Northern Trails maintence masterplan for hidden pond · Hidden Pond Nature Center is responsible for maintaining a portion of parkland that if found in the Pohick Stream Valley. This

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NORTHERN TRAILS

MAINTENCE MASTERPLAN

FOR HIDDEN POND

This plan is a layout of future improvements for the trails in the

Northern Section of Hidden Pond Nature Center Parkland. All

improvements are modern techniques used by professional

organizations to maintain and sustain nature trails.

By: Philip Shutler

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Table of Contents The Northern Area ........................................................................................................................ 2

Pink and White Trails ................................................................................................................. 3

Masterplan Map ....................................................................................................................... 4

Trail Features .................................................................................................................................. 5

Waterbars ................................................................................................................................... 5

Placement .............................................................................................................................. 5

Construction ........................................................................................................................... 6

Retaining Wall ............................................................................................................................ 7

Construction ........................................................................................................................... 8

Slope Maps .............................................................................................................................. 10

Soil Maps .................................................................................................................................. 12

Restoration ................................................................................................................................... 14

Replant Zones .......................................................................................................................... 14

Sub-area 1 ............................................................................................................................ 14

Sub-area 3 ............................................................................................................................ 15

Sub-area 4 ............................................................................................................................ 15

Debris Pickup ........................................................................................................................... 16

Conclusion ................................................................................................................................... 17

References .................................................................................................................................. 17

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The Northern Area

Hidden Pond Nature Center is responsible for maintaining a portion of parkland

that if found in the Pohick Stream Valley. This includes a Northern Portion of land which

consists of the tributary that directly feeds into the pond. This

part of the park is a stream valley that consists of mostly

forested land and some human made wetlands. Two trails

can be found in this region, the pink and the white trail. This is

the area this report will focus on.

In detail the management plan will at entail improving

the trails by, structural additions, removing debris, and

replanting areas that are barren. These recommendations

were created from detailed surveying, GIS analysis, and

research done on trail maintenance.

Due to intense rains and runoff, trails can inadvertently

serve as temporary streams where water will accumulate and

cause erosion. Overtime this erosion will cause the trail to deteriorate and become very

hard to travel on. Most of the trails in this northern part were constructed 20 years ago

and have been left to naturally form within the forest. Updates need to be made to

these trails to ensure safety and extend the trails functionality. These updates include

waterbars and a retaining wall.

Along with trails updates, debris needs to be removed from down trees and

barren areas of forest need to be re-planted. The debris removal is very simple and the

large limbs can be laid along trails to mark the edge, and serve other park

management purposes (ex. Firewood). Replant zones are focused in three areas: storm

water stream, storm water basin, barren understory of forest land. Each zone is a

different habitat and will require guidance from park management on what should be

planted and how it should be planted. Replanted zones may require further

management and will need to be monitored into the future.

In this report we have laid out four sub-areas in this northern region that require

maintenance. Each sub-area will need waterbars, 3 sub-areas will have replant zones, 2

sub-areas require debris removal, and one will require a retention wall.

The main goal is to produce trails that will last for another 20 years by adding

necessary maintenance, removing or using certain debris, and replanting areas for

restoration. All of these items should be done in an ecological manner that does not

create degradation in this northern area of parkland. Be conscious of the environment

around you while constructing features and ensure that they will actually work to their

designed purpose.

Figure 1

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Pink and White Trails

Figure 2

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Masterplan Map

Figure 3

Sub-area 1

Sub-area 2

Sub-area 3 Sub-area 4

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Trail Features

Waterbars

Waterbars are designed to remove water off a

trail in the event of a rain storm. They are made by

placing a long piece of wood along a trail at a 45

degree angle to divert water away from the trail so

that goes completely off the side. Water should not

return back on to the trails if a waterbar was

constructed correctly.

Placement

Due to the sudden amount of water that precipitates on the trails, location is

crucial when placing waterbars along a trail. The location of a waterbar on a trail is

determined by the degree of slope, the soil foundation, and its proximity to other

waterbars along the trail. In the process of construction, it is recommended that

waterbars be built at the top of hills to reduce erosion down further on the trail. The

guidelines to follow in proximate location of construction can be best displayed in the

chart below.

The Northern Region of the park is mostly a stream valley so there are some areas

along the trails with a steep change in elevation. These are the areas where waterbars

will be needed the most. Based on topographical maps and on site surveying, the slope

of these trails has been determined and used in the location of the proposed

waterbars. Refer to the slope maps below to see a detailed placement of each of

these bars.

Looking at the soil composition where construction will occur is the next step in

the process of determining the location of a waterbar. Using soil records and surveying

the trails, soil compositions were determined, and used in determining the location of

where the water bars should be placed. Refer to the soil maps below.

Figure 4

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The proximity of each waterbar to one another was first calculated by placing

waterbar in key location, such as the top of a hill. These key waterbars serve as a

starting point and then using soil data and slope data all other waterbars placements

are determined. This method combined with soil and slope data established where the

waterbars should be places.

