I. CYBUS WAY, CHERRY LANE, PINEWOOD DRIVE AND CARLIN DRIVE A. GENERAL This site is part of Upper Southampton's comprehensive plan to alleviate existing drainage problems that currently exist in the township. The site is located on the northeast intersection quadrant of Street Road and the Reading Railroad and involves several streets (Carlin Drive, Cherry Lane, and Pinewood Drive). The drainage problems are composed of excessive gutter flows and roadway flooding. There are also infiltration inlets on Cybus Way which are open bottom inlets which operate on percolation only. These inlets are located at a roadway low point and have clogged over the years of use due to sediment collection and poorly drained soils. The problem is compounded by a large contributing drainage area, and a limited existing storm collection system downstream. Most of the existing collection has been abandoned by paving over the collection inlets. It would appear that the inlets must have been filled with stone, concrete or other material(s) in order to structurally support the bituminous overlay. The existing collection system exists only in the lower portion of Carlin Drive. There is also a low point on the northwest corner of the intersection of Chrerry Lane and Carlin Drive with no inlet collection device. B. STORMWATER MANAGEMENT In order to correct the above problems, the area has been studied and supporting stormwater computations have been provided for improvements to the area. The study area involves approximately 20 acres which drain to one (1) inlet at the cul-de-sac on Carlin Drive. Stormwater collection systems are designed to collect and convey a 10 year frequency storm. Flows above this are expected to encroach into the roadway and to be conveyed to an outlet without causing harm to properties for up to a 100 year storm event. All flows are conveyed to the low point at the terminus of Carlin Drive via gutter flows presently, so a 10 year design storm is recommended. This is an oversize inlet box, however considering the abandoned upstream inlets and large drainage area, the inlet does not provide sufficient capacity. The outlet pipe from this collection structure is a 24" CMP, also undersized considering the upstream drainage area. …computations indicate the terminal inlet has capacity for about one third the ten year flow, the pipe has capacity for about one third the 10 year flow and the gutter has capapcity for about one twentieth or one third the 10 year storm depending on flow encroachment width into the roadway. Even if the existing system was in service, it is severely undersized and lacking of suitable collection devices. C. PROPOSAL It is proposed to construct a storm collection system from the malfuctioning infiltration inlets located on Cybus Way to the cul-de-sac on Carlin Drive. The system will greatly reduce problems associated with gutter flow and also standing water in the vicinity of the infiltration inlets. There is one infiltration on Cybus Way (west of the two(2) at the low point) which is also not functioning. It is located on a slope, so that standing water is not a problem. No improvements are scheduled for this inlet since it is located at a much lower grade than the proposed collection system and there is no storm ystem in close proximity to connect it to. D. RESULTS The proposed improvements not only correct the filtration inlets on Cybus Way, but provide strategic collection points along the way which will greatly reduce gutter flows and flow encroachments into the roadway. It will also correct the pipe capacity problem at the terminus of Carlin Drive as this pipe size is to be increased. Consideration was also given to an alternate storm sewer routing through residential properties located between Cybus Way and Pinewood Road. This laternate system would provide collection points within the residential property rear yards. This option was not evaluated further because of the potential difficulty of obtaining easements, potential damage to existing plantings, and the fact that the location of the storm sewer located in the streets allows the oportunity to connect additional inlets at the Cybus Way / Pinewood Drive intersection and extensions thereto should future demand require this. In order to correct the above situation the following is required: Some additional right-of-way will be required from the properties on the south side of Cybus Way. An easement will be required from the property owners at the terminus of Carlin Drive in order to replace the existing 24" CMP. It should be determined by what method the existing storm collection system was abandoned and what type of pipe it is constructed of. Since the proposed collection system replaces the existing system in most areas, it is recommended that the old system be entirely removed, especially if the pipe material is CMP. This will eliminate the possibility of differential settlement and sink holes should the old pipe fail structurally. It will be necessary to get mark outs from all utility companies. The proposed improvements will most likely not conflict other utilities since the proposed storm system is located on the opposite side of the roadway. Pipe crossings should be excavated prior to construction and any problems brought to the engineer's attention. Based upon drainage problems reviewed as part of this project it is noted that thes eproblems can be avoided in the future by considering the following: The storm collection system for any proposed improvements should be closely reviewed and confirmed to have adequate collection points, collection and conveyance capacities. Infiltration / percolation systems should not be approved unless adequate storage volume, percolation rates, maintenance