CITY COUNCIL AGENDA MEMORANDUM

Transcription

1 CITY COUNCIL AGENDA MEMORANDUM City and County of Broomfield, Colorado To: From: Prepared by: Mayor and City Council Charles Ozaki, City and County Manager Rich Coufal, Water Division Superintendent David Allen, Director of Public Works Kevin Standbridge, Deputy City and County Manager Meeting Date Agenda Category Agenda Item # June 12, 2012 Council Business 9 (h) Agenda Title: Proposed Resolution No , Authorizing and Approving the Purchase of Three SolarBee Water Circulation Systems for Glasser Reservoir and Great Western Reservoir Summary The Water Supply and Water Reclamation Divisions of the Public Works Department are responsible for managing water quality in two water supply reservoirs: Glasser Reservoir and Great Western Reservoir. These reservoirs are used to meet the peak summer demands for the potable and reuse (non-potable) water systems, respectively. Glasser Reservoir serves as the terminal reservoir for Broomfield s water supplies that originate from the Colorado-Big Thompson (CBT) and Windy Gap Projects and is located north of the Broomfield Water Treatment Facility on 144th Avenue. CBT and Windy Gap supplies are treated, filtered, and disinfected at the Broomfield Water Treatment Facility. Great Western Reservoir is used to store treated wastewater effluent from the Wastewater Treatment Facility, as well as runoff from Clear Creek, Coal Creek, and Walnut Creek, for eventual delivery to the reuse water distribution system. Great Western Reservoir is located approximately one mile southeast of the intersection of State Highway 128 and Indiana Street. Both reservoirs are susceptible to algae blooms during the hottest months of July and August. These blooms affect the quality and performance of the potable and reuse systems. In the potable system, excessive algae can result in drinking water that has a musty or earthy taste and odor. Broomfield currently adds powder activated carbon (PAC) to reduce the unpleasant taste and odors associated with algae. However, there are instances when the PAC cannot fully remove the taste and odors, and staff occasionally receives complaints from customers about the quality of the water even though it meets all health and safety standards. Broomfield currently spends about $46,000 per year for PAC. Since Great Western Reservoir does not have the same type of treatment as the potable system, algae can enter the reuse distribution system and clog irrigation equipment such as strainers, valves, and individual sprinkler heads. In 2010, Broomfield spent approximately $20,500 to repair the clogged irrigation equipment throughout the parks served by the reuse system following an algae bloom in Great Western Reservoir. In 2008, Broomfield installed three solar powered mechanical mixers to help reduce the occurrence of algae blooms, one at Glasser Reservoir and two at Great Western Reservoir. These units are commonly referred to as SolarBees and are designed to create an environment near the surface that inhibits algae growth. The primary advantages of SolarBees over other methods to reduce algae blooms in lakes and reservoirs are the relatively low annual operations and maintenance costs. Other control strategies such as mechanical aeration systems and chemical treatment have higher capital costs, higher operations and maintenance costs, or may be harmful to the environment. The original plans included two SolarBee units at Glasser Reservoir and four at Great Western Reservoir. Staff decided to take an incremental approach to determine the effectiveness of the SolarBees before installing the full amount. During the past several years, the reservoirs have shown signs of improvement but the algae blooms are still recurring. Because of the large surface areas of the reservoirs, the current units do not provide enough mixing to be fully effective. Staff and engineering consultants previously evaluated other alternatives for Glasser Reservoir. These alternatives have included the construction of a bypass pipeline and addition of new treatment processes, with costs ranging from $1.1 million to $3.0 million. Staff is proposing to implement the original SolarBee configuration for each reservoir at this time. Proposed Resolution No would authorize the city and county manager to issue a purchase order in the amount of $160,983 to SolarBee, Inc. for the purchase of three SolarBee units for installation at Glasser and Great Western Reservoirs. Prior Council Action Council adopted Resolution approving the 2012 budget on October 26, Financial Considerations The two SolarBees for Great Western Reservoir have a slightly higher unit cost since they are subject to high winds and require a stronger anchoring system. The proposed sources and uses of funds to purchase three SolarBee units are summarized in the following table: Sources and Uses of Funds Sources: 2012 Budget CIP Water Reclamation $ 110, Budget CIP Water Supply $ 52,000 Total Funds Available $ 162,000 Uses: Glasser Reservoir 1 SolarBee Unit Great Western Reservoir 2 SolarBee Units $ 51, ,972 Total Projected Expenditures $ 160,983 Projected Balance $ 1,017 In addition to the initial purchase, Broomfield would revise an existing maintenance agreement with SolarBee, Inc. to include the new units. The estimated cost of the maintenance agreement is $15,000 per year. Alternatives Do not purchase the SolarBees and pursue other algae control strategies for Glasser and Great Western Reservoirs. Based on the above, it is recommended That Resolution No be adopted. Proposed Actions/Recommendations 9(h) - Page 1

