City of Medora, ND Wastewater Infrastructure Needs Assessment November 2012

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1 City of Medora, ND Wastewater Infrastructure Needs Assessment November 2012 Project made possible by US Dept. of HUD Regional Substantiality Planning Grant and ND Energy Development Infrastructure and Impact Grant Fund programs

2 Summary of Needs Assessment The City of Medora is the only incorporated city in Billings County, North Dakota. The City is experiencing a population increase due to energy development activities and tourism. Although the current population is estimated at 116, the City swells to approximately 2,000 people due to temporary seasonal population, campers, and tourists. In addition to the City s unique tourist population fluctuation, the City is also experiencing increased population demands from surrounding energy development activities. In July 2012, Billings County had approximately 481 producing oil wells and was the eighth top producing county out of the 17 western area oil producing counties as reported by the ND Department of Mineral Resources. While the City is growing, one of its key barriers to growth is the location and size of its wastewater lagoons. This wastewater treatment infrastructure needs assessment is intended as a high-level analysis and concept planning effort focused on key short-term wastewater treatment infrastructure needs recommended to accommodate the anticipated growth and development. Table 1 summarizes the wastewater treatment infrastructure needs assessment, proposed improvements, and opinion of costs included within this report. DESCRIPTION TABLE 1 SUMMARY OF INFRASTRUCTURE IMPROVEMENTS AND COST OPINION COST OPINION Wastewater Treatment Improvements $ million to million Introduction The Vision West ND initiative was commenced in February 2012 to provide planning and technical assistance to a rapidly expanding 19-county area in western North Dakota. The primary goals of the Vision West ND project are to assist communities and counties in the western region of North Dakota to address near-term needs to meet growth management challenges and establish a diversified economy in the future through the development of local and regional strategic plans. Rapid population growth is exerting significant pressure on existing municipal water, sewer, and street systems, and in some cases, infrastructure expansion is necessary to support current and anticipated growth. Participating communities will receive a high-level infrastructure assessment to identify needs and prioritize infrastructure improvements, with opinions of probable costs by a professional engineering team. Advanced Engineering and Environmental Services (AE2S) has provided technical expertise regarding municipal infrastructure for the Vision West ND initiative. AE2S has contributed this assessment to the City and Vision West ND. As wastewater treatment is the primary infrastructure limitation within the City, this assessment is solely on wastewater treatment. City of Medora Infrastructure Needs Assessment 2

3 This report includes a brief wastewater treatment inventory, needs assessment, and opinion of probable costs for improvements for the City of Medora, North Dakota. The information used to prepare this assessment was compiled by AE2S from information provided by City officials and the City of Medora Wastewater Treatment Facility Plan which is expected to be finalized in January COMMUNITY OVERVIEW The City of Medora (City) is located 35 miles west of the City of Dickinson on Interstate 94, approximately 30 miles from the Montana border. Billings County was organized in 1886 and initially included what is now Golden Valley and Slope Counties. The population peak in Billings County was in 1910 with a population of 10,186. Golden Valley County was established in 1912 and Slope County in The City s population has remained at approximately 100 people for the past 60 years. The City is home to several historical points of interest and has developed as a premiere North Dakota Medora City of Medora Infrastructure Needs Assessment 3

4 tourist destination. The renowned Medora Musical is a nightly seasonal event presented in the Burning Hills Amphitheater by the Theodore Roosevelt Medora Foundation. The Medora Musical completed its 47 th season in The entrance to the South Unit of the Theodore Roosevelt National Park is just outside the City. The City is home to five sites placed on the National Register of Historic Places. Much of the City is designated as a Historic Integrity District. CURRENT AND PLANNED DEVELOPMENT Energy development impacts, coupled with a continued focus on increasing tourism have prompted, the City to plan for supporting a summer population of 3,200 and a winter population of 1,800 (combined permanent and temporary/visitor population). The current population increase is causing significant strain on existing infrastructure; most urgent of which is the wastewater treatment infrastructure. WASTEWATER TREATMENT SYSTEM ASSESSMENT AND IMPROVEMENT RECOMMENDATIONS Existing System Description The City s wastewater treatment system is a facultative lagoon treatment system with two separate lagoon systems. Each system consists of two lagoons, for a total of four lagoons for the City. Piping connects the two systems, which are approximately one-half mile from each other on the east end of town. The City holds a North Dakota Pollution Discharge Elimination System permit issued by the North Dakota Department of Health (NDDH). The permit allows treated effluent to be discharged intermittently (generally spring and fall) to the Little Missouri River through the permitted outfall. System Loading Due to the unique population dynamics of the City, the design uses a different hydraulic loading rate in gallons per capita per day (gpcd) for each type of population, as presented in Table 2. Based on the average domestic wastewater flows and expected fluctuating population, the average domestic wastewater flows generated are estimated at 132,000 gpd (92 gpm). The future peak hour factor is assumed at 3.42 resulting in an estimated peak hour flow of 313 gpm. TABLE 2 WASTEWATER FLOW QUANTITIES POPULATION TYPE FLOW VALUE (GPCD) Permanent Resident 100 Hotel 50 Campsite 20 Tourist 20 City of Medora Infrastructure Needs Assessment 4