agreements and bonds are provided. CMP should not be permitted in the township since smooth bore polyethylene pipe or reinforced concrete pipe (RCP) is much more efficient and longer lasting. On-lot drainage shoul dbe considered (in the form of a stormwater collection systems) where excessive flows are developed in the rear of properties. All drainage structures should be provided in easements. Inlets should also be provided in the street at property lines where substantial flows are anticipated. The system's discharge point should be analyzed by a certified soils scientist to ensure that no additional permitting will be required by the Bucks County Soil Conservation District or the Pennsylvania Department of Environmental Protection (PaDEP). Any additional drainage problems in the area should be identified and studied to see if they can be addressed by connecting to the proposed stormwater colelction system. II. EAST MAPLE DRIVE A. GENERAL This site is part of the Upper Southampton's comprehensive plan to alleviate existing drainage problems that currently exist in the township. The site is located on East Maple Road approximately 500' west of the intersection of Marigold Avenue. The problem is frequent flooding of the roadway, flooding of the garage of lot 847 and water encroachment into the yard of areas of lots 847 and 841. Based upon site investigations, it appears that these problems have been exacerbated by slight changes in roadway grades (settling crown, frost heaving near the inlet, accumulation of debris in the gutter), possible changing of driveway grades, additional upstream impervious surface (sheds, additions, etc.) and deterioration of the existing storm collection system. As such, flows are not fully intercepted on the north side of East Maple Drive due to grades and possible storm collection system insufficient capacity. Flows cross the crown of the road where there are no inlets, follow driveway grades and inadequate swales and cause flooding. It is noted that the owner of lot 847 has constructed a bituminous berm across the driveway in order to block flows from entering the garage. B. STORMWATER MANAGEMENT In order to correct the above problems, the area has been studied and supporting stormwater computations have been provided for improvements to the area. Additional inlets are proposed strategically along both sides of the roadway as necessary to intercept flows into the collection system. A larger cross pipe will supply the additional pipe capacity. The swale that the storm collection system discharges to will be enlarged in order to eliminate yard flooding and flooding of the existing shed. Check flows to the north side of East Maple Drive: The calculated flow to this area is 8.8 cfs for a 2 year frequncy storm event. The inlet capacity at this location is 2.5 cfs << 8.8 cfs. The pipe capacity across the road from this location is 4.6 cfs << 14.8 cfs. C. RESULTS In order to correct the above situation the following is required: It will be necessary to add an inlet on the north side of the road. The inlet will be added off the edge of the roadway so that it can be sumped to improve efficiency. This also helps to compensate for minimal roadway crown which currently permits flows to cross the roadway during minor storms. The existing inlet will also be relocated off the edge of pavement and be replaced with a standard PennDOT inlet frame and grate since the existing grate is small, has little capacity and clogs easily. The existing 18" CMP has marginal capacity and should be replaced with a 24" diameter PEP-S (smooth bore). This pipe will more than double the capacity of the storm system and operate for up to a 100 year design storm which will benefit keeping flows from the garage of lot 847. It is noted hat the depth of this pipe is approximately four (4) feet and that a water main crossing is necessary which is expected to be at a depth of greater than four (4) feet. The water main should be excavated prior to construction and, if necessary, construct two (2) new 18" PEP-S pipes instead of the one (1) 24" pipe. We have found no record of easements for the pipe discharge point at the property line between lots 841 and 847. Pipe work is necessary in this area so an easement is required. It is recommended that an easement be obtained from the street right-of-way to the stream. In the case of inlet clogging flows may still cross the roadway. It is noted that the roadway has very little crown (less than one (1) inch near the low point). While flow across roadways is not desirable, but acceptable in major storm events, the direction of flow is toward the exisitng driveway and garage which is not acceptable. Flows currently crossing the roadway enter the residential driveway (lot 847) at the roadway's low point. A small bituminous berm should be constructed across this driveway and additional inlets on the south side of the street. This can be done at less expense than increasing the crown of the roadwayin the vicinity of the low point. These inlets will also be located off the side of the road and provided in a sumped condition for increased efficiency with a swale / berm directing flows to them. The existing property line swale does not have adequate capacity to route the flows without spilling over into the adjacent properties and possibly causing damage to the existing shed. While this does not result in severe property damage, adequate swale capacity may be achieved by simply regrading the swale to provide the required capacity. Since stormwater easements are required for the proposed pipe work, this work should also be considered at this time. A wetlands evaluation of the discharge stream should be performed prior to initiating this