Demonstration of In-Situ Soil Bioremediation of Perchlorate and Explosives. Professor Valentine Nzengung President & CEO

Transcription

1 Demonstration of In-Situ Soil Bioremediation of Perchlorate and Explosives Presented at 2007 JSEM Columbus, Ohio By Professor Valentine Nzengung President & CEO Dr. Walter O Niell, PG Senior Hydrogeologist PLANTECO Environmental Consultants, LLC.

2 Acknowledgements Funding for the laboratory and field phases of the project was provided by the Department of the Army, Rock Island, IL

3 Rationale Dig-and-treat approaches may be challenging at some sites due to: High cost Very high explosive concentrations Heterogeneous spatial and vertical distribution of the explosive compounds The RODs at some sites may require the use of treatment train to cleanup both soil and groundwater or multiple groups of contaminants

4 Objective Demonstrate the effectiveness of in-situ bioremediation of perchlorate and explosives in vadose zone source areas in soils. Verify that in-situ bioremediation of soils does not mobilize the contaminants of concern into the groundwater below.

5 What is SAMNAS? SAMNAS : Surface Application and Mobilization of Nutrient Amendments - In-situ bioremediation technology - A demonstrated remedy for vadose zone source areas and groundwater - Utilizes various electron and carbon sources to stimulate indigenous bacteria to degrade contaminants - No dig-and treat involved - A reactive front progressively mobilized through soil while avoiding the leaching of water miscible contaminants, such as perchlorate

6 Field Pilot Demonstration SAMNAS Site Longhorn Army Ammunition Plant (LHAAP) Proof of Concept Study Completed 2002 Full Scale Implementation - Two Projects 1 - Building 43-X (Completed) 2 - Site 17 Burning ground (Completed)

7 Collection of Contaminated Soils for Bench Scale Treatability Tests

8 Collection of Contaminated Soils for Bench Scale Treatability Tests

9 Pre-Design Column Test

10 2001 Proof of Concept Field Study - LHAAP Horse Manure Chicken Manure Ethanol Chicken Manure Ethanol

11 Proof of Concept Study Results Top Depth = 0 to 1 foot Perchlorate Conc. (mg/kg) Initial 10 Months 31 Months Horse Manure Chicken Manure Ethanol Control Treatment

12 Proof of Concept Study Results Depth = 2 to 3 feet Perchlorate Conc. (mg/kg) Initial 10 Months 31 Months Horse Manure Chicken Manure Ethanol Control Treatment

13 Perchlorate Concentration in Grasses Planted after Study Terminated (expressed in mg/kg dry weight) Grass (Nov. 2001) 1 month after planting Grass (May 2003) 2 years after planting Grass (May 2005) 4 years after planting Horse Manure Highest Initial Conc n Plots Chicken Manure ND Initial 5,500 mg/kg Initial 5,500 mg/kg ND Ethanol ND Control Lowest Initial Conc n Plots Dry weight perchlorate concentrations in LHAAP grasses were over 5,500 mg/kg in soils with perchlorate concentrations of 200 mg/kg (Smith, 2001).

14 Restoration of Building 43-X Project Unique Challenges Perchlorate contamination occurred in the vadose zone soils in a confined space Top 12 to 15 inches of soil in this building consisted entirely of sand underlain by clayrich soils Top soil had been exposed to creosote, an antibacterial agent

15 Restoration and closeout of Building 43-X 6,700 ug/kg perchlorate to BDL (40 ug/kg) in 10 Months Perchlorate (ug/kg) Coarse Sand (0-4"BGS) Red Sand Layer (5-15" BGS) Clay Layer (24-30" BGS) Jun-03 May-03 Apr-03 Mar-03 Feb-03 Jan-03 Dec-02 Nov-02 Oct-02 Sep-02 Aug-02 Date

16 Results Summary Building 43-X Analytical Method Liquid chromatography with mass selective detector Method detection limit of 40 ug/kg for soils Technology SAMNAS Media treated sand underlain by clay Depth of contamination = 30 inches (76 cm) Initial soil concentration of 6,700 ug/kg reduced to 40 ug/kg in 10 months