Construction

Materials:

The building materials to construct a waterbar are 18in sections of rebar and

treated 6inX6in thick wood. The length of the wood will vary with the width of trail and

how far off trail the waterbar will have to extend. You will need a saw, shovel, axe, drill

measuring tape, compass (determine the 45 degree angle of waterbar), level, and a

sledge hammer.

Instructions:

1. The first step is to determine the length your 6inx6in piece of

wood. Do this by determining your 45 degree angle line, and

the starting and finish point of the water bar. The starting point

of a waterbar should be 1 foot off the trail on the uphill side of

the waterbar along the 45 degree angle line. The finish point

should be six inches off the trail or to a point where the water

will not flow back on to the trail. The finishing point is on the

downhill side of the waterbar along the 45 degree angle line.

Use the measuring tape to determine the total length and the

cut the wood to fit the dimension you determined.

2. Then measure where you drill holes should go. Drill holes should

be 2ft apart from each other. Drill in the places you marked at a width that will

allow the rebar to go through.

3. The next step is to dig a trench about 3 inches or more the along your 45 degree

angle. This is to ensure that half of the waterbar is in the ground. Place wood

along the trench and make sure that it is half way in the ground. Make sure the

uphill side can be buried into the ground. All dirt that is excavated should be

placed on the downhill side of the water bar.

Figure 5: This

shows how far

off the trail the

water bar

should start.

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4. The final step is to pound

in the rebar stakes to

hold the water bar in

place. The rebar should

go a foot in the ground

and should not be protrude from the wood. The Water bar should be 4 inches

off the ground facing the uphill side of the trail. This is an important detail which

ensures that a large amount of runoff is diverted during a storm event.

Retaining Wall

A retaining wall will be necessary in

sub area 2 because of a seasonal stream

that runs adjacent to the trail. In a rainstorm

this seasonal stream becomes active and

flows with water causing erosion to the trail.

Our goal here is to create a wall along the

trail that protects it from the stream and

more erosion.

This retaining wall is 54 feet in length and height varies from 6 inches to 2 feet

above ground depending

on the location along the

sloped trail. It will be broken

up into sub sections that are

divided along the slope.

Treat them as separate

walls when creating a

foundation to build upon.

The subsections are shown

in figure 6 as blocks placed

down the hill. They will step

down along the slope

depending how the

sections are broken up.

It is recommended that prerequisite steps are taken in determining the

placement of the sub-sections to give a general guideline in construction and

determine the amount of materials required. To do this, use several stakes and string to

Retaining Wall Stepping Down

Slope

Figure 8

Sub-Section

Retaining Wall

Figure 7

Figure 6

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plan your subsections. Place the stakes in the lower

area below the pre-existing trail where you want the

beginning and end on the subsection to be, and then

tie the strings to both ends. Make sure the string is level

and about a foot off the ground. This is how you will

determine how many subsections will be included in

this retaining wall. This will give you an accurate length

of each subsection and the length of your base

timber. Keep the stakes in the ground and the string

attached, to act as a guideline when digging the

trench in the construction phase.

Construction

Materials:

You will need 6inX6in thick wood, 8 inch 60d spikes, and 18 inch pieces of rebar.

All wood should be treated and pressurized to ensure longer structural functionality of

the wall. The tools you will need are a saw, sledge hammer, level, tape measurer,

tamper, and a shovel.

Instructions:

1. Using the predetermined subsection measurements you found in the planning

phase, cut 6inx6in wood to desired lengths to be used as a base bar.

2. Then begin digging out 12 inch

trenches that are the length of your

subsections along the slope. Refer to

stakes and string you used in the

planning phase to make sure your

trench placement is correct. When

excavating the dirt place it on the

upper area where the trail will be.

Make sure the trenches are wide

enough to completely place the base

bars inside them. Also when you are

close to finish excavating periodically

check to make sure the bottom of the

trenches level. Do this by lowering the timber inside the trench and then placing

a level on the wood to get an accurate reading.

Figure 9

Figure 10

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3. Next place the base bar inside the

trench and situate it to be level.

4. Then drill holes a foot from each end

of the bar, thick enough for the rebar

to go through.

5. After drilling place the rebar inside

the holes and hammer into the

ground. Once this is complete make

sure the base bars are stationary and

firm in place.

6. Then begin stacking other 6x6in timber bars along the base bar one layer at a

time. Do not directly stack them upon each other. They should overlap 6-8

inches off to one side. We will connect the sub sections in the critical points by

adjoining pieces within the

overlap. To secure the wood use

the 8 inch 60d stakes and hammer

them in wood every foot along the

bar.

7. Begin leveling the dirt that was

excavated from the trench and

placed above the trail. Use the dirt

to fill in areas that are not as high

as the retaining wall. Try to make

the trail as flat as possible with a 3

percent angle heading toward the

retaining wall to help with water

drainage.

