Comprehensive Plan Committee
Storm Drainage and Stormwater Management
Status Report - December 19, 2005
Introduction

Recent efforts have been directed at the subject of storm drainage with a focus on improving drainage or the conveyance of water during large rain events in Ocean Pines. This report focuses on the larger components of the Ocean Pines drainage system- storm water management ponds. It is provided to supplement the conclusions and recommendations of the Environmental and Natural Resources Committee dated April 20, 2005, which primarily addressed the stormwater drainage system of vegetated swales with interconnecting ditches and pipes in Ocean Pines. We endorse the committee’s recommendations and provide this report to broaden the perspective by addressing primarily the subject of stormwater management ponds.

Background

The Comprehensive Planning Committee reviewed the following documentation on the subject of storm drainage and stormwater management in Ocean Pines:
1. Motion on Drainage Survey By Heather Cook on October 14, 2005
2. Conclusions and Recommendations from Stormwater Drainage Symposium, April 20, 2005 by the Environmental and Natural Assets Advisory Committee
3. Minutes of Ocean Pines Storm Water Symposium, February 17, 2005
4. Comprehensive Plan for Ocean Pines, revised 2002
5. Recommendations for Canal maintenance, December 17, 2001, by the Marine Activities Advisory  Committee
6. Drainage Analysis for the Ocean Pines Association, February, 2002,  by Soule and Associates
7. Memo to Board of Directors from David Ferguson Re: Drainage Analysis/Status Report & Priority, 6/18/2002
 
The following individuals were also consulted for their personal input on certain aspects on the subject of drainage:
1. Mark Venit
2. Heather Cook
3. Dave Ferguson
4. Bob Abele
5. Dr. Nicholas DeGenarro
6. Joe Reynolds
7. Jim Hudson
8. Dewey Meyer

Development of Ocean Pines

Much of Ocean Pines was originally wetland or low lying woodland that resulted from being on the edge of the coastal plain, which comprises the eastern shore. Wetlands by definition are characterized by the presence of standing water and /or a shallow water table for at least a portion of the year sufficient to change the chemistry and hydrology of the soil. Certain plants adapt to grow in these hydric conditions and become indicators of where wetlands exist. Some of Ocean Pines was also salt marsh and/or tidal waterfront property. The soils throughout much of Ocean Pines do not absorb rainwater well. In some places the presence of a clay layer prevents the water from percolating through the soil resulting in a perched water table. The only way for water to escape such locations is by gradually seeping or flowing to another location or evaporating.

This condition is not uncommon in many areas of the County according to the Final Draft of the Worcester County Comprehensive Plan (September 8, 2005) which states “The County’s topography drains slowly”. Also, “Poor drainage due to inadequate or inappropriately designed/maintained drainage ditches and stormwater management devices result in unnecessary standing water.” The plan specifically identifies “portions of Ocean Pines” as one of several areas of the County that commonly flood during storms. This should come as no surprise because the plan also states “two thirds of the County’s soils are hydric”. If it were being developed today, portions of Ocean Pines would not be approved for development due to legislation protecting wetlands and coastal bays. Those portions that would be approved for development today, would be required to have stormwater management.

In the process of developing Ocean Pines, the original developer, Boise Cascade attempted to maximize the amount of water front property. To do this, much of the marsh and tidal areas adjacent to the St. Martins River, Isle of Wight Bay, Manklin Creek and Turville Creek were bulkheaded to stabilize the land proposed for lots. Intervening areas between the rows of lots were then dredged to create canals and the spoils from the dredging were placed on the adjacent lots to fill them. This resulted in fairly level lots with layers of material having a high content of clay and sand with poor permeability. Minimal drainage ditches or swales were provided. There was a minimum gradient across the relatively flat land and it was not practical to pipe the water underground. Storm drainage for these areas relied largely on the sheet flow of rain water across lots into the canals.  When a house was built on one of these lots, it was usually raised to create improved drainage away from the house and improvements.

