Replacement of the existing Marbach Road substation with the new Hunt Lane substation is required to: (1) improve power reliability and reduce risk of outages due to flooding conditions; (2) support continued growth of customer load/energy demand; and (3) improve reliability through replacement of aging substation infrastructure.

Significant residential and commercial development in the area surrounding the Marbach Road substation has caused redistribution and concentration of floodwaters.  The Marbach Road substation has experienced significant and increased flooding over the past twenty years.  The following chronology depicts the flood events and responsive actions:

• Late 1967 - Substation constructed.
• May 1987 – Flood waters flowed into the substation, causing equipment damage and interruption of service to customers.  A hydrologic study was commissioned to determine the cause of the flooding and possible solutions.  The study concluded that flood waters would rise from backup on the downstream drainage and that flooding could not be prevented by improvements on CPS Energy property.  No corrective action was taken, as it was believed to be a rare occurrence.
• October 1994 – Flood waters flowed into the substation, causing equipment damage and interruption of service to customers.  CPS Energy reviewed the 1987 hydrologic study and studied the possibility of replacing the driveway culvert with a free-standing bridge.  It was determined, due to infrequency of flooding, that the solution presented offered limited benefits in comparison to the cost of implementation.
• Early 1998 – Changes were made to EPA’s Spill Prevention, Control and Countermeasure (SPCC) requirements, forcing installation of a 3-foot flood wall and imbiber oil-separating gravity drains.  Drains include check valves to stop back flow into the substation if flood water rise above substation grade.  Flood wall will act as containment until water recedes. 
• October 1998 – Flood waters flowed over the newly installed flood wall, damaging substation equipment and interrupting service to customers.  This led to an engineering review and recommendation for an additional wall extension.
• Early 1999 – A flood wall extension was added.  Review of hydrologic parameters in original study indicated run-off upstream of substation was increased due to land development.  A new hydrologic analysis indicated the extension should protect the substation against a 100-year flood.
• Early 2000 - Limited drainage through imbibers led to high water inside the flood wall, due to unusually fast/dramatic rainfall on the substation site and runoff from subdivision.  Imbibers were replaced with simple oil-skimming plates.  Electric pumps were installed to remove water when the flow was impeded by high water outside flood wall.
• July 2002 – Flood waters flowed over the flood wall extension, damaging substation equipment and interrupting service to approximately 6,400 customers.  It took approximately 2 hours to restore service to all of the customers.  No corrective action was taken for stream flooding, because any additional extension to the current flood wall would restrict access from the Hunt Lane entrance.  The rear entrance is intended as an emergency entrance and does not accommodate large construction and maintenance equipment.  A diesel powered pump was installed because flooding cut power to the electric pumps.
• May 2007 – A plan was developed to replace Marbach Road substation with the new Hunt Lane substation.  With continued development in the area, it is anticipated that the risk and the severity of flooding events will only continue to increase.  The flooding events have caused interruption of service to customers, shortened equipment life spans, extended outages for cleanup and repair of damaged equipment, and a risk of damage to additional/near-by equipment that could have caused additional customer outages.
  
  Internal studies showed that as flooding severity increases, extended Marbach Road substation outages will result in additional and extended customer outages.  In particular, the area between Marbach, Bandera, Anderson and Cagnon substations is at risk of no service for an extended period of time.
  
  Over the next five years, continued development is expected in the area served by the Marbach Road substation.  This additional development will increase the area’s electrical demand by approximately 17 percent.  An additional substation distribution transformer is required to meet demand levels by the year 2009.  Also, beginning in 2009, aging substation equipment, such as the switchgear supplied by transformers #2 and #3, will require replacement to ensure reliable operation.
  
• July 2007 - Flood waters flowed over the flood wall extension, damaging substation equipment and interrupting service to approximately 7,000 customers.  It took approximately 3 hours to restore service to all of the customers. 
• August 2007 – Flood waters flowed over the flood wall extension, damaging substation equipment and interrupting service to approximately 7,000 customers.  It took approximately 3 hours to restore service to all of the customers.

Each of the above-listed flooding events required approximately 60 hours of round-the-clock work and two additional weeks of normal work to restore the substation equipment to normal operating conditions.  During this time period, the customers served by the substation were at an increased risk of extended outages.

As a municipal electric utility, CPS Energy must represent the interests of all customers by choosing the most cost effective solution to identified needs.  The Hunt Lane substation will facilitate transfer of load-serving functionality from the Marbach Road substation, effectively eliminating the risks associated with anticipated future flooding.  The Hunt Lane substation will be constructed to accommodate the additional substation distribution transformer required for the increasing electrical demand of the area.  The Hunt Lane substation will also be constructed with newer equipment to replace the aging and flood damaged Marbach Road substation equipment.  It is recommended to construct the new Hunt Lane substation by October 2009.

