On the Sunday before Labor Day, House music lovers descend on Grant Park for the annual House in the Park (HITP). The event, founded in 2005, now attracts at least 15,000 attendees, outgrowing its longtime home in Perkerson Park on Atlanta's Southwest side.

In recent years, residents in and around Grant Park have expressed concerns about the event from the traffic clogging the neighborhood's main arteries to illegally parked cars to the trash left behind once the revelers are gone.

This year, after the event ended, neighbors posted their complaints on social media, mostly about trash -- not just in the park, but on the sidewalks surrounding the neighborhood and other areas.

House in the Park organizer Ramon Guyton said he had been contacted via social media and email about the concerns.

"I am very aware that there are complaints," he said when reached by phone on Tuesday. "The park is clean. We apologize that it took longer."

Guyton said the company contracted to clean the park didn't entirely fulfill their duties. "We contract someone and they make promises and they don’t fulfill completely on their part of the job," he said.

Provisions for overnight cleaning or adding more staff in key areas during the event may have helped make a difference, he said, but in the end, the hired company, along with Guyton and City of Atlanta workers, spent Monday and Tuesday picking up trash and restoring order to the park.

That didn't stop conversations online from devolving into name-calling and speculation that the event organizers had intentionally lowballed their expected turnout.

The chatter left some residents and festival organizers wondering if the problem had less to do with the aftermath of the event and more to do with the people in attendance which one resident referred to as exhibiting  "animalistic" behavior.

Here's a look at the action:

Guyton said HITP had been granted a Class C permit by the City of Atlanta which allows for up to 19,999 event attendees. Absent any scientific tools to gauge how many people are entering the park at any given time, Guyton said the estimate between 15,000 and 30,000 is within range.

This year, they attempted to address community concerns upfront, he said. To minimize parking issues, they worked with Parkside Elementary School and a third-party vendor which operated shuttles to and from Turner Field for off-site parking. To help with traffic, they hired five additional patrol officers, said Guyton.

To head-off clean up issues, the group posted on its website prior to the event reminding attendees to pick-up after themselves and place trash in the 30-yard dumpster that was provided. They also asked for volunteers to help with clean up the following day.

But when the party was over, there was trash scattered throughout the park and piled up next to trash cans where it sat overnight and into the following morning before cleanup crews came to take it away. Observers on social media noted that the trash was not confined to the park -- it was also in the surrounding streets and in the parking areas near Parkside elementary.

A similar scenario had surfaced in July after another event in Grant Park. Bronx Day is a 12-year old event that was created by homesick New Yorkers to celebrate music, food and more with a New York focus.

On July 22, about 6,000 people attended the event in Grant Park, said Bronx Day organizer Christopher McArthur. The following day, McArthur was fielding complaints about trash left behind.

It wasn't the first time. In 2015, after they had issues with their cleaning service, they sat down with the Grant Park Conservancy, representatives of Carla Smith and the cleaning contractor and hashed out the problems. As a result, they increased their expectancy and hired a new vendor in 2016. That year, the festival went off without issue, he said.

But this year, they tried another vendor, a reputable company that services other major venues in Atlanta, and unfortunately, they had issues.

"I contacted [the company] and told them they needed to rectify it. They compensated us on the price. We in turn volunteered to (help) clean the park," he said.

When they had been asked to increase their expectancy numbers, they did. Even though their permits required 10 police officers, they hired 14. McArthur felt they had gone above and beyond to make things right.

Last month, in a show of goodwill, the whole team from Bronx Day volunteered with the Grant Park Conservancy and Hands On Atlanta to help beautify the park, he said.

"Sometimes companies fail on their delivery. That is what it is," McArthur said. "We follow the city and state guidelines to a 'T.'"