5 Treatment System Existing Conditions and Deficiencies The wastewater treatment system is comprised of two individual lagoon systems, with separate primary and secondary lagoons in each system. Lagoons 1 and 2 are located to the east of the City and Lagoons 3 and 4 are located near the center of the City. A pipeline interconnects the two systems, and connects to the City wastewater collection system. This connection can occasionally cause problems for the City when wastewater is transferred between systems while wastewater flows from the City are entering the system. The first lagoon system includes Lagoons 1 and 2. Lagoon 2 serves as the smaller primary lagoon and Lagoon 1 serves as the secondary lagoon. The second lagoon system includes Lagoons 3 and 4. Lagoon 3 serves as the primary lagoon and Lagoon 4 serves as the secondary lagoon. The combined area of all of the lagoons is 13 acres, with 12 million gallons of storage. The surface area in acres, and corresponding available storage (in million gallons) is shown in Table 3. The existing lagoons are designed to have a maximum water depth of five feet and a minimum two feet of water must be maintained in the pond at all times, as the bottom two feet of pond area is typically reserved for sludge and solids accumulation. The North Dakota Department of Health (NDDH) requires two to three feet of freeboard from the top of the berm to the high water level. The design criteria for treatment systems in North Dakota are based on the primary lagoon five day biological oxygen demand (BOD) loading rate, the total system BOD loading rate, and a minimum requirement of 180-days of storage volume. All three criteria should be met for successful wastewater treatment. The wastewater treatment system needs to treat and store an expected average day flow of 132,000 gallons, and an expected BOD load of 0.18 lbs per capita per day. There are several issues with the current system. The pipeline interconnect between the systems has several issues when wastewater is being transferred between systems while wastewater flows from the City are entering the system. Raw waste is combining with treated or partially treated water. The TABLE 3 WASTEWATER FLOW VALUES STORAGE (MILLION GALLONS) TREATMENT TYPE AREA (ACRES) Lagoon 1 Secondary Lagoon 2 Primary Lagoon 3 Primary Lagoon 4 Secondary Totals City of Medora Infrastructure Needs Assessment 5

6 existing lagoons reportedly struggled to meet the treatment demands experienced in 2012, and will not meet the projected needs of the anticipated population. Figure 1 includes an illustration of the existing wastewater system capacity, projected flows, and proposed capacity. The existing lagoons cannot be expanded in their current locations. The existing lagoons are landlocked both within the City and by geographic features. Due to the location of the lagoons within the City, odor problems are also an issue. Objectionable odors are a serious concern for the City because of their reliance on tourism. Wastewater Collection and Treatment System Improvement Recommendations Based on the aforementioned deficiencies and limitations of the existing lagoon systems, the City evaluated 11 treatment concepts within the Wastewater Treatment Facility Plan which were narrowed Figure 1: Wastewater System Capacity, Projected Flows, and Proposed Capacity Source: City of Medora Wastewater Treatment Facility Plan City of Medora Infrastructure Needs Assessment 6