work; however, it does not appear that any wetlands exist. A general permit #3 (GP #3) may be required if the discharge stream qualifies as a regulated waterway (according to the Bucks County Conservation District / Pennsylvania Department of Environmental Protection (PADEP)). Based upon drainage problems reviewed as part of this project it is noted that these problems could be avoided in the future by consdiering the following: Always utilize standard inlet grates. These are much less prone to clogging by leaves, ice, and snow. Type 'M' inlets hsould be sumped and located off the edge of pavement if curb is not present. Type 'C' inlets should be provided in areas with curbing. These inlets are provided with an open mouth design which is less prone to clogging than the Type 'M' inlets. Smooth bore pipe should be utilized wherever possible. This pipe has a much higher capacity than corrugated pipes. Polyethylene pipe (PEP) is also recommended as it has proved to be very durable and economical. Roadway crowns should be constructed with no less than 3/8"/ft. cross slope (3.13%). This increase in crown proves to be extremely beneficial in increasing gutter capacity and keeping ponding out of the travel way. III. 945 & 950 EAST MAPLE DRIVE A. GENERAL This site is part of the Upper Southampton's comprehensive plan to alleviate existing drainage problems that currently exist in the township. The site is located immediately north of the intersection of East Maple Drive and Woodland Drive. The problem is continuous flooding of lot 945, 951, and 950, and flooding of the roadway. Based upon site investigations, it appears that this problem is the result of poor lot grading and an improperly sized roadway culvert. The problems have been exacerbated by slight changes in roadway grades (settling crown), accumulation of debris in the drainage way, additional upstream impervious surface (sheds, additions, etc.) and deterioration of the existing storm collection system. As such, the area is very poorly drained, flows cross the roadway crown during minor storm events and the existing culvert appears to have insufficient capacity. B. STORMWATER MANAGEMENT In order to correct the above problems, the area has been studied and supporting stormwater computations have been provided for improvements to the area. A storm pipe colleciton system is proposed across the roadway (culvert replacement) and between the properties to alleviate standing water. The pipe on lot 896 has been enlarged and lowered in order to provide pipe capacity and to permit positive grading across the lot. The edge of roadway shoudl be regarded to direct roadway flows to the proposed flared end section instead of crossing the roadway crown which it does currently. The yard swale will be regraded to inlets which have been sumped for better efficiency and more positive drainage. Check flows to the west side of Maple Avenue: the calculated flow to this area is 12.1 cfs for a 2 year frequency storm event; and, the pipe capacity across the road from this location is 9.2 cfs << 12.1 cfs. C. RESULTS In order to correct the above situation the following is required: It will be necessary to replace the existing 18" CMP roadway culvert with a 24" diameter PEP-S (smooth bore polyethylene pipe). The proposed storm collection system provides capacity to convey up to a 25 year frequency design storm, and up to a 100 year design storm with some minor flooding and minor roadway encroachment. The roadway area and lot 950 yard area will be regraded to this pipe which has a lower invert than the existing pipe to promote positive yard drainage. A flared end section will be provided on the end of the pipe to blend in the grade. An easement will be required from the owner of lot 950. This shouldn't be a problem since his yard area drainage will be greatly improved. This water course is directed at the front door of lot 945. The drainage area is very poorly drained due to inadequate slope. A storm collection system is proposed to be routed around this area providing inlets in a sumped condition that will improve the yard drainage of lot 945. This work will require an easement from lot 945, lot 999 and from Stackpole School (for the discharge point) The owner of lot 945 will reap great benefits from this project so an easement should be easily granted. Only minor encroachment is proposed onto the school's property which will be cleanup work so their easement should also be granted easily. Extensive stormwater easements are required from the owner of lot 999. While lot 999's drainage will be improved this owner should be contacted early on in the project to see if the easements are feasible. If not the easements can be shifted onto other properties (lot 945, lot 1091, 1083 and the school) however utilities and existing trees will increase the cost of the project. The discharge point for the storm collection system will be directed to the existing concrete headwall and 15" CMP on the school's property. We considered replacing the 15" CMP on the school's property with a larger pipe but since this would more than double the cost of the project and the downstream problems aren't severe this work is not recommended. It is noted that once the 15" CMP reaches capapcity the flows will continue across the school's property and not back up into the storm collection system extensively. A wetlands evaluation of the discharge location should be performed prior to initiating this work however it does not appear that any wetlands exist. Based upon drainage problems reviewed as part of this project it is noted that these problems could be avoided in the future by considering the following: A minimum yard slope of 2% should be provided, especially in yard areas. Roadway