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HomeMy WebLinkAboutNC0070408_More Information Received_201808061 TABLE OF CONTENTS I. GENERAL INFORMATION II. ALTERNATIVES ANALYSIS III. PRESENT VALUE ANALYSIS IV. CONCLUSIONS AND RECOMMENDATIONS V. PRESENT VALUE COST CALCULATION VI. APPENDIX Figure 1 Area Map Exhibit 1 CWA Deeds Exhibit 2 Draft NPDES Permit Exhibit 3 Additional Information Request Exhibit 4 Local Government Review Form Exhibit 5 WWTP Site Plan Exhibit 6 CWA Master Plan Exhibit 7 Speedway Plat Exhibit 8 Vestpocket Plat Exhibit 9 Draft NPDES Discharge Limits Exhibit 10 Town of Boone Connection Exhibit 11 Watauga County Soils Map Exhibit 12 Letter from Boone Town Manager, Exhibit 13 Affidavit of Charles Clement Exhibit 14 Affidavit of Dan Godwin Exhibit 15 Curtis Weaver Email 2 I. GENERAL INFORMATION A. INTRODUCTION Clevon Woods Associates, LLC (CWA) is a private North Carolina limited liability company based out of Boone, NC that currently owns 18 acres of highly desirable commercial and residential development property fronting on NC Highway 105 (a main artery leading from Boone to Linville and beyond), located north the intersection of NC Hwy 105 and Aldridge Rd (SR 1594) and a 0.576 acre tract adjacent to Aldridge Rd on the south side of NC Hwy 105 in the Foscoe Community, Watauga County, NC. The 18 acre tract is for a proposed mixed use development and the 0.576 acre tract is to be used for a wastewater treatment plant (WWTP) installation with outfall line to the Watauga River. The Watauga River is classified as a Class B High Quality Watershed Trout Waters at the discharge point. A NPDES Discharge Permit NC0070408 was originally issued through the North Carolina Department of Environmental Quality (NC DEQ) for a capacity of 35,000 gpd for this WWTP in 1987 (the “Art Plaza WWTP”).. A location map of the property and surrounding properties is shown in the Appendix as Figure 1. The deeds for the 18 acre and 0.576 acre tracts are attached in the Appendix as Exhibit 1. The NPDES permit has been re-issued for the property every 5 years since 1987. A draft permit was issued on 9/20/17 by NC DEQ and is attached in the Appendix as Exhibit 2. A Request for Additional Information letter was issued by NC DEQ on 12/14/17 and is attached in the Appendix as Exhibit 3. In response to the letter, this Engineering Alternative Analysis (EAA) has been prepared. A Conditional Use Permit (CUP) was issued for the construction of a WWTP on the CWA 0.576 acre tract by the Watauga County Board of Adjustment on 9/25/17. A copy of the Local Government Review Form is attached in the Appendix as Exhibit 4. B. PROPOSED WWTP A previously permitted used 35,000 gpd WWTP (NC AC 0063789) was purchased for the project in 2016 and is being stored on the 0.576 acre tract. The plant is an extended aeration package plant with tertiary filters. The Authorization to Construct (ATC) application and plans will be submitted to NC DEQ after the NPDES is issued and will be installed immediately after approval. The plant is scheduled to go online in late summer or early fall of 2018. The WWTP Site Plan Sheet C3 is attached in the Appendix as Exhibit 5. C. NEED FOR PROJECT This project is essential to provide wastewater treatment not only for a proposed development, but also for two existing businesses with septic systems that have failed. Those failed systems present existing threats to the groundwater and surface waters. This project will remove those threats. The CWA property is proposed to be a mix of commercial and residential uses that will generate a high volume of wastewater. The anticipated uses and wastewater flows are shown in Section D. A copy of the CWA Master Plan boundary is attached in the Appendix as Exhibit 6. Speedway, LLC owns and operates a gas station and convenience store on a 1.245 acre tract 3 situated at the corner of NC Hwy 105 and NCSR 1151, known as Seven Devils Road). The septic system providing waste disposal for the convenience store failed in 2015 and the property has since been operating under a temporary pump & haul permit for waste disposal. There is not sufficient usable land for septic field repair or construction of an alternate drain field. Speedway has indicated its need and commitment to the proposed WWTP project by contributing $125,000.00 toward its construction, and