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HomeMy WebLinkAboutWOODWARD TECHNOLOGY CENTER - LINK-N-GREENS OVERALL DEVELOPMENT PLAN - ODP120002 - SUBMITTAL DOCUMENTS - ROUND 1 - ALTERNATIVE COMPLIANCE REQUEST (3)■ Odor Testing — Odor characterization tests were conducted prior to, and after plant startup. The odor tests were conducted by St. Croix Sensory, Inc. utilizing the ASTM international E679-4, Standard of Practice for Determination of Odor and Taste Thresholds by a Forced -Choice Ascending Concentration Series Method of Limits. Table A: Odor Characterization Results at Mulberry Water Reclamation Facility Pre -Startup (10/5/2010) Post -Startup (08/10/2011) Sample Detection Recognition Hedonic Detection Recognition Hedonic Characterization Description Threshold Threshold Tone Threshold Threshold Tone Chemical, Medicinal, South Boundary 85 45 -1.6 40 20 -0 8 Offensive Chemical, Medicinal, West Boundary 65 40 -1.6 85 45 -1.0 Offensive Chemical, Medicinal, East Boundary 35 22 -0.6 75 40 -1.0 Offensive Chemical, Medicinal, 42-inch by-pass 85 45 1.0 140 70 -0.6 Offensive Definitions: Detection Threshold —the number of times a sample must be diluted to be just above the limit of a person's ability to smell the odor. Recognition Threshold —the number of times a sample must be diluted to be just above the limit of a person's ability to characterize an odor. Hedonic Tone —the measure of the pleasantness or unpleasantness of an odor. An arbitrary but common scale for ranking odor by hedonic tone is the use of a 21 point scale: +10 Pleasant 0 Neutral -10 Unpleasant ■ Discussion — Analysis of the threshold values is difficult and the fluctuation between the values could be attributed to temperature, wind direction during sampling, and background odors. Comparison of the hedonic tones between the sampling dates indicates that the intensity of the odors between the two test dates was relatively the same. A more definitive confirmation of the effectiveness of the current odor control facilities is the fact that the Utility has received no odor complaints attributed to the Mulberry facility since the plant was re -commissioned in July 2011.Observations by plant staff over the past year indicate that odors should not be detectable beyond the plant boundaries under normal operating conditions. o The reduced buffer exceeds the regulations and policies of the Colorado Water Quality Control Division. As a result, we would like to request an alternative setback distance, acknowledging the upgrades and treatment technologies that have been implemented, to be substituted for the setback distance within the standard 3.4.2(B) - Setbacks from Domestic Wastewater Treatment Works to Habitable Structures. Specific findings for the Alternative Compliance Request ■ The plan will equally well or better accomplish the purpose of this Section than would a plan which complies with the standards of this Section. o Since the 1000' standard was established based on the previous operations of the facility before its upgrades, and significant upgrades with aggressive odor controls and additional treatment technologies have been implemented, the proposed 500' setback distance reflects the current condition of the facility equally well or better than the setback distance in the standard. • The plan acknowledges mitigating factors that now exist to counter the potential for odor problems and/or aerosol drift. o Due to the fact that existing businesses and residences along Riverside Drive were located within the 1000-foot setback, the 2008 Mulberry Improvements Project included substantial upgrades to the plant odor control equipment. These include the following: ■ Process Isolation — Odorous processes in the preliminary, primary, and secondary treatment areas were covered to prevent exposure to the atmosphere. Odor control piping, both above and below ground provides ventilation between these areas and the odor control process. ■ Primary Odor Control — Air from the most odorous processes is drawn through an organic biofilter by two odor control fans. The air is first humidified, and then drawn through a 6-foot thick mixture of wood chips and compost. This media provides an environment for the growth of sulfur -reducing bacteria to treat the hydrogen sulfide and mercaptans which are the primary odor -causing constituents in these areas. ■ Secondary Odor Control -Discharge from primary odor control system is mixed with air drawn from the activated sludge basin and pushed through the secondary odor control system. This consists of a 15-foot diameter horizontal - flow activated carbon filter. The activated carbon strips any remaining hydrogen sulfide prior to discharge into the atmosphere. Considerable effort went into designing system redundancy and ease of maintenance. The primary odor control can be bypassed to the secondary system during maintenance periods and the secondary odor control is divided so one side can remain online while the other is being maintained. Request for Alternative Compliance with 3.4.2(B) regarding Setbacks from Domestic Wastewater Treatment Works to Habitable Structures Link-n-Greens ODP August 30, 2012 Revised September 4, 2012 Concurrent with the Link-n-Greens ODP, we would like to request the following Alternative Compliance with Section 3.4.2(B) regarding Setbacks from Domestic Wastewater Treatment Works to Habitable Structures. Current Standard 3.4.2(B) - Setbacks from Domestic Wastewater Treatment Works to Habitable Structures — Unless specifically authorized pursuant to the provisions of paragraph (C) below, the minimum horizontal distances set forth in subparagraph (2) of this subsection shall be maintained between the various kinds of wastewater treatment works listed in said subparagraph and any of the following uses: (a) any residential use; (b) any commercial/retail use except frozen food lockers, enclosed mini -storage facilities and properties used principally as parking lots or parking garages; (c) any industrial use except warehouses, properties used for recreational vehicle, boat or truck storage, composting facilities, outdoor storage facilities, junkyards, transport terminals, recycling facilities, and resource extraction; (d) any institutional/civic/public use except cemeteries, golf courses, public facilities, parks, recreation and other open lands, places of worship or assembly; and (e) any accessory/miscellaneous uses except agricultural activities, farm animals, satellite dishes (greater than thirty-nine [39] inches in diameter), wireless telecommunications equipment and wireless telecommunications facilities. Description of need for Alternative Compliance The Link-n-Greens ODP is being established to accommodate a new campus for Woodward. The current setback for the Mulberry Water Reclamation Facility is 1000' (see attached exhibit). A portion of the development site falls within the 1000' setback line. However, the Mulberry Water Reclamation Facility has been significantly upgraded with aggressive odor controls and additional treatment technologies. A reduced buffer from 1000' to 500' acknowledging the effects of these measures is proposed.