culvert capacity is determined based upon the pipe size, pipe smoothness, the amount of "head pressure" that is available on the upstream end of the pipe, and the "tailwater" (backup pressure at the downstream end of the culvert or pipe collection system). Smooth bore pipe should be utilized wherever possible. This pipe has a much higher capacity than corrugated pipes. Polyethylene pipe (PEP) is also recommended as it has proved to be very durable and economical. Roadway crowns should be constructed with no less than 3/8" ft cross slope (3.13%). This increase in crown proves to be extremely beneficial in increasing gutter capacity and keeping ponding out of the travel way. IV. 970 & 971 WEST MAPLE DRIVE A. GENERAL This site is part of the Upper Southampton's comprehensive plan to alleviate existing drainage problems that currently exist in the township. The site is located two hundred (200) feet north of the intersection of Central Avenue and West Maple Avenue. The problem is an obstructed drainage way. It appears that the homeowner of lot 970 piped and filled an existing drainage course that intercepts considerable upstream flow. An in-ground swimming pool was constructed on lot 970 and apparently in order to stabilize the steep side bank from the stream, the stream was replaced with a 12" plastic pipe, a 24" CMP and a considerable amount of fill. A sink hole is also occurring above the exisiting roadway culvert which appears to be caused by an improper joint in the culvert where two (2) sections of different diameter pipes (36" and 48") are connected with no junction structure. The upstream culvert is equipped with an inlet / weir structure which does not appear to permit proper swale conveyance which causes overflowing into the roadway area. This structure also presents a safety issue as it is an open 4' x4' x4' concrete pit along side of the roadway. Based upon site investigations, a 36" / 48" CMP discharges to a 12" PEP. It appears that the area immediately downstream of the roadway culvert (36" / 48" CMP) will flood due to inadequate conveyance of the 12" PEP. This flooding most likely raises the water surface elevation during storm events which encroaches further onto neighboring properties than that of the condition prior to installation of the pool, the pipe and the fill. The improper roadway culvert joint must be repaired or the sink hole size will grow and eventually affect the roadway infrastructure. The inlet / weir structure should be replaced with a standard headwall and the upstream area regarded to route flows to the headwall. B. STORMWATER MANAGEMENT In order to correct the above problems, the area has been studied and supporting storm water computations have been provided for improvements to the area. The roadway culvert is to be replaced with a new pipe and headwall structure. The stream encroachment is to be rectified by replacing the 12" pipe with a larger pipe to allow a less obtrusive route for the drainage way. It is noted that the stream capacity prior to construction of the swimming pool can only be assumed, and as such, may not provide the same flow capacity as before the pool. The pipe will decrease flood elevations substantially which will also protect the pool from being contaminated with stormwater runoff. Check flows to the culvert at West Maple Avenue … The calculated flow to this area is 31.45 cfs for a 2 year frequency storm event and 77.41 cfs for a 100 year frequency storm event. The pipe capacity across the road from this location is approximately 60 cfs (inlet control) <64.8 cfs, therefore inadequate pipe capacity exists considering the 36" CMP. It is noted that this condition would flood the street as the flows build up and cross West Maple Avenue. Since this pipe is in poor condition, its replacement with a 36" PEP-S will provide additional capacity to safely convey a 100 year frequency storm. Check flow to the exisitng 12" pipe (12" diameter pipe assumed since it is not evident where this pipe changes to a 24" CMP) … The calculated flow to this area is 32.76 cfs for a 2 year frequency storm event and 80.64 cfs for a 100 year frequency storm event. The pipe capacity at this location is 5.6 cfs << 80.64 cfs. This pipe is severely undersized. The swale over the pipe has a capacity of 25 cfs. Therefore, the pipe and swale combined capacity is 30.6 cfs which is less than a two (2) year design storm capacity. This lack of conveyance indicates the adjacent in-ground swimming pool intercepts stormwater runoff approximately once every two (2) years. C. RESULTS In order to correct the above situation the following is required: It will be necessary to replace the existing 36" / 48" CMP roadway culvert with a 36" diameter PEP-S (smooth bore polyethylene pipe). This will correct the sinkhole situation, provide a replacement for the deteriorated culvert and provide additional capacity to convey the 100 year design storm. The new upstream headwall will substantially decrease inlet losses (increase pipe capacity) and provide a much safer situation. An easement will be required from the owner of lot 896 which shouldn't be a problem since the improvement will decrease flooding on this property. Technically, the 12" / 24" pipe should be removed and the area should be restored to its original stream channel characteristics. This is not possible considering the close proximity of the existing swimming pool without installing gabions and other bank retention features, or removing the simming pool. Also, the owner of lot 970 would not benefit from this proposal by losing avaialble yard area and a swimming pool. Therefore, the 12" / 24" pipe should be replaced with a 36" PEP-S (polyethylene. smooth bore pipe), if permitted by PaDEP. This will