Stormwater and Your Home. Mason Conservation District. Stephanie Bishop, Environmental Specialist Rich Geiger, P.E., District Engineer

Transcription

1 Stormwater and Your Home Mason Conservation District Stephanie Bishop, Environmental Specialist Rich Geiger, P.E., District Engineer

2 This workshop is sponsored by Mason County Public Works & funded by a grant from the Washington State Department of Ecology

3 Practical Ideas for Stormwater Management at Home Stormwater Basics: What s Going On? Make Soils & Vegetation Work for You. Specific drainage situations: Low-tech solutions When to call in the Big Guns: Engineering

4 Mason County Receives an annual average of 64 of rain. Over 5 feet of rain! Soil type & groundwater level influence whether water soaks into the ground or whether it runs-off. How we manage our land personally (& collectively) also determines what happens when it rains. Will we manage it to become a problem... or an asset?

5 Mason County has very different conditions around the County. 968 square miles 7 major watersheds Lower Hood Canal Hood Canal Oakland Bay Totten/Little Skookum Skokomish Case Inlet Chehalis 90+ miles shoreline 100 freshwater lakes Miles of streams

6 Background: When it rains in undisturbed areas......we see minimal run-off Soils for Salmon

7 Development Changes Where & How stormwater moves. Soils for Salmon MOST water now runs-off impervious surfaces.

8 A natural Puget Sound shoreline: Hammersley Inlet Washington State Department of Ecology

9 Hammersley Inlet Shoreline, increased development (1992) Washington State Department of Ecology

10 Many Stormwater Impacts are Obvious Washed out roads Flooded roads Flooded pastures

11 and some aren t so obvious Economic impacts Non-point source pollution Diminished groundwater

12 Stormwater Basics What do you need to know to protect your property? 1. Limit Impervious Surface 2. Protect Native Vegetation 3. Avoid Soil Compaction 4. Use the RIGHT Drainage Systems

13 Do not be this guy!

14 1. LIMIT Impervious Surfaces

15 How can you limit impervious surfaces? Replace impervious surfaces with alternatives that allow drainage. Plan ahead: plan LID into your new project Enhance natural drainage

16 Property layout: Where can you make changes? Lawn Driveways Walkways

17 Make simple changes Manage water close to where it falls, when it makes sense to do so. Image from Environmental Services, City of Portland

18 Lawn Alternatives Save money! Save time! Landscaping Beds using native vegetation Raised Bed Gardens Rain Gardens

19 Landscape with Native Plants Pacific Northwest Natives are beautiful & versatile. Plant in layers use groundcovers, shrubs & large trees. Minimal maintenance Mulch, mulch, mulch! Photograph by Richard Hartlage Oregon grape Twinberry

20 Simple Reasons to Use Native Plants Adapted to climate & soils Save time less maintenance. Save money less fertilizer. Help the neighbors manage water on your property Protect our local economy protect water quality Conserve natural resources for our children... and their children

21 Free Planting Plans King County Department of Natural Resources & Parks Website:

22 Rain Gardens...slow the flow of water and allow it to soak into the soil. Image courtesy of Seattle Public Utilities and the Low Impact Development Center

23 Pervious Pathway Alternatives Replace concrete/gravel walkways with stepping stones & plants to allow drainage. Make paths narrow to reduce impervious area.

24 Driveway Alternatives Replace impervious concrete or compacted gravel with flagstones, pervious pavers, broken concrete sections, narrow country lane drives with grass center strips... be creative

25 The Green Roof A green roof consists of a waterproofing membrane and a soil support system. The roof is planted with grasses, sedums and other appropriate plants. Start simple... Installing a green roof on a house or garage requires engineering... but it s possible!

26 2. Preserve Native Vegetation Remove as little native vegetation as possible. Plants work for us when it comes to stormwater management.

27 A simple equation: Bare Soil = Soil Erosion= Instability Washington State Department of Ecology

28 Managing Trees: Pruning or removing Leave native trees in place whenever possible. It will take YEARS to recover the services provided by that tree: Soil protection Land stabilization Stormwater runoff management Wildlife habitat Remove trees only when they become a hazard. Talk to a certified arborist for guidance. International Society of Arboriculture (ISA)

29 Pruning for Views Leave 70% of the original canopy. Prune in late fall/winter Don t TOP Trees it usually weakens them & turns them into hazard trees. Images Washington State Department of Ecology

30 Compacted soil = impervious surface 3. Avoid Soil Compaction

31 Soils & Compaction Compaction results from... Construction activities Vehicle & livestock traffic Heavy use when soils are saturated THE FIX...? 1. MINIMIZE compaction 2. RECONDITION compacted soils

32 Compaction: Residential/Construction Limit traffic Create temporary roads

33 Minimize Compaction A poorly designed facility: muddy, compacted paddock during wet seasons. Specially designed confinement areas: Healthier livestock Much more chore-friendly & less mud. Healthier families- no mosquito habitat.

