Copyright Materials. Advanced Water Movement in Soils How It Really Works! What is Soil? Advanced Water Movement in Soils How It Really Works!

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1 Soils - How Copyright Materials Soils How This presentation is protected by US and International Copyright laws. Reproduction, distribution, display and use of the presentation without written permission of the speaker is prohibited. Barrett L. Kays, Ph.D., FASLA, Landis, PLLC, Raleigh, NC The American Society of Landscape Architects Jeffrey L. Bruce, FASLA, J.L. Bruce & Company, North Kansas City, MO 1 2 Soils How Part I Soils are complex systems. What is Soil? Soils are constantly changing through interaction with environment. Jeffrey L. Bruce, FASLA J.L. Bruce & Company, North Kansas City, MO 3 4 Jeffrey Bruce 1

2 Soils - How New Order Anthropogenic Soils Soils resulting from human activities which have led to a profound modification, truncation or burial of the original soil horizons, or the creation of new soil parent materials by a variety of mechanical means. 5 Urban Soil Legends Amending native soil will dramatically improve soil performance 6 Urban Soil Legends Subdrainage is effective in improving native soil performance Urban Soil Legends The site contains native topsoil that is uniform and productive. 7 8 Jeffrey Bruce 2

3 Soils - How Urban Soil Legends Traditional landscape approaches are sustainable in abused or urban landscapes. Soil is Composed of Solid Particles and Voids 9 10 Soil Texture is Ratio of Soil Particles Various Classification Systems Jeffrey Bruce 3

4 Soils - How Bulk Density Measure of Compaction Bulk Density is the weight of a given volume of soil which includes the pore spaces. Dry Weight / Unit Volume LBS per Grams per Cubic Foot Cubic Centimeter Asphalt Cement Loose Soil Compacted Soil Dry Clay **** g/cc x = pounds per CF 14 Bulk Density Relative Values Type of Material Bulk Density Measurement (grams/cm3) Normal soils 1.0 to 1.6 Soils with restricted root growth 1.4 to 1.6 Bricks 1.4 to 2.3 Effect of Compaction on Pore Space Total Pore Space Bulk Density Particle Density % g/cc g/cc Soil commonly found at construction sites 1.7 to Jeffrey Bruce 4

5 Soils - How Field Variation of Water Content Determining Bulk Density Field or Lab Determination Gamma Probes Core Collection Test Methods AASHTO T 19M/T (2004) ASTM C 29/C 29M-97 (2003) Total Pore Space Total Pore Space Total Pore Space (%) = (1-(Bulk Density/Particle Density)) x 100 The size of the tank that holds water or air. The volume of non-solid area in soil. Occupied with either gas or water. As Bulk Density Advanced Increases Water Movement Total in Pore Space Decreases Jeffrey Bruce 5

6 Soils - How Soil Moisture Water Phases in Soils Gravitational water Capillary water Hygroscopic water Sample Soil Composition Capillary Size Effects of Water Retention and Flow Rate Jeffrey Bruce 6

7 Soils - How Water Absorption in Soils as a Function of Energy Water Retention Varies by Soil 25 Texture Field Capacity (% vol) Perm. Wilting Point (% vol) Available Water (% vol) Sandy Loam Loam Clay Heavy Clay Moisture by Soil Type Soil Water Storage Capacity Jeffrey Bruce 7

8 Soils - How KCPAC Stormwater Storage Capacity Water Pore Space Relationship Macro Pore Space Volume 203,140 gals Micro Pore Space Volume 76,563 gals Hydroscopic Water Volume Green Roof Coverage Advanced Water 146,153 Movement SF in 15,307 gals 306,144 gals 29 total 30 Sand Based Water Release Water Filled Pores vs. Water Content Volumetric Water Assessment Degree of Saturation (%) Depleted Available Water Start Irrigation Volumetric Water Content (%) 32 Jeffrey Bruce 8

