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Nitrates/Land Planning Info.

The concentration of nitrates in groundwater are a continual concern of developers, engineers, and users of the groundwater. The use of on-lot septic systems has caused concern about the release of high volumes of treated effluent to local groundwater. The effluent can cause nitrate nitrogen (NO₃-N) concentrations in groundwater which exceed the upper limit of 10 ppm established for drinking water supplies by the EPA.

The use of individual on-lot subsurface disposal systems and community on-lot subsurface disposal systems requires extensive site evaluations. These systems are dependent upon a very sensitive system of physical, chemical, and biological processes which use the soil and groundwater to renovate and dispose of sewage.

The EPA’s National Primary Drinking Water Regulations published in 1997 sets 10 parts per million (ppm) nitrate nitrogen as the upper limit for safe drinking water. The documents base this limit on studies in which infant cyanosis was linked with high concentrations of nitrate nitrogen in potable water supplies. These nitrates change the hemoglobin in the infant’s bloodstream to methemoglobin. Methemoglobin cannot carry oxygen, and oxygen deprivation occurs.

The Department of Environmental Protection (DEP) and some municipalities require that hydrogeologic studies be prepared as part of the planning for on-lot subsurface disposal systems. A hydrogeologic study prepared by a registered geologist reviews the geologic formations, groundwater recharge, and permeability of the soil to determine the impact of new on-lot sewage disposal flows on existing groundwater.

The hydrogeologic study begins with the collection of site-specific water samples to determine the background of current nitrate nitrogen levels in the groundwater. The geologist uses this and other published data to determine the size of the proposed building lot or easement required to negate any impacts to the groundwater for the on-lot subsurface disposal system.

As the background levels in the groundwater, identified through water testing, approach 10 ppm nitrate nitrogen, the size of the lots or easements become large and an effective development of the land is sometimes difficult. The options at this point are 1) don’t develop the land and 2) provide for treatment of the wastewater prior to discharge into the septic field. In fact, if current background levels exceed 10 ppm, nitrate nitrogen treatment of the waste is the only identified option. The permitted systems are known as the Biomicrobics "Fast" System and Cromoglass System. These systems, which can permit planning and subdivision in areas of elevated nitrates in water, do not come without cost. We have been advised that installation costs for the systems can be $6,000.00 - $9,000.00.

If high nitrates are initially found in the groundwater by the water tests, DEP does allow a request to use denitrification units rather than conducting a preliminary or detailed hydrogeologic study. This is accomplished through the sewage planning module process.

The Lancaster County Planning Commission (LCPC) has adopted the EPA’s National Primary Drinking Water Regulations as the minimum standards for water supply throughout the county. In areas of Lancaster County where the LCPC has approval power of subdivision and land development plans, they will require assurance that water meeting the EPA’s regulations is provided to each lot or land development. The reduction of nitrates in drinking water can be achieved with the installation of certain filters and treatment processes. The LCPC does not have a set standard for treatment or procedure of planning, and the approval time becomes lengthy. The time factor for the review and approvals required by DEP and LCPC must be considered in any planning timeline.

The information outlined herein is taken from a variety of sources both published and unpublished. It is provided as a basic overview of the nitrate nitrogen concern in groundwater. The rules and regulations are constantly changing, and it is difficult to provide an absolute procedure. DEP has verbally indicated that they may abolish denitrification treatment systems for on-lot systems. In fact, Rapho Township has been the first municipality to do so for on-lot systems. If DEP places a ban on the denitrification systems, the whole process will be placed in further confusion and the outcome is unknown.

32 Mount Joy Street - P.O. Box 128 - Mount Joy, PA 17552-0128 - (717) 653-5308

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Last Updated: 10/10/2008