2 SolarBee Water Circulation Device Purchases Page 2 BACKGROUND The Water Supply and Water Reclamation Divisions of the Public Works Department are responsible for managing water quality in two water supply reservoirs: Glasser Reservoir and Great Western Reservoir. These reservoirs are used to meet the peak summer demands for the potable and reuse (non-potable) water systems, respectively. Glasser Reservoir was constructed in 1995 and serves as the terminal reservoir for Broomfield s water supplies that originate from the Colorado-Big Thompson (CBT) and Windy Gap Projects. It is located north of the Broomfield Water Treatment Facility located on 144th Avenue. CBT and Windy Gap supplies are treated, filtered, and disinfected at the Broomfield Water Treatment Facility. It has a storage capacity of 386 acre-feet, a surface area of 23 acres, an average depth of 18 feet, and a maximum depth of 25 feet at full capacity. Great Western Reservoir was constructed in 1903 and currently stores treated wastewater effluent from the Broomfield Wastewater Treatment Facility, as well as runoff from Clear Creek, Coal Creek, and Walnut Creek, for eventual delivery to the reuse water distribution system. Great Western Reservoir is located approximately one mile southeast of the intersection of State Highway 128 and Indiana Street. It has a capacity of 2,488 acre-feet, a surface area of 115 acres, an average depth of 19 feet, and a maximum depth of 58 feet at full capacity. WATER QUALITY ISSUES Both reservoirs are susceptible to algae blooms during the hottest months of July and August. When environmental conditions are right, algae can grow very quickly in water bodies such as lakes and reservoirs. General prerequisites for algae growth are high levels of nutrients such as phosphorous and nitrogen, warm water temperatures, and direct sunlight. These algae blooms affect the quality and performance of Broomfield s potable and reuse water systems. In the potable system, excessive algae can result in drinking water that has a musty or earthy taste and odor. Broomfield currently adds powder activated carbon (PAC) to reduce the unpleasant taste and odors associated with algae. However, there are instances when the PAC cannot fully remove the taste and odors, and staff occasionally receives complaints from customers about the quality of the water even though it meets all health and safety standards. Broomfield currently spends about $46,000 per year for PAC. This annual cost is expected to increase as Broomfield continues to grow and expand. Since Great Western Reservoir does not have the same type of treatment as the potable system, algae can enter the reuse distribution system and clog irrigation equipment such as strainers, valves, and individual sprinkler heads. In 2010, Broomfield spent approximately $20,500 to repair the clogged irrigation equipment throughout the parks served by the reuse system following an algae bloom in Great Western Reservoir. 9(h) - Page 2

