Chesapeake Bay Trust

Montgomery County Watershed Restoration and Outreach Grant Program

Rock Creek Conservancy Project Narrative

Conservation Landscaping at Derwood Station 2

Project Goal(s)

The primary goal of this project is to install conservation landscaping in a common area in the Derwood Station 2 community to reduce and manage stormwater runoff onsite before it reaches Crabbs Branch, a tributary of Rock Creek. The project area, situated just uphill from Crabbs Branch, is significantly impacted by concentrated stormwater flow from a drainage pipe that collects runoff from the surrounding impervious areas, such as roofs of local homes, driveways, and the surrounding streets in the development, and discharges it into the grassy area. Additional runoff is contributed to the site through surface flow from the surrounding area. A secondary goal for the completed project is to facilitate the education of local residents about stormwater and their connection to the Rock Creek watershed, and to serve as a demonstration site for other HOAs, institutions and organizations to learn about an effective and aesthetic approach to stormwater management.

In the spirit of innovative approaches, it is proposed that a small trial be included in this project to evaluate the effectiveness of “green mulch” —low-growing native groundcovers—as a potential replacement of traditional hardwood mulch in quickly covering the ground and preventing soil erosion from stormwater runoff. We hope to increase the knowledge about which species might best serve this purpose and under what conditions. The information gained from this trial could potentially provide new tools for and contribute to the knowledge base and decision-making of the sustainable landscape professionals community; interested homeowners, residents, and the stewards of larger organizational and commercial properties; and Montgomery County technical staff, such as those in the RainScapes program. (See attached summary for further detail.)

Background:

In the summer of 2015, representatives of the Derwood Station #2 HOA Board of Directors consulted with the Montgomery County RainScapes staff to devise a solution to address a stormwater issue in an approximately 2-acre common area. The common area, off Buena Vista Drive, and composed primarily of turf, connects directly to the Crabbs Branch Stream Valley, a tributary of Rock Creek. A large stormwater pipe daylights near the top of the property, and during rain events, sends untreated storm water flow through the length of the site and towards Crabbs Branch. Large rain events create flooding and erosion of the site from rapid water flow, while also carrying sediment and surface pollutants from uphill areas. (See photos)

The RainScapes staff calculated the drainage area and amount of impervious surface impacting the site, and devised a practice that would help slow down and infiltrate as much of the stormwater as possible using a 200-foot-long, thickly vegetated conservation landscape planting and series of berms extending downslope from the pipe outfall. Through consultation with a landscape designer, the practice was reworked to expand the goals of the site to both capture and control more water, provide wildlife habitat, attract pollinators, and also serve as a highly aesthetic community amenity. The design’s intent is to make a stronger physical and ecological connection to the Crabbs Branch Stream Valley. The design revision, to be completed at the beginning of the project period, includes a series of stone check dams rather than earthen berms, with a stone infiltration zone behind each dam; a mix of native grasses, rushes and flowering perennials and shrubs; and plantings of trees native to the floodplain forest community that speak to the locale. A master plan for the site, completed in December 2015, also includes an asphalt walking path that traverses the site, and a number of seating locations that maximize the views and contribute to the community’s enjoyment of the area.

The Derwood Station #2 HOA board has completed some of the work called for in the master plan, namely, to install the pathway and to obtain and plant the native trees and some of the shrubs. The results of a perc test they conducted, along with consultation of soil survey maps, indicate soils with good drainage (primarily Gaila silt loam, Hydrologic Soil Group B). The funds for installation of the stormwater practice, the most important and integral feature of the plan, have not been available to date, meanwhile the flooding and erosion events continue unchecked. Installation of the proposed practice would help address the stormwater issue occurring in the common area while lessening stormwater impact to Crabbs Branch, and benefit the remediation work on the waterway planned by M-NCPPC through the ICC Environmental Stewardship-Compensatory Mitigation (ES-CM) Project RC-74.

Rock Creek Conservancy has chosen to support this project due to its significant need and potential positive impacts on Crabbs Branch and the Derwood Station community. Further, we are interested in making this project a demonstration for other HOAs in the area.

Project context

Rock Creek Conservancy has recently embarked on a new strategic plan that will guide our work for the next five years. One of the four goals of this plan is restored and protected natural habitats with substantial gain in water quality and forest health. To this end, we have adopted an objective to use green infrastructure to manage and reduce polluted runoff. This project will help us further this goal while creating a green infrastructure demonstration site that we can use to educate other HOAs and institutional properties about stormwater management.

This project fits into our strategic plan as it supports the use of green practices to manage stormwater in a tributary of Rock Creek. Our current programs to meet this goal include Rock Creek Restoration Gardens and Backyard Habitats. Both programs seek to encourage the installation of green landscaping on residential and institutional properties, respectively. Backyard Habitats, which was partially funded by the 2014 Montgomery County Watershed Restoration grant, is in the process of completing conservation landscaping projects on four institutional properties.

This project relates to both the Maryland and Montgomery County Watershed Implementation Plans (WIPs). The Montgomery County DEP developed a Watershed Implementation Plan for Rock Creek in order to quantitatively demonstrate compliance with the County’s National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) Permit, issued by Maryland Department of the Environment for the Phase II WIP Contributions. The WIP for Rock Creek gives a good overview of the impervious and pollution diagnosis for the watershed and outlines projects that help the County meet its NPDES and MS4 requirements. The Rock Creek WIP notes that the “County MS4 Permit area comprises 69% of the total Rock Creek watershed area.” This guided our decision in selecting DEP as our primary partner, as they are responsible for managing stormwater pollution for majority of our watershed.

