A number of contractors have refused to deposit the silt in our common areas for a number of reasons. I would question if the hiring of the single vendor who is willing to deposit the silt, when all others have flatly refused to do so, is the most qualified vendor to do the work. No Reply
Are the Corp of Engineers, Department of Natural resources and the Environmental Protection Agency aware of the fact that these valuable wetlands will be replaced by a parking lot? Reply - Gwinnett County is a Local Issuing Authority (LIA), and, as such, performs erosion control reviews in lieu of the Georgia DNR or EPD. For a municipality to become a LIA, they must adopt and enforce erosion and sedimentation control regulations at least as stringent as the EPD’s. Plans, a request for jurisdictional waters determination (JWD), and a pre-construction notification (PCN) for Nationwide Permit (NWP) 3a – Maitenance and NWP 18 – Minor Discharge have been submitted to the U.S. Army Corps of Engineers (USACE) for their review and approval. Authorization of the NWP application is pending.
Gwinnett County has regulations regarding construction adjacent to a state water (like Allen Lake and the creek that originates downstream of its outlet pipe). There exists a 50' undisturbed buffer measured from the top of bank from the creek and lake that may not be encroached upon without approval of a stream buffer variance. There are also exists a 75' impervious setback measured from the top of bank of the creek and lake edge that may not be encroached within by any paved (impervious) surface. Does the proposed location of the parking lot have the proper setbacks to meet this criteria? Reply - Gwinnett County buffers mentioned do not apply to Rivermoore Park since this phase was platted prior to March 22, 2005. Per the Gwinnett County Stream Protection Ordinance (see Section 3.1.4), previous land disturbance projects that were not yet approved, but part of a larger master development, are grandfathered with their approved stream buffers. In this case, a twenty-five foot buffer is required, which falls under the purview of the EPD. However, the parking lot has been designed with pervious construction techniques at a distance of 76 feet from the top of the stream bank, at its closest point.
Has a cultural resources survey been performed to evaluate the impacts of the parking lot? What were the findings? What mitigation is proposed? Reply - A Phase I Cultural Resources Survey is not required as a component of the NWP 3a application as this specific NWP contemplates maintenance, replacement, etc., of a previously authorized activity. However, for the NWP 18 portion of the application, a review of the National Park Service National Register of Historic Places (NRHP) online files for Gwinnett County, Georgia, were reviewed to identify the presence of historic properties within close proximity (<0.25 mile) of the project site. No historic properties were located within a one-mile radius of the project. Regarding compensatory mitigation, none is required for this NWP application. Specifically, compensatory mitigation is required for impacts to waters of the U.S. (e.g., wetlands and streams) in excess of 0.1 acre and 100 linear feet, respectively (see Savannah District 2007 NWP Regional Conditions, RC D.1&2). Proposed impacts to wetlands for construction of the pervious parking field is approximately 0.03 acre.
Has a Finding of No Significant Impact (FONSI) been granted by the authorities having jurisdiction? What were the findings? Reply – A FONSI is not applicable to this specific Section 404 permit application. A FONSI is a National Environmental Policy Act (NEPA) document concluding that federal actions evaluated in an Environmental Assessment (EA) will not significantly affect the quality of the environment.
Has a geotechnical engineering boring study been performed to evaluate the subsurface conditions of the soil upon which the parking lot is to be built? What were the findings? Reply - No geotechnical borings have been provided in the proposed parking area. Due to the nature of the fill to be placed in the area, consolidation and settlement are expected. The parking lot is to be constructed of gravel base and pavers, which would allow for easier repair as settlement occurs.
Has a maintenance plan and agreement been accepted for all authorities having jurisdiction for maintenance of the post-construction storm water system? Reply - The intent of the proposed project is maintenance of the existing lake. Deposited sediment would be removed along with the rusted outlet control structure. A siphon system would replace the failing outlet, and the earthen spillway would remain. No specific post-construction maintenance agreement has been required by all authorities having jurisdiction due to the maintenance nature of the proposed activities.
Has a National Pollutant Discharge Elimination System (NPDES) permit coverage been obtained from the Georgia DNREPD? Has NPDES permit coverage been obtained from the US EPA? Reply - The project does not meet the requirements for coverage under the NPDES Permit No. GAR 100001. Specifically, Section I(C)1) states that only projects that exceed one acre of land disturbance require coverage under the permit. Land disturbance associated with this project is less than one acre.