provide capacity to convey a 100 year design storm. An easement will be required from the owner of lot 970. This shouldn't be a problem since the yard area will be improved by providing a more level surface and less frequent flooding will occur to the property and swimming pool. It will be necessary to have PaDEP review the project prior to preparing a final design. It would appear that the channel once had defined banks thus classifying it as "regulated waters of the Commonwealth" and making it necessary to obtain PaDEP approvals for the proposed construction. A "Request for Determination" should be submitted for both culvert replacements. A wetlands evaluation should also be performed. It appears that the 12" / 24" pipe replacement portion of this project is required because the stream was enclosed improperly by the owner of lot 970. The township should investigate to see if permits were drawn for the pool construction and whether or not those permits included any details on filling the existing drainage way. The project should be discussed with the property owner of lot 970 and a possible contribution discussed if it is determined that he is at fault. PaDEP may also levy fines if it is found that the stream was filled illegally. Based upon drainage problems reviewed as part of this project it is noted that these problems can be avoided in the future by consiodering the following: Residents should be notified / reminded that permits are required for all proposed buildings, pools, earth disturbances, fences, disturbances to wet areas, etc. This could be done in the form of a newsletter, or an article in the newspaper. The township may consider increasing policing actions by the code enforcement officer. This would require the code enforcement officer to patrol the township on a regular basis looking for unuthorized construction projects. Pipe junctions should always be made with concrete structure units or concrete easements. Open concrete structures present safety hazards and should never be permitted. All stromwater drainage collecting substantial flows (say from more than ten lots) should be bounded by an easement in order to preserve and protect the drainage way. V. HILLSIDE DRIVE / HILLSIDE FARMS This site is part of the Upper Southampton's comprehensive plan to alleviate existing drainage problems that currently exist in the township. The site is within the Hillside Farms subdivision which is located off of Churchville Road approximately 3,500 feet northeast of the intersection of Churchville Road and Street Road. The drainage problem exists throughout the development but is worst along Hillside Drive approximately 300' from Churchville Road. At this location, substantial flows are conveyed to TMP's 48-18-17 and 38 which make for wet, swampy and unusable yards as well as creating roadway flooding. The flows are created by a large drainage area (10 acres) with no pipe or other means of picking up the concentrated flows prior to discharge into the rear yard of TMP 48-18-23 has constructed retaining walls, berms and swales in order to keep the flows away from the house. These precautions will most likely not be sufficient in a major storm event due to the magnitude of runoff directed to this location (27 cfs). From here the problem extends into Hillside Drive which is serviced with roadside swales and driveway culverts. The culverts are sized inadequately and one; in front of TMP 48-18-25 has been completley filled which creates a large pond on the upstream side of the culvert during even minor storms. The property owner across the street has installed a bituminous curb in order to keep the water out of his yard, whichnow pools in the street. The Hillside Drive roadway cross culvert is a 24" RCP which feeds into a 15" CMP which is mostly blockd in the inlet structure due to the inlet structure configuration. Several trees and root systems also appear to be too close to the existing storm collection system and are possibly obstructing the pipes. This 15" pipe appears to weave through TMP 48-18-48, discharges to a small swale, enters a 12" CMP routed along the southwest side of Manor Lane, discharges to a 24" RCP roadway cross culvert, to an inlet where it transitions back to a 15" pipe. In essence, it appears that the subdivision was designed with open swales except for 24" culverts at all road crossings. These 24" pipes are acceptable for about a ten (10) year frequency storm event. However, considering that the intermediate areas (swales) are insufficiently piped and filled, the floodplain may now extend out to inlude the residential structures. Some of the drainage, about 7 cfs of the 27 cfs getting to this area is jumping the roadway centerline crown on West Maple Avenue and causing additional flooding of yards and garages. VI. MILLER ROAD A. GENERAL This site is part of Upper Southampton's comprehensive plan to alleviate existing drainage problems that currently exist in the township. The site is located immediately east of the intersections of Miller Road and Williams Drive. The drainage problem is the flooding of Miller Drive / Clair Road at the roadway low point during major storm events. The problem appears to be an inadequate stormwater collection system as very few inlets are provided in this area of the development other than at the roadway low point. This causes all runoff to be conveyed (via gutter flow) to the low point where considerable flows converge from both directions. Inadequate inlet capacity at this point creates flooding of the street, street overtopping, and flows across residential lots to the creek. B. STORMWATER MANAGEMENT In order to correct the above problems, the area has been studied and supporting stormwater computations have