TreePeople is a nonprofit organization that addresses urban issues, such as water and energy conservation, flood prevention, and stormwater pollution. The TreePeople Center for Community Forestry is a state-of-the-art environmental education campus in California's Coldwater Canyon Park.

Designed to achieve a LEED Platinum rating, the center features a 250,000-gallon underground concrete cistern. The largest of its kind in the continental U.S., this tank captures rainwater to irrigate the center's gardens and forests. The cistern is covered with landscaping, including an elaborate labyrinth. Because access for maintenance and repairs is almost impossible, the owners needed a permanent waterproofing solution for the structure.

Because conventional waterproofing membranes deteriorate over time, the center's owners opted instead to add a cementitious admixture to fresh concrete and the manufacturer's waterproofing system.

When it is added to the concrete mix, this admixture cures to form crystals that fill the spaces between concrete particles, permanently water-proofing the structure. It also reacts with incoming water to self-seal any small concrete cracks, providing lasting protection against leakage from any direction.

Project Participants

OWNER: TreePeople, Los Angeles

CONCRETE PRODUCER: Catalina Pacific, Los Angeles

GENERAL/CONCRETE CONTRACTOR: PCL Construction Group, Edmonton, Alberta, Canada

MATERIAL SUPPLIER: Kryton International, Vancouver, British Columbia, Canada