has placed $125,000 in escrow with a Boone attorney. A gravity sewer line is designed to tie the Speedway property into the WWTP when completed and operational. The existing wastewater flow is shown in Section D. A copy of the Wilco Hess (now Speedway) boundary survey is attached in the Appendix as Exhibit 7. Vestpocket Investments, LLC (VI) has an existing 100 seat restaurant across from the WWTP site on Aldridge Rd. Its septic field has also failed and there is not enough usable land for repair. The restaurant will tie into the plant after it comes online. The existing wastewater flow is shown below. A copy of the VI boundary survey is attached in the Appendix as Exhibit 8. D. WASTEWATER FLOW PROJECTIONS Based on the existing and proposed projects in the vicinity of the WWTP, a total peak wastewater flow of 35,000 gallons per day (GPD) is ultimately projected for these properties. A breakdown of the total flow is described below. All wastewater flows have been calculated according to the NC DEQ Administrative Code Section 15A NCAC 02T .0114. Proposed Flows 1. 30 residential connections X 2 bedrooms X 120 GPD per bedroom = 7,200 GPD 2. One (1) 15,000 square foot shopping center X 100 GPD/1,000 ft² = 1,500 GPD Existing Flows 1. One (1) convenience store with four (4) water closets X 250 GPD/water closet = 1,000 gpd 2. One (1) 100 seat restaurant X 40 GPD/seat = 4,000 GPD Total Proposed and Existing Flow = 13,700 GPD Total w/ 2.5 Peak Factor = 13,700 GPD X 2.5 = 34,250 GPD Curtis Weaver, PE, Hydrologist with USGS provided, at our request, the flow characteristics for the Watauga River at the proposed discharge point. The 7Q10 is approximately 1.8 cfs. The annual 30Q2 flow ranges from about 2.9 to 4.6 cfs (average about 3.8 cfs, median about 4.0 cfs). The average annual discharge ranges from about 11.6 to 15.2 cfs (both average and median about 12.8 cfs). See email from Curtis Weaver attached as Exhibit 15. According to NC DEQ NPDES Discharge maps, there are currently five (5) wastewater discharges into the Watauga River Basin upstream of the Art Plaza discharge point: 1. Tynecastle NC0062961 30,000 gpd 2. Adams Apple Condominiums NC0042358 20,000 gpd 4 3. Smoketree Lodge NC0049174 10,000 gpd 4. Valley Creek NC0058891 10,000 gpd 5. Valley Creek Apartments NC0033448 5,000 gpd Total discharge = 75,000 gpd (existing) + 35,000 gpd (proposed) = 110,000 gpd = 0.17 cfs For High Quality Waters, 15A NCAC 2B .0224(1)(b)(v) requires that the total combined discharge of treated wastewater not exceed fifty per cent of the 7Q10 flow. As the calculations above show, the total of all wastewater discharges into the Watauga at this point would be less than ten per cent (10%) of 7Q10 flow—the lowest flow predicted for any seven day period in a ten year period—including the discharge proposed from the current project, far less than the maximum allowable. It is also worth noting that the total combined discharge would be about 1.3 per cent of the average flow in the Watauga River. E. NPDES PERMIT LIMITS The draft NPDES permit limits are attached in the Appendix as Exhibit 9. These permit limits were provided by DEQ. No difficulty meeting these limits for these discharges and this package plant would be expected. II. EVALUATION OF DISPOSAL ALTERNATIVES A. DESCRIPTION OF ALTERNATIVES This section of the report will evaluate several alternatives for the disposal of the treated wastewater. As guidance requires, the following alternatives will be evaluated: A. Connection to a publicly owned treatment works (POTW) B. Drip or spray irrigation of treated effluent on land in area C. Wastewater Reuse D. Discharge to the Watauga River E. Disposal Combination B. ALTERNATIVES ANALYSIS A. Alternative A - Connection to the Town of Boone WWTP The Town of Boone WWTP is the closest municipal system, with an existing gravity sewer line 8 miles east of the CWA property. A hypothetical sewage transmission system would consist of two (2) sewage pump station(s) and 42,000 L.F. of 4-inch force main along N.C. Highway 105. The Town of Boone WWTP has a capacity of 5.0 MGD and currently receives an average daily flow of approximately 2.4 MGD. However, this hypothetical project is not technically feasible because:  The Town of Boone will not allow it. Boone is not accepting any connections from the area in question, since it is within the Town of Seven Devils. See attached letter from Boone Town Manager, attached as Exhibit 12. 