This is one of Philly’s biggest illegal dumps. Cleaning it up is a logistical nightmare.

Viewed from below, the scale of the illegal dump is daunting, spanning the length and depth of a steep ravine for about a block, spilling along before coming to a dirty halt near a clear stream.

Viewed from above, it’s a vertiginous array of broken appliances, ratty furniture, dirty toys, old tires, used mattresses, and other detritus. The rear hatch of a white Toyota RAV4 pokes through weeds. A boat is still hitched to a trailer loaded with rusting liquid propane tanks.

City officials don’t know how long the slope off Pennway Street in Northeast Philadelphia has been the site of illegal dumping. But they know it presents a big logistical task to clean it out.

“It’s certainly one of the larger dumps we’ve had to deal with,” said Carlton Williams, director of the city’s Clean and Green Initiatives Office.

Williams expects that it will be far more difficult to clean than the 4,000 tires found in last April in Tacony Creek Park. Those were hauled out by city workers and 200 volunteers.

» READ MORE: A muddy army of volunteers helps clean up Philly’s biggest tire dump

“We’ll probably have to get cranes. And it’s going to be challenging to get equipment back there,” Williams noted. “This has been a hidden place for people to illegally dump for some time.”

The first obstacle to cleaning out the dump is its location. It begins at the edge of an alley under high-voltage wires. Area residents park their cars in the alley and some have erected sheds.

The top of the slope is treacherous, filled with trash, chunks of concrete, and thickets of bramble that are easy to snag or trip on.

Using volunteers to haul things out is probably not practical given the potential danger, Williams said.

From below, the dump is hidden by woods that adjoin the grounds of Friends Hospital. To view it, you have to leave a small trail, walk down a vegetation-choked embankment, ford a spring-fed tributary of Tacony Creek, and trudge through wetlands.

There is no direct access road from the bottom.

On a recent day, a man was picking through the rubble.

“Looking for metal,” he mumbled.

The second major obstacle will be untangling ownership of all properties the dump might span, sorting out responsibility, and paying for it.

Williams said the city is currently tracking down ownership of whatever parcels might be involved.

Much of the property is owned by Peco. Peco spokesperson Candice Womer said the utility company owns the property along Pennway Street and that is leased to SD Real Estate.

The power lines are part of Peco’s infrastructure, she said in a statement issued Tuesday.

“We take concerns about illegal dumping seriously and work within our legal agreements and with appropriate stakeholders to support efforts that protect the community and environment,” the statement said.

It noted that Peco has developed strategies to tackle illegal dumping in the area for years.

“We are reviewing the current situation and coordinating with the tenant and other relevant parties to enhance those efforts,” Peco’s statement said.

It’s not clear who is doing the dumping — construction crews, residents, or both.

“We’re still trying to figure out a plan,” Williams said, adding, “We have to gain access.”

Williams also said it will be a challenge to prevent dumping in the future.

Philadelphia already has 400 surveillance cameras used to monitor known dump sites and can tap a broader network operated by the police department and other agencies. It anticipates purchasing an additional 100 cameras.

It has also installed bollards and gates that prevent vehicles from entering dump locations and is more aggressively pursuing and fining violators.

The dump was first reported to the city by the nonprofit Tookany/Tacony Frankford Watershed Partnership (TTF), which helps manage the city-owned Tacony Creek Park.

TTF has an office at the Friends Hospital complex off Roosevelt Boulevard. The nonprofit is helping with a yet unnamed 50-acre preserve on the hospital grounds that connects to Tacony Creek Park.

A portion of the dump is behind a broken fence at the edge of the grounds.

“This is one of the harder ones to tackle,” said Justin DiBerardinis, executive director of TTF. “We’re at the beginning of a journey to take care of one of the biggest dumps that a lot of us have seen.”

DiBerardinis suspects contractors are dumping there, but also residents.

Cleaning it up, he says, will be “extremely complex.”

He’s also heartened by what he sees as the city’s willingness to address the logistical challenges presented by illegal landfills.

DiBerardinis said the dump mars the landscape, and rests only yards from a tributary of Tacony Creek that serves as the edge of the 50-acre preserve.

“That stream is really clear, like spring-fed water coming from the earth,“ DiBerardinis said. ”To have that in our city is such a rare and special thing.“

He senses growing community support for tackling litter and a backlash against dumping. Last Saturday, about 100 volunteers came to the preserve to help clean it, though the dump remained inaccessible.

He thinks the community can play a role in the cleanup, if even for moral support and watchful eyes in the future.

“I’m seeing people getting inspired at the possibility of the restoration and the protection of those places, and to have access for them and their children,” DiBerardinis said. “Dumping like that has a huge psychological impact on a community.”

This story has been updated to reflect a statement by Peco.