DELPHI, Ind. (AP) — A volunteer contractor says progress has been slower than expected on the construction of a $1 million memorial park for two teenagers who were killed while hiking in northern Indiana.

The grandparents of 14-year-old Liberty German and 13-year-old Abigail Williams requested help from volunteers to build the 20-acre park. The girls were killed in February 2017 while hiking near Delphi, about 60 miles (95 kilometers) northwest of Indianapolis.

The Journal and Carrier reports that contractor Rob Cochran said Thursday that construction efforts at the Abby and Libby Memorial Park in Delphi have been hindered by recent rain.

Cochran says “the conditions haven’t been the best,” but that his contractors will do as much as they can before road construction resumes in earnest next week.

The girls’ slayings remain unsolved.