Design Guidance Documents

The DNR has developed design guidance manuals for five technologies in an effort to broaden the number of treatment options considered for managing wastewater within Iowa's communities (with populations ranging from 25 to 250) and provide uniform design guidelines for everyone involved to follow.

The five alternative technologies evaluated are: Recirculating Media Filters, Sand Mounds, Drip Dispersal, Constructed Wetlands, and Alternative Collection Systems. Understanding the design guidance is important for consulting engineers and planners involved in the planning, funding, and design, and construction of wastewater treatment improvement projects since they are not addressed in current rules.

• Recirculating Media Filter Technology Assessment and Design Guidance Manual
• Sand Mound Technology Assessment and Design Guidance Manual
• Drip Dispersal Systems Technology Assessment and Design Guidance Manual
• Constructed Wetlands Technology Assessment and Design Guidance Manual
• Alternative Collection Systems Technology Assessment and Design Guidance Manual
  • Appendix A - Primary Treatment Units, Septic Tanks For Small Community Systems
  • Appendix B - Pressure Distribution Network Design

Due to revisions to Iowa’s Water Quality Standards, many communities have been faced with more stringent NPDES Permit limits for bacteria and end-of-pipe ammonia limits. Communities may experience significant costs associated with upgrading existing or building new wastewater infrastructure to meet effluent limits. These conditions created a need to broaden the treatment options considered for managing wastewater in Iowa communities.

The DNR has evaluated several new technologies for wastewater treatment as provided in section 14.4.3 “Required Engineering Data for New Process Evaluation” in the  the Iowa Wastewater Facilities Design Standards (IWFDS). These technologies are not addressed by detailed design criteria in the IWFDS. 

After research and data analysis, DNR staff developed technical design guidance for alternative wastewater treatment technologies. These assessments in addition to the applicable IWFDS are intended to provide guidance to designers for project submittals to DNR for review and approval based on current empirical information relative to the capabilities of the process in various applications. These processes were evaluated for technical capability for treating small municipal systems with primarily domestic wastewater only without industrial or significant commercial loads.

These assessments are not design standards, but when used in conjunction with design standards, should serve as expectations of the Department for permit approval. Based on information and experience, additional design standards may be developed in the future.

• Assessment No. 09-01 LemTec Biological Treatment
• Assessment No. 09-02 AdvanTex Treatment
• Assessment No. 11-01 SAGR Treatment (Updated December 2016)
• SAGR Example Calculations

Sequencing Batch Reactors (SBRs)

• Iowa DNR Design Guidance and Criteria for SBRs

Geotechnical Report Guidance Presentation

• Geotechnical Reviews Presentation (presented by Iowa Geological and Water Survey 2/21/12)