Land Development Notice


Land Development Services
12055 Government Center Parkway
Fairfax, Virginia  22035
703-324-1780, TTY 711


Please Note: Technical Memorandum 14-05, Moratorium on Stackable, Modular Plastic Units as Underground Stormwater Management Facilities Suspended supercedes this notice.


Feb. 9, 2012

Moratorium on Use of Stackable Modular Plastic Units for Underground Stormwater Management Facilities

Due to two recent failures in the field, Fairfax County is re-evaluating the adequacy of current materials, design, construction, and inspection requirements for these systems.  Until further notice, underground stormwater management facilities constructed with stackable modular plastic units, including but not limited to StormTankTM, RainStore3TM, RainTankTM, StormblocTM, and CUDOTM, will not be allowed under the innovative BMP provisions of the Public Facilities Manual or as an alternative to pipes or vaults for underground detention. 

This prohibition applies to all plans that have not received final plan approval. Any plans under review that include these types of systems cannot receive final plan approval during this time frame unless a plan revision is made to replace the system with a facility that can be approved by the Director of the Department of Public Works and Environmental Services.  In addition, plans that incorporate this type of system will not be accepted until the moratorium is lifted. 

For projects that have already received final plan approval or are under construction, developers and their engineers are advised to:

  1. Review facility designs for compliance with the manufacturer’s latest design and construction specifications;
  2. Assure that project managers, site superintendents, and contractors have available to them copies of the manufacturer’s latest construction specifications; and
  3. Provide oversight of the installation by a licensed design professional.  The moratorium does not apply to underground facilities, where allowed, constructed from stackable modular concrete units or unstacked pipes and arches made from concrete, CMP, or HDPE approved for use in drainage applications.

If you have any questions, please contact Site Code Research and Development Branch at 703-324-1780, TTY 711.


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