RPA Mitigation
Not familiar with the term RPA? An RPA, or Resource Protection Area, is an area designated for conservation by the Chesapeake Bay Protection Act. Enacted in 1988, this law regulates activity on land that is within 100’ of shorelines, wetlands, and perennial streams in Virginia. Though there are plenty of examples of pre-1988 construction that are now within these protected areas, new construction in RPAs is no longer allowed. If you happen to own one of those pre-1988 houses perched right above of some tidal creek, consider yourself lucky!
Having said that, there are exceptions to the ‘no construction’ rule. Things like clearing vegetation for vistas, installation of fences, and construction of access paths to water are often permitted—pending official review and approval of course. Occasionally even larger encroachments into RPAs are allowed, depending on the special conditions of individual lots. Your local municipality will make that call on that on a case by case basis, and you need to make a very strong case to be granted a construction permit.
At Hertzler & George, we’ve dealt with the regulations of the Bay Act on many projects. As an example of what can be done, let’s take a look at a patio we built in the Kingspoint neighborhood of Williamsburg.
For this property, H&G had already worked to address drainage problems in the front yard (read more about that here), but the client also hoped to get more use out of their back yard, which overlooked a beautiful wooded ravine. To give them more space for entertaining and relaxing, we designed a new patio right off their existing back deck.
Because Hertzler & George cares about the environment, building in an RPA is not something we take lightly. But for this property, we felt there were some good reasons why the patio might be built:
- The existing back yard was sloped and unusable for any kind of recreational activity. Creating a flat patio would allow the owners to enjoy their yard
- This particular lot had a higher percentage of RPA area within the lot compared to most houses in the neighborhood
- The patio and adjacent walkway provided a paved walking surface from the back to the front of the house, where there previously was none
- The patio was kept at a reasonable size
For projects like this, the proper way to proceed is to first fill out the necessary paperwork. In James City County, we contacted the Division of Engineering and Resource Protection. The first step was to fill out the county’s Sensitive Area Activity Application. After H&G’s application had been reviewed and commented on, it was determined that the project would need to be referred to the county’s Chesapeake Bay Board for final approval. At the CBB meeting we presented our plan to the board members and made our case as to why the new patio should be allowed. The Engineering division also weighed in with their recommendation to approve the plan.
To support our case for building within the RPA, we incorporated several mitigation measures into our design. The purpose of the mitigation was to ensure that the storm runoff created by the patio would be equal in quality to the runoff that would be generated in a natural environment (which naturally cleanses stormwater runoff).
Our main solution involved constructing a gravel infiltration trench to filter rain runoff from the patio as well as from parts of the existing roof. To determine the size of the trench, we completed calculations based on typical rainfall and infiltration rates. And to ensure our methods would work, we had the clay soil analyzed to test the percolation rate. Luckily, the results were positive.
The infiltration trench was constructed with pea gravel, sand and drainage stone, as well as perforated pvc pipes. When runoff reaches the trench, it fills the pipes and the voids between the stone and slowly seeps into the ground where it recharges the water table. To keep leaves from clogging up the new trench, we installed leaf guards on the gutter downspouts.
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