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HomeMy WebLinkAbout2.0 BOCC Staff Report 02.10.2003PROJECT INFORMATION AND STAFF COMMENTS BOCC 2110103 TP Application for Site Approval for Construction of a new Domestic Wastewater Treatment Facility at the Hanging Lake Rest Area Colorado Department of Transportation (CDOT) Church & Associates, Inc. Hanging Lake Rest Areas is located on the south side of Interstate 70, approximately 8 miles east of the City of Glenwood Springs, in the NE1/4, NEl/4, Section 30, T5S, R87W of the 6th P.M. REQUEST: APPLICANT: ENGINEERS: LOCATION: I. SUMMARY OR REQUEST CDOT is proposing the construction of a wastewater treatment facility ("WTF") at the Hanging Lake Rest Area. II. DESCRIPTION OF TIIE PROPOSAL The restroom facility is a part of the Glenwood Canyon I-70 construction, which has existed since the early 1990s. There is no zoning in Glenwood Canyon by the County. The canyon and site is within the US Forest on property owned by the CDOT. The Hanging Lake Rest Area ("Rest Area") is currently served by on-site water wells and by an individual sewage disposal system ("ISDS") consisting of septic tanks and a drain field. The request is to abandon the existing ISDS drain field and convert the composting toilets to flush toilets. The wastewater will be treated by the proposed WTF. The proposal is to discard the treated wastewater to the Colorado River. The "service area" will consist only of the Rest Area. PRorscreD PoPULATIoN According to the engineering report, the projected population for the proposed WTF is based on daily people counts provided by CDOT for the year 2001and a portion of year 2002, and on the projected increase in usage of the Rest Area to the year 2015. 1. Hanging Lake Area Site Application Board: February 10,2003 Page 2 One thousand (1,000) people per day were documented for a significant number of days during the months of July and August, typically over the weekends and holidays. These counts are significantly greater than the midweek counts. An average 1,400 people were identified. Per CDOT projection, the usage of the Rest Area will increase approximately 50 percent by the year 20L5. An average daily usage of 2,100 people per day is proposed for design. WasrtwarER FLow Average daily wastewater flows have been estimated by monitoring the daily water usage at the No Name Rest Area and daily people count data at the Hanging Lake Rest Area, and taking into account the type of fixtures planned for restrooms. An average flow of 2 gallons per person per usage is proposed. An average daily flow (qro,,) of 4,200 gallons per day ("GPD") is proposed. Proposed Average Daily Flow (q,0,) : (2,100 people/day) X (2 gallons/person) : 4,200 GPD WlrnR AND SANITATION DrSrNrCrS There are no water and sanitation districts located within a 5-mile radius of the proposed WTF. There are 8 commercial and/or industrial permitted wells located within a 5-mile radius of the proposed WTF. These include: 1. One well located at the Bair Ranch rest area to the northeast. 2. Four of the wells permitted are for industrial/irrigation and commercial uses and are located at the Rest Area. 3. Two commercial wells are located at the Gizzly Creek rest area to the west. 4. One well permitted for domestic use is located at the Rest Area. 5. All of the wells are owned by CDOT. No water supply intakes are located within a S-mile radius of the proposed WTF. The City of Glenwood Springs watershed, the closest down stream municipality, does not have a water intake structure along the Colorado River. There is one well registered with the Division of Water Resources of the Colorado State Engineers Office permitted for domestic use and located at the Rest Area. Hazmns According to the engineering report, there are no significant geologic hazards that would prevent the development as proposed. However, there is some risk of rockfall that may potentially damage the above grade components of the proposed WTF. The proposed facility is located 2. J. 4. Hanging Lake Area Site Application Board: February 10,2003 Page 3 higher than the identified 100-year floodplain. DnscnrprroN oF Srlrcrnn At,rrnNl.rrvr A Packed-Bed Filter (PBF) treatment system consisting of a septic tank, recirculation tank, geotextile packed filters, and disinfection system with surface discharge is proposed for the Rest Area. The treatment system will be located east of the rest area and north of the access road. The following description of the PBF system was taken from the Engineering Report. The PBF system includes a standard, two-compartment septic tankfor solids retention and digestion. Effiuentfrom the septic tankwillflow to a recirculation tankwhere an effluent pumping system will dose ffiuent to the surface of geotextile filters. The geotextile filter media develops aerobic bacteria, which bio-chemically treat the ffiuent, and convert ammonia nitrogen to nitrate nitrogen. The treated effluentJlows back to the recirculation tank where it mixes with the anaerobic septic tank ffiuent. Additional bio- chemical reactions occur which convert the nitrate nitrogen into a harmless and odorless nitrogen gas, which is ventedfrom the system. Total nitrogen reductions of 40ok and 50ok can be anticipated. After j-5 passes through the geotextile filters, the ffiuent is ready for discharge to the proposed ultra-violet light disinfection system. Once disinfected, the ffiuent will discharge to Colorado River. The bio-chemical oxygen demand (BOD) and total suspended solids (TSS) concentrations should consistently be less than l0 mg/l. According to the engineering