ST. LOUIS — The volunteer program at the Gateway Arch is seeking 100 people or more to “team up to clean up” the St. Louis riverfront. This is all in celebration of National Park Week. The Mississippi River is one of the largest sources of oceanic plastic debris. Last year’s clean-up brought in 35 bags of trash, 40 pounds of plastic, and 54 pounds of other recyclables kept out of the river. All volunteers will receive gloves, trash bags, water, and snacks. Volunteers are asked to park at the Kiener West Garage. You will receive validation. There’s a clean-up happening from 9 to 11 this morning and another one from 11 to 1 this afternoon.