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HomeMy WebLinkAboutAgenda - 06-02-2004-9dORANGE COUNTY BOARD OF COMMISSIONERS ACTION AGENDA ITEM ABSTRACT Meeting Date: June 2, 2004 Action Agenda Item No. ~_~ SUBJECT: Northern Human Services Center (NHSC) Wastewater Treatment System Alternatives DEPARTMENT: Health, County Manager ATTACHMENT(S): Consultant's Report & Timeline (Attachment A) County Staff Report (Attachment B) Chart Summarizing Design Options (Attachment C) PUBLIC HEARING: (Y!N) No INFORMATION CONTACT: Ron Holdway, Env, Health Director, ext 2360 Tom Konsler, Env. Health Supervisor, ext 2360 Paul Thames, County Engineer, ext 2300 TELEPHONE NUMBERS: Hillsborough 732-8181 Chapel Hill 968-4501 Durham 688-7331 Mebane 336-227-2031 PURPOSE: To provide the BOCC with information on design options and projected costs for a wastewater treatment system serving the County's Northern Human Services Center (NHSC). BACKGROUND: Far a number of years, Orange County has been working to maximize the use of the NHSC, To date, that use has been limited largely by the capacity of the existing on- site wastewater treatment system, To this end, Board directed staff to begin steps to acquire additional nearby property (Vincent tract located directly across NC 86 from the NHSC) for the siting of components for an expanded on-site wastewater treatment system (primarily a nitrification field). This turned out to be, given complications due to multiple heirs, a longer than usual process culminating with clear title to the County in early 2004. Meanwhile the Board, given its interest in studying the use of alternative ornon-traditional treatment systems in this project, approved a contract with Innovative Design (architectural consultant) on December 9, 2003. Innovative Design was authorized to conduct a feasibility analysis of sustainable design elements at the NHSC and to design an expanded capacity (up to 6000 gallon per day [gpd]) wastewater treatment system for the NHSC, Innovative Design and its engineering/sail scientist subcontractor (Landis, Inc.) submitted a preliminary design report/proposal to County staff containing three design "Steps". These Steps (or design alternatives) are summarized below: • Step 1 -Provides flow equalization to 6000 gpd for four consecutive days only, uses existing septic tank primary treatment components and existing front lawn nitrification field • Step 2 -Provides 3000 gpd "Living Machine"-type secondary treatment technology and flow equalization to 6000 gpd for four consecutive days, uses existing septic tank primary treatment components and existing front lawn nitrification field Step 3 -Provides 6000 gpd septic tank primary treatment, 6000 gpd "Living Machine"- type secondary treatment technology, flow equalization to allow up to 12,000 gpd for four consecutive days, and subsurface disposal capacity of 6000 gpd on the Vincent property Steps 1 and 2 would use the existing treatment system components buried in the front lawn of the NHSC and Step 3 would use the Vincent property. The consultant ultimately recommended that the County implement Step 2 and cited the reasons below: • the probable maximum average daily flow from the facility (after retrofitting the facility with low flaw plumbing fixtures) should not exceed 3000 gpd • peak flows have historically exceeded the existing system design flows by approximately 50% and average daily flows by nearly 300% • peak flows are projected to be +/- 6000 gpd at maximum building use with reduced flow plumbing fixtures • provides a treatment capacity and a subsurface discharge capacity of 3000 gpd to address average flows of up to 3000 gpd and will address peak flows of up to 6000 gpd for four continuous/consecutive days • provides the least cast initial investment using advanced treatment technology (and would allow the potential for additional subsurface discharge capacity by expanding to Vincent tract as necessary). Attachment A is the complete report from the Consultant including their proiected timeline. Orange County Environmental Health and Engineering staff evaluated the consultant's proposed Steps (design alternatives) in light of state and local permitting requirements and taking into account existing conditions and proposed uses at the NHSC. Environmental Health staff determined that Steps 1 and 2 were insufficient to meet local or state regulatory (permitting) requirements associated with expanded building use for the following reasons: ® the capacity of the existing nitrification field cannot be permitted (from a regulatory standpoint) with an application rate greater than its current rate (2400 gpd with existing lines, less if lines are removed for the front drive) given the age of the system and building utilization that includes food preparation activities wastewater flow records for the existing system show average peak flows in excess of 3760 gpd for more than 90 consecutive days (1/24/03 through 4/24/03) flows associated with or generated by the expanded use of the facility, park use or potential development of park and ride facilities far exceed the projected 3000 gpd ® significant components of existing peak flow appear to include leaking plumbing fixtures (toilets continuing to run after flushing), extended building use (athletic events) and ground water