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Aggregate Determination of Flows and Nitrogen Loading and Program Update Part 1. Nitrogen Aggregation Loading Plan. Goals Regulatory requirements Permitting process Case Study MassDEP’s Guidelines for Title 5 Aggregation of Flows and Nitrogen Loading , dated 7/01/98.

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Aggregate Determination of Flows and Nitrogen Loading and Program Update Part 1

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Aggregate determination of flows and nitrogen loading and program update part 1 l.jpg

Aggregate Determination of Flows and Nitrogen Loading and Program Update Part 1


Nitrogen aggregation loading plan l.jpg

Nitrogen Aggregation Loading Plan

  • Goals

    • Regulatory requirements

    • Permitting process

    • Case Study

  • MassDEP’s Guidelines for Title 5 Aggregation of Flows and Nitrogen Loading, dated 7/01/98


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Regulatory Requirements

  • 310 CMR 15.214:

    • No system serving new construction in Nitrogen Sensitive Areas … shall be designed to receive or shall receive more than 440 gallons of design flow per day per acre.

    • No system served by both a well and septic system shall receive more than 440 gallons of design flow per day per acre. (a.k.a. “private well areas”).


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Do Nitrogen Loading Limitations Apply*?

  • Interim Wellhead Protection Areas

  • Zone II of Public Water Supply Well

  • Nitrogen Sensitive Embayments or other areas as designated

  • Areas served by both on-site septic systems and drinking water supply wells

* Refer to 310 CMR 15.214 and 15.215


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Interim Wellhead Protection Areas (IWPA)

A protective radius around the public water supply well, typically based upon the pumping rate of the well.


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IWPA


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Zone II

A Zone II is an area of an aquifer which contributes water to a well under the most severe pumping and recharge conditions.


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Zone II


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What do we mean by 440 gpd/acre?

  • Design flow/acreage of facility

  • Acre = 40,000 sf (310 CMR 15.002)

  • Easy rules of thumb for residential projects:

    • 1 bedroom needs 10,000 sf

    • 2 bedrooms need 20,000 sf

    • Etc.

  • More complicated for non-residential projects


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Basic Example of N-Loading


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Nitrogen Loading Aggregation Plan

  • Provides for flexibility in meeting the 440 gpd/acre equivalency.

  • Obtain credit land to meet the 440 gpd/acre loading

    • Clustered subdivision with common space as credit land

    • Easement on a parcel in same NSA


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Using Credit Land


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Nitrogen Loading Plans

  • Community Aggregation Plan

  • Facility Aggregation Plan


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Facility Aggregation Plan

  • A document that restricts the flow (amount of bedrooms) on the Facility Land

  • A document that restricts the introduction of nitrogen and promotes recharge on the Credit Land.


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Facility Aggregation Plan Illustrated

  • 29-lot proposed subdivision served by on-site septic and wells

  • Part of the project is in a Zone II


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Undeveloped Parcel


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Proposed subdivision layout


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Sensitive Receptors Now Shown

Zone II


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Start the Analysis

  • Consultant should provide the following information (or it can be obtained from the Definitive Subdivision Plans):

    • Lot numbers

    • Square footage of each lot

    • Number of bedrooms for each lot

    • Describe which lots are within a nitrogen sensitive area and which lots are not.

    • Square footage of Credit Land and location


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Analysis (cont.)

  • All lots within subdivision are served by private wells and septic systems.

  • Some of them are within the Zone II.

  • All lots must all meet the 440 gpd/acre.

  • The calculation is easiest when organized in a chart.


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Chart – Basic Calculation


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Credit Land

  • Total Credit Land needed = 275,000 sf

  • Must meet certain criteria:

    • Within same NSA as Facility Land

    • Prohibit man-made sources of N

    • Prevent artificial impervious areas

    • Not within Velocity Zone or Regulatory Floodway identified by FEMA

    • Not under surface water, but wetlands are acceptable

    • Not already being used as Nitrogen Credit Land


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Credit Land

Lots outside Zone II

Lots inside Zone II


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Credit Land (cont.)

  • For lots outside of Zone II:

    • Considered private well areas

    • Credit land must be of sufficient amount to meet 440 gpd/acre (for those specific lots) and be within the same subdivision.

  • For lots inside of Zone II:

    • Considered NSA

    • Credit Land must be of sufficient amount to meet 440 gpd/acre (for those specific lots) and be withinthe Zone II.


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Calculation

Need 100,000 sf of Credit Land within the subdivision.


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Calculation (cont.)

Need 175,000 sf of Credit Land within Zone II


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Final Layout

Over 100,000 sf of Credit Land outside of Zone II

Over 175,000 sf of Credit Land within Zone II


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Summary - Important Notes

  • Calculate the amount of Credit Land for each and every lot, not just using the sum total of Facility Land.

  • Always calculate using square feet.

  • Areas within R.O.W. are not considered acceptable as Credit Land.

  • Delete all detention basins/ponds from Credit Land calculations.


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The Permit

  • Typically two documents:

    • One document restricts the Facility Land to a specific flow (number of bedrooms).

    • One document restricts the Credit Land from any sources of Nitrogen.


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Program Updates Part 1


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I/A Remedial Use Approvals

  • Approvals are currently being modified

  • Applicable to RUAed I/As that provide treatment

  • Permits LUA approvals without MassDEP approval under BRPWP64c

  • Look for updates on MassDEP’s website www.mass.gov/dep


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Groundwater Permitting Changes*

  • New 2-part process

    • Hydro-geo evaluation

    • Permitting

      • General Permit

        • <50,000 gpd

        • Not in a IWPA/Zone II

      • Site-Specific Permit

  • Current projected schedule

    • Spring 2008 – public hearings

    • Fall 2008 - promulgation

*Proposed regulatory changes . The proposed changes and

implementation schedule are still draft and subject to change.


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