hampton comp waterway management plan my briefing remarks 121410

8/8/2019 Hampton Comp Waterway Management Plan My Briefing Remarks 121410

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Hampton Comp Waterway Management Plan

12/14/10 Briefing Notes on Previous Studies

by Fred Whitley, PE, URS Corporation

[Listing of studies slide] Introductory remarks:

This briefing is to help the steering committee understand what

work the city has already done on this subject, so it can be aware

of what has been recommended and/or implemented and perhaps

utilize and/or build on some the previous work

The summaries of these studies are contained in the notebooks, in

Tab N

These summaries are based on the full studies, which are available

for reading on both the citys website and the project websiteThe order has been changed slightly from what is in the notebooks

and this briefing will be a summary of those summaries.

1) Newmarket Creek Flooding [Title slide]

Initiated in March 2007 by council to address citizen

concerns about flooding along Newmarket Creek

There are 3 primary causes for flooding in Hampton:

1. Higher than normal tide (includes wind driven waves)

2. Rainfall intensity exceeding the capacity of the storm

drains, drainage ditches and canals

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3. Obstructions in the storm drainage system- naturally

occurring and manmade- fallen trees, illegal dumping

( even grocery carts)

Some areas of the city are only affected by 2 out of the 3 causes.

But, because of its geography and heavy vegetation, NewmarketCreek is highly susceptible to all three.

The study was conducted by a 15 member citizens

committee supported by city staff and a consultant, working

together for about 4 months

[Aerial Slide]Watershed aerial slide-(orientation)/what is a

watershed? (This is the largest watershed in Hampton)

Watersheds dont respect municipal boundaries-drains some

of NNews/most of the watershed is in Hampton

Waterway flows out past the Coliseum and under Mercury

Blvd and La Salle Ave, near Riverdale, to the Back River

Background- flooding in Newport News/Hampton- 1960s

Corps constructed project for northern segment ( Newmarket

Shopping Center) solved part of the flooding problem

Today there is recurring flooding all along the creek with one

of the worst areas around the Paula Maria/City Line Road

Apts Study involved a series of meetings with the committee and

the public and the committee noted some ideas which they

didnt recommend along with some ideas that they did

recommend.

[refer to list slides]

2) Mary Peake Watershed Study- [Title slide]

This study was the result of the Newmarket Creek Study- it

did not involve a citizens committee

[aerial slide] This area is a subset of the Newmarket Creek

basin ( orientation)

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[aerial slide ] Describe subwatershed boundaries- describe

canal system in this area, draining higher ground, how

development spread that way from downtown, and

distinguish with lower lying areas drainage.

This was the first project of its kind commissioned by the

city, using sophisticated computer modeling of thewatershed- this modeling inputs all of the topography,

drainage pipes, ditches and development in the area across

the entire watershed and it show how for various rainfall

intensities, where there will be bottlenecks in the drainage

system and the probable extent of the flooding. It can also

reveal how a modification in the drainage system, or a new

development, might affect the drainage in the rest of the

system. The study identified a number of specific projects that would

improve the drainage in the watershed which are identified in

the full report- most of these involve the replacement of

undersized drainage pipes.

City is considering these drainage improvements in its capital

improvements planning.

3) Farmington Canal Area Drainage Study [Title slide]

This study was commissioned as a result of street and yard

flooding from several storms in 2007- highest land in the city

( approx 20 above sea level) but still susceptible to flooding

in a heavy rainfall event

[Map slide] This slide shows the study area (orientation)

History- Bethel High School construction- drainage canal

dug- years ago this area was known as Sawyers Swamp, and

Big Bethel Road was then known as SS Road The new canal allowed subdivisions to develop in the area

-Farmington, Forest Ridge and Micheals Woods in

accordance with subdivision design standards but, this was

before the city had computer tools like watershed modeling-

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each subdivision designed to drain its own water w/o looking

at the bigger picture in the canal.

