{"id":60,"date":"2022-06-20T15:10:48","date_gmt":"2022-06-20T19:10:48","guid":{"rendered":"https:\/\/opentextbc.ca\/plumbing3a\/chapter\/describe-manholes\/"},"modified":"2022-08-17T11:55:12","modified_gmt":"2022-08-17T15:55:12","slug":"describe-manholes","status":"publish","type":"chapter","link":"https:\/\/opentextbc.ca\/plumbing3a\/chapter\/describe-manholes\/","title":{"raw":"Learning Task 1","rendered":"Learning Task 1"},"content":{"raw":"A manhole is a composite or concrete chamber installed at specific intervals along sewer lines, that allow access to the pipes entering and exiting them. Sometimes referred to as inspection chambers, manholes allow inspection, cleaning, and maintenance of sewers without needing to dig them up. They are normally installed at every bend, junction, change of gradient or change of diameter of the sewer. The sewer line between any two manholes is normally laid straight with consistent gradient to minimize the chance of blockages forming at any point between manholes.\r\n<h1>Types of Manholes<\/h1>\r\nManhole types are mainly classified into two categories, which are:\r\n<ul>\r\n \t<li>Based on depth<\/li>\r\n \t<li>Based on construction material<\/li>\r\n<\/ul>\r\n<h2>Manholes based on depth<\/h2>\r\nUsing overall depth as the factor, manholes are further classified into three categories, these being:\r\n<ul>\r\n \t<li>shallow manholes<\/li>\r\n \t<li>normal manholes, and<\/li>\r\n \t<li>deep manholes<\/li>\r\n<\/ul>\r\n<h3>Shallow manholes<\/h3>\r\nManholes with a depth of 0.75m to 0.9m (2.5 to 3 ft) are called shallow manholes.\u00a0They are used where the expected amount of traffic over them is low and, consequently, the piping between them is at relatively shallow depths. These manholes can be either round or rectangular in shape and are sometimes referred to as inspection chambers.\r\n<h3>Normal manholes<\/h3>\r\nA manhole with an overall depth greater than 0.9m (3 ft) but not more than 2m (6 ft) is called a normal manhole. These manholes typically have a thick cover to support heavy loads over them and, similar to the shallow variety, are either round or square in shape.\r\n<h3>Deep manholes<\/h3>\r\nDeep\u00a0manholes are those with an overall depth of more than 2m (6 ft). These types of manholes are mainly circular in shape and consist of multiple \u201cstacked\u201d sections rather than being one-piece like the shallow or normal manholes.\r\n<h2>Manholes based on construction material<\/h2>\r\nDepending on the construction material used, \u00a0manholes fall into three categories, which are:\r\n<ul>\r\n \t<li>precast concrete manholes<\/li>\r\n \t<li>plastic manholes, and<\/li>\r\n \t<li>fiberglass manholes<\/li>\r\n<\/ul>\r\n<h3>Precast concrete manholes<\/h3>\r\nThis type of manhole is precast (constructed off-site) and is the predominant style that is used worldwide. It has two steel cable loops embedded in the concrete and protruding out of opposite sides of each section, used for lifting it. They may also have anodized steel rungs embedded to form a self-contained ladder for easier access and egress. Runged sections are rotated so that the rungs are aligned vertically. Precast concrete manholes are available with or without a poured bottom.\r\n<h3>Plastic manholes<\/h3>\r\nPlastic manholes are made of polyethene\u00a0material, which makes them lighter than the concrete versions, allowing for possible placement by hand. They come in various thicknesses and the walls can be either smooth or ribbed. They normally have a bottom to them for structural integrity. Once buried, they normally won\u2019t be affected by ultraviolet rays from the sun and so should last many years. Plastic manholes do not require much maintenance and are highly resistant to the effects of corrosive liquids and soils.\r\n<h3>Fiberglass manholes<\/h3>\r\nLike plastic manholes, fiberglass manholes are lightweight, durable, and easier to handle than the concrete versions. Also like the plastic varieties, they commonly have a bottom built into them and generally have more strength than the plastic versions but also tend to be more expensive than plastic. Pipe penetrations are accomplished in a similar fashion to that of the plastic manholes.\r\n<h1>Manhole covers<\/h1>\r\nManholes have lids that normally have a smaller opening built into them for access to the manhole. If the lid is flat, the smaller opening is cast eccentrically into the lid, allowing the lid to be rotated to align the smaller opening with the self-contained ladder below it. Tapered precast sections are also available for the same purpose, as seen below.