Solution for CEE 330 HW 5 Use EPIWIN to get property data Include summary from EPIWIN and structure of the compound in your report When several values are reported for a given property use the experimental data Problem 1 A 50cm3 sample of dry soil from an aquifer weighs 100g When it is poured into a graduated cylinder it displaces 35 cm3 of water a What is the porosity of the soil b What is the average density of the actual solids contained in the soil Problem 2 Based on observations of the rate of travel between two observation wells of a tracer element having retardation factor equal to 1 0 it is determined that the average linear flow velocity in an aquifer is 1 0 m day when the hydraulic gradient is 0 0005 A sample of the aquifer is tested and found to have a porosity of 0 2 Estimate the hydraulic conductivity Problem 3 An aquifer has a gradient of 0 00115 a hydraulic conductivity of 1 000 m day and a porosity of 0 23 Consider 3 monitoring wells each located at the vertex of an equilateral triangle The distance between any pair of wells is 300 m The head at each well referenced to some common datum is as follows well 1 100m well 2 100 3 m well 3 100 3 m a What is the Darcy velocity b What is the average linear velocity of the groundwater c If the front edge of a plume is perfectly straight how long would it take to travel to well 1 after first arriving simultaneously at wells 2 and 3 assuming a retardation factor of 2 Problem 4 An underground storage tank leaks tetrachloroethylene PCE at a rate of 100 mL day This continues for a year before the leak is discovered and stopped The tank lies at the water table so all of the PCE released enters the sand aquifer but not necessarily immediately dissolved in the groundwater The aquifer is 4 0 m deep and composed of sand with fraction of organic carbon of 1 The actual groundwater velocity is 0 09 m d and the hydraulic gradient is 0 0005 The bulk density of the sand is 1600 kg m3 Specific gravity of PCE is 1 63 g mL or density of PCE is 1 63 g mL 1 List relevant chemical and physical properties i e Molecular weight logKow water solubility Henry law constant biodegradation soil ad sorption coefficient Koc BCF given by EPIWIN Include structure of the compound in your report When several values are reported for a given property use the experimental data 2 What is the hydraulic conductivity of the aquifer Hint find porosity from a table found in the lecture slides 3 What is retardation factor R 4 How far would you expect the PCE to have traveled down gradient during the one year period 1 5 Assume the dissolved PCE distributes uniformly in the aquifer and forms a plume 2 0 m wide 4 0 m deep and extending as far as you calculated What is the average PCE concentration in the plume Is there a separate phase What is mass of this phase 6 What is MCL of PCE Is MCL higher than concentration of PCE in groundwater 7 How long will it takes to remove PCE from the aquifer Solution 1 a porosity 50 35 50 0 3 b density 100 g 35 cm3 2 86 g cm3 2 86 kg L Solution 2 vact 1 m day R 1 dh dL 0 0005 0 2 hydraulic conductivity K vact 1 m day 0 2 400 m day dh dL 0 0005 Solution 3 a K 1000 m d dh dL 0 00115 v K dh 1000 m d 0 00115 1 15 m d dL b vact v 1 15 m d 5 m d 0 23 c S 300 150 260 m 2 2 vact 5 m d 2 5 m d R 2 t S vconta min ant 260 m 2 5 m d 104 day vconta min ant Solution 4 1 List relevant chemical and physical properties i e Molecular weight logKow water solubility Henry law constant biodegradation soil ad sorption coefficient Koc BCF given by EPIWIN Include structure of the compound in your report When several values are reported for a given property use the experimental data Cl Cl Cl Cl 2 Molecular weight 165 83 Log Octanol Water Partition Coef logKow 3 47 Exper Ref Hansch C et al 1995 Water Sol Exper database match 206 mg L 25 deg C Exper Ref HORVATH AL ET AL 1999 Henrys Law Constant 25 deg C Exper Database 1 77E 02 atm m3 mole Expert Survey Biodegradation Results Biowin3 Ultimate Survey Model 2 1400 months Biowin4 Primary Survey Model 3 2060 weeks Soil Adsorption Coefficient Experimental Log Koc 2 4 database Bioaccumulation Estimates from Log Kow BCFWIN v2 17 Log BCF from regression based method 1 918 BCF 82 79 with log Kow used 3 40 expkow database 2 What is the hydraulic conductivity of the aquifer vact 0 09m day 0 34 61 2m day dh dL 0 0005 porosity is from Table 5 11 hydraulic conductivity K 3 What is retardation factor R R 1 Kd B 1 K oc f oc B 102 4 L kg oc 0 01 kg oc kg soil 1 6 kg soil L 1 12 8 0 34 4 How far would you expect the PCE to have traveled down gradient during the one year period R vact vconta min ant vact 0 09m day 0 007m day R 12 8 distance 0 007m day 365day year 2 56m year vconta min ant 5 Assume the dissolved PCE distributes uniformly in the aquifer and forms a plume 2 0 m wide 4 0 m deep and extending as far as you calculated What is the average PCE concentration in the plume Is there a separate phase What is mass of this phase Consider a controlled volume of 2 0 m wide 4 0 m deep and 2 56 m long V 2 0m 4 0m 2 56m 20 5m3 Average dissolved concentration of PCE in groundwater is 10 of its solubility in water and it is 20 6 g m3 Maximum mass of dissolved PCE in this control volume is mmax 0 1Sw V 20 6g m3 0 34 20 5m3 143 6g Mass of PCE leaked to the aquifer is mleak 100mL day 1 63g mL 365day 59 500g 3 Total mass released massPCE in water mass PCE in sed soil mass PCE in NAPL Mass PCE in sed soil Cw Koc foc Msed Cw Koc foc Vsed sed 20 6g m3 Koc foc Vsed sed g m3 water Lwater kgOC 102 4 0 01 3 m water 1000 Lwater kgOC kgsoil kgsoil 1000 Lsoil 20 5 0 66 m3 soil 1 6 Lsoil m3 soil 1120 g 20 6 Maximum mass is much smaller than mass of PCE leak to the aquifer It means that PCE will remain in groundwater and as a separate phase DNAPL Mass of DNAPL 59500 1120 …