1. 2013 Ammonia Criteria Update
Tom Wallace
Geosyntec Consultants
REGFORM Water Seminar
September 5-6, 2013
Columbia, Missouri

2. New vs. Old
Criteria magnitudes are expressed as total ammonia nitrogen (mg TAN/L) at pH = 7.8 and 26˚C. Criteria assume
Oncorhynchus spp. absent, early life stages (ELS) present, and Unionid mussels present.

3. Acute Ammonia Criteria
 Lasmigona subviridis, Green Floater
 Epioblasma capsaeformis, Oyster mussel
 Villosa iris, Rainbow mussel
 Lampsilis sp., River mussels
Normalized to pH 7.0 and 20˚C

4. Chronic Ammonia Criteria
 Lampsilis spp., Wavy-rayed lamp mussel and
Fatmucker
 Villosa iris, Rainbow mussel, Oyster mussel
 Lepomis spp., Bluegill and Green sunfish
 Musculium transversum, Long fingernailclam
Normalized to pH 7.0 and 20˚C

5. Potential Permit Limits
Small lagoon
Big River
Max dilution
ZID = 10 x DAF
Small stream
WWTF
Zero Dilution

6. Typical Ammonia Effluent

7. Flexibilities for States Applying EPA’s
Ammonia Criteria Recommendations
 Recalculation Procedure for Site-Specific
Criteria Derivation
 Site-specific pH and
Temperature?
 Variances
 Revisions to
Designated Uses
 Dilution Allowances
 Compliance
Schedules

8. Mussel Surveys
 Objective – Determine
presence or absence of
Order Unionoida
 Downstream extent subject
to ammonia impacts
 Site-specific criteria
development:
 Recalculation Procedure, or
 Mussel absent criteria
(Appendix N)
 Subject to EPA review

9. Distribution of 29 Common Mussel Species
from Order Unionoida
Source: MDC (1999), Missouri’s Freshwater Mussels

10. When may permits be affected?
New plants and plants with
currently planned ammonia
removal requirements
Now
All existing plants with
ammonia limits
Following adoption by Missouri
and as permits are re-issued.
Existing Plants with
Monitoring Only
Depending on the effluent data

11. Summary Points
 The new ammonia criteria is out and it’s more stringent.
 With no dilution or mixing zones (end-of-pipe), the likely average
monthly limits will be:
Summer: 0.6 mg/L….down from 1.4 mg/L
Winter: 2.2 mg/L…..down from 2.9 mg/L
 Wastewater plants may struggle to consistently meet effluent limits
based on the new criteria.
 There are flexibilities to conduct site-specific studies that may
potentially support higher effluent limits.
 Timing will hinge on the current need to add ammonia removal,
Missouri’s adoption of the criteria, and permitting cycles.

12. Thank You!
For further information:
Tom Wallace
Geosyntec Consultants
1123 Wilkes Blvd., Suite 400
Columbia, Missouri 65201
Phone: 573.443.4100
Email: twallace@geosyntec.com