Study identified deficiencies in the canal that slowed the flow

of water- city has the corrective work done

Some areas still susceptible to backwater in a major storm

when the Newmarket Canal outfall becomes full of stormwater.

Study raises the question of doing future modeling of the

Newmarket canal watershed, perhaps by the Corps since the

watershed includes two cities

4) Pochin Place Canal [Title slide]

[Aerial photo slide] This is another watershed study usingcomputer modeling, this time in the Wythe area ( orientation)

History of Wythe development- before there were

subdivision design standards with drainage calculations

requirements, drainage systems were expanded as far as

possible without much regard for downstream capacity

Recognizing this problem, the city has completed a number

of drainage improvements in this watershed- diversion of

some water near Pembroke, a dry basin , and canal widening

at lower end

But, flooding along the canal still occurs in major storms

primarily due to downstream channel siltation and tidal

encroachment from Hampton Roads

Study recommended tide gate at Kecoughtan Rd, and

dredging of waterway. City is working on a project to get

easements from adjacent property owners for dredging, and

permits from the Corps and VMRC would be required.

5) Corps of Engineers- Ches. Bay Storm Damage Reduction

Study [Title slide]

This was the mother of all studies, performed by the

Army Corps of Engineers, taking 8 years and costing many

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hundreds of thousands of dollars (and hundreds of trees

lives). The Corps follows a very regimented, phased process

that results in an end product that is very thorough, its just

very tedious and expensive. Fortunately for Hampton, most

of the expense was federally funded.

[Aerial slide of shoreline]. The study began by looking atthe environmental impacts, probable costs and benefits of

improving Hamptons shoreline along the Ches Bay in order

to increase the ability of the shoreline/ adjacent structures to

withstand damage from flood tides and wave action ( coast is

a mosaic of ownership, some areas are developed and some

undeveloped)

A number of public meetings were held to discuss the project

Corps primary criteria for funding actual improvements is thebenefit/cost ratio, and only a few areas had a benefit cost

ratio greater than 1, the public beach areas that had

development in the vicinity ( in order to have something to

protect)

Some areas opted out of the study due to not wanting to grant

public access, such as Malo Beach

Final report identified Buckroe Beach as an eligible project.

Council committed a cost share and, in 2005, the Corps

oversaw the pumping of sand on the beach from an offshore

source (which has a very large quantity of beach quality

sand) to provide more storm damage protection. Sand was

also pumped onto the Salt Ponds public beach at 100% local

expense.

Periodic beach nourishment is required as sand is constantly

drifting away- however, breakwaters have been added to

slow the movement of sand. One was in place at the time of

the Corps project, one was added last year and a third will beconstructed in a few months.

6) Floodplain Management Plan- [Title slide]

[Study results slide]

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7) Salt Ponds Inlet Study [Title slide]

Ken Dierks will talk about this one since he was involved in

the study

8) Back River Flooding and Shoaling [Title slide]

Background- rapid disappearance of the sand spit at the

mouth of the Back River [ Aerial photo of before condition]

known to most as Factory Point ( former menhaden

processing plant in late 1800s)

Gave rise to concerns about increased susceptibility to waves

in the Back River, shoreline erosion, loss of the recreational

feature, loss of wildlife habitat, and an increase in siltation of

the boating channels in the vicinity Council authorized citizens committee to look into this, with

staff and consultant support

Committee had a number of findings [Findings slide] and

recommendations[Recommendations slide]- their highest

priority was the restoration of Factory Point

Many of these findings and recommendations are relevant

still to what this committee will be considering

After 6 months of design effort, over 2 years of permitting

effort, and constant battles with Mother Nature, in the spring

of this year, boating channels were widened and deepened,

and FactoryPoint was restored, and this is what the finished

product looks like, with breakwaters added to protect the

restored spit. [After aerial photo]

Questions?

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hampton comp waterway management plan my briefing remarks 121410

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