7 to three feasible alternatives for further evaluation. These alternatives considered the challenges of the current wastewater facilities, in addition to reducing the burden of operation and maintenance, minimizing land requirements and impacts, maintaining historical integrity of the area, and logical phasing to avoid over expansion. The City has submitted environmental solicitation letters for these three alternatives and is awaiting agency responses before selecting the preferred alternative. The future improvements to the City s wastewater treatment system include decommissioning the existing lagoon system. Alternative I is located west of the existing City limits and the Medora Campground, as illustrated in Figure 2. This alternative includes construction of an activated sludge mechanical treatment facility with two deep storage ponds. Wastewater would be conveyed to the new system via an 8-inch PVC forcemain (approximately 1.0 mile) from a new influent pumping station located adjacent to the existing influent lift station. The mechanical plant would include mechanical bar screen, aeration tanks, clarifiers, blowers, aerated sludge holding, sludge storage tanks, and a process building. The mechanical plant would discharge into two 15-feet deep, 4.6-acre storage ponds to store the treated effluent until discharge in the spring and fall to the Little Missouri River. The proposed outfall to the river would be in the vicinity of the Figure 2: Alternative I Mechanical Treatment Near Campground City of Medora Infrastructure Needs Assessment 7

8 proposed treatment site. The mechanical treatment plant would be designed to meet anticipated BOD, total suspended solids (TSS), and ammonia limits with disinfection accomplished in the storage ponds. The opinion of probable cost for Alternative I is presented in Table 4. Alternative II is located on the same site as Alternative I, and includes construction of two aeration ponds and two deep storage ponds as illustrated in Figure 3. Wastewater would be conveyed to the new system via an 8-inch PVC forcemain (approximately 1.0 mile) from a new influent pumping station located adjacent to the existing influent lift station. The improvements would include an influent grinder, two 0.5 acre aeration ponds, surface aerators, and associated site and process piping. The aeration ponds would discharge into two 15-feet deep, 4.6-acre storage ponds to store the treated TABLE 4 OPINION OF PROBABLE COST WASTEWATER SYSTEM IMPROVEMENTS ALTERNATIVE I # DESCRIPTION QTY UNIT UNIT PRICE TOTAL 1 Lift station upgrades 1 LS $ 150,000 $ 150,000 2 Forcemain 1 LS $ 500,000 $ 500,000 3 Mechanical treatment plant 1 LS $ 1,730,000 $ 1,730,000 4 Yard piping 1 LS $ 130,000 $ 130,000 5 Storage ponds 1 LS $ 2,000,000 $ 2,000,000 6 Stormwater management 1 LS $ 40,000 $ 40,000 7 Electrical and controls 1 LS $ 560,000 $ 560,000 Direct Construction Subtotal $ 5,110,000 Mobilzation/Bonds/Insurance 2 7% $ 358,000 Contingency Construction Subtotal (2012 dollars) 20% $ 1,022,000 $ 6,490, Construction Cost 1 3.1% $ 6,898,617 Floodplain Study $ 30,000 Land Purchase 15.5 $20,000/ac $ 310,000 Engineering 20% $ 1,298,000 Legal & Administrative 5% $ 324,500 TOTAL 2 $ 8,862,000 1 The ENR 20 year average Construction Cost Index is +3.1% (as of November 2009), so capital costs are projected to an anticipated construction date in 2014 using an annual 3.1% inflation rate. 2 Estimate rounded up to nearest thousand City of Medora Infrastructure Needs Assessment 8

9 Figure 3: Alternative II Aeration Ponds Near Campground effluent until discharge in the spring and fall into the Little Missouri River. The proposed outfall would be in the vicinity of the proposed treatment site. The system would be designed to meet BOD and TSS removal in the aeration ponds, and TSS polishing and disinfection in the storage ponds. The opinion of probable cost for Alternative II is presented in Table 5. Alternative III is located nearly three and half miles south of Medora near the Bully Pulpit Golf Course irrigation ponds, as illustrated in Figure 4. This alternative includes construction of an activated sludge mechanical treatment facility while utilizing the three existing Bully Pulpit irrigation ponds for storage and reuse (for irrigation). Wastewater would be conveyed to the new system via an 8-inch PVC forcemain from a new influent pumping station located adjacent to the existing influent lift station. There are two forcemain alignment options to convey wastewater to the proposed wastewater treatment system site. The first option would follow mostly in the right-of-way along East River Road for approximately 4.2 miles, and includes several road crossings. The second option would follow the Little Missouri River Valley for approximately 4.1 miles, and includes six river crossings. The mechanical plant improvements would include mechanical bar screen, aeration tanks, clarifiers, blowers, aerated sludge holding, sludge storage tanks, UV disinfection, and a process building. The mechanical plant would discharge into one existing 9.5-acre irrigation pond. A berm separating the City of Medora Infrastructure Needs Assessment 9