inflow/intrusion during prolonged periods of wet weather, While providing water efficient fixtures will significantly reduce normal water use, it will probably not eliminate fixture malfunction, nor will it address inflow problem, much of which results from aged and inaccessible wastewater lines (under building slab) Additional issues that are non-regulatory that staff believe would not support the implementation of Steps 1 and 2 are: use of the existing nitrification field planes significant limits on use of the facility's front lawn area (for example, constructing a cira~Iar drive for easier and safer drop-off/pickup of seniors or young children; 15 minute parking; a more welcoming front entrance/fagade that faces the public, given the nature of and demands on the County's ability to plan and fund major capital projects, it may be increasingly difficult to fund additional system expansion/improvement in the future,. County staff has determined that the consultant's proposed Step 3 could be a viable option to provide for an expanded use of the facility, Step 3 provides an expanded capacity wastewater treatment system at the NHSC, because it includes a 6000 gpd treatment and subsurface disposal capacity, but there is; however, some question about the need to provide the 4-day 12,000 gpd flow equalization component that the consultants include, County staff believes that a system providing a 6000 gpd treatment capacity will be sufficient tc address average daily flows of 3000 gpd as well as short-term (heavy facility use) and long-term (infiltration) peak flows without the use of a flow equalization component, As a result of analysis, County staff recommends that the BOCC consider approving one of the following options: A modified version of the Step 3 system, or what staff refers to as Step 3A, providing a 6000 gpd treatment (septic and secondary treatment systems) and subsurface disposal (on the Vincent property) capacity but omitting the 12,000 gpd flow equalization component; OR A new Step 4 in which some other advanced secondary treatment technology that meets State approval (e.g. recirculating filtration component) is used in lieu of the Living Machine component. Attachment B is the complete report from County Staff on its review of the design proposed by the Consultant. Attachment C is a chart depicting ALL design options as proposed by both the Consultant and County staff. FINANCIAL IMPACT: The consultant's recommendation, Step 2, has a projected construction cast of approximately $162,000. The total construction cost for the Step 3A is not available yet projected since the cost savings tied to eliminating the flow equalization component has not been calculated. However, Step 3A is expected to be less than the $324,000 cost projected by the consultant for Step 3. The projected total construction cost for Step 4 is approximately $250,000. By way of background, there are out-of-pocket annualized operating costs (contract operator) for Steps 2, 3 and 3A that are projected at $40,000 for the Living Machine type component. This cost is based on recent consultation with State regulators on operational requirements for this component and does not account for operation of the rest of the system, It is passible that Environmental Health staff could serve as the subsurface-certified operator for the remainder of the system but that cannot be finally determined without further information from State permit/review staff, RECOMMENDATION(S): The Manager recommends that the BOCC review the staff findings and authorize staff or the consultant to move forward with capacity and design options Step 3A or Step 4, as outlined in the agenda abstract, for the construction of the NHSC wastewater treatment system ,4iTctc~~w~ ,~ ~. Report on Wastewater Alternatives Northern Services Center Orange County, NC Executive Summary April 19, 2004 By Barrett L. Kays, Ph.D. Landis, Inc. Raleigh, NC Michael H. Nicklas, FAIR Innovative Design, Inc. Raleigh, NC Executive Summary -Innovative Design, Inc.. and its consultant Landis, Tnc. have conducted an evaluation ofthe wastewater alternatives for the Northern Services Center. A preliminary site plan has been developed by Innovative Design that will allow for both expansion of the parking and the continued use of the existing wastewater nitrification fields at the center. The wastewater flow data and water flow data for the Northern Services Center was provided to Landis by the Orange County Health Department, Landis has determined that the existing wastewater problem is primarily due to unusually high peals flow rates. Landis has also determined that the existing wastewater nitrification fields may be more than sufficient for the proposed use of the facility if the peak flow rates can be controlled. The consultants have made the following technical findings: • Tlne existing wastewater pernnit is based upon an average daily flow of 2,400 gallons per day (GPD). • The wastewater flow records from March 1999 through .January 2004 indicate that the average flow rate for the facility has been 1,324 gallons per day (GPD). • New commodes and urinals are proposed to be included in the improvements to the center and they will reduce the average flow rate from the facility by about 30 %, • The facility has had a problem of peak wastewater