Has a Notice of Intent (NOI) been filed with the Georgia Department of Natural Resources? Reply - Since the amount of land disturbance is less than one acre, no NOI is required for the project (see NPDES Permit No. GAR 100001, Section I(C)1).
Has a Storm water Management Plan been prepared by a registered architect or engineer and approved by all authorities having jurisdiction (AHJ)? Reply - A stormwater management report has been prepared and approved for the proposed maintenance activities, including the work downstream of the dam. This study was reviewed and approved by Gwinnett County Planning and Development prior to land disturbance permit issuance.
What mitigation is proposed for the increased impervious area? Reply - The only new impervious area is associated with the entrance to the proposed parking area. The parking spaces and drive aisles would be pervious paver construction. Due to the minimal increase in impervious areas and maintenance work proposed, calculated post-development flow rates did not exceed the current condition.
How will the post construction rate of runoff be maintained to pre-development levels? What type of system is proposed? Has this system obtained approval by all AHJs? Reply - The post-development runoff rates would be limited to current levels by the installation of the proposed siphon system, instead of the existing standpipe. The proposed configuration has been approved by Gwinnett County Planning and Development.
Has a Traffic Impact Study (TIS) been performed by a qualified professional to evaluate traffic impacts and sight distance lines? What were the findings? Reply - No Traffic Impact Study has been performed for the proposed lake maintenance or parking area addition. The parking area and lake are to be utilized by Rivermoore Park residents only, and, therefore, should not produce additional traffic in the community. Sight distance has been verified and was found to be adequate per Gwinnett County standards.
Has an endangered species survey been performed to evaluate the impacts of the parking lot? What were the findings? What mitigation is proposed? Reply – Yes, as part of the NWP application, a review of the Fish & Wildlife Service (USFWS) and Georgia Department of Natural Resources, Natural Heritage Program (NHP) internet databases revealed several protected species that potentially occur in Gwinnett County, Georgia. An in-house review of the web-based protected species information was performed prior to field evaluation of the property. Habitat suitable for sustaining listed protected species was not observed on, or in close proximity, to the project site. Consequently, the proposed parking field installation will not adversely affect federally listed species potentially located in Gwinnett County, Georgia.
Has an Erosion and Sedimentation Control and Pollution Prevention Plan been prepared and sealed by a Level II Certified Design Professional and approved by all authorities having jurisdiction? Reply - Yes, this was required for Gwinnett County Planning and Development plan approval.
Has the Corp of Engineers, the State and Federal Environmental Protection Agency given final approval for the dredging and dumping of possible pollutants in a residential neighborhood? Reply – USACE approval for the Nation Wide Permit (NWP) application is pending. The NWP application would authorize proposed maintenance activities to the storm water detention facility (NWP 3a) and installation of the pervious parking field (NWP 18). Section 404 of the Clean Water Act (CWA) refers to "discharges" but does not refer to the regulation of excavation or dredging materials. In this instance, the USACE does not have regulatory purview over dredging and disposal activities, and nor does the USEPA (see Tulloch Rule).
Has the proposed construction area had a wetlands survey performed by a qualified wetland scientist? Reply - Yes, waters of the U.S. (e.g., wetlands and streams) were field delineated by Gaia Environmental Consulting on August 6, 2011, following guidance provided by the USACE in their 1987 Wetlands Delineation Manual and their 2010 Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Eastern Mountains and Piedmont Region. Waters of the U.S. were demarcated in the field with black/pink surveyor’s flagging.
Has the Rivermoore board of directors complied with all aspects of the Federal migratory waterfowl act? Reply - The Migratory Bird Treat Act (MBTA) and the Executive Order on the Responsibility of Federal Agencies to Protect Migratory Birds (EO 13186) requires the protection of migratory birds and their habitats. The MBTA and EO 13186 are applicable to federally funded activities. The proposed maintenance project is privately funded. What is more, habitat suitable for sustaining migratory birds is limited at best, on and near the project site.
Have a post-construction storm water system been designed to treat all Pollutants of Concern (POC)? What were the findings? Reply - Pollutants of Concern and specific treatment methods for them are associated with individual NPDES discharge permits. The scope of the proposed maintenance activities do not meet criteria for an individual NPDES permit.
Have all Gwinnett County land disturbance permits been obtained? Reply - Yes.
Have all of the hydraulic grade lines been evaluated and found to be below the surface for the 100-year storm event? What were the findings? Reply - The culverts have been evaluated at the downstream road crossing. The postdevelopment 100-year hydraulic grade line was found to be beneath the road surface.