been provided for improvements to the area. Stormwater collection systems are designed to collect and convey a 10 year frequency storm. Flows above this are expected to encroach into the roadway and to be conveyed to an outlet without causing harm to properties for up to a 100 year storm event. This study involves a nine (9) acre drainage area which flows to the inlets located at the low point on Miller Drive. This is a substantial drainage area considering it is to be collected via only two (2) inlets. Normal inlet capacity is approximately 4 cfs, although higher flows, up to 12 cfs can be expected per inlet in sumped conditions (at low points). In order to alleviate the substantial flows to the low point, it is necessary to intercept flows via addiitonal inlets strategically placed upstream. Approximately three (3) acreas are directed to the low point from the west (Miller Road and Williams Drive). An additional six (6) acres are contributed from the east (Clair Road). Optimally, additional inlets / collection piping should be extended toward the east and west to intercept excess gutter flow and route the flows to the low point via underground stormwater piping. However, substantial flows can be intercepted with little disruption to the roadway and existing utilities by only picking up flows from the west and directing them directly to the stream. This alternative avoids expensive roadway cuts and connections to existing inlet structures. It will reduce flows to the low point by aproximately 30%. SHould the reduction not prove to be acceptable once installed, the storm collection system may then be extended toward the east to intercept the desired amount of excess gutter flows. The existing low point currently attempts to intercept 27 cfs during a 10 year frequency design storm. This figure represents more than double the flows that it should be expected to accept. This figure represents more than double the flows that it should be expected to accept. The proposed storm collection system will intercept approximately 8 cfs, thereby reducing flows to the low point to approximately 10 cfs per inlet. While this figure is still excessive, and some roadway flooding is expected (especially if the inlets become partially clogged with vegetation debris), it may be sufficient to maintain the runoff within the roadway and prevent it from overtopping the curb and flowing across residential properties. Another issue studied is the capacity and possible restriction of the stream culvert located at the roadway low point. This 40" x 60" elliptical culvert accepts runoff from a significant, 58.5 acre watershed. Culvert computations performed indicate that this pipe capacity is marginal for a ten (10) year storm event. Normally these larger roadway culverts are designed to flow a one hundred (100) year frequency storm due to potential property flooding, etc. The alternate proposed provides a separate discharge point to the stream, thereby diverting flow and adding capacity to the 40" x 66" culvert during major storm events. C. RESULTS The above alterations will greatly improve the inlet flooding condition at the low point on Miller Road as well as to provide additional pipe capacity for the 66" x 40" culvert located at the Miller Road low point. In order to correct the above situation the following is required: A stormwater easement must be obtained from the owner of the property where the piping is proposed It will be necessary to get mark outs from all utility companies. The proposed improvements will most likely not conflict with existing water or sanitary sewer systems, however underground cable, electric, or telephone may exist in the Miller Road right of way. The stream area should be delineated for wetlands and waters of the United States by a qualified soil scientist. If these are present it will be necessary to obtain a general permit #4 (GP-4) which will permit construction of an outfall structure within fifty (50) feet of regulated areas. Based upon drainage problems reviewed as part of this prject it is noted that these problems can be avoided in the future by considering the following: Inlet capacity should be verified and additional storm collection system installed if necessary. Large roadway culverts should be designed to convey a 100 year storm event. VII. BEAVER ROAD A. GENERAL This site is part of Upper Southampton's comprehensive plan to alleviate existing drainage problems that currently exist in the township. The site is located just north of the intersection of Beaver Drive and Orcap Way. The site is in the Burgundy Hills development just west of Bristol Road The drainage problem is flooding of Beaver Road and the property of 279 Beaver Road. The problems appear to be undersized storm sewers and poorly graded yards. Beaver Road floods severely at this low point which has a large contributing drainage area and substantial runoff accumulation to the low point in Beaver Road. Compounding this problem is that inlets are spaced infrequently and gutter flows may be bypassing the inlets during large storms creating wide gutter flows and turbulent conditions at the low point. Much of these flows are directed to a 24" CMP which appears to be undersized. This pipe is designed to route these flows across the street to a 48" CMP which traverses house #279 Beaver Road where it discharges to a large culvert under Bristol Road. This large pipe also has a very large drainage area and if insufficient capacity exists will possibly flood #279 Beaver Road. B. STORMWATER MANAGEMENT In order to correct the above problems, the area has been studied and supporting stormwater computations have been provided for improvements to the area. It is noted that the study area involves