(CNN)After a month of torrential rain around Freetown, Sierra Leone, a sound like an explosion shattered the peaceful morning and the ground trembled. Mount Sugar Loaf was falling down.
On August 14, 2017, a river of mud, trees and boulders cascaded into the city, killing more than 1,100 people, including seven members of Alhaji Siraj Bah's adopted family.
The 17-year-old might have died with them, but he was working a night shift. When he tried to return home the next morning, his path was blocked. After several hours, he was told that no one in the house had survived.
Bah, now 20, was born in a remote village 160 miles from Freetown. His father died when he was 12 and the youngster traveled by bus to the nation's capital. "I lived on the street for four years," he told CNN. "I used to do so many odd jobs just to get food to eat ... I used to fetch water, wash clothes.
"I was not scared, I just had that belief in that one day, I will make it."
'The next Oprah Winfrey'
The mudslide precipitated an environmental awakening for the teenager. He learned from the television that the catastrophe was worsened by deforestation and poor waste management around the rapidly expanding capital city.
Freetown lost 31 percent of its dense southern forest between 2001 and 2015, according to Global Forest Watch. Without trees, soil on the high ground around the city is saturated by downpours, and the land is eroded.
A lack of waste collection services in Freetown means garbage is often dumped in streets, gutters and river courses. This blocks drains and can leads to flooding, soil erosion and the spread of disease.
"I realized I needed to step up and do something," says Bah. "I would be the next Oprah Winfrey."