Frequently Asked Questions

1. What is the problem?
   
   In recent years, excessive levels of nutrients, specifically nitrogen and phosphorus, have resulted in eutrophication (i.e. algal blooms) in several of the town's surface water bodies. These events are predominately caused by nitrogen originating from onsite wastewater systems (fully functioning Title 5 septic systems, cesspool systems, etc.) in the areas that contribute groundwater to saltwater estuaries or harbors known as a watershed. Similarly, watersheds that contribute surface water or ground water to ponds can convey too much phosphorus to freshwater ponds. Excessive amounts of these nutrients causes the algal blooms resulting in an unhealthy environment.
2. What proof is there that a problem exists?
   
   In some instances, waters are periodically covered with mats of algae, smell like decaying fish, and therefore do not support the ecology of the Cape. For example, in 2009, an algal bloom occurred in Swan Pond creating aesthetically displeasing waters, fish kills due to depleted oxygen levels in the pond, and an odor that permeated the neighborhood for weeks. Shellfish crops also continue to decline.
3. Why is the problem arising now and a bigger issue on Cape Cod than other communities?
   
   Cape Cod has less than four % of the Massachusetts population but 20% of the septic systems in the state. The rapid population growth on the Cape over the past 50 years has resulted in excessive nutrient loading in surface and groundwater, largely from manmade sources, has migrated to the region's estuaries, particularly those downstream of highly developed or populated areas. Over time, nutrients build up within an estuary as a result of limited flushing.
4. If our drinking water is safe, what's the problem?
   
   Public health-related nitrate thresholds (10 mg/l) are ten times higher than the thresholds established for healthy estuarine ecosystems (typically 0.5 mg/l or lower); therefore, it is common to meet drinking water standards while still greatly exceeding the nitrogen levels in groundwater required to protect the saltwater environment. Freshwater bodies and groundwater supply wells are more resilient to nitrogen impacts than saltwater embayments.
   
   The freshwater shorelines are classified as "coastal plain pondshores," which provide habitat to rare and endangered plants and animals. As water quality declines, the tourist industry will decline as well. Property values and tax revenues in coastal areas will decline, and the burden of maintaining town services will shift inland, to those who can least afford it.
5. What if our town sticks with the status quo and does nothing?
   
   We have seen a decline in the quality of our water resources and we cannot ignore this situation any longer. Our quality of life is being impacted. Our tourist economy will be impacted. The cost to address the issues will only increase and should not be left solely to future generations to address. If the town does not initiate this project on its own terms, the project could be forced upon us by regulators, such as the Cape Cod Commission. In this case, local residents will have less say on important issues regarding cost, traffic disruption, the timeline and economic redevelopment.

1. Why don't they?
   
   Typically over 85% of the controllable nitrogen comes from water leaching from fully compliant Title 5 septic systems down to the groundwater table, which ultimately surfaces in our streams and estuaries. This type of system was designed to remove solids and bacteria. Title 5 systems only remove about 10 to 15% of the nitrogen in waste discharged to them. It is important to understand that effluent leaving a Title 5 septic system on a lot 300 feet or 3 miles from an estuary can still affect the water quality of the receiving estuary. The septic system effluent infiltrates down to the groundwater table where the groundwater then conveys it as it flows toward an estuary before daylighting in the open water body.
2. My septic works fine. Why should I have to pay for another solution?
   
   All septic systems contribute to nitrogen loading in some capacity. It is in the town's interest to retain local control of this future large capital project. The state and federal environmental regulatory authorities are under pressure from a lawsuit to enforce the water quality standards of the federal Clean Water Act. If the town does not initiate this project on its own terms, there is a real possibility that the project will be forced upon us by an outside agency in which case local residents will have less say on important issues regarding cost, traffic disruption, the timeline and economic redevelopment.
3. Why don't septic systems impact our drinking water?
   
   Septic systems are designed such that they are located at an appropriate distance from drinking water sources and convey wastewater away from drinking water sources. Dennis' drinking water supply is well protected through a combination of maximizing land ownership and control within the Zone IIs (the area of an aquifer that contributes water to a well under the most severe pumping conditions) to its wells, maintaining a town Wellhead Protection District, and conducting annual household hazardous waste collection days. Historically, the Dennis Water District has been very proactive by purchasing land to protect the town's drinking water areas. Additionally, as stated above, drinking water threshold values are higher than those values which may impact a healthy estuarine ecosystem.
4. Does keeping my septic system pumped help?
   
   What if I don't have it pumped? Performing regular maintenance on your septic system, such as pumping out the solids, is recommended to allow the system to function as intended and help prevent back-ups or solids overflow into the leaching field. Portions of the town are likely to always utilize Title 5 or related on-site systems.
5. I just installed a new septic system-if everyone knew there was a problem, why didn't I have a better alternative?
   