approximately 110 acres. A substantial portion of the contributing drainage area (45 acres) is in Northampton Township. While the Northampton drainage area is substantially developed (residential) it is noted that a large detention basin is provided for this area with a 12" RCP outlet pipe. This facility would appear to approximately reduce the Northampton Township flows to that of the pre-developed flow conditions which was assumed for the attached analysis. Stormwater collection systems are designed to collect and convey a 10 year frequency storm. Flows above this are expected to encroach into the roadway and to be conveyed to an outlet without causing harm to properties for up to a 100 year storm event. Since all flows appear to be conveyed to the low point on Beaver Road, additional methods of collecting runoff upstream were not considered. Inlet collection in the vicinity of the low point appears to be inadequate. An existing inlet on the west side of Beaver Road is expected to collect runoff from a 7.5 acre upstream watershed. The computations performed indicate that this inlet capacity is marginal for a 10 year storm based upon submersed inlet capacity. It is noted that this condition will not be acceptable if substantial flows bypass the upstream inlets as discussed above. An additional inlet is recommended at this location. The inlet conveys flows across Beaver Road via a 24" CMP. Flows to this 24" CMP are approximately 44cfs which far exceeds the capacity of the pipe. It is recommended that this pipe capacity be increased by adding another 24" cross pipe. This cross pipe can be added in conjunction with the additional inlet recommended above. Flow capacity of the existing 48" CMP was also studied. The computations indicate that this pipe has capacity to covey a 10 year frequency storm with minor ponding in the street. Conveyance also needs to be provided to convey the flows to an outlet without damage to property. In this case when the pipe capacity is exceeded, Beaver Road floods and flows eventually discharge via a swale between house #279 and 267. A storm easement is in place at this location for the existing 48" CMP. This swale should have capacity to flow the difference between the 100 year design storm and the 48" CMP capacity (210 cfs - 125 ± = 85 cfs). It is noted that pipe capacity could also be increased however this would be very costly. It is therefore recommended that the swale be reconstructed to provide a minimum capacity of 85 cfs. C. RESULTS The above alterations will greatly improve the flooding condition in the vicinity of the inlet on the west side of Beaver Road, as well as provide additional inlet capacity on both sides of the street. It is noted that roadway flooding depth as measured at the inlets has been eliminated from a 1' depth during a 2 year frequency storm and from complete inundation to about 6" during a 10 year storm event. The increased swale capacity will eliminate flooding of house #279 during large storm events (including a 100 year storm), however flood depth in the roadway are still expected to reach a depth of about 2 feet in severe storms (greater than 10 year frequency). Consideration was given to replacing or constructing a parallel pipe to the 48" CMP. This was found to be very expensive. PADEP and PennDOT permitting would also be required due to the discharge location. It was disregarded because the pipe operates for the designated 10 year frequency design storm. Should this pipe ever have to be replaced due to its condition, it may be considered to also upgrade the pipe's flow characteristics at this time. Another option is to raise the roadway thereby gaining additional head pressure to convey the flows. By raising the road 6", a 10 year frequency storm would be able to be conveyed with no ponding in the roadway. In order to correct the above situation the following is required: The owners of house #279 and 267 should be contacted to verify that the 48" CMP is not restrictive in small storm events. If it is restrictive, further pipe evaluation will be necessary to determine if it is blocked or collapsing. It is noted that a tree is planted very close to the pipe which should be relocated so that roots do not grow into the pipe and cause pipe failure. It will be necessary to get mark outs from all utility companies. The prposed improvements will most likely not conflict other utilities since the work involved is very close to the existing 24" CMP cross pipe. Based upon drainage problems reviewed as part of this project it is noted that these problems can be avoided in the future by considering the following: CMP (corrugated metal pipe) should not be permitted in the township since smooth bore polyethylene pipe or reinforced concrete pipe (RCP) is much more efficient and longer lasting On-lot drainage should be considered (in the form of stormwater collection systems) where excessive flows are developed in the rear of properties. All drainage structures should be provided in easements. Inlets should also be provided in the street at property lines where substantial flows are anticipated. VIII. YALE DRIVE AND NEW ROAD A. GENERAL This site is part of the Upper Southampton's comprehensive plan to alleviate existing drainage problems that currently exist in the township. The site is located on the northern and eastern intersection corner of New Road and Yale Drive, approximately 2,500 feet west of Street Road. The drainage problem is the flooding of New Road and of TMP's #48-6-5-24 and 48-6-6. The existing New Road culvert appears to be undersized as well as the existing storm collection system which runs through private properties at the above referenced intersection. Flows build up on New Road and at an existing lawn