\r\n\r\n[caption id=\"attachment_59\" align=\"aligncenter\" width=\"576\"]<img class=\"size-full wp-image-53\" src=\"https:\/\/opentextbc.ca\/plumbing3e\/wp-content\/uploads\/sites\/408\/2022\/06\/Tapered-precast-concrete-barrel-sections.jpg\" alt=\"\" width=\"576\" height=\"581\" \/> Figure 1 Tapered precast concrete barrel sections[\/caption]\r\n\r\nTraditionally, manhole covers are constructed of cast iron, concrete, or even a combination of the two. These materials are preferred due to specific qualities like durability, cost, and being heavy enough to stay in place without needing a locking mechanism. However, technology has led to various alternative manhole cover materials like composites, fiberglass, and plastic. Recessed type covers are used for residential projects and service industry projects like hospitals, hotels, malls, etc. Ductile iron covers are often used for airports, docks, roads, and pedestrian walkways where long lifespans in heavy traffic areas is required. Solid top covers are preferred in industrial areas and heavy-duty manufacturing workshops.\r\n\r\n[caption id=\"attachment_59\" align=\"aligncenter\" width=\"500\"]<img class=\"wp-image-54\" src=\"https:\/\/opentextbc.ca\/plumbing3e\/wp-content\/uploads\/sites\/408\/2022\/08\/Manhole-lid-and-cover.jpg\" alt=\"\" width=\"500\" height=\"375\" \/> Figure 2 Manhole lid and cover[\/caption]\r\n\r\n[caption id=\"attachment_59\" align=\"aligncenter\" width=\"400\"]<img class=\"wp-image-91\" src=\"https:\/\/opentextbc.ca\/plumbing3e\/wp-content\/uploads\/sites\/408\/2022\/08\/Plstic-manhole-lid-1-scaled-1.jpg\" alt=\"\" width=\"400\" height=\"300\" \/> Figure 3 Plastic manhole cover[\/caption]\r\n<h1>Applications<\/h1>\r\nWhile manholes were initially meant to provide workers with access to pipes and other underground utilities, they are often used for equipment access as well. They can be an access point for an underground public utility such as an underground storm reservoir or lift station, allowing inspection, maintenance, and system upgrades. Most underground services utilize manholes, including water, sewers, telephone, electricity, storm drains, district heating, and gas. Work crews can lower inspection cameras into manholes to gather CCTV footage to assist in determining the need for cleaning and routine maintenance. Manholes also allow the placement and use of remotely controlled equipment. This keeps people above ground and immune from the possible safety and cost implications of entering a confined space that may contain fumes, bacteria, debris, and sewage flows.\r\n<h1>Manhole Locations<\/h1>\r\n<h2>Indoor Manholes<\/h2>\r\nAlthough mainly used outdoors, manholes are sometimes installed inside commercial buildings to allow access to services such as underground electrical cables. Using this type of manhole, sometimes referred to as a work chamber, cable chamber or vault, an electrician can enter it to inspect and service existing circuits or to add more cables to service new equipment.\r\n\r\n[caption id=\"attachment_59\" align=\"aligncenter\" width=\"500\"]<img class=\"wp-image-56\" src=\"https:\/\/opentextbc.ca\/plumbing3e\/wp-content\/uploads\/sites\/408\/2022\/08\/Triple-sealed-access-cover-for-interior-manhole-1.jpg\" alt=\"\" width=\"500\" height=\"457\" \/> Figure 4 Triple-sealed access cover for interior manhole[\/caption]\r\n\r\nClause 2.4.7.3. (1) (c) of the NPC requires that a manhole installed inside a building needs a vent to the exterior, with Sentence 2.5.7.6. (1) stating that the vent must be a minimum size of 2 inches. The codes don\u2019t specify what the manhole is used for, only that a vent is required if it is indoors.\r\n<h1>Storm Manholes<\/h1>\r\nStorm manholes are used in conjunction with catch basins to move untreated stormwater\u00a0to disposal areas such as ditches or larger bodies of water. \u00a0Storm manholes can have multiple inlet pipes at varying elevations and usually have only one outlet pipe. Because storm manholes are usually installed with a sealed bottom, there will be a standing water level within it. At the outlet, a hood or a downturned 90-degree elbow with its inlet below the standing water level prevents floating material from entering the outlet pipe. A backwater valve is sometimes installed at the outlet as well. The backwater valve prevents reverse flow back into the manhole caused by downstream drainage issues such as overloading.