   The town is actively working to develop a town wide plan to combat the nitrogen contamination issue. It is likely that homeowners that newly installed Title 5 septic systems will be given a grace period to comply with the selected implementation scenario. The town wide plan is also likely to take 30 plus years to fully implement.

1. Current levels in our watersheds vs. allowable levels
   
   The table below provides the current attenuated nitrogen load in each of the watersheds within the Town of Dennis compared to the threshold nitrogen load. The threshold load is the amount of a substance that can be assimilated into a natural environment to maintain the water body's designated uses:
   
   

   Watershed	Current Attenuated Total Loading (kg/day)	Threshold Total Loading (kg/day)
   Bass River	217.8	114.5
   Swan pond	43.7	10.7
   Herring River	62.8	47.9
   Chase Garden Creek	135.2	207.1
   Sesuit Harbor	Results pending release of final MEP report	N/A

2. Healthy drinking water
   
   2020 Annual Range of nitrate as N found in drinking water supply wells: Non detect up to 2.1 mg/L vs. a Maximum Contaminant Level (MCL): 10 mg/L.
3. Title 5 septic system output
   
   Effluent from a Title 5 septic system contributes approximately 6.2 kg of nitrogen/yr/parcel, leaving a nitrogen concentration in the recharged effluent at a concentration of about 35 mg/L.
4. I/A system output
   
   Effluent from an advanced innovative and alternative (I/A) wastewater treatment system contributes approximately 3.1 kg of nitrogen/yr/parcel, leaving a nitrogen concentration in the recharged effluent at a concentration of 13 to 19 mg/L.
5. PRB attenuation
   
   The Town of Dennis has included permeable reactive barriers (PRBs) in their wastewater management plan. These barriers would provide increased nitrogen removal from the watersheds. For the sites that include PRBs, the intention would be to install them around the perimeter of the effluent recharge basins as a final polishing step or downgradient of Town owned landfills and other sites that are suspected of contributing high concentrations of nitrogen to the surrounding watersheds. Site specific investigations will need to be performed in order to determine the PRB's effectiveness in removing nitrogen at each site. The treatment technologies chosen for application at the WWTP are capable of achieving an effluent nitrogen concentration of 3 mg/L, which is required by the TMDL set in the MEP reports for the Bass River and Swan Pond River watersheds. As stated in the CCC 208 plan, treatment of wastewater through a PRB can result in a 75% to 95% reduction in the concentration of nitrogen in the effluent. Assuming that the application of a PRB around effluent recharge ponds will result in an effluent nitrogen concentration of 1 mg/L is a conservative approach, as this would indicate that the PRB was capable of reducing nitrogen by 67%.
6. What is Permeable Reactive Barrier (PRB)?
   
   A PRB is a subsurface permeable barrier, comprised of either inorganic or organic material, chosen to target the reduction of specific contaminates. This material provides a carbon source for denitrification to occur
7. Natural Attenuation
   
   Values of natural nitrogen attenuation vary greatly depending on the media the wastewater travels through, including ponds, streams and marshes. Natural attenuation can account for anywhere between 30 to greater than 50% nitrogen attenuation depending on the path the groundwater travels prior to entering the estuaries.
8. Allowable levels of nitrogen to restore our estuaries are defined above. Is there value in seeking interim values that could be more affordable but only achieve some fraction of the total reduction needed?
   
   The rate at which the estuaries are deteriorating will already take many years to slow down and ultimately reverse the impacts, even if immediate action is taken; therefore is it recommended that the full threshold values be targeted. However, the town wide plan is likely to be implemented in phases within each watershed and the water quality monitored between phases to determine progress in meeting the targeted values.

1. What is the role of the Wastewater Implementation Committee (WIC) and what have they accomplished?
   
   The WIC is a committee consisting of 10 members; eight community volunteers appointed by the Select Board, and two members of the Select Board. Other Town staff are involved in the WIC as well, including the Town Engineer, the Director of the Office of the Board of Health and representatives from the Town Administrator's Office and the DPW senior management team.
   
   In recognition of the importance of preserving, restoring, and maintaining high-quality water resources, the WIC has been involved in the development of the Town's Comprehensive Wastewater Management Plan (CWMP).
2. Will decentralized sewer systems help and are there alternatives to sewers?
   
   Decentralized sewer treatment systems consist of collection, treatment and dispersal of wastewater from individual homes, larger industrial or commercial facilities, clusters of homes or entire communities. These systems can be stand alone or be tied into existing centralized systems and can therefore be seen as an alternative to town wide sewering. Onsite I/A systems are also being considered.
3.  What will happen to sludge from any proposed centralized sewer treatment facility?
   
   The sludge generated from a centralized wastewater treatment facility will be treated and either beneficially reused or disposed of in an existing approved landfill.
4. What are Advanced Innovative and Alternative (I/A) systems. What are the pros and cons of such systems?
   
   I/A systems are onsite advanced septic systems designed for nutrient reduction. These are more sophisticated than a Title 5 system and must be monitored by a licensed operator.
   