In contrast, most of the woodland lots were built near or at existing grade to avoid disturbing the existing trees and minimize costs.  Ditches and swales were the primary means of conveying the water away from these lots. The storm water management system and its associated network of ditches Boise Cascade designed for Ocean Pines was intended to serve a vacation home development. It was minimal at best. It was not designed for the year round residential development that Ocean Pines has become.  Essentially, the ditches were installed to drain water off the roads and lots. It is doubtful whether they were sized to meet the requirements of all the lots proposed to be built. The facilities in the first sections of Ocean Pines were built to standards that do not meet those required of developers today. Occasional heavy rain events were rarely a problem. After all, this was a vacation community and most people were not here during inclement weather.
Storm Drainage Ponds

Many sections are not served by any retention ponds. All the stormwater from these areas flows directly over each property or through the ditches and swales into near-by canals and tributaries. When the water must drain a long distance as is the case with many of the older lots, the water backs up. Also, when the tides are high in some areas, the water can not flow through the ditches and swales.

The ponds that were built by Boise Cascade are not adequate for build-out conditions. They were not primarily intended to serve as stormwater ponds. The two largest of them, which are on either side of Cathell Road, were initially borrow areas for materials used in construction and were later, converted into aesthetic features. The same is believed to be true of the pond at the north gate. Today these ponds provide a minimal amount of stormwater management for some of the streets and open space around them.

The areas where development generally occurred in this manner were sections 1,2,3,4,5,6,7,8,9,10,11,13,14A,14B,14C,14D and 15A. If the ponds in these sections had been built to today’s standards, they would have had to limit the post construction runoff to the preconstruction levels as well as prevent silt and nutrients from passing into the tributaries they feed. In section 10 only about 100 lots out of almost 1300 drain into a pond, in this case the South gate pond. The pond that serves the most dwelling units within the sections listed above is located in Bainbridge Park. The stormwater from about 300 lots flow through this pond but even this pond is inadequate. 

To exacerbate these conditions, as homes were built here and there, their lots were filled prior to construction in an uneven pattern to avoid drainage problems. It is believed this was done in many cases to a greater extent than the one foot above ground level allowed by the Declaration of Restrictions. This often caused surface water to drain onto adjacent lots. If and when the drainage system was not able to convey the water away quickly enough, the water backed up and entered rather than exited some of the lower lots. There has also been a trend in recent years to build larger homes or expand existing ones. Many homes, both old and new, are having new or larger driveways and walkways added. This has substantially increased the amount of impervious surface on each lot that will not absorb any rain water. This has generated larger volumes of stormwater that need to be managed by the public system.

There are also several clusters of homes, particularly in the some of the older sections such as 2, 3, 10, 11 and 13 where water lays in the yards of the homes because of lack of surface drainage. Water will pond in these clusters of yards because they share a common low point. Public Works is unable to provide assistance with their problem because these properties have no drainage easements or swales to convey this water to near-by street ditches.
 
In addition to these factors, a vast area of land owned by the Maryland State Highway Administration runs through the center of Ocean Pines. This contains a huge area of impervious asphalt surrounded by medium to steeply sloping shoulders designed to shed rainwater quickly. This roadway, which was built to similar standards for stormwater management as those for the older sections of Ocean Pines, generates a very large volume of stormwater.  Some of this water appears to flow into the pond between MD 90 and Cathell Road. Otherwise, this water runs over the surface or is conveyed via swales and ditches along and through parts of Ocean Pines to its destination in Manklin Creek, our canals and the St Martins River. This water competes for the limited capacity we have in some of our swales and ditches and contributes to the flooding that occurs during heavy rain events. This is particularly apparent near hole 11 of the golf course and the MD 90 underpass where ditches converge as they empty into the tidal canal along Ocean Parkway. 

More recent developers such as Balfour and Centex have been required to meet contemporary State and County requirements for stormwater management – namely - the dual functions of water quantity control and water quality based on full build out of the area to be served. This has resulted in them providing stormwater management and storm drainage facilities that are capable of limiting runoff to the prescribed preconstruction level. These consist of the Inner Links(12), Whitetail Sanctuary(15B), the Parke(16), the Pointe(17), Colonial Village(18), and Harbour Village(19).