report, numerous PBF systems have been installed in the United States since the early 1990s. Audits and routine monitoring by county, state, and federal agencies have shown generally excellent results, even with a wide variation in incoming flows. The average daily wastewater loading to the proposed WTF is 4,200 GPD. The system will be operated and maintained by either a certified wastewater system operator, by CDOT personnel, or through a contract with a wastewater system management company. TnTITvTnNT ALTERNATIYES The Applicant indicated that several wastewater system alternatives were considered. These altematives include the following: 1. Connect to an existing Treatment Facility: The closest WTF is located in Glenwood Springs, which is approximately 8 miles from the Rest Area. The closest other WTF is the recently constructed WTF at the Gnzzly Creek rest area. Due to the distance, difficult terrain, and costs in general, this option is not feasible for the anticipated flows. Hanging Lake Area Site Application Board: February 10,2003 Page 4 Consolidation of Treatment Facilities: The Colorado Department of Public Health and Environment ("CDPHE") requested an evaluation be conducted for the consolidation of treatment facilities for Bair Ranch, Hanging Lake, and Gizzly Creek Rest Areas. Due to fill including significant large boulders and the installation of as much as 5 miles of connection sewer line making consolidation of the three treatment plants impractical and prohibitively expensive. Install New Subsurface Drain Fields: There is adequate area for installing new drain fields for the anticipated wastewater flows. However, an anticipated 10 mg/l nitrate limit required for drain fields would require treatment that is cost prohibited. Packaee Treatment Plant: This option evaluated extended aeration and sequential batch reactor technologies. The primary consideration is the relatively small, highly variable flows encountered from a single source used with seasonal peaks. The PBF system was chosen due to its filter media treatment capabilities, its recirculation characteristics, and its ability to be designed in modular form minimizes the concems for highly variable flows. A similar PBF system was approved by CDPHE for use at the Gizzly Creek Rest Area. IMpI,SN{TNTATIoN Pr,.r,N AND ScHEDULE The following is the anticipated WTF permitting, construction and operation schedule. l.Permitting: a. By December 2002 - submittal of the application for site approval to the CDPHE with signatures from the associated govemment agencies b. By June 2003 - submittal of the completed wastewater system design to Garfield County and CDPHE Construction: a. By August 2004 - begin construction b. By November 2004 - complete construction Operation: a. By July 2004 - submit application for a Discharge permit b. By November 2004 - place system into operation RELATIONSHIP TO THE COMPREIIENSIVE PLANuI. 2. aJ. 4. 2. The Garfield County Comprehensive Plan of 2000 identifies the area of the WTF as a Open Space (Federal Lands) IV. ISSUES AND CONCERNS State Statutes: C.R.S. 25-8-702(2Xa-c), and the "Regulations for Site Applications for Domestic Hanging Lake Area Site Application Board: February 10,2003 Page 5 Wastewater Treatment Works, defines the parameters by which the Water Quality Control Division ("Division") shall review and approve or deny a site application for a wastewater treatment works. The Division is required to determine that each site location is 1) consistent with the long range, comprehensive planning for the area in which it is to be located; 2) thatthe plant on the proposed site will be managed to minimize the potential adverse impacts on water quality; and 3) must encourage the consolidation of wastewater treatment works whenever feasible. The Applicant is required to obtain a recommendation of approval, denial or no cornment from the Garfield County Board of Health and County Board of County Commissioners and various other local and regional agencies. Garfield County's involvement in the process is to determine whether or not the proposed wastewater treatment work is consistent with "the long-range comprehensive planfor the area as it affects water quality and any approved regional wastewater management planfor tlte area". The Garfield County Comprehensive Plan ("Plan") identifies the site as Open Space (Federal Land). With respect to the "Septic System Constraints" m&p, this area has not been identified as an area consisting of a high water table, slow perc rate or solution evaporite minerals. The Plan provides very little guidance through the goals and objectives section of the plan with respect to the WTF. One of the applicable Water and Sewer Services goals is: "To ensure the provision of legal, adequate, dependable, cost ffictive and environmentally sound water and sewer services for new development. " Objective 7.5 of the Plan, provides the most direct guidance to this issue. It states that: "Garfield County will strongly discourage the proliferation of private water and sewer systems." V. RECOMMENDATION 1. Staff recommends that the Garfield County Board of County Commissioners recommend APPROVAL of the site application for the Hanging Lake Rest Area Wastewater Treatment Facility and authorizethe Chairman to sign the site application. 2. Hanging Lake Area Site Application Board: February 10,2003 Page 6 Staff recommends that the Garfield County Board of Health recommend APPROVAL of the site application for the Hanging Lake Rest Area Wastewater Treatment Facility and authorize the Chairman to sign the site application.