Loading...
HomeMy WebLinkAboutWQ0019907_Hydrogeologic Review_20230426DWR Division of Water Resources State of North Carolina Department of Environmental Quality Division of Water Resources Non -Discharge Branch Hydrogeological Investigation Report Review Form WQ0019907 Onslow Water and Sewer Authority Southeast Regional Water Reclamation Facility 228 Georgetown Road Jacksonville, NC 28540 Primary Permit Reviewer: Eric Saunders Hydrogeological Investigation Report Reviewer: Leah Parente Date of review completion: 04/26/2023 1. Are the following elements included in the hydrogeological investigation report? a. Report signed and sealed by a PE, LG, or LSS no b. Cursory examination of nearby properties and wells within 500 feet no c. Field observations yes d. Maps (topographic, overview, and site detail) yes e. Published reports yes f. Sufficient number of bore holes with drilling/sampling logs in the area of system operation yes g. Sufficient number of wells with drilling/sampling logs in the area of system operation yes h. Shallow aquifer tests with detailed supporting data and appropriate analyses no Groundwater modeling results with supporting test data and reasonable assumptions yes List any missing elements, including others not mentioned above: The seal on the Soil and Hydrogeologic Site Evaluation was not signed. WQ0019907 Southeast Regional Water Reclamation Facility Page 2 of 4 2. Was a field visit conducted? Yes a. Was the physical information contained in the hydrogeological investigation report verified by the field observations? Yes. If no, List any discrepancies: 3. Aquifer parameters were determined by pumping tests. 4. Was a mounding analysis submitted? Yes 5. Was the methodology used for analysis adequate? N/A Please list areas of concern: Methodology for the Mounding Analysis and Solute Transport Analysis was not thorough explained, so it cannot be determined at this time if it is adequate (see additional information requests below) 6. Approximate depth to groundwater mound at steady state: This is not mentioned in the submitted report. This is a major area of concern due to the relatively shallow depth to groundwater present at the site. Page 3-2 (132) listed the average depth to water to be 1-6 feet at the site. 7. Site conditions to be maintained as assumed in the analysis (e.g. drainage features): No, the site will be under construction during the addition of high -rate infiltration basins, so site conditions will be changing. 8. Was a contaminate transport analysis submitted? No 4 Please provide commentary on the necessity of a contaminate transport analysis: A solute transport analysis was only submitted for Total Nitrogen. A more thorough solute transport analysis should be completed at this site due to its historical use as spray irrigation fields (see additional information request below). 9. Effluent quality used in analysis demonstrating protection of 2L standards: No information submitted 10. Are there concerns with protection of 2L standards at the Compliance Boundary? Yes List the areas of concern: Total Nitrogen, Total Phosphorus, and Ammonia WQ0019907 Southeast Regional Water Reclamation Facility Page 3 of 4 11. Are monitoring wells needed at this facility? Yes a. The number and locations of the monitoring wells should consider such factors as the size of the application area, the locations of the Compliance and Review Boundaries, and the existence of nearby water supply wells. Do the number and locations of the monitoring wells proposed in the hydrogeological report concur with the recommendations of the APS? Yes b. The recommended substances to be monitored are as follows: Pending waiting on receipt of additional information 12. The hydrogeologic report should meet the following standards described in the Aquifer Protection Section's Hydrogeologic and Reporting Policy and Groundwater Modeling Policy of May 31, 2007. Does the hydrogeologic report: a. Focus on the waste application area? Yes b. Include borings advanced to a depth of 20 feet or more? Yes c. Include enough borings in appropriate locations to create a reasonable hydrogeologic conceptualization of the waste application area? Yes d. Include a sufficient number of slug tests or pumping tests that were properly performed and analyzed for basic hydrogeologic parameters? Yes e. Utilize appropriate calculations or computer software to assess the potential for mounding beneath the application area and/or contaminant transport beyond the Compliance Boundary? No f. Use recognized assessment methods that are consistent with standard scientific practices and interpretations? Yes g. Have analyses and/or conclusions which include "safety factors" such as conservative assumptions to compensate for gaps in the field data or questionable test results? No WQ0019907 Southeast Regional Water Reclamation Facility Page 4 of 4 13. List in detail any additional information or items that are needed to evaluate the site: • The water balance did not account for actual rainfall and evapotranspiration accumulated into/out of the lagoon itself. These calculations should be redone accounting for this factor. • The nomenclature for basins in Section 2.3 appears to be incorrect for certain fields. For example, the descriptions of Basins 15 and 16 state "...aquifer matrix conditions found as Basin 14 was best defined by...". It should be clarified whether this is a typo, or if conditions for Basin 14 were used to represent conditions for Basins 15 and 16. • An explanation of the solute transport model for nitrogen was not observed in the report. An explanation should be submitted, and it should include an analysis of the Total Nitrogen entering the groundwater lowering system. • The solute transport analysis discussed in Section 4.4 was only performed for Total Nitrogen. At minimum, a solute transport analysis should also be submitted for Total Phosphorus and Ammonia. • A discussion of Figures 7A through 7C should be submitted regarding the mounding analysis results. • A topographic map showing the location of all current and proposed monitoring wells should be submitted. 14. List in detail any special conditions related to groundwater monitoring or hydrogeological issues that should be included in the permit: none at this time 15. Other areas of concern or importance: mounding is a potential limiting factor in the water balance 16. Recommendation on permit issuance based on hydrogeological investigation report: Request additional information based on above comments.