Soule Report

In 2002 OPA contracted with Soule and Associates to do an engineering analysis of problems with drainage in certain areas identified by the Department of Public Works. Soule provided information and recommendations on which OPA could determine its priorities and plan to implement the recommended improvements. A review of these recommendations with Dave Ferguson, General Manager on November 1, 2005 indicates most of the projects recommended by Soule had been completed or are in progress.

The Soule report cited the fact that the State of Maryland emphasizes the importance of grassed or otherwise vegetated swales to provide water quality in stormwater management. The plants in vegetated swales serve to remove nutrients and pollutants before they enter near-by tributaries and are preferred over a closed pipe system. It was also noted that a number of the swales studied by the engineer were considered to be wetlands and it was doubtful that the State of Maryland would agree to approve the installation of pipe in place of these swales because of the presence of the wetlands. The engineer recommended against piping swales for this reason. The swales are the primary means of removing sediments and nutrients from the water before it enters our canals and tributaries given the fact that so little of Ocean Pines’ drainage is managed by stormwater management ponds. This points to the importance of exercising care to avoid the removal of desirable vegetation from the ditches when they are maintained.

Page 123 of the Comprehensive Plan for Ocean Pines identified four projects “that will require priority attention over the next several years”.  Two of these have been completed. The two that have not been completed consist of 1) the backup of stormwater in sections 2 and 3 caused by the smaller sized storm pipe across the River Run Golf Course than the one that crosses under Beauchamp Road and 2) some of the drainage improvements at nine locations in section 10.

New technology   The concept of using sand infiltration systems to increase infiltration of water into the soil was cited in the Comprehensive Plan.  Various forms of this have been used over the years in concentrated locations such as parking lots. One form of this, advocated by Ocean Pines resident and engineer Dr. Nicolas DeGenarro, consists of  boring large diameter holes through the layers of clay to pervious material below. The holes are filled with granular material such as sand and covered with geotextile filter cloth and other materials to prevent silt and debris from clogging the voids in the material.

This could be used to enhance drainage and alleviate ponding in low lying areas, and could be especially useful in areas where there is limited land surface such as a pond would require. It also has the advantage of dealing with the water near the source of the problem rather than conveying it to another location for it to drain into a tributary or pond. This would meet the meet the need stated in the Comprehensive Plan to better manage water quality through bioretention “which relies on infiltration into the soil horizon as opposed to conveyance from the site”. Geotechnical testing would be advisable to locate subsoil conditions that would have suitable permeability and sufficient depth to the water table for large amounts of water to be absorbed into the ground. Sites near the Ocean Pines wells should be avoided. State Health Department approval may also be necessary to ascertain there is no impact on our aquifer.

Conclusions

1. Much of Ocean Pines was constructed on land characterized by hydric soils which impede percolation of water into the ground.
2. The majority of stormwater from residential lots in sections 1,2,3,4,5,6,7, 8, 9,10,11,13,14A,14B,14C,14D and 15A drains into canals or adjacent waterways without passing through retention ponds to control flooding pollutants. Therefore the homes in the above sections receive little or no benefit from ponds.
3. The vast area of land owned by the State Highway Administration for MD 90 drains along or through Ocean Pines without much of its stormwater being managed by ponds.
4. These conditions contribute to: a) flooding during heavy rain events, b) siltation of adjacent canals and tributaries and c) adversely affecting the ecology of the canals, tributaries and bays 
5. There are several shortcomings in the stormwater management system in Ocean Pines. No single solution is likely to correct them all. Therefore, a multi-faceted approach is needed
6. The conveyance system of swales and ditches works well for small rain events. Ocean Pines must continue to maintain the system at a high level to keep problems with the system to a minimum.
7. The County did increase the size of the pipe under Beauchamp Road to improve the drainage from section 3 and 4 as proposed in the Comprehensive Plan. However, the rest of the drainage system in this area is inadequate to handle the volume of water flowing out of Ocean Pines at this location.
8. Most of the drainage projects OPA identified that were recommended for completion in the Soule Report have been completed or are in progress.
9. Other projects identified by OPA that Soule recommended against doing, largely because of the presence of wetlands, still need to be addressed. This is especially true of some of the projects the Comprehensive Plan identified in section 10.
10. Some of the vacant lots owned by Ocean Pines are subject to periodic flooding and may provide stormwater management capacity as they are.
11. There are some areas where water lays on private property for an undesirable period after rain events for which there are no ditches or easements for Public Works to access or work on the property.

