In an effort to rehabilitate Virginia tidal water bodies, the Chesapeake Bay Foundation (CBF) received a permit from the Virginia Marine Resources Commission (VMRC) to build artificial oyster reefs as part of restoration work in the Lynnhaven Watershed, including in front of the Brock Environmental Center.
Originally, the reefs were built by placing oyster shells in designated areas. However, in some areas much of the shells sank into the soft tidal mud resulting in considerable loss of the valuable donated shells. To address this, CBF received a permit amendment allowing them to use crushed concrete as a base material, having a similar chemical composition to oyster shells, and then placing oyster shells on top. An independent non-profit organization constructed the reefs.
Later, some citizens raised concerns after noticing unauthorized or deleterious materials like steel, asphalt, and glass mixed in with the crushed concrete. The concern focused primarily on asphalt, which can leach harmful polycyclic aromatic hydrocarbons (PAHs) into the water. Rather than recovering the unauthorized materials, the VMRC ordered the removal of some reefs, even though removal could harm the developing aquatic habitat by disturbing the sediment and resident marine life.
Some of the artificial reefs were removed. However, the last reefs under scrutiny were those in front of the Brock Center, which were considered a showcase reef.
At that point, MSA was brought in to assess the situation. MSA:
- Surveyed the reefs
- Conducted a site investigation at low tide.
- Used an underwater scope to search for deleterious materials.
- Found very limited unauthorized materials.
- Recovered some asphalt samples and had them tested for PAHs.
- Collected young oysters growing on asphalt pieces and native oysters and tested for
- PAHs.
- Conducted a controlled study using river water and recovered asphalt placed in an
- isolated tank submerged in the creek and then testing after 1 week, 1 month, and 3
- months.
- Tested surface water above the reefs and from creeks near heavily developed, paved
- areas.
The results showed:
- Only trace levels of PAHs in the collected asphalt samples.
- No measurable PAHs released into the water during the controlled study.
- No measurable PAHs in oyster tissue from artificial reef or native oysters.
- Those results demonstrated that most of the harmful material had already leached out,
- posing no remaining environmental threat.
- The only detected PAH in Lynnhaven watershed surface water was discovered in creek
- water near paved developed areas; none around the artificial reefs in question.
- Healthy marine life such as minnows, baby crabs, periwinkles, oyster spat and juvenile
- oysters was found inhabiting the reefs — indicating that a vibrant habitat had formed.
MSA compiled these findings into a report for CBF who submitted it to the VMRC, showing:
- Minimal unauthorized material was present.
- No environmental harm was currently occurring.
- Removing the reefs would likely cause more harm than good.
The VMRC agreed, and the reefs were saved.
They remain in place today in front of the Brock Center, continuing to support the local ecosystem.
Tags: environmental, watershed