\r\n\r\n[caption id=\"attachment_59\" align=\"aligncenter\" width=\"702\"]<img class=\"size-full wp-image-57\" src=\"https:\/\/opentextbc.ca\/plumbing3e\/wp-content\/uploads\/sites\/408\/2022\/08\/Storm-manhole.jpg\" alt=\"\" width=\"702\" height=\"446\" \/> Figure 5 Storm manhole[\/caption]\r\n<h1>Sanitary Manholes<\/h1>\r\nSanitary manholes are used in conjunction with gravity or pressure fed piping systems\u00a0engineered\u00a0to move raw sewage\u00a0to treatment plants. Manholes are commonly placed every 100 \u2013 120m (300-400 ft) in sewer collecting lines, but this may vary depending on municipalities, engineers, codes, and design standards. Sanitary sewer manholes are most commonly made of precast concrete. They have concrete bottoms into which are sculpted channels for moving raw sewage, containing solids, from multiple inlets into a single outlet. The inlets and outlet are at elevations that differ only by the amount of grade required to allow flow by gravity between them.\r\n\r\n[caption id=\"attachment_59\" align=\"aligncenter\" width=\"651\"]<img class=\"size-full wp-image-58\" src=\"https:\/\/opentextbc.ca\/plumbing3e\/wp-content\/uploads\/sites\/408\/2022\/08\/Sanitary-manhole.jpg\" alt=\"\" width=\"651\" height=\"582\" \/> Figure 6 Sanitary manhole[\/caption]\r\n<h1>Specialty Manhole Types<\/h1>\r\n<h2>Drop Manhole<\/h2>\r\nAs previously stated, the flow through a sanitary manhole must be channeled, which means the entry and exit pipe elevations must be almost the same. \u00a0A drop manhole describes the piping arrangement sometimes provided at the junction point of a high-level sewer inlet and a low-level main sewer outlet. The use of a drop manhole avoids an unnecessary steep gradient of the sewer piping feeding into it and thus reduces the quantity of earthwork required, while it also negates the possibilities of sewage being thrown onto personnel entering the\u00a0working chamber of the manhole.\r\n\r\n[caption id=\"attachment_59\" align=\"aligncenter\" width=\"400\"]<img class=\"wp-image-27 size-full\" src=\"https:\/\/opentextbc.ca\/plumbing3e\/wp-content\/uploads\/sites\/408\/2022\/08\/Manhole-components.png\" alt=\"\" width=\"400\" height=\"640\" \/> Figure 7 Manhole components[\/caption]\r\n<h2>Lamp Manhole<\/h2>\r\nA lamp manhole is a small opening on a sewer that is extended vertically to the ground\u2019s surface for the purpose of lowering a lamp or light inside it. The lamp holes were provided at places where inspection of the flow through the sewer was necessary due to bends in the sewer or where there was greater length between manholes than desired due to difficulty in installing or locating a \u201cstandard\u201d manhole. A lamp hole could also be used as a flushing point if needed, and if its top cover was perforated, it could assist in the ventilation of the sewer.\r\n\r\nAlthough existing lamp manholes can be found in some jurisdictions, they are not referenced in either the NPC nor the BCPC as such and their allowable use is debatable. Sentence 2.2.6.2. (1) of the NPC alludes to the existence of \u201cmaintenance holes\u201d and if a lamp manhole could be categorized as such, it might be allowable by code.\r\n\r\n[caption id=\"attachment_59\" align=\"aligncenter\" width=\"386\"]<img class=\"size-full wp-image-59\" src=\"https:\/\/opentextbc.ca\/plumbing3e\/wp-content\/uploads\/sites\/408\/2022\/08\/Lamp-manhole.jpg\" alt=\"\" width=\"386\" height=\"290\" \/> Figure 8 Lamp manhole[\/caption]\r\n<h3>Media Attributions<\/h3>\r\n<ul>\r\n \t<li>Figure 1 <a href=\"https:\/\/kohnenconcrete.com\/wp-content\/uploads\/2020\/03\/2-MH-Cones_Feature.jpg\">Tapered precast concrete barrel sections<\/a> \u00a9 <a href=\"https:\/\/kohnenconcrete.com\/\">Kohnen Concrete Products, Inc<\/a>. Used with permission.<\/li>\r\n \t<li>Figure 2 <a href=\"https:\/\/www.flickr.com\/photos\/gtzecosan\/4427168758\/in\/photostream\/\">Manhole lid and cover<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/gtzecosan\/\">SuSanA Secretariat<\/a> is licensed under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">CC BY 2.0 licence<\/a>.<\/li>\r\n \t<li>Figure 3 Plastic manhole cover by Greg Wirachowsky\u00a0is licensed under a\u00a0<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA licence<\/a>.