5  It is an unknown whether easements and rights of way could be obtained from NC DOT and private property owners over the eight miles of such a hypothetical project, and in fact it is believed that it would be impossible to obtain those. See Affidavit of Charles Clement, attached as Exhibit 13. The estimated total project cost for Alternative A would be $2,987,500, excluding future O&M if it were feasible. A detailed cost estimate is included at the end of this section. A plan of the hypothetical connection to the Town of Boone is attached in the Appendix as Exhibit 10. Neither Watauga County nor the Town of Seven Devils operates a central sewage treatment facility to which connection could be made. According to Mr. Joe Furman, Watauga County Planning Director, there are no current or future plans to fund any regional water and/or sewer facilities in the area. B. Alternative B - Drip or Spray Irrigation of Effluent Alternative B includes the construction of the WWTP, but instead of discharging to the Watuaga River, the treated effluent would be applied to land in the area by either drip or spray irrigation. It should be noted that land application requires that the effluent be treated to tertiary limits. A review of the Watauga County soils map and characteristics of soils in the area reveal that the CWA tract has 2 distinct soil types. The lower area adjacent to NC Hwy 105 is a Cullasaja with 8% to 15% slope and the upper areas are Chestnut-Edneyville with 15% to 30% & 30% to 50% slope range. In conversations with Mr. Steve Price, RSS, with these types of soils in the area, a best case loading rate for the treated effluent is 0.045 gpd/SF. Utilizing this loading rate, 18 acres of effective area would be required for 35,000 gpd, not including setbacks. According to State regulations, a drip irrigation system requires 50 foot setbacks, and spray irrigation systems require 150 foot setbacks from property lines. Therefore, a drip irrigation system will be less costly than a spray irrigation system. A copy of the Watauga County Soils Map is attached in the Appendix as Exhibit 11. Utilizing the 50-feet setback requirement, a drip irrigation site would need to have a total area of approximately 20 acres for 35,000 gpd. The total amount of acreage will vary depending on the shape of the tract of land, but will be more than 18 acres and approximating 20. The State regulations require a minimum of 30 day storage pond to hold the effluent during wet or freezing weather. An effluent pump station and force main will be needed to transmit the effluent to a drip irrigation site. I have reviewed both a parcels map and the Watauga County soil survey map of the area surrounding the CWA tract. Based on the descriptions of the soil types on these properties in Watauga County Soil Survey, existing creeks and existing disturbed areas, it is my professional opinion that none of these tracts are suitable for drip, spray, or sub-surface systems for a wastewater flow of 35,000 gpd. In short, this hypothetical alternative is also technically infeasible. There is inadequate land available for either a drip or spray irrigation field within any reasonable proximity of the project. Even if land were identified that could hypothetically host an adequately-sized field, no tract that size of any description is available for purchase in the vicinity. See Affidavit of Dan Godwin attached as Exhibit 14. 6 The total estimated cost for hypothetical Alternative No. 4 is $3,514,000 excluding future O&M, if it were drip irrigation. A detailed project cost estimate is provided at the end of this section. As noted earlier, spray irrigation land and facilities would be greater in cost than drip irrigation facilities. C. Alternative C – Wastewater Reuse This alternative involves all or a portion of the wastewater generated at the WWTP to minimize or eliminate the need for surface water discharge. Potential reuse options include drip or spray irrigation, industrial process cooling water, the use of reclaimed water for toilet flushing, etc. Drip/ spray irrigation systems were discussed in this report as Alternative B and eliminated as a possibility. This is not an industrial operation that could reuse cooling