Duffield Associates, Inc. 1060 South Governors Ave., Suite 101 Dover, DE 19904 Phone: 302.239-6634 Fax: 302.239-8485 duffnet.com May 6, 2020 Via Electronic Mail Mr. Rick Quill White Bucks, LLC 407 East Market Street Lewes, DE 19958 RE: Project No. 12588.EA Assessment of Water Resource Protection Area Cape Henlopen Drive Tax Parcels 335-4.20-189.0 and 190.0 Lewes, Delaware Dear Mr. Quill Duffield Associates Inc. (Duffield) has completed a review of the City of Lewes Code related to Water Resource Protection Areas (WRPAs) and its application to your property. The portion of the Lewes Code pertaining to WRPA is very important to maintain the quantity and quality of groundwater in aquifers supplying drinking water. However, it is Duffield’s opinion that the intent of the Code is not applicable to your property, and other areas between the Lewes and Rehoboth Canal, and the Delaware Bay. Site Setting The property is situated between two salt-water bodies, including the Delaware Bay and the Lewes and Rehoboth Canal (Figure 1). Published maps and literature suggest that the shallow, unconfined aquifer in this area differs in geology and hydrology from the regional, inland unconfined aquifer. Mapping by the Delaware Geological Survey (DGS)(1) indicates that the area between the Lewes and Rehoboth Canal and the Delaware Bay is unique, in that it is underlain by Dune and Spit sand deposits that are underlain by marine deposits extending beneath the Delaware Bay. Accordingly, the unconfined aquifer in this area is hydraulically connected to the marine deposits and water recharged to the subsurface likely mixes with salt-water, and eventually discharges into the Delaware Bay. Water recharged in this area does not contribute to portions of the main, inland aquifer from which the City of Lewes supply wells draw water. Summary of the Lewes Code Section 197-75 of the Lewes Code applies to WRPAs. As indicated in the first three declarations of 197-75, Part A, the intention is to protect drinking water supplies: Enhancing our community one project at a time. Mr. Rick Quill RE: Project No. 12588.EA May 6, 2020 Page 2 (1) The purpose of this article is to protect the quality and quantity of groundwater supplies. The City herein adopts the overlay maps delineating, as source water protection areas, wellhead protection and excellent groundwater recharge potential areas. To ensure the protection of these drinking water supplies, this article establishes a zoning overlay to be known as the "Source Water Protection Overlay." (2) The purpose of the Source Water Protection Overlay is to protect public health and safety by minimizing contamination of aquifers, preserving, and protecting existing and potential sources of drinking water supplies. It is the intent to accomplish this purpose through both public education and public cooperation, as well as by creating appropriate land use regulations that may be imposed in addition to those currently imposed by existing zoning districts or other state and county regulations. (3) The intent of this section is to provide clarification on the environmental constraints and requirements for development in environmentally sensitive areas and to protect public drinking water resources from contamination and pollution. Protection areas include source water resource protection areas. The Code goes on in 197-75 Part C to define source water protection areas as “wellhead protection areas and excellent water recharge potential areas. All such areas are as depicted on source water protection area maps located in City Hall as adopted as part of the update and implementation of the 2005 Comprehensive Land Use Plan. These maps are also available in GIS overlays from the Delaware Department of Natural Resources and Environmental Control, Division of Water Resources, Source Water Assessment and Protection Program. These areas shall be managed as required by this article to protect public drinking water resources from activities and substances that may harm water quality and subtract from overall water quantity.” Wellhead Protection Areas for the Lewes Supply Wells The Department of Natural Resources and Environmental Control, Source Water Assessment Plan includes designated wellhead protection areas around public wells. The wellhead protection areas are designed to protect the groundwater potentially flowing to the wells beneath these areas. The wellhead protection area for the Lewes supply wells was delineated using a computer-modelling program known as Visual MODFLOW. The Visual MODFLOW model uses existing water level data, regional stream flows, recharge estimates and hydrologic characteristics of the local geology to create a computer-generated representation of the aquifer system. Simulations of pumping from the supply wells can then be completed to estimate how water flows to the wells over time. The groundwater model for the Lewes and Rehoboth Beach supply wells is documented in a report published by the DGS and titled Report of Investigations No. 65 Wellhead