Prior to the Rain Garden, this area was a pond garden and rock garden collection area. There were site problems during every rain, causing the ponds to overflow. The rock garden plants were not thriving. Both collections were relocated and the rain garden was developed in this site near the lower conservancy. This is an image of the first day of construction when the ponds were being demolished.

The ponds are removed; the stone is stockpiled for reuse later in the facing of the concrete walls, construction of the seat walls and for the dry stream beds and as a backdrop on the lower bioretention cell.

The lower cell of the Rain Garden is being excavated. The volume of native soil is replaced with special bioretention media to treat the stormwater.

The lower cell required 3 ½ feet of excavation; this part of the garden is in full sun.

57 Stone is loaded into the bottom of the lower cell of the Rain Garden. This provides water storage to promote infiltration and runoff volume reduction.

Coarse gravel is placed in the bottom foot of the lower cell and an underdrain is placed on top of the gravel. The area below the pipe is extra storage for larger stormwater runoff.

The underdrain pipe is perforated so that excess water can seep into the pipe and be released from the garden area after being filtered through the bioretention area.

The underdrain is covered with filter fabric to keep sediment out of the pipe and planting media is added.

Bioretention mix is added to the lower bioretention cell.

Shredded pine chunks are used as an organic amendment to add texture to the bioretention mix.

The upper bioretention area is excavated and the underdrain is set in place. This underdrain is linked to the upper permeable interlocking concrete paver area and then directed to the lower bioretention cell underdrain. The upper rain garden cell is in the shade.

The permeable interlocking concrete paver area is prepared with excavation and underdrains. The underdrains are tied into the lower bioretention cell underdrain.

Detail of the permeable interlocking concrete pavers. The gaps between the stones allow water to infiltrate through the pavement. The paver blocks are not pervious.

After the pavers are set, aggregate is swept over the top to fill the spaces between the blocks.

The slope below the upper bioretention area will be planted with native species evergreens.

Water running down the upper walk is intercepted by the trench drain and directed into the bioretention cell.

The upper permeable pavement area is under construction; the rounded area on the right will provide visitors a place to step off the path and get a good view of the plantings of the upper area of the rain garden.

A view back from the upper rain garden cell towards the trench drain and pavement areas before the seat wall is constructed.

The area for the Crimson Queen Maple is prepared prior to moving the tree.

This Crimson Queen specimen was moved out from being crowded by the Ginkgo tree and reused adjacent to the Rain Garden.

The Crimson Queen Japanese Maple in its new home links the the Rain Garden and the rest of the collections above the Rain Garden.

Panoramic view of the Rain Garden construction in mid-September. The lower pavement is finished.

View up the axis of the lower biorention area after the planting media is installed but before mulching and planting.

At the end of the 10 year storm, there was 3” of water on the surface of the biorention area. (Note: Area was not mulched yet.)

Bioretention cell 4 hours after the end of a 10 year storm.

The runoff flows across the top of the permeable pavement and then filters down through the aggregate.

The area that wraps around the Rain Garden is improved with gathering space and a seat wall to view the lower portions of the garden. Rock facing the wall was salvaged from the original ponds and rock garden areas.

Shredded pine bark is used for the 3” mulch layer for the bioretention areas.

Planting of the area in the Rain Garden that is outside of the biorention areas begins using recycled plants from the previous gardens and some new selections.

The trench drain intercepts water that runs down the sidewalk and redirects it into the upper rain garden bioretention cell. Excess flow carries over the permeable pavement and infiltrates into the pavement; after pavement infiltration, water is redirected to the upper rain garden bioretention cell with an underdrain.

Water temporarily ponds on the surface of the upper and lower bioretention cells; it will infiltrate and leave the surface within 4 hours of the end of the rainstorm.