flows that have reached approximately 3,800 gallons per day (GPD), • The proposed expansion in uses in the center should increase the average flow rate for the facility to about 2,062 gallons per' day (GPD). • The proposed expansion in uses in the center should increase the peak flow for the facility to about 5,980 gallons per day (GPD). The State On-Site Wastewater regulations allow for the use of actual wastewater flows in lieu of the general flow rates for various types of uses in the regulations. The actual wastewater flow from the facility is the preferred method to plan improvements and expansion to an existing facility. hn addition to the wastewater flow analysis, the architects have evaluated the building to determine the maximum allowable number of people, types of use, and estimated wastewater flow with water conservation features,. This architectural analysis is based upon the maximum use of the building under the State Building Code and projected uses from information given the architects from the future building occupants, The results indicated that the maxinnmr use of the building should on average generate wastewater flows of about 3,000 gallons per day (GPD), All of the above analysis has led to the recommendation that improvements to the wastewater system be based upon logical steps as they become necessary over time. The first two of the steps are based upon the most cost effective means to solving the existing problems and needs for the facility, Based upon the wastewater flow data and the architectural analysis, it does not appear to be necessary to expand over to the Vincent property, however Step #.3 provides for further expansion onto the Vincent property if it becomes necessary. A preliminary cost projection has been made for each step. The following steps appear to most logical order: Step #1-Installation of Flow Equalization Tanks to Control the Peak Flows This step will provide approximately .3,000 GPD of daily wastewater flow and will provide for control of peak flows to 6,000 GPD for' four continuous days, This step will allow for expansion of proposed uses in the center and will allow for some additional capacity for park uses. The projected construction cost of this step is: 1,. Subsurface System $ 10,000 2. Additional Tanks -15,000 gal. PS 48,000 .3. Miscellaneous 12,000 $ 70,000 The advantage to Step #1 is that monies aze applied to a cost effective solution of the most important factor that is limiting the expansion of the center.. This step will in essence almost triple the capacity of the existing facility. However, this step does not address the environmental concerns that the existing facility may be contributing to contamination of the groundwater within the water supply watershed, Step #Z -Installation of Pretreatment System to Extend the Life of Existine Fields This step will provide for tertiary treatment of the wastewater prior to disposal in the nitrification fields. This will allow for extended life of the nitrification fields and it will prevent any future contamination of the groundwater. This step may provide for a limited amount of increased capacity depending upon the detailed soil and hydrologic testing to be conducted by the consultants. The projected construction cost of this step is: 1. Pretreatment Unit 2. Pretreatment Structure $ 64,000 28,000 ~ 92,000 The advantage to Step #2 is that monies are applied to both provide environmental protection and to minimize the need for future expansion of the wastewater facility to the Vincent property.. Therefore, this step is a very conservative approach to save money and protect the environment. Step #3 -Expansion of Capacity (if needed) by Adding New Fields Across the Flighway on the Vincent Property This step will provide expansion to approximately 6,000 GPD of daily wastewater flow and will provide for control of peak flows to 12,000 GPD for four continuous days. This step will allow for expansion considerably beyond the current proposed uses of the center. The projected construction cost of Uris step is: 1. Subsurface System - 6,667 lin.it.@$8,50 $ 56,670 2, Pressure Manifold Units - 6 @$5,000 .30,000 3. New Pump Station - 15,000 gal, PS 48,000 4. Drive & Fencing 15,000 5. Miscellaneous 12,000 $161,670 Overall Cost Projection (Step #1 throuEh Step #3) Step #1-Flow Equalization Component $ 70,000 Step #2 -Pretreatment Component 92,000 Step #3 -Field Expansion to Vincent Property 161,670 Total Construction Cost $.323,670 Decision by the Commission The consultants need to begin their technical study of site and soils on the property, The soils testing will involve detailed evaluation of soils, hydraulic conductivity testing of the soils, deep boring to groundwater, and modeling the effect of vazious hydraulic wastewater loads on the groundwater elevations under the site, The consultants need to determine where they should conduct the testing, Currently the testing is proposed to be completed on the existing nitrification system at the center. This testing will allow for the engineering design of Step #1 and Step #2 above. This report is being presented to the Commissioners because the consultants believe that Step #1 and Step #2 will be sufficient for' the proposed uses at the center and will be less costly than expanding the wastewater facility to