Customers currently served from the Marbach Road substation should expect to have more reliable service from the new Hunt Lane substation.

• Initial Considerations – The property between Hunt Lane & Ellison Drive, containing the four existing 138-kV transmission lines, was the obvious first consideration due to the current CPS Energy property ownership.  The substation can be constructed above the flood plain within the existing property and adjacent to current property owners.  Additionally, the site was chosen because it presents the least expensive alternative for connection to the existing distribution hub.  Identification of any other location was dismissed due to: the possibility of additional transmission being located adjacent to currently nonadjacent property owners, the substation site being located adjacent to either currently adjacent or nonadjacent property owners, and the additional cost to extend the distribution lines a farther distance from the existing distribution hub.
• Move the substation closer to Ellison Drive – The properties on either side of Ellison Drive are sufficient for construction of a substation, because they are not located in a flood plain.  However, the substation property would have to be acquired from the current property owner and the location would be adjacent to either currently adjacent or nonadjacent property owners.  In addition, there is significant additional cost to extend the distribution lines an additional 3,000 feet from the existing distribution hub to an Ellison Drive site.  Any other possible location farther west along the existing transmission lines will present the same difficulties and greater expense for distribution line extensions.
• Relocate the substation to the SAWS property, south of the existing substation – There is a site located on the southeast portion of the SAWS property that is sufficient for construction of a substation, because it is not located in a flood plain.  The site would have to be acquired from SAWS.  To facilitate this location, a new transmission line would have to be constructed from the existing transmission line, south of the existing Marbach Road substation, to the new location.  The transmission line would require a routing/siting analysis to determine a route, would be routed adjacent to currently nonadjacent property owners, would be located within the existing flood plain, and would significantly impact the cost of the project.  In addition, there is significant expense required to extend overhead and underground distribution lines from the existing distribution hub, through a flood plain, to the SAWS site.  Locating these distribution lines through a flood plain will increase the risk of power outages and create issues associated with emergency maintenance operations.

A drainage improvement project could improve flooding conditions at the existing Marbach Road substation, however the substation’s proximity to the 100-year flood plain makes it impossible to flood-proof the substation. While the substation’s original placement had only moderate risk of flooding, development and changes to the nearby grading over time have significantly contributed to flooding problems. There is no expectation that this could be changed.  With a continued risk of flooding, the substation remains vulnerable to excessive power outages and flood damage.  In addition to the expense of improving the drainage system, there are multiple projects required within the existing Marbach Road substation to replace aging substation infrastructure and to support continued development in the area.

Previous attempts to keep flooding outside the substation footprint have failed.  The streambed on CPS Energy property was improved and a barrier wall was constructed around the substation, but recent flooding has increased in severity.  Flooding arises not only from the adjacent streambed, but also from runoff from the adjacent subdivision.

A drainage improvement project for the Marbach Road substation would have to be undertaken by the City of San Antonio (CoSA).  The project would undergo prioritization by CoSA and, if selected and funded, would follow the same process as other drainage projects.  This requires an extensive hydrologic study of the adjacent watershed, choice and engineering of drainage improvements, approval by affected land owners and the Army Corp of Engineers, acting on behalf of the Federal Emergency Management Agency.  The proposed project would require improvements on CPS Energy property and non-CPS Energy / non-CoSA properties.  Easements must be acquired on properties that require drainage improvements.  The drainage improvement project must provide proof that it would not adversely affect any other properties downstream.  If the drainage improvement project receives the required authorizations, it is expected that completion of the project may be accomplished within a five year timeframe.

The EPA has mandated that facilities with the possibility of releasing petroleum fluids into waterways must possess a preventative system.  Electric substations, such as the Marbach Road substation, contain insulating/cooling oil used in power transformers.  The system must be operational for a 100-year flood event.  The Marbach Road substation is within a 100-year flood plain.  Therefore, flood waters must be kept out of the substation for the spill containment system to be functional.  An additional concern is that the substation has experienced flooding conditions greater than a 100-year flood event.

A drainage improvement project would conceptually alleviate the risks associated with a selected flood event.  However, the drainage improvement project would not eliminate the substation’s vulnerability to larger flood events brought on by continued development, greater than 100-year rainfall amounts, or possible changes to the planned operation of the drainage system.  Since flooding remains a conceivable risk, based on best engineering practices, the substation should be relocated to a site well above the 100-year flood plain.

Raising the elevation of the existing Marbach Road substation can improve flooding conditions, but the substation’s proximity to the 100-year flood plain makes it impossible to flood-proof the substation.  With a continued risk of flooding, the substation remains vulnerable to power outages and flood damage.  Raising the substation’s elevation would displace floodwater, both on CPS Energy and adjacent property, thereby requiring drainage system improvements similar to the aforementioned process.  Raising the substation’s elevation would require a complete rebuild of the existing substation.  The substation would have to remain energized during the rebuilding operation; thereby costs would be significantly greater than relocating the substation.  In addition, adjacent transmission towers would require modifications or replacement, increasing the project costs further.