water, nor are there any known industries that are planning to locate a facility near the WWTP that could reuse the wastewater effluent as either a process or cooling water. It is possible that a minor amount of gray water could be reused for toilet flushing, though such an idea is of doubtful utility given the public nature of the bathrooms involved. In any event, there is nothing about this alternative that would eliminate the treatment plant or the need for an NPDES Permit to discharge into the river. Therefore, as an alternative, it is also technically infeasible. D. Alternative D - Discharge to the Watauga River Alternative D is the preferred alternative, after consideration of the other options. It consists of constructing a dual train 35,000 WWTP. The proposed WWTP will include flow equalization basin, aeration basins, clarifier units, tertiary filters, blowers, internal piping, ultraviolet disinfection, and control panels. Sludge will be treated in a digester included with the package plant to provide a Class B bio-solids. Sludge disposal will be contracted with the Town of Boone WWTP. There is adequate land on-site for the construction of the proposed facility. The estimated project cost in 2018 dollars is $656,250.00, exclusive of future O&M. A detailed project cost estimate and a proposed plant schematic are provided at the end of this section. The plant design will be based on the discharge limits in the draft NPDES Permit which is included in the Appendix. This is the only technically feasible alternative. E. Alternative No. 6 - Disposal Combination This alternative would involve combining different waste disposal methods. 1. Combining connection to municipal sewer system and any of the other options. As discussed in detail above, the municipal connection alternative is technically infeasible, so combining it with any other alternative is also technically infeasible. Even if there were some way of overcoming the technical infeasibility, its extremely high cost, added to the cost of any 7 other alternative, would make it economically infeasible. 2. Combining drip or spray irrigation with any of the other alternatives. As discussed in detail above, the drip or spray irrigation alternative is technically infeasible, so combining it with any other alternative is also technically infeasible. Even if there were some way of overcoming the technical infeasibility, its high cost, added to the cost of any other alternative, would make it economically infeasible. Conclusion: There is no combination of disposal methods that would eliminate the need for the WWTP and discharge to the Watauga. III. PRESENT VALUE ANALYSIS A. Alternative A - Connection to the Town of Boone WWTP The operation and maintenance costs associated with transmitting the flow to the Town of Boone WWTP for the 35,000 gpd are estimated to be $18,000.00 per year. Utilizing a 5% discount for 20 years, the present value of this alternative is $3,211,816.00. A detailed estimate of the O&M costs is included at the end of this section. B. Alternative B - Drip Irrigation of Effluent The operation and maintenance costs associated with the drip irrigation system alternative are estimated to be $57,000.00 per year for the 35,000 gpd flow. Utilizing a 5% discount rate for 20 years, the present value of is estimated to be $4,224,334.00. A detailed estimate of the O&M costs is included at the end of this section. C. Alternative C – Sub-Surface Drip Irrigation of Effluent The operation and maintenance costs associated with the sub-surface drip irrigation system alternative are estimated to be $57,000.00 per year for the 35,000 gpd flow. Utilizing a 5% discount rate for 20 years, the present value of is estimated to be $4,724,334.00. A detailed estimate of the O&M costs is included at the end of this section. D. Alternative D - Discharge to the Watauga River The operation and maintenance costs associated with the 35,000 gpd WWTP are $40,000.00 per year. Therefore, the present value utilizing a discount rate of 5% for a 20-year time period is $1,123,730.00. A detailed estimate of the O&M costs are provided at the end of this section. Summary. The table below summarizes the present values of the treatment and disposal alternatives. 