the Vincent property.. A portion of the Vincent property will be reserved for the future if such an expansion becomes necessary. However, if the County wants to budget additional monies to this project, the consultants can conduct additionally testing of the Vincent property and can design additional future facilities to be located on the Vincent property. The County has currently budgeted construction monies for Step #1 and 2. However, the County could amend the construction budget for all three of the steps. Orange County Northern Human Services Center Wastewater System Schedule Schedule of Tasks 1. Preapplication meeting with local health department a, Review of application process for site approval b. System wastewater design flow c. Existing system component evaluation 2, Soil/site evaluations a. Proposed site plan b, Soil scientist's field evaluation c. Local health departments site evaluation 3, County's land surveyor prepares field topographic map 4. Soil scientist's site loading capacity and groundwater impact 5. Soil scientist's revised site plan 6. State OSWS review and approval 7. LHD issues Improvement Permit for Site Approval 8, Engineer's meeting with State OSWS staff 9. Engineer prepares engineering plans for wastewater system 10. Design review and approval 11. LHD issues Authorization to Construct 12, Advertisement for bids 13. Bid opening 14. Award of construction contract 15. Start of construction 16. Substantial completion of construction 17. Final inspection; LHD issues Operation Permit Step.#1-2 Step.#1-3 Schedule Schedule Week 1 -t 2 Weeks Week 2-3 +6 Weeks Week 4-5 +2 Weeks Week 4-5 +4 Weeks Week 6 Week 7-11 +4 Weeks Week 12 Week 12 Week 12-16 +4 Weelcs Week 17-23 +12 Weeks Week 24 +4 Week Week 26 Week .30 Week .31 Week 32 +8 Weeks Week 40 +12 Weeks Weelc 42 +4 Weeks 42 Weeks 104 Weeks * Step 3 requires a new site, new permit, more extensive soil and geologic testing, more detailed site groundwater hydrology modeling, and more extensive state soil and engineering review. ~~~~~n~,-~ B~ MEMORANDUM TO: Ccunty Commissioners John Link, County Manager COPIES: Gwen Harvey, Assistant County Manager Rosie Summers, Health Director Pam Jones, Purchasing/Central Services Director Lori Taft, Recreations and Parks Director David Stancil, ERCD Director Mike Nicklaus, AIA, Innovative Design Barrett Kays, PhD, Landis, Inc, FROM: Ron Holdway, Environmental Health Director Tom Konsler, Environmental Health Supervisor Paul Thames, PE, County Engineer DATE: May 27, 2004 SUBJECT: County staff identified issues and recommendations related to proposed expansion of wastewater treatment system serving the County's Northern Human Services Center Background Qrange County's Northern Human Services Center (NHSC) has had a history of wastewater treatment system issues related to system regulatory compliance, operation and capacity. The system currently serving the facility - a relatively high capacity (2400 gallon per day [gpd]) pump conventional septic system -was completed and put into operation under near-emergency conditions (mandatory decommissioning of existing system) in early 1994, This system replaced an existing discharging sand filter system (discharging to the No, 1 sedimentation structure protecting Lake Qrange) that was non-complaint under the then (and still) current state wastewater treatment and watershed protection regulations, The pump-conventional septic system currently in use was designed by County Environmental Health and Engineering staff and permitted under local environmental health rules by the County Health Department, The system design was limited to a 2400 gpd capacity because, after extensive site evaluation of the entirety of the NHSC property by County Environmental Health Specialists and Soil Scientists, it was determined that a maximum of 2400 gpd could be accommodated in a contiguous nitrification field (a small non-contiguous nitrification field area was located west of the building and reserved as repair area), The new system was permitted with far less than the 100% nitrification field repair area typically required for such systems because the construction of the new system was regulated as an emergency repair, Soon after the new system became operational, system flow recording instrumentation indicated that it was being overloaded by wastewater flow often significantly in excess of system design rapacity. Comparison of wastewater flow and potable water flaw (from the on-site well) data indicated that there were several probable sources of excess flow: heavy though sporadic use of the building facilities during organized athletic/recreational events (basketball/softball league play); malfunctioning toilets and urinals; and infiltration of ground water during prolonged rainy periods into the hundreds of feet of old terra cotta (clay) wastewater drain lines. Over the years prior to 2000, County Public Works staff replaced all accessible terra cotta sewer lines (essentially all lines not located under the existing building slab) with new watertight plastic sewer pipe. While replacing the old sewer line did appear to address the bulk of the infiltration problems, some level of infiltration remained. For example, during the very rainy period of the first quarter of 2003, sewer flows averaging 3767 gpd (157% of design