9 Soils - How Water Filled Pores vs. Time Soil Moisture Meters PR 1 Probe Data % Water Filled Pores Volumetric Water % DEPTH (cm) Time :30:02 0:00: :31:40 0:01: :46:40 0:16: :00:24 0:30: :01:59 0:31: :05:46 0:35: :06:29 0:36: :09:48 0:39: :10:55 0:40: :13:36 0:43: :15:32 0:45: :17:48 0:47: :19:03 0:49: :19:23 0:49: :21:12 0:51: :22:02 0:52: BD = 1.67 Soils g/cmtotal - How Pore It Really Space Works! = 36.94% Water Movement into Soils Infiltration Rate Test Methods Constant head double-ring infiltrometer ASTM D , Infiltration Rate of Soils in Field Using a Double- Ring Infiltrometer Infiltration Rate = (Percolation Rate)/(Reduction Factor) ASTM D , Infiltration Rate Using a Double-Ring Infiltrometer with a Sealed-Inner Ring Guelph permeameter 35 Constant head permeameter (Amoozemeter) 36 Jeffrey Bruce 9

10 Soils - How Saturated Flow in Soils Saturated Hydraulic Conductivity (ksat) Permeability F Standard Test Methods for Saturated Hydraulic Conductivity Unsaturated Flow in Soils Jeffrey Bruce 10

11 Soils - How Perched Retained Water Profile Retained Water Differing soils with differing particle sizes Same soils with differing depths Material Bridging Concepts (USGA) Performance Factors Bridging Factor Permeability Factor Uniformity Factors Recommendation D15 (gravel) less than or equal to 8 X D85 (root zone) D15 (gravel) greater than or equal to 5 X D15 (root zone) D90 (gravel) / D15 (gravel) is less than or equal to 3.0 No particles greater than 12 mm Not more than 10% less than 2 mm Not more than 5% less than 1 mm 43 Soils How Part II Barrett L. Kays, Ph.D., FASLA Barrett L. Kays, Ph.D., FASLA Landis, PLLC, Raleigh, NC 44 Jeffrey Bruce 11

12 Soils - How Landscape Hydrology Natural v. Man-Made Landscapes The soil water and intermediate zones are both unsaturated zones. Runoff rarely occurs because the soil rarely becomes saturated. Gravity percolation only occurs in large saturated pores that are connected to the ground surface. In some landscapes the unsaturated zone is very thick in depth. In other landscapes the unsaturated zone is very thin or does not exist. 45 Basic Landscape Hydrology Runoff seldom occurs Infiltration normally all of rainfall infiltrates except for interception losses Evapotranspiration significant amount of rainfall is transmitted back into the atmosphere Lateral Interflow occurs on hill slopes when a perched water table occurs above the subsoil Deep Seepage significant amount of infiltration comes out as year round low flow into the closed stream channel Groundwater Table fluctuates closer to the ground surface during the wet periods of the year and when evapotranspiration Advanced Water Movement rate is in low 46 Man-Made Structural Soil Profiles for High Rate Infiltration Advantages of High Rate Infiltration Zero Runoff Landscapes Manufactured Planting Soil 75 90% Medium to Coarse Sand Unsaturated Soil Rebuilding On- Site Soils for Planting & Drainage Loamy Sand Saprolite Fill After Removing Clayey Material High rate infiltration allows designer to use a large portion of the urban landscape to achieve zero runoff for very large rainstorms, or High rate infiltration allows designer to use a small portion of urban landscape to treat stormwater runoff from the design storm Coarse Sand Fine Gravel Subgrade Fine Gravel Drain Lines Existing Loamy Sand Saprolite 47 Drains to Groundwater 48 Jeffrey Bruce 12

13 Soils - How High Rate Infiltration in NY High Rate Infiltration Central Park, NY, NY Intensive Approach for Dense Urban Landscapes or Special Purpose Sites Dense urban sites: 50 to 95% impervious surfaces, First used in Central Park for restoration of Great Lawn, later used on Nelson B. Rockefeller Hudson River Park, and 49 Custom structural sand/organic mix was used in 1992 design of 24-acre infiltration system in Central Park to infiltrate 100-year storm events (infiltrates up to 1-foot of rainfall occurring 3 hours before a concert without any ponding or runoff) 50 Principles of Water Movement Sandy Soil over Gravel Layer P-1: When saturated to the surface water flows in proportional to size of pores, head, and drains readily into the gravel layer When the soil is completely saturated it is at zero negative pressure (soil moisture tension = 0) The gravel layer has large pores which are at zero negative pressure (soil moisture tension = 0) Therefore water can flow from the soil layer into the gravel layer Principles of Water Movement Sandy Soil over Gravel Layer P-2: Uniformly graded coarse and medium sand conducts water faster when saturated than well graded sands Uniformly graded sands means that all of the finer and larger sand particles has been screen out and the remaining is only coarse to medium sand (0.25 to 1.0 mm in diameter) Well graded sands include very fine sand, fine sand, medium sand, coarse sand, and very coarse sand. When compacted the different sizes lock together, thus it makes a good concrete sand, but a bad sand for drainage Jeffrey Bruce 13