inlet on private property (TMP #48-6-5-24) which causes flooding. The existing system is difficult to trace and appears to make a 90 degree bend underground with no drainage structure just downstream of the inlet in front of TMP #48-6-6. New Road has very little longitudinal slope such that when this system backs up, it floods a large portion of the roadway. B. STORMWATER MANAGEMENT In order to correct the above problems, the area has been studied and supporting stormwater computations have been provided for improvements to the area. A fairly large upstream drainage area contributes runoff to the study area (3 acres) which is developed as a residential subdivision. A pipe design has been proposed which involves replacing the New Road culvert and routing flows from the culvert through a a new storm collection system, along New Roadto the intersection of Yale Drive. At this point a storm manhole is proposed as a junction and the storm continues along Yale Drive to the inlet to which it currently discharges. This proposed system will benefit the private properties by routing all upstream flows around the propoerties. The system will be most beneficial to the flow of the system as it will be 24" PEP-S which is smooth bore polyethylene pipe in lieu of the existing 18" CMP (corrugated metal pipe). The new pipe has a much smoother interior, increasing capacity as does the increase in pipe diameter. It is noted that the proposed 24" PEP-S ties into an existing 24" CMP and that not much flow enters the system between the 24" and 18" pipes, thereby another indicator that the 18" pipe is undersized. C. RESULTS The pipe system capacity must be increased in order to eliminate the flooding conditions as the existing yard piping system floods during a 2 year frequency design storm. The existing 18" CMP running diagonally across the front yard of TMP #48-6-6 (not in an easement) is not a good situation. THe curves/bends in the 18" CMP are prone to high friction losses, clogging, bad joints and sink holes. It is recommended that the 18" CMP be removed. This pipe could be replaced with a larger pipe in an easement or the storm collection system can be relocated into New Road and Yale Drive. Replacing the pipe in an easement would help partially, however the downstream yard inlet has very little available head. In other words, this inlet will flood the property due to the low elevation of the inlet as compared to the downstream inlet in Yale Drive. A temporary easement will be required to enter upon the lands of TMP # 48-6-6 to remove the existing pipe. It is recommended to remove the pipe rather than abandon it because it is a CMP (corrugated metal pipe) which will eventually rot and collapse. To acquire an easement on this property for pipe removal or pipe improvement shouldn't be a problem since the property owner will reap the benefits of better drainage. The costs to improve this pipe is not much less than re-routing the entire storm collection system, plus much more pipe capacity will be available by re-routing the storm systemas this will provide a partial parallel system. We found that the parallel pipe system has a capacity for a 100 year design storm while the proposed piping through the yard (Alt #1) only has capacity for a 10 year storm. We therefore recommend that a secondary, parallel pipe collection system be constructed within the roadway of New Road and Yale Drive. We note that this system will be less expensive to construct if located further into the roadway so as to not disturb the existing roll curb. We therefore also recommend that this design (design #1) be constructed. The New Road culvert analysis was performed as a separate computation so that impacts on tail water from the downstream piping system can be evaluated. We found that the New Road culvert will flood in less than a 2 year storm in the existing condition. If the piping downstream of New Road is improved per Design #1, the culvert will have capacity to flow a 2 year storm, but not a 5 year storm. If the New Road culvert is replaced along with the downstream piping, it will flow a 100 year design storm. In order to correct the above situation the following is required: A temporary grading easement will be required from the property owner of TMP #48-6-6 and across New Road at TMP #28-536. The owner of TMP #48-6-5-24 should also be contacted to discuss the project since it will affect his property. Neither of these easements should be a problem since both properties will benefit from the proposed storm improvements. It will be necessary to get mark outs from all utility companies. It is noted that the recommended pipe design is close to a 4" gas main. Also, a water service connection will have to be crossed and may have to have the elevation adjusted to gain the necessary clearance from the proposed storm pipe. The existing New Road culvert is very shallow. This may be because of a conflict with the existing 4" gas main, water system or sanitary sewer. All utilities must be accurately located prior to construction. Based upon drainage problems reviewed as part of this project it is noted that thes eproblems can be avoided in the future by considering the following: Pipe junctions should always be made with standard concrete structure units or concrete encasements. CMP (corrugated metal pipe) should not be permitted in the township since it has a short life expectancy. Smooth bore polyethylene pipe or reinforced concrete pipe (RCP) is recommended. All stormwater drainage collecting substantial flows (say from more than ten (10) lots) should be bounded by an easement in order to preserve and protect the drainage way. All drainage structures should be provided in an easement. Site design by DiAnn Ohama.