Tri-Town Septage Treatment Facility Evaluation

Prepared for Wastewater Management Steering Committee
Town of Orleans, Massachusetts By:

Wright-Pierce
99 Main Street
Topsham, Maine 04086

AUGUST 2005
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The Tri-Town facility is nearing 20 years of age, and the original tanks and equipment are showing signs of wear. The District's Board of Managers and the Town of Orleans have agreed that it is time to formulate a plan to upgrade the facility. At the same time, the Town of Orleans is embarking on comprehensive wastewater management planning, and the Towns of Eastham and Brewster may follow suit. Given that setting, this report is intended to accomplish two goals:

* Identify the upgrading needs of the existing septage treatment facilities, and establish a capital budget, and
* Determine if the Tri-Town site may be suitable to satisfy some or all of the future needs of the Town of Orleans for wastewater treatment, wastewater disposal, or both.

 

 

 

 

 

 

 

 

 

 

 

The facility, shown above, is designed to treat up to 45,000 gallons per day of septage, grease and related trucked wastes.  It was built to serve the Towns of Orleans, Eastham and Brewster, but it also receives trucked wastes from the three Lower Cape towns of Provincetown, Truro and Wellfleet, as well as small quantities from other nearby towns.

 The report noted that although the Tri-Town plant is well operated and maintained, some of the equipment is nearing the end of its useful life. Proposed upgrading steps will cost about $1.8 million without inflation.

While the Tri-Town plant is allowed to discharge up to 50 mg/l total nitrogen, the District staff has worked hard to maximize nitrogen removal, even though there are no formal nitrogen removal processes at the plant. In recent years, the plant effluent has contained, on average, 30 to 40 mg/l of total nitrogen, well below the permit limit.

The Tri-Town plant has sufficient capacity for the projected quantities of septage and
liquid sludge from the three District towns under build-out conditions. Unfortunately, there is a marked seasonal variation in septage generation rates, such that the plant runs below capacity in the winter and must turn away septage trucks in the summer.

There is significant unused land at the Tri-Town site that could accommodate a much higher volume of effluent application than is currently discharged. A conventional layout of additional rapid infiltration beds indicates the capacity to discharge a sustained peak flow of about 750,000 gallons per day (gpd), or about 15 times the current permitted volume.  Assessing the environmental impacts of the expansion was not addressed in the study and is the focus of on-going studies performed by the Massachusetts Estuaries Project (MEP), however USGS Modeling did evaluate the projected plume paths of various discharge rates.

The report investigated the following broad options for septage and wastewater management at the Tri-Town Site:

  • Option 1--Upgrading the existing septage treatment facilities to extend their useful life by 20 years, without any increase in capacity or treatment level.
  • Option 2--Extending the service life by 20 years and providing nitrogen removal to a 10-mg/l limit, without increasing the capacity.
  • Option 3--Extending the service life, proving nitrogen removal, and increasing the capacity from 45,000 gpd to 60,000 gpd.
  • Option 4--Improving and expanding the septage facility as described in Option 3 and building facilities for wastewater treatment and/or disposal.
REPORT RECOMMENDATIONS
  • The Tri-Town staff should continue its excellent record-keeping program that tracks the source of all septage loads received at the plant. Annual review of this information is warranted to monitor any trends toward higher quantities in any of the District towns or other towns served.
  •  Barnstable County should develop a program for receiving and analyzing data from all regional septage facilities to track similar trends Cape-wide. 
  • The Board of Managers could embark on a multi-year phased program of capital improvements to address the upgrading recommendations of this report. In so doing, consideration should be given to maintaining the flexibility for the plant to receive and treat liquid sludge from a co-located or nearby wastewater plant or plants.
  •  The Board of Managers should consider offering long-term contracts to other Lower Cape towns to receive and treat their septage. These contracts would commit the Board of Managers to expand the plant if and when necessary, and would provide for capital payments from those towns to assure that capacity. By expanding the plant concurrent with addressing other upgrading needs, economies of scale can accrue to all participating parties
  • Either as part of inter-municipal agreements or through pricing policies, the Board of Managers should provide incentives to level the normal seasonal peaks in septage generation.
  •  As the Towns of Orleans, Eastham and Brewster undertake comprehensive wastewater management planning, the Tri-Town site should receive serious consideration as one of the possible sites for a wastewater treatment plant, as well as a site for effluent disposal.
  • The Town of Orleans should monitor the availability of land near the Tri-Town site as possible effluent disposal locations.
  •  Both the Board of Managers and the Town of Orleans should provide close coordination, input and oversight of the MEP studies of the Cape Cod Bay watersheds to ensure that a fair appraisal is made of the assimilative capacity of Namskaket Creek and other impacted watersheds. This must involve the incorporation of past and ongoing USGS studies of Namskaket Marsh. 
  • The Town of Orleans should undertake detailed hydrogeologic evaluations of the Tri-Town site as part of the CWMP consistent with the MEP study results.
  •  The Town of Orleans should conduct a cost-effectiveness analysis of options for new public-works-type facilities, including the Tri-Town site. This effort should be coordinated with the CWMP so that the relative value of Parcels 1 and 1A can be fairly assessed. If wastewater treatment and disposal needs can be handled elsewhere and/or if other potential public works sites are difficult to acquire or develop, than the reuse of the compost shed at the Tri-Town site may be a very desirable option. Conversely, if the CWMP shows that the Tri-Town site is particularly valuable for wastewater treatment and disposal, and/or the public works function are easily accommodated elsewhere, it may be in the overall best interests of the Town to locate the public works facilities elsewhere. The right decision can only be made when the relative costs and merits of other sites are considered
  •  The Board of Managers should be prepared to add denitrification facilities in the event that the plant is expanded or if the MEP studies show that the current 50 mg/l standard is not sufficiently protective.
  • The Board of Managers should continue to place high priority on effective odor and noise control to extend the record of good performance established over the last few years. Funding for equipment repairs and for carbon replacement should continue to be a high priority.