17 Bioremediation of Perchlorate & Explosives in Soil SAMNAS -ACost-effective In-Situ Bioremediation Technology for Simultaneous Restoration of Soils and Groundwater Contaminated by: Explosives Perchlorate Chlorinated Solvents Location: Site 17, LHAAP, Karnack, TX

18 Large-Scale Demonstration LHAAP Burning Ground 17 (OBOD) Silt- and clay-rich sandy soils Depth to groundwater 6-10 feet Various contaminants in soils and groundwater Very heterogeneous distribution of contaminants

19 May Amendments Delivered to Site

20 Soils and Amendments Tilled to 3 Feet Below Grade

21 Soils and Amendments Tilled but Not Disked

22 Remnants of Munitions

23 Irrigation System Working Site Covered with Hay

24 Treatment Area Covered with Landscape Fabric Sprinkler Heads Tensiometers

25 SAMNAS Demonstration on 1 Acre Site Initial Perchlorate Concentrations in Soils

26 SAMNAS Demonstration Perchlorate Conc. in Soils after only 8 Months

27 Perchlorate in Groundwater 250 LH LH17-17WW02 LH17-17WW06 LH17-17WW13 LH17-17WW01 LH17-17WW03 Perchlorate Conc. ( ppm) /21/ /10/2002 1/29/2003 3/20/2003 5/9/2003 6/28/2003 8/17/ /6/ /25/2003 1/14/2004 Date

28 Nitrate in Groundwater US EPA MCL 10 ppm Before Treatment After 2 Months Treatment After 4 Months Treatment After 6 Months Treatment Nitrate Conc., ppb 10 0 LH17-17WW02 LH17-17WW13 LH LH17-17WW03 LH17-17WW01 LH17-17WW04 LH17-17WW06 Date

29 Perchlorate Concentration (ppm dry weight) in Vegetation and Soil after SAMNAS Treatment Terminated 2003 Season Winter 2004 Season Spring 2005 Season Spring 2005 Vegetation Senescence Soil North of Site 17 (mg/kg) 61 ND Vegetation New Growth 28 South of Site 17 (mg/kg) ND ND Dry weight perchlorate concentrations in LHAAP grasses were over 5,500 mg/kg in soils with perchlorate concentrations of 200 mg/kg (Smith, 2001).

30 TNT Treatment Using SAMNAS TNT Treatment Using SAMNAS 3,500 3,000 2,500 2,000 1,500 1, Initial Afte r 8 M onths Concentration (ppm) 0 2,4-DNT 2,4,6-TNT 1,3,5-TNB 2,6-DNT 4-Nitrotoluene 2-Nitrotoluene 4-Amino-2,6-DNT 2-Amino-4,6-DNT Explosive Compound

31 Distribution of Explosive Compounds in Soil (mg/kg) Results of Analysis of the Site Soils in 2005 were Non-detect Explosive Compounds Initial After 8 Months 1,3,5-Trinitrobenzene 487,000 13,436 2,4,6-TNT 3,357,333 16,231 2,4-DNT 3,104,033 17,599 2,6-DNT 1,273,333 7,624 2-Amino-4,6-DNT 45,800 5,798 4-Amino-2,6-DNT 2,500 4,528 2-Nitrotoluene 3, Nitrotoluene 3,

32 Biodegradation of TNT

33 Site 17 in 2004 Achieved Non-detect and was Revegetated

34 Additional Monitoring of Site 17 in 2004 & 2005 for Perchlorate Uptake by Plants

35 Conclusions PLANTECO s demonstrated in-situ bioremediation technology simultaneously treats multiple energetic compounds in vadose zone source areas. No evidence of leaching of perchlorate from soils to groundwater, if soil moisture is maintained below field capacity. SAMNAS is cost-effective and attains cleanup goals faster. PLANTECO offers performance guarantee on SAMNAS.