   Pros: I/A systems are more efficient in removing contaminants such as nitrogen and solids from the wastewater over conventional technologies.
   
   Cons: Regulatory hurdles due to the new technology. The Department of Environmental protection (MassDEP) will need to approve the plan for a I/A technology prior to implementation.
5. Why all the talk about oysters?
   
   Oysters have the ability to uptake and remove nitrogen from impaired water bodies. On Cape Cod, there are at least three examples where oyster aquaculture demonstration projects have been employed to help restore water quality and remove nitrogen from coastal estuaries. The Town of Dennis is intending to pilot this process and is considering it's use longterm as a polishing step to further remove nitrogen.

1. What is the impact of nitrogen on fresh water? What are the impacts of Phosphorous?
   
   Currently, MassDEP does not have a numerical criterion for nitrogen unless the water body is subject to a Total Maximum Daily Load (TMDL) or site-specific criterion; however, discharges that result in excessive aquatic plant or algal growth (eutrophication) need to be controlled. In some highly eutrophic lakes (which have excess phosphorus - more than plants need to grow), nitrogen can become the limiting nutrient for plant productivity. In these cases, an ecological advantage is afforded to certain blue-green algae that have the ability to obtain nitrogen from the atmosphere (called fixing nitrogen) and use this nitrogen as a nutrient source to fuel algal growth. Thus nitrogen limitation in ponds with excess phosphorus concentrations can be a factor in blue-green algal blooms. However, most freshwater ponds on Cape Cod are phosphorus limited.
   
   Similarly, there is no numerical criterion for phosphorous unless the water body is subject to a TMDL or site-specific criterion. Phosphorus is a key nutrient influencing plant growth in ponds. Phosphorus is usually the limiting nutrient to freshwater ponds here in New England, such that increasing its concentration alone will result in greater plant productivity.
2. Scargo Lake looks great-is there a problem?
   
   Conditions of Scargo Lake have worsened and the pond is becoming impaired. The Scargo Lake Memo, written by The Cape Cod Pond and Lake Stewardship (PALS) program, recommends that the town consider hypolimnetic aeration as a remediation measure for Scargo Lake. This entails providing aeration to the bottom layer of the lake during the period of the year when the lake is stratified (May through September). This and other methods will be considered in the town wide water resources program.
3. How many fresh water bodies do we have?
   
   The Town of Dennis has approximately 29 ponds with a total area of 749 acres, including three ponds shared with neighboring towns.

1. What are the plan elements and how are they of value to Dennis?
   
   The Cape Cod Commission's Area-wide Water Quality Management Plan Update ("the 208 Plan") has been developed to address federal regulatory requirements. The 208 Plan discusses the nitrogen problem Cape-wide and presents a suite of options towns can consider in solving their nitrogen loading issues. The 208 Plan's recommendations are based on meeting the goals outlined in each Massachusetts Estuaries Project (MEP) report. The Cape Cod Commission has designated each Cape Cod town as the Waste Management Agency responsible for meeting the Clean Water Act requirements for water resource protection. 208 refers to the section of the Federal Clean Water Act requiring a regional plan to be developed.
2. The 208 plan advocates use of purportedly lower cost I/A systems and consideration of centralized sewer systems as the last approach. Is Dennis following this guidance?
   
   Yes, to distinguish between proposed scenarios in the Dennis Water Quality Evaluation and Mitigation Alternative Study, a detailed evaluation matrix was developed. Within the matrix, I/A systems were given a higher rating and centralized sewer was given a lower rating value.

1. What are the short and long-term cost projections to homeowners?
   
   Short-term homeowner costs will be determined at the time of construction. In collaboration with the WIC, the Town decided to move forward with three different means of cost recovery for the Recommended Plan. These include revenue from the Landfill Solara Fund, a 2% increase in the Local Rooms Tax Fund, and allocation from the Wastewater Infrastructure Investment Fund (WIFF). The resultant average tax increase over the 70-year period for a $350,000 assessed home is $224 using all three cost recovery methods.
2. This is a lot of money. Can the town afford this?
   
   This will be an expensive program but it will be implemented over a 30-year period. This is similar to the Dennis Water District public water supply which has already been implemented.
3. Is state, federal or other funding sources possible?
   
   Typical funding mechanisms for wastewater programs include general taxes, betterments, connection fees, infrastructure investment funds and user fees. In addition, more innovative funding mechanisms must also be considered in the development of a comprehensive funding approach that spreads the financial burden of such a program across all benefactors in an affordable way. As noted in Question/Response 7.A. the Town is implementation a variety of cost recovery methods for the program. These methods would be used to repay capital funds borrowed to implement the recommended program, which are typically borrowed via the Clean Water State Revolving Fund (SRF) loans for a 20 or 30-year period at up to 2% interest. Additionally, The Town is also planning to use American Rescue Plan Act (ARPA) State Fiscal Recovery Funds to supplement the above programs.

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