flow) occurred for 91 consecutive days (1/24/03 to 4/24/03).. Beginning in early 1998 with acquisition of a large adjoining tract adjacent to the western boundary of the NHSC property (Kennedy tract) intended for park development, the BOCC's interest in improving/remodeling the NHSC and maximizing its use was renewed, Staff was directed to develop strategies for addressing the limitations imposed on program expansion by the capacity of the existing wastewater treatment system. County Environmental Health and Engineering staff made a preliminary determination that a wastewater treatment system having a capacity in the 5000 to 6000 gpd range could provide the treatment capacity necessary to accommodate a maximized expansion of program activity in the NHSC building and the adjoining park. Furthermore, the system would provide sufficient excess capacity to sustain peak flows generated by very high system use and accommodate potential system infiltration, assuming the existing building and park facilities would be fitted or retrofitted with high efficiency plumbing fixtures. Environmental Health staff then evaluated the Kennedy tract to locate an area containing sails suitable for siting a 5000 to 6000 gpd nitrification field with 100% repair area. Unfortunately, the only suitable soils on the Kennedy tract were located in the area that also contained a significant stand of mature hardwood trees, The BOCC concluded that protecting the viability of the stand of hardwoods, which was determined to be inconsistent with the siting of a large nitrification field, should be the prevailing value in the use of the Kennedy tract. Environmental Health staff was then directed to evaluate the nitrification field siting potential of other adjoining properties not then under County ownership with the intent to acquire the necessary additional property, By 2002, the Environmental Health staff had determined that the Vincent property, located on the east side of and across NC 86 from the NHSC, would accommodate a nitrification field (with 100% repair area) having a capacity of 6000 gpd or more. The BOCC targeted the Vincent property for acquisition, a process that was not completed until late February 2004 (a consequence of unclear and convoluted heir title circumstances), At its 9 December 2003 meeting, the BOCC took another step in the process to upgrade the NHSC facility by approving a contract with Innovative Design (an architectural consulting firm). The contract included provisions for producing an evaluation of sustainable design elements far the building and a design far wastewater treatment system including a secondary treatment component using "Living Machine" technology, Specifically, Innovative Design was authorized to "design, assist in bidding, and provide construction administrative service to Orange County in implementing a Living Machine type system capable of treating up to 6000 gpd of waste," Synopsis of Preliminary Consultant ReportlRecommendations On 19 April 2004, after several meeting meetings between the consultant's staff (and sub- contracted consultants) with various County technical and management staff, Innovate Design submitted a report entitled "Report on Wastewater Alternatives Northern Services Center Orange County, NC -Executive Summary" (authored by Barrett L. Kays, Ph.D, of Landis, Inc, and Michael H. Nicklas, FAIA of Innovative Design). In the report, (as clarified or amended with subsequent emails and project development schedule) the consultant outlined three potential wastewater system design alternatives (or Steps as per the report format) based on the following findings of fact related to the existing and projected wastewater flow conditions at NHSC: • the permitted capacity of the existing wastewater treatment (and its components) is 2400 gpd; and • wastewater system flow records of March 1999 through January 2004 indicate an average daily wastewater flow of 1324 gpd; and • peak wastewater flows have reached approximately 3800 gpd; and • installation of water efficient plumbing fixtures should reduce average daily flow rates by approximately 30%; and • proposed additional uses of the facility should generate a total (new plus existing) average daily wastewater flow of approximately 2062 gpd (after the installation of the efficient plumbing fixtures); and • the probable maximum average daily flow that could be generated by maximum use of the facility (after retrofitting the facility with low flow plumbing fixtures) should not exceed 3000 gpd; and • the probable maximum daily peak flow associated with the projected expansion of facility use (after retrofitting the facility with low flow plumbing fixtures) is estimated at approximately 5980 gpd Step 1, with an estimated price of approximately $70,000 and completion time of approximately 42 weeks, outlines a system design that is basically a modification to the existing treatment system by incorporating a new flow equalization component (Flow equalization allows the system to balance surges in flow from peak uses or plumbing infiltration from rain events. Excess flows are stored in a large holding tank and metered to the drainfield in regular doses over several days of lighter (below capacity) flows). The proposed flow equalization component would essentially address peak flow conditions