Figure 11

Figure 12

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Slope Maps

Figure 13

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Figure 14

Figure 15

Figure 16

Figure 17

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Soil Maps

Figure 18

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Figure 19

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Restoration

Disturbances have occurred in the Northern Region due to structural and storm

water development. This presents an opportunity to restore these areas to their natural

setting and habitat. Some areas will require replanting zones because they are barren

and lack vegetation. Other areas will need debris to be picked up, mostly fallen trees

that have been managed and the cut timber was just left at the site of the fallen. We

want to restore these areas to benefit the ecosystem and to create a more natural

setting for visitors to observe and appreciate.

Replant Zones

Replant zones have a significant lack of native vegetation. The goal is to restore

these areas to serve as natural habitat and to become part of the ecosystem. This will

be done by spreading seed or planting seedlings depending on the particular

environment the replant zone is located. All seed or seedling species that are going to

be planted need to be approved by Hidden Pond park management. This will ensure

that invasive species do not invade these disturbed areas. There are three replanting

zones and each has a specific environment which will require induvial management

strategies for replant growth to succeed.

Sub-area 1

Sub-Area 1 replant zone is located in a

storm water basin deigned to limit the

amount sediments that would flow

downstream and enter the pond. This area is

mostly saturated and during a storm event

will act as a miniature pond due to its design.

Right now the area is completely without

vegetation and full of debris. With the

amount of saturation and plentiful healthy

soil, this area would be replanted as a

wetland. Wetland species can handle the

saturation and would provide a habitat for

an abundance of species.

When replanting this area species will

need to be selected based on their ideal

saturation rates. Species along the outside of

Figure 20

Figure 21

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this area will have a low saturation

tolerance as opposed to the ones that

are in lower elevated area which will

require a higher saturation tolerance.

Aquatic grasses and water tolerant shrubs

will be the main species planted in this

area. Park Management will decide the

specific type of species and will manage

the area after planting has occurred.

Sub-area 3

This replant area is in a forested

landscape that has a lot of different bike and

pedestrian trails which have made the

understory nonexistent. Due to bikers and a lot

of pedestrian traffic this has caused an area of

disturbance. The large bike jump will need to

be destroyed and smaller side trails will need to

be closed off for restoration.

This area will have all forest species that

have a high shade tolerance. Closing off this

area to the public will also allow for naturally

spread seeds to have a chance to grow

without disturbance. This area will have to be

managed and ensure that there is no

pedestrian traffic to allow the plants to

establish their niche.

Sub-area 4

This zone is along a storm water creek that is only active during rain events. The

creek is very steep, has many rocks that were put there during construction, and is

infested with Japanese Stiltgrass (Microstegium Vimineum). Constructing this storm

water management stream created a disturbance which allowed the Japanese

Stiltgrass to infiltrate and spread. Our goal with this area is to try and introduce a

competitive plant species that can live among the stilt grass and unique terrain.

Figure 23

Figure 24

Figure 22

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This stream is located under some trees that have a thick canopy. Plant species

in this replant zone will need to be somewhat shade tolerant. The main species that we

will introduce is wild Jewelweed (Impatiens). This species has been able to compete

with the Japanese Stiltgrass along the edges of Hidden Pond and Pohick Stream. The

result of this replant zone should be the establishment of Jewelweed along this storm

water stream to compete with invasive species that are present and to prevent other

species from invading the area.

Debris Pickup

Along some areas of the trails there are trees

and debris that has fallen down and needed to be

cut so that they did not block the trail or create a

safety hazard. These piles of brush have been left

and have created disturbances in the forest. This

can create areas where no vegetation will grow

and allows for perfect infiltration areas for invasive

species. It is commonly mistaken thought that these

brush piles will decompose quickly and provide

benefits for the forest. These large logs and

branches need to be dispersed within the forest and

not be piled up. Some long branches can be used

to line the trail as to make a distinct boundary. Large

logs that were cut from a tree can be dispersed in the forest as habitat for bugs and

amphibians. Spreading out these brush piles ultimately will help the forest by providing

more habitat for ground creatures, making trails the more distinct, and not creating a

disturbance that can lead to negative effects.

Figure 25

Figure 26

Figure 27

Figure 28

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Conclusion

All these recommended additions and management projects will enhance the

northern sections ascetics, ecosystem, and trail functionality. All the projects are to be

done in an ecofriendly manner and be implemented to last for a substantial amount of

time after they are constructed. Adhering to this management plans guidelines and

following park management instruction will create a better more enhanced northern

section of hidden pond parkland.

References

DIY Network. "Building a Timber Retaining Wall." DIY Network. Scripps Networks, LLC.,

2015. Web. 1 Oct. 2015.

Fairfax County Goverment. Typical Retaining Wall Details. Fairfax, VA: Fairfax County

Virginia, 2012. PDF.

National Park Service. Chapter 5 TRAIL STRUCTURES. N.p.: National Park Sevice, n.d. PDF.

Office of Water. Protecting Natural Wetlands. Washington D.C.: Environmental

Protection Agency, Oct. 1996. PDF.