10 TABLE 5 OPINION OF PROBABLE COST WASTEWATER SYSTEM IMPROVEMENTS ALTERNATIVE II # DESCRIPTION QTY UNIT UNIT PRICE TOTAL 1 Lift station/grinder upgrades 1 LS $ 210,000 $ 210,000 2 Forcemain 1 LS $ 500,000 $ 500,000 3 Aeration ponds 1 LS $ 560,000 $ 560,000 4 Yard piping 1 LS $ 260,000 $ 260,000 5 Storage ponds 1 LS $ 2,000,000 $ 2,000,000 6 Stormwater management 1 LS $ 50,000 $ 50,000 7 Electrical and controls 1 LS $ 240,000 $ 240,000 Direct Construction Subtotal $ 3,820,000 Mobilzation/Bonds/Insurance 2 7% $ 267,000 Contingency 20% $ 764,000 Construction Subtotal (2012 dollars) $ 4,851, Construction Cost 1 3.1% $ 5,156,424 Floodplain Study $ 30,000 Land Purchase 17 $20,000/ac $ 340,000 Engineering 20% $ 970,200 Legal & Administrative 5% $ 242,550 TOTAL 2 $ 6,740,000 1 The ENR 20 year average Construction Cost Index is +3.1% (as of November 2009), so capital costs are projected to an anticipated construction date in 2014 using an annual 3.1% inflation rate. 2 Estimate rounded up to nearest thousand two irrigation ponds would be raised to provide the required storage capacity. From the irrigation pond, the wastewater could be used as reuse water for the golf course or stored until discharged into the Little Missouri River. The outfall would be in the vicinity of the proposed treatment site. The mechanical treatment plant would be designed to meet anticipated BOD, TSS, disinfection, and ammonia limits. The opinion of probable cost for Alternative III is presented in Table 6. The three alternatives being considered would change the location of the discharge point, but would be the same receiving body. All three alternatives would serve a permanent population of 450, and a temporary population of 1,650. CONCLUSION The City is currently evaluating the three wastewater alternatives identified within this assessment. The City will make a selection based upon feedback from environmental solicitation letters and City of Medora Infrastructure Needs Assessment 10

11 Figure 4: Alternative III Mechanical Treatment Near Bully Pulpit additional required reports are identified. It is estimated the City will need to implement between $6.740 million and $8.862 million in wastewater treatment facility improvement to support growing demands. City of Medora Infrastructure Needs Assessment 11

12 TABLE 6 OPINION OF PROBABLE COST WASTEWATER SYSTEM IMPROVEMENTS ALTERNATIVE III # DESCRIPTION QTY UNIT UNIT PRICE TOTAL 1 Lift station upgrades 1 LS $ 300,000 $ 300,000 2 Forcemain 1 LS $ 1,600,000 $ 1,600,000 3 Earthwork 1 LS $ 100,000 $ 100,000 4 Mechanical Treatment Plant 1 LS $ 1,880,000 $ 1,880,000 5 Yard piping 1 LS $ 270,000 $ 270,000 6 Stormwater management 1 LS $ 30,000 $ 30,000 7 Electrical and controls 1 LS $ 590,000 $ 590,000 Direct Construction Subtotal $ 4,770,000 Mobilzation/Bonds/Insurance 2 7% $ 334,000 Contingency 20% $ 954,000 Construction Subtotal (2012 dollars) $ 6,058, Construction Cost 1 3.1% $ 6,439,418 Cultural Resource Study $ 30,000 Land Purchase 2 $20,000/ac $ 40,000 Engineering 20% $ 1,211,600 Legal & Administrative 5% $ 302,900 TOTAL 2 $ 8,024,000 1 The ENR 20 year average Construction Cost Index is +3.1% (as of November 2009), so capital costs are projected to an anticipated construction date in 2014 using an annual 3.1% inflation rate. 2 Estimate rounded up to nearest thousand The work that provided the basis for this publication was supported by funding under an award with the U.S. Department of Housing and Urban Development. The substance and findings of the work are dedicated to the public. The author and publisher are solely responsible for the accuracy of the statements and interpretations contained in this publication. Such interpretations do not necessarily reflect the views of the Government. City of Medora Infrastructure Needs Assessment 12