of up to 6000 gpd for up to four consecutive days or lesser peak flows conditions for a proportionally longer period of time. While flow equalization would address some of the shortcomings/problem areas of the existing system, it would not provide any higher level of treatment (or protection to the environment) than that provided by the existing system. Step 2, with an estimated price of approximately $162,000 and completion time of approximately 42 weeks, outlines a system design consisting of the flow equalization component outlined in Step 1 above with the addition of a 3000 gpd capacity secondary treatment system component. This component, using tidal vertical flaw wetland or wetland plant-type treatment technology, provides the natural ecological wastewater treatment technology of the "Living Machine" and similar systems of interest to the BOCC as a means of providing an enhanced level of wastewater treatment/effluent discharge quality and the associated higher level of environmental protection. Step 3, with an estimated price of approximately $324,000 and completion time of approximately 104 weeks/24 months, outlines a system design consisting of larger capacity versions of flow equalization (12,000 gpd) and wetlands-type secondary treatment components (6000 gpd) outlined in Steps 1 and 2 above with the addition of a 6000 gpd capacity subsurface nitrification field component located on the Vincent tract (both the Step 1 and 2 alternatives envision the use of the existing nitrification field, perhaps with fewer nitrification lines should any have to be removed with the development of a new front circular drive layout). ~~ County Environmental Health and Engineering staff evaluation of consultant report Since the inception of the NHSC BOCC/staff work group (charged with evaluating the facility upgrades at the NHSC necessary to expand its programmatic utilization), Orange County Environmental Health and Engineering staff have been engaged in addressing the NHSC wastewater treatment issue, Environmental Health staff has also been responsible for operating the existing treatment system for the past ten years. Likewise, these same staff members have worked to identify and overcome the root causes of problems affecting the existing wastewater treatment system, County Environmental Health and Engineering staff do not have in-depth knowledge of or experience with the technology incorporated in a Living Machine type component of wastewater treatment systems, However, Environmental Health staff is aware of and educated in other plant based wastewater treatment alternatives (e,g., constructed wetlands), Additionally, staff does have tens of years of general experience in conventional and alternative on-site wastewater system permitting, siting, design, construction, etc., as well as specific knowledge of the NHSC facility and its environs, Furthermore, County Environmental Health staff will be solely responsible for permitting any new or modified treatment system of less than 3000 gpd treatment capacity and jointly responsible (in conjunction with state Environmental Health staff) for permitting treatment systems with greater than 3000 gpd capacity, In this light, County Environmental Health and Engineering staff have evaluated the consultant's report with particular emphasis on how the proposed alternatives would: a) comply with the applicable environmental health regulations (as interpreted and enforced by the Environmental Health staff of the Orange County Health Department and the NC Division of Environmental Health [DEH]); b) address the existing conditions at and projected needs of the NHSC and the Cedar Grove Park; c) compare, from the standpoints of construction and operating costs and development (design, permitting and construction) time, Living Machine technology systems with other advanred level secondary treatment technology systems; and d) account for the function of and limitations inherent in the County CIP process. The essence of that evaluation is as follows: Step 1 and/or 2 are not viable options for the expanded capacity wastewater treatment system necessary to expand the uses of the NHSC for the following reasons: • Step 1 would address only some of the overloading concerns applicable to the existing system; and • Step 2 would provide a higher quality system effluent, but the subsurface discharge capacity of the existing nitrification field (with or without drain line and treatment capacity reductions consequent to developing a front drive) still cannot be permitted with an application rate (or total system capacity) greater than its current rate (2400 gpd with existing lines, less if lines are removed) given the age of the system and building utilization that includes food preparation activities (an acknowledged facility programmatic objective); and • wastewater flow records for the existing system show average daily peak flows in excess of 3760 gpd (nearly 300% of average daily flow) for more than 90 consecutive days (1/24/03 through 4/24/03), far exceeding the proposed four-day flow equalization '~~ capacity; and • the consultant's projected 3000 gpd maximum average daily wastewater flow (based nn flow numbers generated by the maximum building use capacity) does not appear to address potentially significant flows associated