Raising the elevation of the existing Marbach Road substation would conceptually alleviate the risks associated with a selected flood event.  However, the elevation change would not eliminate the substation’s vulnerability to larger flood events brought on by continued development, greater than 100-year rainfall amounts, or possible changes to the planned operation of the drainage system.  Since flooding remains a conceivable risk and with the project cost anticipated to be significantly greater than relocation, it is practical to relocate the substation to a site well above the 100-year flood plain.

Installing taller barriers around the perimeter of the existing Marbach Road substation can improve flooding conditions, but the substation’s proximity to the 100-year flood plain makes it impossible to flood-proof the substation.  With a continued risk of flooding, the substation remains vulnerable to power outages and flood damage.  Installing taller barriers also would displace floodwater, thereby requiring drainage system improvements similar to the aforementioned process.  The existing flood wall has created accessibility issues and installation of a taller barrier would make access to the substation even more difficult, not only for the larger equipment, but also for the smaller vehicles used for more frequent construction, maintenance, and operations functions.  In addition to the expense of installing taller barriers and improving the drainage system, there are multiple projects required within the existing Marbach Road substation to replace aging substation infrastructure and to support continued development in the area.

Installing taller barriers around the perimeter of the existing Marbach Road substation would conceptually alleviate the risks associated with a selected flood event.  However, the increased flood wall height would not eliminate the substation’s vulnerability to larger flood events brought on by continued development, greater than 100-year rainfall amounts, or possible changes to the planned operation of the drainage system.  Since flooding remains a conceivable risk using best engineering practices, the substation should be relocated to a site well above the 100-year flood plain.

The substation will be constructed by a contractor whose normal working hours will be Monday-Friday, 7:00 a.m.-6:00 p.m., with the possibility of working on Saturdays, as needed, to maintain construction schedules.  There will be a CPS Energy representative on site at all times for the duration of the substation construction.

The substation will be constructed by a contractor whose normal working hours will be Monday-Friday, 7:00 a.m.-6:00 p.m., with the possibility of working on Saturdays, as needed, to maintain construction schedules.

In general, the strongest EMF around the outside of a substation comes from the power lines entering and leaving the substation. The strength of the EMF from equipment within the substations, such as transformers, reactors, and capacitor banks, decreases rapidly with increasing distance. Beyond the substation fence or wall, the EMF produced by the substation equipment is typically indistinguishable from background levels.

The line terminals are the structures where the transmission lines stop, before they enter the substation. For operational and safety purposes these structures must be at least 52 feet tall to accommodate safe clearances during construction.  Since we can not have an extended outage on this transmission line during construction, the new line terminals will be used to temporarily route the transmission line over the substation during construction to allow enough overhead clearance to construct the substation beneath them with minimal transmission line outages. 

The Hunt Lane Substation will be a “low-profile” design.  The majority of the structures are as low as they can be while still maintaining safe electrical clearances for the vehicles that are required to maintain the substation in the future.  This substation will have fewer structures than the current Marbach Road Substation.

All Storm water runoff from the substation will be temporarily captured in a storm water detention basin and released gradually over a period of time after each rainfall event.  Runoff will be directed from the detention basin towards a drainage feature, west of the substation, that runs South between Mossy Creek Dr. and Fort Donelson Dr.  

Buzzing/humming will be produced inside the substation by the power transformers, which is a normal phenomenon created by these power transformers.  It will be reduced by installing a masonry panel screen wall surrounding the substation.  The wall will be approximately 10 feet tall.

The power transformers are the main source of the steady sound coming from the substation.  The sound pressure level has been measured to be between 55 dBA and 60 dBA at a distance of 50 feet from the transformer.  The transformers will be placed almost midway in the 200-feet-wide CPS Energy property.  The sound levels will be reduced by the masonry panel screen wall surrounding the substation on the north and south.  As a comparison, the sound pressure range of normal talking at a distance of 1 meter is between 40 dBA to 60 dBA.

Phase 1 of the project is to build the new Hunt Lane substation.  Construction is planned to start as early as October 2008 with a completion date of October 2009.

Phase 2 will be to decommission the existing Marbach Road station.  This process is expected to be completed by December 2010.

CPS Energy cannot determine at this time if adjacent property values would be affected by the placement of a substation at the proposed location given that the proposed site is in an existing power line right-of-way.

CPS Energy only compensates landowners from which easements and/or fee property is being acquired, but, based on law and practice, does not compensate neighboring landowners.  Compensation is based on fair market value of the easement or fee property.  This project, however, does not require any acquisition of property since CPS Energy already owns the site.