Protection Area Delineations For the Lewes-Rehoboth Beach Area, Delaware(2). The model delineated a Mr. Rick Quill RE: Project No. 12588.EA May 6, 2020 Page 3 boundary around the well field in which a five-year travel time is estimated for the groundwater to reach the supply wells. The proposed wellhead area was expanded by the DGS to include a 100-meter buffer zone added to the 5-year boundary to “provide means to protect the quality of water entering the wells under the full range of expected conditions”. Exhibit 1 is a map derived from the referenced report, showing the Wellhead Protection Areas recommended by the DGS. The Wellhead Protection Area for the Lewes supply wells is located approximately 9,000 feet south, and up-gradient of the property. Exhibit 2 is another map from the referenced report showing contours of water-table elevation produced from the groundwater model. Because groundwater flows from higher to lower elevation, the direction of groundwater flow indicated by the model is towards the east, north, and south, in the direction of the Atlantic Ocean, the Delaware Bay, and Rehoboth Bay. Groundwater does not flow from the property in the direction of the supply wells. Excellent Recharge Potential Area The DGS published a map in 2003 showing groundwater recharge potential for Sussex County titled Ground-Water Recharge Potential, Sussex County, Delaware(3). Areas of recharge potential are presented on the map, ranging from “Poor” to “Excellent” based on water- transmitting properties of sediments in the interval between land surface and 20 feet below land surface. As indicated on the map, “Water-transmitting properties are a key factor in determining the amount of water that recharges Delaware’s aquifers and the susceptibility of aquifers used as sources of water supply to contamination from near-surface pollutant sources.” The recharge potential is based on the lithology and the ability of the shallow unconfined aquifer to transmit water. However, the mapping does not differentiate excellent recharge areas in coastal zones where: (1) the water table is very shallow; (2) the aquifer may be hydraulically connected to salt water bodies; and (3) the aquifer does not contribute to fresh water portions of aquifers supplying drinking water sources. The area of the property is mapped in an excellent recharge potential area because of the sandy nature of the soils beneath the property. However, the shallow aquifer beneath the area between the Lewes and Rehoboth Canal and the Delaware Bay is hydro-geologically unique in that it contains salt water and the potential ability to focus recharge into the subsurface is limited by a very shallow water table. The ground surface elevation is approximately 3 to 4 feet above sea level, and the top of the water table is likely within two to three feet of the ground surface. Confirmation of Salt Water Conditions The property is located between the Delaware Bay and the Lewes and Rehoboth Canal, and groundwater in the shallow, unconfined aquifer is hydraulically isolated from the inland portion of the aquifer, but hydraulically connected to the saline surface water bodies and marine deposits beneath the Delaware Bay. Mr. Rick Quill RE: Project No. 12588.EA May 6, 2020 Page 4 The DGS published Report of Investigation No. 13: The Occurrence of Saline Ground Water in Delaware Aquifers in 1969. As quoted directly from the report, “The data reveal a few incidents of abnormally high chlorides in known Columbia aquifers. Three such cases – New Castle, Lewes, and Rehoboth Beach have been known for some time and have been discussed by Marine and Rasmussen (1955). Lewes has alleviated its problem by drilling new wells farther inland with resulting lowering of chlorides in the older wells nearer Delaware Bay.” The referenced report also indicates that chloride concentrations in fresh water of the Eastern United States is usually less than 250 parts per million (ppm). Chloride concentrations in the older Lewes supply wells contained chloride concentrations exceeding 1,400 ppm, suggesting salt-water impact. These former wells were located on the landward side of the Lewes and Rehoboth Canal. In calibrating the groundwater model for the Lewes Wellhead Area in DGS Report No. 65, the author indicates, “Implementation of no-flow boundaries for cells in layers 2 through 4 under the Lewes and Rehoboth Canal tended to increase the head in cells near the boundary. One problem area for calibration was in this area (Fig. 19), indicating that there may be some locations along the canal where layers 1-4 are saturated with salt water”. This quote suggests that calibrating the model to reflect existing conditions indicates the presence of salt-water beneath the Lewes and Rehoboth Canal. Code Requirements for Environmental Assessment Impact Reports and Recommendations The Lewes Code requires that an Environmental Assessment Impact report be prepared if the impervious cover of a property within an excellent recharge potential area will exceed 20%.