeway when you want waffles and grits. It seems to me that if you’re traveling hundreds of miles on an Interstate an extra block would be no biggie.)
It’s not so much driving the extra block. It’s that something is going to be at the second location. That something is very likely to be a Denny’s or a Perkin’s or a Cracker Barrel or something similar because if it’s a good location for one of them , it’s a good location for all. And lots of people don’t have a strong enough preference between similar restaurants to go to any extra trouble- even if that extra trouble is simply making left turns into and out of the parking lot rather than right turns. Waffle House doesn’t want to lose the business from one direction of travel just because it’s easier to get to Perkins.
I believe Starbucks locations are all corporate-owned. So if they open a second one close to an existing one, they may not care too much if it cannibalizes some business from the existing store, just as long as the location isn’t occupied by a competing coffee chain. Perhaps Waffle House sees things the same way?
At the closest major intersection to me, there are 2 gas stations - a Shell, and a BP. The Shell has a big minimart and car wash - but no service bays. The BP has only cigarettes and candy bars in the small office area, and 2 repair bays. There are any number of auto repair/lube/oil change shops within a mile or 2.
I often wonder what folk bring their cars to the gas station for service/repair, but it generally seems to have business.
My guess/observation is that the Shell does quite a bit more business than the BP. It occupies a considerably larger lot. Their gas prices are generally w/in a cent of each other - both higher than gas I can get on my 6 minute commute in the other direction…
I’ve seen the opposite at work. When I first moved into my suburb of 20,000, there were 7 gas stations in town including four at one 6 pointed intersection, one in the centre of the town and two more on the periphery. Now there are only 3. The four are down to 2, the one at the centre is long gone and one of the two on the periphery also closed. One of the two at the big intersection is primarily a repair shop and the other one is a convenience store plus a car wash, so they don’t really compete.