Influence of Infrastructure
Rehabilitation Liners on Rinse Water
Quality: Polymer Enhanced Cement
Mortar and Polyurea Liners
Matt Tabor, Maryam Salehi, Ph. D.,
Jesus Estaba, Andrew J. Whelton,
Ph.D.
Department of Civil Engineering
University of South Alabama
August 6, 2012
Overview
• Significance of stormwater
infrastructure rehabilitation
• Laboratory leaching testing
– Objectives
– Methods
– Results
• Conclusions,
Recommendations
To Avoid Expensive Open Trench Techniques
Trenchless Technologies are Being Used
Trenchless Technologies
CIPP
Polyurethane (PU) Stormwater
Polyurea (PEUU)
Study
PU/PEUU Blends
Cement Mortar (CM)
Polymer Enhanced CM
(PECM)
Open-trench repair:
Traffic, Heavy Equip.
Excavation, Inconvenience
Installation, Cover
Polymer Enhanced Cement Mortar (PECM) Provides
Structural Strength to Host Pipe
Ingredients
Calcium silicate cement,
Crushed stone or gravel, Sand,
Mineral clays, Fly ash,
Crystalline silica
Cures in 24 hr
Extreme temperature resistance
High early and long-term strength
Low porosity
Polymer type unspecified
Crosslinked coating achieved
when fully cured
No Data for PECM
Possibly Water
Quality
Impacts?
Polyurea Coatings Only Require Minutes for
Complete Cure and are Reportedly Economical
Coating cures within minutes
Thin wall thickness
Cold temperature curing ability
Low cost because of ingredient versatility
No Data for Polyurea
Possibly Water
Quality
Impacts?
Our Goal was to Characterize the potential that
PECM and PEUU alter rinse water quality
Specific Objectives:
1. Expose newly installed lining materials to
synthetic water for 30 days
2. Document inorganic and organic contaminant
levels in those contact waters
3. Analyze and interpret results
Methods: A Static Leaching Procedure was Applied
1 day
Install
10 days
Removal
Testing
Synthetic Water
Water pH 7.1 + 0.2
Alk. 42.5 + 3.1 mg/L as CaCO3
3-day water changes, 22° C
Control
PECM
Organic Aquatic Significance
Inorganic
Water Quality
TN, BOD5
pH, Alkalinity TOC, COD,
was
UV254
Characterized
PEUU
Results: Water pH was Significantly Affected by both
PECM and PEUU Coatings
* Every 3 days old water was replaced
12
PECM
Water pH
11
10
9
Control
8
7
6
PEUU
5
0
3
6
9
12 15 18 21
Exposure Duration, Days
24
27
30
Water pH Changes can be Explained by
Understanding Material Chemistry!
14=pH + pOH
Diisocyanate Resin
Carbamic Acid Functional Group
Diamine
Alkalinity, mg/L as CaCO3
Results: PECM Increased Alkalinity due to the
Addition of Hydroxide Ions
PECM
600
500
100
400
50
300
0
6
200
9
12
15
18
21
24
27
30
27
30
100
0
0
3
6
9 12 15 18 21 24
Exposure Duration, Days
PEUU Consistently Released Organics to the Water For 30
days while PECM Released Organics for Only 6 Days
25
PEUU
4
3
20
TOC, mg/L
5
2
1
15
0
9
12
15
18
21
24
27
30
10
5
0
0
3
6
9 12 15 18 21 24
Exposure Duration, Days
27
30
COD Results Imply Organics Released from PEUU
have an Oxygen Demand
120
PEUU
COD, mg/L
100
80
60
40
20
LOD 3 mg/L
0
0
3
6
9
12 15 18 21
Exposure Duration, Days
24
27
30
BOD5 Results Demonstrated that the Majority of
Contaminants Released were Not Readily Consumed
by Aerobic Organisms
BOD5 Raw Data
Control
0
PEUU
9.2 + 0.5 mg/L
PECM
0
Ratios
Biodegradability Ratios
WWTP
PEUU 3-day
COD/BOD5
1.5 to 4.0
10.5
COD/TOC
2.0 to 3.5
4.9
Total Nitrogen was Detected in PEUU Leachate
Waters After the first Three Day Exposure Period
2.8 + 0.3 mg/L of Total Nitrogen Detected
Average TN naturally occurring in rivers
of Virginia is between 0.21 mg/L to
0.87 mg/L of TN
US EPA (2000)
Fate of Nitrogen Unknown
Biodegradation (Nitrification)
Chemical Transformation
Recalcitrant
Based on Experimental Data Contaminant
Concentrations Should Increase as Pipe Diameter
Decreases
Pipe
Interior
Diameter,
inches
Material and Contaminant Concentration, mg/L†
PECM
PEUU
TOC
Alkalinity
COD
TOC
TN
36
621
70,994
6,832
462
195
24
860
98,300
9,640
640
270
12
1,577
180,217
17,343
1,173
495
† Results were calculated by applying experimentally data to a 10 foot long
pipe where surface area and water volume calculations were completed.
Conclusions
1. PECM and PEUU altered water quality
for 30 days
2. PECM raised the pH and alkalinity for
30 days and released TOC for 6 days
3. PEUU released organics for 30 days
(COD and TOC) and nitrogen and
BOD5 for 3 days
 Dynamic test procedure is needed
 Document water quality impacts caused by
different formulations, installation procedures
 Cautious approach: Rinse coatings after
installation and responsibly dispose of waters
Acknowledgement
Ms. Laura Linn (Dauphin Island Sea Laboratory)
Ms. Bridget Donaldson (Virginia Department of
Transportation)
Ms. Eddy Colmenarez (University of South Alabama)
Dr. Kevin White (University of South Alabama)
Ms. Suzanne Lindblom (Mobile Area Water and Sewer
System)
Matthew Tabor
Dr. Andrew J. Whelton
Department of Civil Engineering
University of South Alabama
mlt1002@jagmail.southalabama.edu
Department of Civil Engineering
University of South Alabama
ajwhelton@usouthal.edu