Old Town Brick Permeable Patio Redesign

Introduction

The purpose of this work is to outline the scope of a project completed June-July 2019 in Old Town, Alexandria, Virginia. The project provided substantial improvements to the sustainability of the property by installing a permeable hardscape and stormwater management infrastructure. All parts of the project sought to maintain and exemplify the highest industry standards possible with extra emphasis on sustainability standards as set by the Interlocking Concrete Paving Institute (ICPI) and Chesapeake Bay Landscape Professionals (CBLP). 

Please note, all prices associated with materials, equipment, and labor were given at the time of the projects. These figures are subject to change over time due to inflation and yearly increases in our business rates. 

Site Preparation & Containment (06/27/2019)

The TLC team began the project by preparing the site. We moved existing furniture on-site into storage to avoid any damage during the scope of the project. Additionally, we transplanted a handful of yew and azalea shrubs into our nursery for preservation and reintroduction after the completion of the project. Once these fixtures of the previous design had been set aside, we proceeded with the cleaning of the project area. 

We power washed the existing brick patio to remove stains and prepare them for storage. After all the bricks had been cleaned, we staged them in a secure location on-site for reintroduction into the new patio design.
One unique issue of this project addressed during this phase was removal. Because there is no direct point of entry to the project from the street, we would have to remove all debris through the client’s home. This required sealing off the hallway and multiple rooms of the house with tarps and plastic lining to minimize any damage or dirtying. Additionally, our team members wore protective shoe coverings and they exercised extreme caution while moving through the area. 

Scope Cost: $3,170.00

Excavation & Stormwater Management Infrastructure Installation (07/03/2019)

Our team excavated roughly 11 cubic yards of soil to start the project. This soil was subsequently removed from the site and disposed of. At this point, we used a rototiller to scarify the ground so that it would be able to absorb more water. Once the ground was ready, we began the installation of a new drainage line.

First, we laid strips of non-woven geotextile to increase structural integrity and minimize weed and root infiltration into the area. Then, we laid 25 feet of 4-inch perforated pipe below the subbase of the patio at an angle to ensure proper grade. We connected this pipe to the existing drainage system in the rear of the backyard so that stormwater would disperse safely into the street and avoid issues of pooling and the increased maintenance it causes. In heavy storm events, this drainage pipe will serve to increase this system’s capacity for rainwater, greatly improving the sustainability of the property.

Scope Cost: $575.00

Subbase Prep & Permeable Hardscape Installation (07/30/2019)

To begin preparing our aggregate base, our team spread a 6-inch layer of No. 2 stone. We then spread a 4-inch layer of No. 57 stone. Above these stone layers, we installed additional strips of non-woven geotextile for more structural integrity and suppression of weed and root infiltration. Finally, a 2-inch layer of bedding stone was spread as the base for the pavers to sit upon. This permeable aggregate base of differing sized stones allows water to dissipate and prevent it from pooling on the surface. At the perimeter of the excavated area, we installed a 12” X 12” area of dense aggregate base. Into this base, we secured black aluminum L-shaped edging to contain the area.
Next, our team installed brick pavers along with some of the bricks from the previous design. These bricks were laid in a basket weave pattern with spacers between. These spacers serve to increase the permeability of the brick patio, making it much more sustainable. Lastly, we filled the joints between the pavers with No. 8 stone. 

MATERIAL COST: $4,826.00

Aggregate Base: $3,851.00

Edging: $400.00

Brick Pavers: $575.00

LABOR COST: $1,950.00

Technician Hours: 30 @ 65/hr. = $1,950.00

Scope Cost: $6,776.00

OVERALL PROJECT COST: $14,521.00

Summary & Findings 

Throughout the course of the project, we provided significant, multidisciplinary improvements to the property. Overall, we installed one drainage pipe and 100 square feet of permeable patio. This drainage pipe will reduce the stress on the existing drainage system by increasing its capacity for removing water during heavy storm events. This 100 square feet of patio will allow roughly 1,744.40 gallons of water to permeate more sustainably in 2021. (Calculated by taking square footage and multiplying it by the product of .623 gallons per inch of rain and Alexandria’s estimated yearly rainfall of 40”, then multiplying that figure by 70% infiltration rate).

This project, though relatively small in scope, has an immense impact in the work that was completed. The installation of stormwater drainage pipes and a permeable patio transform this area from simple outdoor space to living, sustainable infrastructure that will improve this property for years to come. It is through the completion of many small home improvements such as this that our TLC team has made the greatest impact on the sustainability of Old Town. As our team expands and begins to tackle larger, more comprehensive projects throughout the region, we will always have a particular passion in our hearts for improving the properties of our neighbors in the limited space of Old Town, Alexandria.