7510 - SPILLWAY AND DAM REHABILITATION RIVERS DAM MUNICIPALITY OF RIVERDALE

Rehabilitation of the existing spillway and embankment dam including:

• installation of new seasonal safety boom and pile foundations in approach channel upstream of spillway;
• installation and removal of temporary cofferdams as required each season (upstream and downstream);
• raising the existing embankment dam by increasing the height of the impervious fill and upstream riprap;
• raising the existing upstream wingwalls;
• raising the existing spillway walls along the length of the spillway chute;
• demolition and removal of the existing spillway stilling basin walls and slab;
• construction of new reinforced concrete stilling basin walls, slab, chute blocks, basin blocks, and end sill;
• select demolition of existing spillway chute slabs for the installation of new under-slab drains at each transverse joint in the spillway;
• installation of new concrete manholes to connect to the new underslab drains;
• installation of joint sealant along all transverse joints and along the four existing longitudinal spillway joints;
• installation of joint armouring along transverse joint between chute and stilling basin; 
• installation of new post-tensioned anchors in the existing spillway crest structure;
• removal and replacement of portions of existing handrail and fence with new handrail and fence on chute walls;
• miscellaneous concrete repairs on existing spillway structure; and
• installation of riprap and grading of outlet channel.