with or generated by park use or potential development of park and ride facilities; and • significant components of existing peak flow appear to include leaking plumbing fixtures (toilets continuing to run after flushing), extended building use (athletic events) and ground water inflow/intrusion (during prolonged periods of wet weather). While providing water efficient fixtures will significantly reduce normal water use, it will probably not eliminate fixture malfunction, nor will it address the inflow problem, much of which occurs as groundwater leakage into and through the permeable joints of the aged and inaccessible wastewater lines (under building slab); and • use of the existing field places significant limits on future use or landscaping of facility's front lawn area; and • given the nature of and demand on the County's capital improvement program, it may be difficult to fund additional system expansion/improvement in the future. Step 3 does appear to be a viable option for an expanded capacity wastewater treatment system at the NHSC, in that it does provide a 6000 gpd treatment and subsurface disposal capacity. There is some question as to the need to provide the 4-day 12,000 gpd flow equalization component included in this alternative. It is the County staff opinion that a system providing a 6000 gpd treatment capacity will be sufficient to address average daily flaws of 3000 gpd as well as short-term (heavy facility use) and long-term (infiltration) peak flows without the use of a flow equalization component.. Staff recommends that the BOCC consider an alternative, designated as Step 3A, which is identical to the consultant's Step 3, in that it has a 6000 gpd capacity primary treatment (septic tanks), 6000 gpd secondary treatment (Living Machine) and 6000 gpd subsurface disposal (nitrification field located on the Vincent property), but does not have the proposed 12,000 gpd flow equalization component. The Step 3A alternative would provide the same level of actual treatment and environmental protection as the Step 3 alternative while achieving a level of construction cost savings (unknown at this time) realized by omitting the flow equalization component.. Preliminary discussion with state environmental health regulatory/permitting staff indicates that the operation of this system will probably require daily visits by a Grade II-certified wastewater treatment plant operator either having an additional subsurface disposal certification or working in conjunction with a second operator having a subsurface disposal certification„ If the state does ultimately determines such operating procedures are to be integrated into the system permitting requirements, the required expertise would have to be secured on a contract basis (within the Environmental Health staff there are individuals certified as subsurface operators but none certified or likely to be certified as Grade II operators). The minimum estimated annual out-of-pocket costs for a contract Grade II operator (with Environmental Health providing a coordinating subsurface operator) is $40,000. Comparison of Treatment System Technology Other than Living Machine Staff recognizes that the BOCC has expressed a preference to provide the NHSC with a wastewater treatment system that utilizes advanced or "cutting edge" technology such as that provided by the proposed Living Machine technology secondary treatment component. ~~ However, this technology is more expensive than more conventional technology. Furthermore, the Living Machine -unlike more conventional treatment components - lacks a track record in North Carolina (insofar as state environmental health permit regulators are concerned),. This means an extended system review and permitting time for the Living Machine technology than that required for secondary treatment technclagies and components that are already state approved. Accordingly, staff recommends that the BOCC take into consideration a more conventional treatment system alternative for comparative purposes. A more conventional advanced wastewater treatment technology (designated as Step 4 (to distinguish it from the alternatives in the Innovative Design/Landis report) recommended by , staff recommends of BOCC consideration is one in which a 6000 gpd recirculating filtration component be used in lieu of the Living Machine component. This would provide an advanced level secondary treatment component in a system could be designed by the consultant or by County staff, It could be constructed at a cost savings of $50,000 to $75,000 (compared to Step 3A and Step 3 respectively) and be put into operation in just over half the time needed for a Living Machine system (permitting time is much shorter), This system, while it might not provide quite the same level or quality of treatment as that provided by a Living Machine system, would nonetheless provide a high quality effluent that meets all regulatory requirements (nitrogen, BOD, coliform and suspended solids removal) related to subsurface effluent disposal, Furthermore, County staff has the expertise to operate and maintain this system, which is not the case with a Living Machine system (representing annual out-of-pocket expense savings of $40,000). If we may provide additional information or clarification on this matter, please advise.