Have all permits, State, Federal and local been received? Reply - A permit has been issued by Gwinnett County Planning and Development. Permit approval from the USACE is pending. These are the required permits for the maintenance project.
Have all requests for additional information (RAI) from all AHJs been properly dispositioned? What mitigation is proposed? Reply - Yes, when jurisdictions have requested additional information, it was provided.
Have engineered site plans been prepared and sealed by a registered architect or engineer and approved by all authorities having jurisdiction (AHJ)? Reply - Yes, this was required for Gwinnett County Planning and Development approval.
Have you received a section 404 permit from the core of engineers to fill in the area that will be the parking lot? Reply - The proposed fill below the dam will be covered under the USACE’s NWP 18; the permit application is under review by the USACE.
Is the construction certified to be in compliance with Section 404 of the Clean Water Act? Authorization for proposed activities in waters of the U.S. is pending approval by the USACE.
Silt from the bottom of a lake is a very unstable soil that is unsuitable for construction of permanent structures. Construction of a parking lot on top of dredged silt will result in a very short lifespan of a parking lot and will require excessive funds to maintain the parking lot due to the differential settlement that will occur. Dredging from a lake requires a Section 404 permit from the U.S. Army Corps of Engineers since the incidental spill of dredge material back into the lake during the dredging operation is inevitable. Has the Section 404 permit been obtained? When does the public notice period expire? Reply - Section 404 of the CWA refers to "discharges" but does not refer to the regulation of excavation or dredging materials. In this instance, the USACE does not have regulatory purview over dredging and disposal activities, and nor does the USEPA (see Tulloch Rule).
Since the county refuses to permit a paved parking lot on top of the deposited silt that to use pavers is an ill advised attempt to circumvent the county. The installation of a paver parking lot is not an acceptable alternative and will result in our community having to spend additional money when those conditions mandating the paved parking lot be denied, by the county, come to fruition. Reply - A paved parking lot was never proposed to Gwinnett County. The paver surface is proposed since settlement is expected in the area. Pavers would be less costly to maintain than an asphalt parking lot in this situation.
The area downstream of the lake is within a Dam Breach Zone. This is an area that would have rapid and catastrophic inundation during the event of the dam unexpectedly breaching. Has the dam been evaluated by a geotechnical engineer for dam stability and found to be stable? Has a Dam Break Analysis been performed to understand the limits and depth of inundation? Loss of Life (LOL) may occur during a dam breach event for people in a parking lot during the dam breach event. This is a great liability for the HOA. Reply - No geotechnical testing has been performed on the dam. The dam seems to be stable per visual inspections, and has no record of stability problems. No dam break analysis has been performed on the impoundment. The parking area would be above outflow from the lake, since it has been designed higher than the road crossing.
It’s not good to build anything on a weak foundation. Building a parking lot on silt is wrong and would create maintenance costs and risks. Reply - The dredged material from the lake would be allowed to consolidate for a period of time prior to the installation of the parking surface. As consolidation occurs, the strength of the fill area would improve.
Most of the area downstream of the lake on the east side is within an area of inundation during the event of the emergency spillway cresting. This could potentially cause cars to flood which would create liability for the Association. Reply - The elevations of the proposed parking area are above the downstream road crossing. Highwater elevations have been evaluated in the area and were calculated lower than the road surface.
Have mitigation fees been paid for destruction of a wetland? Reply - Per the US Army Corps of Engineers, mitigation is not required for wetland impacts of less than 0.1 acre. The amount of impacts associated with fill placement beneath the dam is approximately 0.03 acres.
Have wetland permits been obtained from the US Army Corps of Engineers for destruction of a wetland? Reply - The proposed fill below the dam will be covered under the USACE’s NWP 18; the permit application is under review by the USACE.
Has the Department of Natural Resources approved the destruction of valuable wetlands that are a natural habitat for Federally protected migratory birds namely the Canadian geese and other protected species that nest and raise their young in these lakes and wetlands? Reply - The GA DNR does not have regulatory purview over this activity. The wetland area that would be impacted is actually a maintained grassed field. Following completion of the proposed work, the result will be a small parking lot and a maintained grassed area.
Will mitigation of impacts be performed onsite or at an offsite mitigation bank? Reply - Per the US Army Corps of Engineers, mitigation is not required for wetland impacts of less than 0.1 acre. The amount of impacts associated with fill placement beneath the dam is approximately 0.03 acres.