14 Soils - How Sand Content in Structural Soil, % Saturated Hydraulic Conductivity v. Percent Medium to Coarse Sand in Layered System Saturated Hydraulic Conductivity, Inches/Hour 53 Principles of Water Movement Sandy Soil over Gravel Layer P-3: When unsaturated, water stops flowing into gravel layer, due to the greater negative pressures in the sandy soil After a small amount of water drain out of the sandy soil, it is no longer saturated and the negative pressure (soil moisture tension) has increased When unsaturated water flows in the direction of the greatest negative pressures (greatest soil moisture tension) and since the tension in the gravel is still zero, the water cannot move downward The gravel layer acts to impede unsaturated water movement from moving downward, thus leaving considerably more water in the sandy soil 54 Sand Content in Structural Soil, % Plant Available Water With and Without Gravel Layer w/o Gravel Layer Plant Available Water, % by Volume w/ Gravel Layer Drainage Saturation 55 Principles of Water Movement Sandy Soil over Gravel Layer P-4: When unsaturated more water is held in the sandy soil with uniformly graded medium and coarse sand, than in well graded sands More water is held in the uniformly graded sands because it has a higher porosity Well graded sands have a variety of sand sizes that pack together and have a lower porosity 56 Jeffrey Bruce 14

15 Soils - How Principles of Water Movement Sandy Soil over Loamy Layer Which profile will drain the fastest when fully saturated? P-5: When unsaturated water continues to drain from the sandy soil because the underlying loamy soil has a greater soil moisture tension Profile #1 Profile #2 Profile #3 When unsaturated water flows in the direction of the greatest negative pressures (greatest soil moisture tension) and since the tension in the loamy soil is greater, the water continues to move downward until the sandy soil is dry Medium Sand 0.25 to 0.50 mm Coarser Coarse Sand 0.50 to 1.00 mm Coarser Very Fine to Coarse Sand 0.05 to 1.00 mm Coarse Sand Medium Sand Fine Gravel Fine Sand Coarse Sand 57 All profiles have free drainage at base. 58 Which profile will hold the most moisture after draining? Soil Profile Design Finish Grade Profile #1 Profile #2 Profile #3 Medium to Coarse Sand 0.25 to 1.00 mm Medium Sand 0.25 to 0.50 mm Coarse Sand 0.50 to 1.00 mm Very Fine to Coarse Sand 0.05 to 1.00 mm Bridging Factor Existing Grade Min. Ksat = 3.33 in/hr Fine Gravel No Filter Fabric ADS Drain Line Coarse Sand Medium Sand Landfill Soil Cap Fine Gravel Fine Sand Coarse Sand Landfill Rubble All profiles have free drainage at base. 59 CMP Drain Line 60 Jeffrey Bruce 15

16 Soils - How Keys to Making it Work Installation with Heavy Equipment Key #1 - Must maintain zero negative pressure in gravel layer Vent the drain pipes out to the atmosphere Key #2 - Must use uniformly graded sands in the mix Must strictly adhere to the USGA uniformity standard Sandy Planting Soil Key #3 - Must not allow the sandy layer to fall into the gravel layer Must strictly adhere to the USGA bridging standard 61 M-78 Gravel Over Drain Lines Compacted Subgrade 62 Great Lawn in Central Park Making Sure It Will Work By Computer Modeling Ksat = 5 inches/hour Capacity = 6.8 million gallons DRAINMOD Simulation Model Jeffrey Bruce 16

17 Soils - How DRAINMOD Computer Simulated Model DRAINMOD Computer Simulated Model DRAINMOD determines water balance on daily or hourly basis in soil profile using climatic records to simulate performance of: Infiltration Evapotranspiration Runoff Depth to water table DRAINMOD input files include: Soil depth, Ksat, and soil moisture release curves for each layer using both field and lab data Weather daily or hourly rainfall and temperature data from nearest official meteorological station Plantings depth of rooting, plant data and growing season, Drainage system files type of drainage structures, size, depth and spacing Amount of drainage through soil Amount of irrigation DRAINMOD Computer Simulated Model Testing the Soil Design for Wettest Year of Record DRAINMOD allows us to accurately focus on: Most extreme climatic conditions of record Simulation with subsurface drainage Actual soil characteristics, infiltration rates, and runoff volumes (not peak flows) Determining the affect of proposed changes in soil profile to achieve enhanced infiltration 67 Medium to Coarse Sand Layer 0 to 51 cm Fine Gravel Layer 51 to 76 cm Drain lines at 66 to 76 cm 68 Jeffrey Bruce 17