In Rock Creek, residential land use is the dominant land use in the watershed, covering about 65 percent of the watershed. The roofs of single family homes account for the largest percentage of impervious cover in the watershed at just over 26 percent. In the Rock Creek WIP, DEP advocates that to reduce stormwater pollution on private property, stakeholder outreach is recommended that will explain the need for watershed stakeholders to capture some of the precipitation that falls on their roofs and allow for groundwater recharge, hence slowing the flow of surface waters and potential erosion impacts.

Lastly, this project will support a Stormwater Management Pond Retrofit Project as part of the ICC Mitigation that DEP is already undertaking at Crabbs Branch adjacent to Derwood Station.

Community Context

The Derwood Station HOA has shown a commitment to the natural environment of their development. Their Environment Committee has spearheaded this project and has available a cadre of resident volunteers whom they engage in various stewardship activities in the Derwood community. They have already installed the path that is included in this project design as well as worked with Tree Montgomery program to plant shade trees that are native to the floodplain forest species in the project area as well as in other locations throughout the neighborhood.

If this project is funded, the HOA has proposed providing incentives to homeowners choosing to install downspout disconnects and rain barrels. This group will provide volunteer labor for the some of the installation and maintenance (such as invasive species monitoring and weeding) and have proposed undertaking the full maintenance of this installation beyond the two-year project period.

Demographic Information

Derwood Station is located in Derwood, Maryland in central eastern Montgomery County. The demographics for this area as reflected in the public schools are 40% Caucasian, 20% Asian, 15% African American, and 15% Hispanic with Free and Reduced Meals Rates, an indication of lower income, and ESOL rates of 15% each. Rock Creek Conservancy regularly works in neighborhoods throughout Montgomery County and Washington, DC with similar demographics. We have established stream teams, local groups that “adopt” sections of Rock Creek for stewardship activities.

Criteria

As described in the project background, a design for this conservation landscape and series of check dams was developed over a year ago based on initial consultation with and review by the Montgomery County RainScapes staff. It has not been installed due to a lack of funding, but is otherwise essentially “shovel-ready.” In preparing for this project, we walked the site with CBT and will incorporate some design modifications based on that discussion. The proposed project design, along with requested site descriptions and technical documents, are provided as attachments.

Project Evaluation

The proposed timeline includes progress reporting to the Trust at milestone intervals throughout the duration of the grant period, and builds in an evaluation component that will assess four zones of impact.

The first will be to evaluate the performance and effectiveness of the installed green practice (conservation landscape and berms), through regular monitoring and photo documentation, particularly following large rain events. Signs of soil erosion, plant and stone displacement and washouts, as well as qualitative observations of high water flow during rain events, and silt-laden water will be noted, and corrective action will be proposed and/or taken when feasible. The second, and related evaluation will be for the performance and effectiveness of the green mulches. Each area will be monitored on a quarterly basis and evaluated for its effectiveness in helping to absorb and manage stormwater flow, to quickly establish and cover the ground, and to crowd out weed species. Photo and written documentation will be recorded at regular intervals over the course of the grant period. Outcomes, including a description of the site conditions and process, will be documented and shared through a final report at completion of the grant period.

Experience

Rock Creek Conservancy has significant experience in the management of comparable large projects. We are in the midst of managing the complete restoration of a five-acre section of Rock Creek Park in Washington, DC to include invasive species removal, trash removal, and tree and shrub planting. From 2011-2014, we managed a RiverSmart Washington program. RiverSmart Washington is an environmental initiative designed to combine attractive, cost-effective landscaping with innovative streetscaping methods to help reduce stormwater pollution in Rock Creek. The program was tested in two local neighborhoods. The RiverSmart Washington program operates under a public-private sector partnership led by the District Department of the Environment, the District Department of Transportation, Rock Creek Conservancy, DC Water, LimnoTech, and Casey Trees. Rock Creek Conservancy conducted extensive neighborhood outreach to educate residents about the program and to recruit participants for eco-friendly landscaping such as conservation landscaping and permeable paving, worked with landowners to choose appropriate work to meet the project’s goals, and coordinated with contractors and property owners on all installations. We completed over 100 installations through this project.

Lastly, we are in the process of completing a Montgomery County Watershed grant for Backyard Habitats. This project is installing conservation landscaping and raingardens on four institutional properties in Montgomery County.

To increase our management strength, we will be working with a landscape designer and a landscaping company to manage the installation of this project.

Consultants

We plan to work with Darlene Robbins, the landscape designer who created the plans for this project. Ms. Robbins was formerly with John Shorb Landscaping and specializes in sustainable landscape design. She currently is self-employed and working with us on another restoration project in the Forest Hills neighborhood of Washington, DC.

We will also consult with an engineer to visit the site and review the plans to ensure that the final design specifications will effectively manage large water flows discharging from the pipe.

In addition to Ms. Robbins, we will be hiring a contractor to complete the installation work for the project. We currently have the original bid for this project from John Shorb Landscaping, but plan to seek up to two competitive bids. We will select landscaping companies with experience in green infrastructure projects and circulate the final plans and the specifications for the project.

Sustainability

As part of our agreement with the HOA, they will vote to take on the maintenance of the installation once the project period is complete. (see attachment for full maintenance plan). The HOA has been involved in this project from its inception. Rock Creek Conservancy will work with them to make them both stewards of this project as well as ambassadors for other HOAs in the region who are considering similar stormwater management projects.

Regulatory Issues

This program will not exceed regulatory requirements.

Technical information

We have no additional technical information.