TRAINING AGENDA Engineer Module – September 21, 2005 Afternoon Session: 1:30 pm to 4:00 pm Engineers Training Exercise Break: 2:15 – 2:30pm

–LID Project Objectives –Master Planning Process Integration into Site Analysis, Benefit Analysis, Site Design Selection, Plan Development Green Roof –Discuss Traditional Site Plan vs. LID Approach

LID Project Objectives

LID approaches and techniques for the design of the MARFORLANT headquarters facility –Feasibility –Potential effectiveness

LID Project Objectives Utilizing LID techniques and practices to meet: –Regulatory requirements –Federal government program goals Water conservation Energy conservation Environmental stewardship –Natural resource program management objectives

MARFORLANT: Master Planning Process Meet Virginia Department of Conservation and Recreation (VDCR) stormwater management regulations. rainfall used for non-potable uses –irrigation or toilet flushing Ancillary benefits energy conservation –vegetated roof –strategic siting of vegetation.

MARFORLANT: Master Planning Process “GOVERNMENT BY EXAMPLE” Eliminate pond option by replacing the hydrologic and hydraulic functions with LID practices such as bioretention. –eliminating pond maintenance –pond vector issues.

Master Planning Process: Case Study MARFORLANT Integration into: –Site Analysis –Benefit Analysis –Site Design Selection –Plan Development

Master Planning Process: Site description 7.1 acres in size. Site slopes gently from the north and south Low point in the center of the property. mix of woods and grass The soils on site are compacted.

Master Planning Process: Proposal 55,000 sq. ft. building northern portion of site 280 parking spaces Future building planned western side of proposed facility. Conventional stormwater on western edge Woods should remain undisturbed

Master Planning Process: Hydrologic Analysis The Commonwealth of Virginia requires peak runoff post-development condition to equal or be below the discharge from the pre-development condition for: –2-year 24-hour storm (with a six-inch depth ) LID practices is three (3) percent, or 0.2 acres –10-year 24-hour storm event for urban areas LID practices is eight (8) percent, or 0.6 acres Pre-and Post-development conditions are compared to determine a storage volume

Master Planning Process: Non-potable water Secondary non-potable usage –toilet flushing, cooling, irrigation Daily water demand 4,500 gpd for 300 office workers (15 gal per person per day) Cistern size of 14 diameter and height of 37 ft to capture and reuse water.

Master Planning Process: Non-potable water

LID Site Design Requirement of 8% of the site in LID features (10 yr 24 hr storm) –Runoff will sheet flow to a centralized bioretention facility with several perimeter bioretention facilities –Permeable surfaces on walkways –Green roof

Master Planning Process Green Roof

Conditions that have spurred green roof development –Prevalence of combined sewer systems –Antiquated and over-taxed sewer and waste treatment facilities –Widespread pollution of rivers and estuaries –Frequent nuisance flooding –Limited space for instituting large management facilities

Green Roof (continued) Driving factors for Green roof at MARFORLANT facility –Mitigate water runoff impacts –Compensate for the loss of green space –Limited treatment options for site are limited due to location of low point and high water table –Increases service life of roofing system –Reducing energy cost

Layers of Green Roof Waterproofing membrane Root barrier (if the waterproofing is not certified as root resistant) Drainage layer Separation layer Growth media layer Plants

Green Roof: Pollution Removal It is estimated 30% of all nitrogen and phosphorus in local streams is from roof runoff Green roof have demonstrated the removal of: –68% of total phosphorus –80% of total nitrogen

Green Roof Benefits: Energy Estimated 10% reduction in air- conditioning related energy costs Roofing system is expected to last 2-3 times longer than normal

Traditional Site Plan vs. LID Approach

Conventional large capital investments in complex and costly engineering strategies pipes water to low spots as quickly as possible LID Design Integrates, green space, native landscape, natural hydrology functions to generate less runoff. Uses micro-scale techniques to manage precipitation close to where it hits the ground

Traditional Site Plan vs. LID Approach

Conventional vs. LID:

Conventional vs. LID

Conventional vs. LID Total costs Cost per length of pipe per ft C = 0.54D for D = $14.40 (12in) D = $30.10 (24 in) C ($/ft) = (12 in) – (24 in) 1999 dollars Cost of grass swale per ft C/L = K K = 5-14 C ($/ft) = No land cost where considered, but could be significant