Recommendations

Based on our review of the above documents and discussions with the people named, the Comprehensive Planning Committee offers the following recommendations in addition to those of the Environmental and Natural Assets Advisory Committee:

1. Follow up on all items recommended by Soule that have not been completed. Address each and decide how that item is to be implemented.
2. Follow up with the County and request assistance in developing and implementing a solution to resolve the drainage bottleneck that occurs at the location on Beauchamp Road where the drainage pipes cross under the road and flow through River Run.
3. Request funding from the County and State to help finance the retrofit of stormwater projects. The Maryland Department of Environment has a new funding program that provides 75% of the cost to construct pond retrofits. Engineering costs can be used for the 25% match. Funds are limited and may not last long.
4. Apply for grants from the Maryland Coastal Bays Program to finance projects or studies that will improve flooding, water control and water quality.
5. Retain an engineer who has a good working knowledge of the latest technology in stormwater management pond design to inspect the conditions of all existing ponds built prior to current standards to determine which could be modified to improve their performance during large rain events. Modifications to be considered should include the following: a) meet the need for pollutant removal, b) improve peak runoff water volume control, c) enhance habitat for aquatic forms of life, d) increase retention capacity, and e) increase the areas served by the pond. The engineer’s analysis should be done first on the ponds at the north gate, on either side of Cathell Road and at Bainbridge Park. One such modification could be to install new outlet structures to make the pond release water more slowly and at graduated rates of flow.  The engineer should also examine where it might be feasible to construct additional ponds in sections 1,2,3,4,5,6,7,8,9,10,11 and 13.
6. Retain an engineer to make a similar determination regarding potential upgrades to the 5 existing ponds at the Country Club without compromising their ability to promptly remove water from the golf course.
7. Identify where the sand infiltration systems advocated by the Comprehensive Plan, and a form of that advocated by Dr. DeGenarro, could be used to enhance drainage and alleviate ponding. Depending on the cost and feasibility, designate a test project to determine the effectiveness of this method.
8. Identify areas where flooding occurs on lots with no ditches or easements for Public Works access. Where unanimity exists, obtain easements from these homeowners so OPA can work on these areas. Otherwise, these homeowners could be advised of the potential of sand infiltration systems if they chose to try this method privately.
9. Some vacant parcels owned by OPA flood periodically. These should be preserved for that purpose to serve as overflow capacity for storm drainage during major storm events. These might also be good candidates for sand infiltration. This should be done before a decision is made on which lots are to be offered for sale following the recent referendum. A cross check should also be done to verify these lots are not offered for sale in the future.
10. Follow up with the County and State to determine if remediation can be done to improve management of the runoff from MD90 that currently enters our community and bays unimpeded.
11. An engineer should also be consulted to identify what alternative measures can be taken to alleviate the problems OPA identified in 2002 but which Soule recommended against due to the presence of wetlands, especially in section 10.

We believe investigation of these improvements and implementation of those found to be feasible will result in substantial improvement of the stormwater management system’s ability to remove stormwater from our neighborhoods and convey it to discharge points with far less adverse impact on homes and the environment.

Prepared by Jim Duke-/ Signed/

Submitted by the Comprehensive Plan Committee

Arthur Sachs,
Chairman, Comprehensive Plan Committee

R-12/20/05