One Merriweather: Under the Boardwalk

A new commercial development offers insights into how stormwatermanagement strategies and design solutions can engage people and allow them to experience the landscape in a new way.

The One Merriweather office building and parking structure are the first major components of a new $68 million development directly adjacent to the popular Merriweather Post Pavilion event venue in Columbia, Maryland, near Washington, D.C. Combined with the adjacent office building, Two Merriweather, it features 322,000 square feet of total new office space, as well as 25,000 square feet of new retail and restaurant space.

A new shared parking structure serves One and Two Merriweather office tenants during the day and Merriweather Post Pavilion concertgoers at night and on weekends. That opened the door to an opportunity — create a uniquely distinctive experience for tenants and a positive first impression for event-goers.

While ADA access to the north building was possible from the parking structure, with the expansion of the new development to the south, developers wanted to address accessible circulation over a 16-foot grade change, as well as a technical solution for stormwater management requirements. In addition to accessibility, project stakeholders were looking to incorporate active and passive uses on the site, all in a single coherent design.

With the project’s proximity to Symphony Woods, a 36-acre park that features trails and large mature trees, developers identified a strategy: enhance the overall walkability of the neighborhood with a multifunctional boardwalk amid a lushly planted landscape that also serves as an integrated stormwater solution.

Stormwater Management System and Construction

Stormwater management can be a critical consideration early in the design phase because it impacts or informs the architecture and affects how the landscape needs to be planned to support it.

For Merriweather One and Two, the design team worked closely with civil engineers from GLW of Burtonsville, Maryland, to address stormwater needs on a site that had been a forest. They balanced the technical requirements of stormwater conveyance and retention with the aesthetics of the site design by using bioretention in multiple tiers, pervious pavement and other techniques.

The biggest challenge to effective stormwater management on a budget is a cohesive design that meets the technical needs in an aesthetic yet functional way.  Stormwater management is best executed by integrating multiple trades, such as landscape architecture and civil and geotechnical engineering.

A construction plan that protects and preserves the landscape is a good approach. During construction, landscape architects and civil engineers should be on site to supervise the work.

The comprehensive stormwater solution at One Merriweather fits into the context of its distinctive location and enhances the pedestrian experience. Large trees help scale down the architecture of the office buildings and make pedestrians feel comfortable without blocking views or overplanting.

All this infrastructure is integrated into the landscape in an aesthetically intriguing manner. The placement of trees and selection of plants creates a place that is more naturalistic, complementing Symphony Woods while simultaneously addressing stormwater management.

Appropriate plant materials can accommodate various microconditions including slopes, sun/shade and periods of inundation. At the same time, the local jurisdictions as well as the regional climate influenced the planting palette.

The selected plant species can tolerate water inundation as well as drought.  Native tree species such as sweetbay magnolia, black gum and river birch provide a deciduous canopy, and American hollies provide evergreen coverage. Six native shrub species are part of the development. These include clethra, which has fragrant flowers in summer, and winterberry, which provides winter interest with bright red berries.  More than 20 species of perennials and grasses fill the understory spaces. They have staggered bloom times, which provides a dynamic visual experience throughout the seasons.

Soil quality is key for the landscape architecture team, because compacted soil will not provide adequate infiltration. The design incorporates overflows for stormwater so that water can move through the system when each tier reaches maximum capacity.

The design also includes pervious pavers used in pedestrian plazas, complementing a comprehensive stormwater strategy and a low-impact development.

On the Boardwalk

The accessible, elevated boardwalk at One Merriweather is 350 linear feet. It traverses the landscape in a crisscross pattern that appears to hover above the landscaped area while also providing places for people to gather. There are multiple levels and areas along the boardwalk designed to provide a variety of distinct gathering spaces for tenants and pedestrians. This creates opportunities for people working in the nearby offices to use the spaces in a meaningful way — to take a call, have a quiet lunch or a small, informal meeting.

Below the boardwalk, plant material is strategically placed where the boardwalk is highest and the structure is most exposed, helping conceal the underside of the boardwalk structure. To achieve the appearance of a floating path, the selection of appropriate plants accommodates micro conditions, such as slopes and inundation, contributing to a low-impact development.

The design originally included composite decking with a mostly transparent metal rail and cable system. This would give the illusion of a floating boardwalk. However, to meet the budget for the project, the team used pressure-treated lumber and heavier rails. A wooden bottom rail allows users to rest their feet without stepping on the cables and conceals a linear LED light system that illuminates the walkable surface while keeping the light source hidden from view.

Technical constraints and the natural aesthetic of Symphony Woods also influenced the selection of structural materials. Marine-grade timbers serve as the structural system for the boardwalk, minimizing the footprint below. These timbers are typically found on docks along the ocean because of their resistance to water and durability once installed in wet conditions.

The structural engineer chose this construction approach because of its limited impact to the stormwater systems below, as well as for its cost-effectiveness and inconspicuousness. The construction process was unconventional, with a large machine driving 60-foot-tall timbers. A surprising hurdle was finding contractors with the required expertise who were willing to do a single project that wasn’t on the coast.

It’s More Than Landscaping

Landscape architecture doesn’t just impact stormwater quality. It also influences the overall appearance of the project, as well as more practical considerations, such as maintenance costs related to gardening, replacement of bioretention media, and plant material that would endure through time and seasonal change.

The Merriweather project achieves this goal in a way that is cost-effective and manageable, which ultimately makes the result more sustainable for the owner. It also contributes to an educational-aesthetic narrative for visitors to follow, which imbues the space with meaning.

Brian Reetz is a principal with Baltimore-based Design Collective, Inc., and Anna Dennis is an associate.