34 Recondition Compacted Soils Where appropriate, try the following to improve drainage : Rip compacted soils with equipment to break up the layers. Dig a test pit to see how deep you have to rip. If it s deeper than agricultural equipment can reach, you may need to talk to a construction contractor. (Not for bluffs). Core through compacted lawn using an aerator or a rebar pole (every few feet). If this doesn t solve the problem, go to the next step... Deep bore with an auger, look for impermeable layers (gray soils). Consider filling holes with gravel socks wrapped in geo-textile. Top-dress lawns with ¼-1/2 of finely screened (3/8 ) compost, once in the spring (mid-april) & fall (September).

35 Improving Road Drainage How can you divert water off of gravel roads & driveways (instead of towards your house)? Water Bars Open-top Culverts Out-sloped Roads

36 Improving Road Drainage 1. Open-Top Culverts for Roads (Box Culverts)

37 Improving Road Drainage 2. Water Bars a ridge or berm made of compacted gravel, concrete, or asphalt that diverts waters off of a roadway at regular intervals. Water is diverted into a protected dispersion area such as a level spreader or well vegetated area, as wide as possible. 3. Out-sloped roads slightly graded (2%) in one direction with no ditch line. Water drains into vegetation or into an infiltration trench. Image Source: USDA

38 Intercepting & Moving Excess Water How can you manage excessive water when it ponds in your yard or when it places your home at risk? (Bluffs, stream banks, landslide areas...) French Drain Systems & (Curtain Drains) Open Ditches Open ditches work, but not in areas with direct livestock access - unless properly designed and fenced. Preparing a trench for a French drain system

39 What s needed? Perforated PVC pipe (ASTM 3034, 4 + dia.) Geotextile fabric, (Mirafi 500x or equivalent) Washed Drain Rock A 1-2% slope towards the outlet. A plan for where you will outlet the pipe & how you will protect the outfall area... Don t forget pipe protection: animal guard. French Drain Systems

40 French Drains for Subsurface Water No geotextile fabric! This may fail over time. Don t do this! Trench, geotextile fabric, drain rock, outlet protection

41 Gutters & Roof Water Management How can you manage roof run-off so that it doesn t flood your yard? When Diversion Makes Sense 1. Bluffs & Tight-lines 2. Landscape enhancement When Infiltration Makes Sense 1. Level Spreaders 2. Infiltration Galleries or Drywells When Storage Makes Sense 1. Rainwater catchment (cisterns & rain barrels)

42 Roof Water Management When Diversion Makes Sense To keep clean water clean: barns and agricultural properties. For sites with soils that don t drain well. For sites on bluffs or banks above steep slopes. Step 1: Plan where your gutters will outlet and pipe the water. Protect the outlet with rock, animal guards & vegetation. Include clean outs for maintenance. A clean out A French drain system connected to a closed pipe. Barn roof water piped away from paddocks.

43 Roof Water Management When Diversion Makes Sense For bluffs or banks above slopes: Connect gutters systems to tightlines that outlet at the toe of the bluff. Use rigid pipe whenever possible less chance of a break. Anchor pipe to bluff Use multiple tightlines rather than concentrating all run-off into a single pipe Protect the outlet at the bottom of the bluff (a rock basket will diffuse energy)

44 Roof Water Management When Diversion Makes Sense Most properties have a variety of soils. If you have areas with good drainage rates, direct your water to them. Be creative! Don t forget rain gardens. This landowner made a landscaping feature to manage his driveway run-off.

45 Roof Water Management When Infiltration Makes Sense For level sites with soils that drain well. NOT for bluffs or banks above steep slopes. Option 1: Dry Wells Dry Wells we recommend moving them farther from the house foundation...

46 Roof Water Management When Infiltration Makes Sense Dry Wells

47 Gutters & Roof Water Management When Infiltration Makes Sense Infiltration Trenches for Gutter Systems:

48 Rainwater Collection Systems Cisterns & Rain Barrels American Rainwater Catchment Systems Association Cisterns: Industrial Materials Exchange (google - IMEX) United Pipe

49 When do you need engineering? When required by County (checklist or permit requirement) When failure or problems could cause damage On your property On downstream properties Close to steep or unstable slope If discharging to another engineered system If in doubt call MCPW or MCD

50 Services Available In Mason County Mason Conservation District Mason County Community Development/ Public Works WSU Mason County Ext , ext. 680