8 Alternative Description Present Value A Connect to Town of Boone $ 3,211,816.00 B Drip Irrigation $ 4,224,334.00 C Sub-Surface Drip Irrigation $ 4,724,334.00 D Construct WWTP $ 1,123,730.00 IV. CONCLUSIONS AND RECOMMENDATIONS Based on the detailed alternatives and present value analysis for treatment and disposal of the 35,000 gpd of wastewater for the CWA tract and existing flows, construction of the proposed WWTP with a discharge into the Watauga River is the only technically feasible and the only economically feasible alternative. It is recommended that the Permit be issued for this alternative. To date, funds in excess of $200,000.00 have been expended on the land, permitting, planning, engineering, surveying, environmental studies, legal agreements, and the used WWTP components for the 35,000 gpd WWTP construction and another $125,000.00 is being held in escrow (Speedway’s contribution). Without an adequate method of wastewater disposal, the two neighboring failed septic systems cannot be addressed and the CWA tract cannot be developed to its highest and best use, resulting in both the threat of raw sewage breakouts and a significant loss of economic growth and jobs in the community. To allow for this growth, it is in the best interest of the community and CWA to provide a method of wastewater disposal with the proposed WWTP. V. PRESENT VALUE COST CALCULATIONS Alternative A Connection to Town of Boone Estimate of Hypothetical Probable Cost Operation & Maintenance Cost Estimate Item Estimated Annual Cost Operation & Maintenance $12,000 Laboratory - 1. Sewage Pump Station – 2 @ $250,000 $500,000 2. 42,000 lft of 4” Forcemain 1,680,000 3. Easement Acquisition 210,000 Construction Cost Subtotal $2,390,000 10% Construction Contingency 239,000 Engineering 239,000 Construction Administration 119,500 Total Project Cost $2,987,500 9 Sludge Disposal - Electricity 5000 Miscellaneous 1,000 Total $18,000 Present Value 20 year present value at 5% $2,987,500 + $18,000 (P/A=12.462) = $3,211,816 Alternative B Drip Field Construction Estimate of Probable Cost Operation & Maintenance Cost Estimate Item Estimated Annual Cost WWTP & Drip Field Operation & Maintenance (Contract) $36,000 Laboratory 2,000 Sludge Disposal 2,000 Electricity 15,000 Miscellaneous 2,000 Total $57,000 Present Value 20 year present value at 5% 1. 35,000 GPD Package Plant, Installed $350,000 2. 1.05 million gal Holding Pond 500,000 3. Effluent Pump Station 150,000 4. 5,280 lft of 4” Forcemain 211,200 5. Drip Irrigation System 800,000 6. Land Acquisition 800,000 Construction Cost Subtotal $2,811,200 10% Construction Contingency 281,120 Engineering 281,120 Construction Administration 140,560 Total Project Cost $3,514,000 10 $3,514,000 + $57,000 (P/A=12.462) = $4,224,334 Alternative C Sub-Surface Drip Field Construction Estimate of Probable Cost Operation & Maintenance Cost Estimate Item Estimated Annual Cost WWTP & Sub-Surface Drip Field Operation & Maintenance (Contract) $36,000 Laboratory 2,000 Sludge Disposal 2,000 Electricity 15,000 Miscellaneous 2,000 Total $57,000 Present Value 20 year present value at 5% $4,014,000 + $57,000 (P/A=12.462) = $ 4,724,334 1. 35,000 GPD Package Plant, Installed $350,000 2. 1.05 million gal Holding Pond 500,000 3. Effluent Pump Station 150,000 4. 5,280 lft of 4” Forcemain 211,200 5. Sub Subrface Drip Irrigation System 1,200,000 6. Land Acquisition 800,000 Construction Cost Subtotal $3,211,200 10% Construction Contingency 321,120 Engineering 321,120 Construction Administration 160,560 Total Project Cost $4,014,000 11 Alternative D WWTP Construction Estimate of Probable Cost Operation & Maintenance Cost Estimate Item Estimated Annual Cost WWTP Operation & Maintenance (Contract) $24,000 Laboratory 2,000 Sludge Disposal 2,000 Electricity 10,000 Miscellaneous 2,000 Total $40,000 Present Value 20 year present value at 5% $625,250.00 + $40,000 (P/A=12.462) = $1,123,730 1. 