3 Page 3 INITIAL PURCHASES Broomfield installed three solar powered mechanical mixers to help reduce the occurrence of algae blooms in One unit was installed at Glasser Reservoir and two were installed at Great Western Reservoir. These units are commonly referred to as SolarBees and are designed to create an environment near the water surface that inhibits algae growth. One of the Great Western SolarBees is shown in the photograph below. The primary advantages of SolarBees over other methods to reduce algae blooms in lakes and reservoirs are the relatively low annual operations and maintenance costs. Other control strategies such as mechanical aeration systems and chemical treatment have higher capital costs, higher operations and maintenance costs, or may be harmful to the environment. The original installation plans would have resulted in two SolarBee units at Glasser Reservoir and four at Great Western Reservoir. However, staff decided to take an incremental approach to determine the effectiveness of the SolarBees before installing the full amount since the equipment was not introduced until During the past several years, the reservoirs have shown signs of improvement but the algae blooms are still recurring. The current units do not provide enough mixing to be fully effective because of the large surface areas of the reservoirs. Staff and engineering consultants have evaluated other alternatives to minimize the taste and odor issues in Glasser Reservoir. One approach included construction of a separate bypass pipeline around the reservoir. This bypass alternative was part of the 9(h) - Page 3

4 Page 4 larger proposed Broomfield Reservoir project and would have cost approximately $1.1 million. Another approach that was evaluated included the construction of an entirely new chemical treatment process at the Water Treatment Facility. The estimated cost for this alternative was $2 to $3 million, depending on the type of treatment chemical used. Rather than pursuing these alternatives, staff is proposing to implement the original SolarBee configuration for each reservoir as shown in the figures below: Figure 1 Glasser Reservoir Solar Bee Locations Figure 2 Great Western Reservoir Solar Bee Locations 9(h) - Page 4

5 Page 5 FINANCIAL CONSIDERATIONS The two SolarBees for Great Western Reservoir have a slightly higher unit cost since they are subject to high winds and require a stronger anchoring system. The proposed sources and uses of funds to purchase three SolarBee units are summarized in the following table: Sources and Uses of Funds Sources: 2012 Budget CIP Water Reclamation $ 110, Budget - CIP Water Supply $ 52,000 Total Funds Available $ 162,000 Uses: Glasser Reservoir 1 SolarBee Unit Great Western Reservoir 2 SolarBee Units* $ 51, ,972 Total Projected Expenditures $ 160,983 Projected Balance $ 1,017 *The SolarBees at Great Western have a stronger anchoring system to cope with the strong winds experienced at that location. Broomfield is currently contracting with SolarBee, Inc. to provide repairs and adjustments to the three existing units on an annual basis. The cost of the current maintenance agreement is $6,000 per year. If the additional units are purchased, the maintenance agreement would be amended to include the removal of the Great Western Reservoir units each winter and reinstallation each spring to avoid damage by high winds and ice cover. The total estimated cost for the revised maintenance program for all six units, plus the annual removal and reinstallation of the four Great Western Reservoir units, is $15,000 per year. BROOMFIELD COMPREHENSIVE PLAN IMPLEMENTATION This project works towards implementing and is consistent with the following policies in Broomfield's Comprehensive Plan: Policy ES-B.1: Use sustainable development standards, policies and practices for new development and redevelopment that encourage and support the use of alternative energy resources. Policy UT-A.2: Develop and manage all utility systems to increase reliability on a daily basis and in time of need. Policy UT-A.3: Seek out new and innovative technologies to improve utility system planning, construction and maintenance. 9(h) - Page 5

6 Page 6 Policy UT-D.2: Utility structures should be maintained in a manner that does not degrade the appearance of the community. PROPOSED RESOLUTION NO Proposed Resolution No contains the necessary actions to authorize the City and County Manager to issue a purchase order for three SolarBee water circulators from SolarBee, Inc. for installation at Great Western and Glasser Reservoirs. Staff recommends approving this resolution. 9(h) - Page 6

7 RESOLUTION NO A RESOLUTION AUTHORIZING AND APPROVING THE PURCHASE OF THREE SOLARBEE WATER CIRCULATION DEVICES BE IT RESOLVED BY THE CITY COUNCIL OF THE CITY AND COUNTY OF BROOMFIELD, COLORADO: Section 1. The city and county manager is authorized to approve a purchase order for $160,983 to SolarBee, Inc. for three SolarBee units. Section 2. This resolution is effective upon its approval by the City Council. APPROVED on June 12, THE CITY AND COUNTY OF BROOMFIELD, COLORADO ATTEST: Mayor City & County Clerk APPROVED AS TO FORM: City & County Attorney 9(h) - Page 7