18 Soils - How Testing the Soil Design for Driest Year of Record Simulation without irrigation High Rate Infiltration & Deep Seepage Greensboro, NC Medium to Coarse Sand Layer 0 to 51 cm Fine Gravel Layer 51 to 76 cm Drain lines at 66 to 76 cm High Rate Infiltration in Saprolite Saprolite is weather material under clayey or loamy subsoil and consisting of sand and feldspar and was used as an on-site sandy material; sandy and loamy sand textured saprolite are preferred Eastern Piedmont Saprolite Region High Rate Infiltration systems have been used on: Dense urban sites: 50 to 95% impervious surfaces, HRI system uses 3 to 5% of watershed, Friable saprolite can transmit water at 1 to 2.5 feet per day when saturated, and The treated stormwater slowly migrates downward and eventually reaches the groundwater in about 8 to 12 months Jeffrey Bruce 18

19 Soils - How Reconstruction of Soil Profile Saprolite Infiltration & Groundwater Recharge System Clay Loam Topsoil Coarse Sand ADS B-Horizon - Clay Cut 4 to 10-feet Saprolite Mined On Site < 10% Clay C-Horizon Clay Loam Fill Ksat = 1.5 feet/day Drainage Time = 5 Days CR-Horizon 40 feet to Saprolite Ground <10% Advanced Clay Water Movement Water in Saprolite - Existing 73 Storage Capacity = 5,542,266 gallons 74 Saprolite Infiltration & Groundwater Recharge System CSUPAW Hydraulic Model Yearly loading = 45-in/year x 0.80 imp. x 10 acres = 30 ac-feet/year Ksat of saprolite = 1 to 2.5 feet/day Measure Ksat in deep borings prior to design, 10-acre drainage area 30-acre feet of stormwater / year Groundwater elevation will rise under system 75 Measure depth to and flow direction of groundwater, and Use Colorado State Univ. Pit and Well program (CSUPAW) to analysis groundwater mounding. 76 Jeffrey Bruce 19

20 Soils - How Groundwater Mound Under High Rate Infiltration Basin CSUPAW Mounding Analysis Groundwater Rise, Feet Distance Across Mound, Feet 90 Days 180 Days 270 Days 360 Days 77 Infiltration basin soil and subgrade is saprolite Recharge rate = 0.25 feet/day Transmissivity = sq. ft./day (K=11.22 gal/sq. ft./day aquifer depth = 10 feet) Specific yield = 0.25 Groundwater depth = 20 feet Basin dimensions = 100 feet by 150 feet Distance to adjacent stream = 125 feet After 360 days, the mound height is: 8.1 foot rise at center of basin, 6.5 foot rise at edge of basin, 0.5 foot rise at stream, and Stream flow is increased by 38 cubic feet/day 78 Great Lawn at Central Park New York, NY Stormwater components and capacity for 100 Year Event High rate infiltration system Stormwater wetland pond Total storage capacity Storage capacity = 6,625,088 gallons 977,486 gallons 7,602,574 gallons Cost of stormwater system High rate infiltration system $0.70/gallon $4,638,500 Stormwater wetland pond $1.28/gallon $1,250,000 Total stormwater system $0.61/gallon $4,639,750 Middle & High School Campus Greensboro, NC Stormwater components and capacity for 100 Year Event Preserved natural areas Rainwater harvesting Enhanced infiltration High rate infiltration system Stormwater wetland ponds Total storage capacity Storage capacity = 5,172,049 gallons 378,499 gallons 6,057,720 gallons 8,175,230 gallons 6,646,810 gallons 26,430,308 gallons Cost of stormwater system Preserved natural areas $0.01/gallon $ 51,700 Rainwater harvesting $0.03/gallon $ 182,000 Enhanced infiltration $0.04/gallon $ 265,000 High rate infiltration system $0.25/gallon $2,043,800 Stormwater wetland pond $1.48/gallon $ 560,000 Total stormwater system $0.12/gallon $3,102, Jeffrey Bruce 20

21 Soils - How Q & A 81 Jeffrey Bruce 21