35,000 GPD Package Plant, Installed* $350,000 2. Foundation & Sitework 100,000 3. Emergency Generator & Electrical 75,000 Construction Cost Subtotal $525,000 10% Construction Contingency 52,500 Engineering 52,500 Construction Administration 26,250 Total Project Cost $656,250 *35,000 GPD Package Plant Cost Breakdown Purchase from Aqua NC $30,000 Breakdown & Transportation 30,000 Tank Repairs & Anti Buoyancy Plates 20,000 New UV Unit & Tank 80,000 New and/or Internal Piping 30,000 New and/or Rehab Pumps & Blowers 50,000 Generator w/ ATS 50,000 Electrical 50,000 Effluent Gravity Line 10,000 Total Cost $350,000 12 APPENDIX 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 Exhibit 15 Curtis Weaver Email Mr. Warren, In response to your inquiry about the low-flow characteristics (7Q10, 30Q2, average annual discharge) for a location on the Watauga River near Foscoe in southwestern Watauga County, the following information is provided: A check of the low-flow files here at the USGS South Atlantic Water Science Center (Raleigh office) indicates a previous low-flow determination for the point of interest, identified by the lat/long coordinates (36 08 47 N // 81 47 30 W) provided via map image attached to your email dated June 12, 2018. Estimated in June 1987, the low-flow characteristics were determined for Watauga River near Foscoe (station id 0347871902, drainage area 6.1 sqmi), based on transfer of flow characteristics from a downstream continuous-record streamgage on the Watauga River near Sugar Grove (station id 03479000, drainage area 92.1 sqmi). No USGS discharge records are known to exist for the point of interest. In the absence of site-specific discharge records sufficient for a low-flow analysis, estimates of low-flow characteristics at ungaged locations are determined by assessing a range in the low-flow yields (expressed as flow per square mile drainage area, of cfsm) at nearby sites where such estimates have previously been determined. A basin delineation completed using the online USGS StreamStats application for North Carolina (http://water.usgs.gov/osw/streamstats/north_carolina.html) indicates the drainage area for the point of interest (36.14625, -81.79125 NAD83) is 6.09 sqmi. For streams in Watauga County, low-flow characteristics published by the USGS are provided in the following reports: (1) The first is a statewide report completed in the early 1990's. It is USGS Water-Supply Paper 2403, "Low-flow characteristics of streams in North Carolina" (Giese and Mason, 1993). An online version of the report is available at http://pubs.usgs.gov/wsp/2403/report.pdf. The report provides the low-flow characteristics (based on data through 1988) via regional relations and at-site values for sites with drainage basins between 1 and 400 sqmi and not considered or known to be affected by regulation and/or diversions. (2) The second is a statewide report published in March 2015. It is USGS Scientific Investigations Report 2015-5001, "Low-flow characteristics and flow-duration statistics for selected USGS continuous-record streamgaging stations in North Carolina through 2012" (Weaver, 2015). The report is available online at http://pubs.usgs.gov/sir/2015/5001/. The report provides updated low-flow characteristics and flow-duration statistics for 266 active (as of 2012 water year) and 48 discontinued streamgages across the state where a minimum of 10 climatic years discharge records were available for flow analyses. Inspection of the above reports indicates the presence of eight (8) nearby selected USGS partial-record sites (5) and continuous-record streamgages (3) in general vicinity of the point of interest where low-flow characteristics were published. Among these 8 sites, the low-flow discharge yields for the indicated flow statistics are as follows: Annual 7Q10 low-flow yields ==> from 0.20 to 0.40 cfsm (average at 0.29 cfsm, median about 0.3 cfsm) Annual 30Q2 low-flow yields ==> from 0.47 to 0.75 cfsm (average at 0.62 cfsm, median at 0.65 cfsm) Average annual discharge yields ==> from 1.9 to 2.5 cfsm (both average and median about 2.1 cfsm) Application of the above range in yields to the drainage area (6.09 sqmi) for the point of interest results in the following estimated low-flow discharges: Annual 7Q10 discharges ==> from about 1.2 to 2.4 cfs (both average and median about 1.8 cfs) Annual 30Q2 discharges ==> from about 2.9 to 4.6 cfs (average about 3.8 cfs, median about 4.0 cfs) Average annual discharge ==> from about 11.6 to 15.2 cfs (both average and median about 12.8 cfs) Please note the estimated flows are provided in units of cubic feet per second (cfs). Please understand the information provided in this message is based on a preliminary assessment and considered provisional, subject to revision pending further analyses. Hope this information is helpful. Thank you. Curtis Weaver 49