Cost Savings of LID Techniques Reduced downstream erosion and flood control. –preventing costly clean up and stream bank restorations. Infrastructure and development costs. –LID techniques reduces infrastructure requirements decreases the amount of pipes, roadways, detention facilities

Cost Savings of LID Techniques Improved groundwater recharge, drinking water, and decreased treatment costs. –Atlanta’s tree cover has saved over $883 million by reducing the need for stormwater facilities. –forest cover in the source area can reduce treatment cost 50 to 55% –Every 10% increase in forest cover treatment and chemical costs decreased approximately 20%

Funding Aspects

Funding Joint Effort –Department of Energy National Renewable Energy Research Laboratory (NREL) –Federal Management Program (FEMP) –Atlantic Division of the Naval Facilities Engineering Command (LANTDIV)

Design Exercise H and H methods Strategies and Techniques Results

Picture NRCL Norfolk

VS/VR

Solution of Runoff Equation

PG Chart

Filterra Sizing/Freq Dist Rainfall Runoff Volume (cu ft / hr) Runoff Treated (cu ft / hr) Cumulative Frequency Probability Frequency (c) x (e) (cu ft / hr) (b) x (e) (cu ft / hr) (in / hr) Totals

Simple Method L = x R x C x A Where: L = Annual load (lbs) R = Annual runoff (inches) C = Pollutant concentration (mg/l) A = Area (acres) = Unit conversion factor

Simple Method D = L x (1-E) Where: D = Annual load reduction (lbs) L = Annual load (lbs) E = Pollutant removal efficiency (fraction)

Bioretention Files AB = area of bioretention, ft 2 C = rational c coefficient I = rainfall intensity, in/hr A = drainage area, acres Tc = time of concentration, min Ds = storage depth in bioretention, in. Db = bioretention media depth, ft Ir = soil infiltration rate, in/hr

LID Techniques and Objectives Low-Impact Development Technique

Maintain Time of Concentration (Tc) X X X X X X X Low-Impact Development Technique

Example Retrofit: Anacostia Annex of the Washington Navy Yard Currently no stormwater management –quantity or quality controls Replacement of the parking area is required. Drainage inlets and old brick drainage structures need to be replaced. Sidewalk needs to be replaced The site does not comply with Americans with Disabilities Act (ADA) Standards.

PROJECT OBJECTIVES Integrate LID practices into the repaving of parking areas Repair the sidewalks Re-landscape Pollutants of concern for this watershed are: –oils and grease –total suspended solids –nitrogen and phosphorus.

RANK AND PRIORITIZE OPPORTUNITES Greatest potential to reduce non-point source pollutant loads Minimal costs for new materials Minimal maintenance cycles, costs, and training Ancillary benefits (landscaping, energy conservation, water conservation)

SITE CONDITIONS The site has minimal topographic relief. groundwater table is approximately 3 feet below the surface. soils have poor infiltration rates. There is an existing drainage system below the buffer.

LID Site Conditions

Results

MWR Pics

Addressing Drainage (1-5) Drainage Areas One through Three: –three bioretention cells, a bioretention swale, and a footpath using permeable pavers. Drainage Area Four: –A tree box filter Drainage Area Five: –Permeable pavers will be constructed in the existing valley

Addressing Drainage (6-9) Drainage Area Six: A bioretention cell will be constructed within a vegetated island. Drainage Area Seven: Pavement will be removed and replaced with a bioretention cell. Drainage Area Eight: Permeable pavers will be constructed, a sand layer may be incorporated to increase efficiency. Drainage Area Nine: A bioretention cell will be located to the east of the access road.

LID Site Design

Site

Proposed Conventional

Composite Curve Number Calculation for Existing Condition Weighted CN = Sum of Products ÷ Drainage Area

Curve Number Existing Condition and Proposed Condition ConditionRunoff (in) Existing (CN = 63)1.5 Proposed (CN = 80)2.9

Proposed LID

Conventional vs. LID ConditionCNTcTc Peak Discharge (CFS) Runoff depth (in.) 2-year (3” depth) 10-year (5” depth) 2- ye ar 10-year Existing Condition Proposed Condition – conventional CN Proposed Condition using LID site design

Conventional

LID

Conventional

LID