<\/li>\r\n \t<li>Figure 4 <a href=\"https:\/\/kentstainless1.b-cdn.net\/wp-content\/uploads\/2020\/09\/STAINL2-2.jpg\">Triple-sealed access cover for interior manhole<\/a> \u00a9 <a href=\"https:\/\/kentstainless1.b-cdn.net\/\">Kent Stainless<\/a>. Used with permission.<\/li>\r\n \t<li>Figure 5 Storm manhole by ITA\u00a0is licensed under a\u00a0<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA licence<\/a>.<\/li>\r\n \t<li>Figure 6 Sanitary manhole\u00a0by ITA\u00a0is licensed under a\u00a0<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA licence<\/a>.<\/li>\r\n \t<li>Figure 7\u00a0<a href=\"https:\/\/reliner.com\/\">Manhole components<\/a>\u00a0\u00a9\u00a0<a href=\"https:\/\/reliner.com\/\">Reliner<\/a>, used with permission.<\/li>\r\n \t<li>Figure 8 Lamp manhole by Greg Wirachowsky\u00a0is licensed under a\u00a0<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA licence<\/a>.<\/li>\r\n<\/ul>","rendered":"<p>A manhole is a composite or concrete chamber installed at specific intervals along sewer lines, that allow access to the pipes entering and exiting them. Sometimes referred to as inspection chambers, manholes allow inspection, cleaning, and maintenance of sewers without needing to dig them up. They are normally installed at every bend, junction, change of gradient or change of diameter of the sewer. The sewer line between any two manholes is normally laid straight with consistent gradient to minimize the chance of blockages forming at any point between manholes.<\/p>\n<h1>Types of Manholes<\/h1>\n<p>Manhole types are mainly classified into two categories, which are:<\/p>\n<ul>\n<li>Based on depth<\/li>\n<li>Based on construction material<\/li>\n<\/ul>\n<h2>Manholes based on depth<\/h2>\n<p>Using overall depth as the factor, manholes are further classified into three categories, these being:<\/p>\n<ul>\n<li>shallow manholes<\/li>\n<li>normal manholes, and<\/li>\n<li>deep manholes<\/li>\n<\/ul>\n<h3>Shallow manholes<\/h3>\n<p>Manholes with a depth of 0.75m to 0.9m (2.5 to 3 ft) are called shallow manholes.\u00a0They are used where the expected amount of traffic over them is low and, consequently, the piping between them is at relatively shallow depths. These manholes can be either round or rectangular in shape and are sometimes referred to as inspection chambers.<\/p>\n<h3>Normal manholes<\/h3>\n<p>A manhole with an overall depth greater than 0.9m (3 ft) but not more than 2m (6 ft) is called a normal manhole. These manholes typically have a thick cover to support heavy loads over them and, similar to the shallow variety, are either round or square in shape.<\/p>\n<h3>Deep manholes<\/h3>\n<p>Deep\u00a0manholes are those with an overall depth of more than 2m (6 ft). These types of manholes are mainly circular in shape and consist of multiple \u201cstacked\u201d sections rather than being one-piece like the shallow or normal manholes.<\/p>\n<h2>Manholes based on construction material<\/h2>\n<p>Depending on the construction material used, \u00a0manholes fall into three categories, which are:<\/p>\n<ul>\n<li>precast concrete manholes<\/li>\n<li>plastic manholes, and<\/li>\n<li>fiberglass manholes<\/li>\n<\/ul>\n<h3>Precast concrete manholes<\/h3>\n<p>This type of manhole is precast (constructed off-site) and is the predominant style that is used worldwide. It has two steel cable loops embedded in the concrete and protruding out of opposite sides of each section, used for lifting it. They may also have anodized steel rungs embedded to form a self-contained ladder for easier access and egress. Runged sections are rotated so that the rungs are aligned vertically. Precast concrete manholes are available with or without a poured bottom.<\/p>\n<h3>Plastic manholes<\/h3>\n<p>Plastic manholes are made of polyethene\u00a0material, which makes them lighter than the concrete versions, allowing for possible placement by hand. They come in various thicknesses and the walls can be either smooth or ribbed. They normally have a bottom to them for structural integrity. Once buried, they normally won\u2019t be affected by ultraviolet rays from the sun and so should last many years. Plastic manholes do not require much maintenance and are highly resistant to the effects of corrosive liquids and soils.<\/p>\n<h3>Fiberglass manholes<\/h3>\n<p>Like plastic manholes, fiberglass manholes are lightweight, durable, and easier to handle than the concrete versions. Also like the plastic varieties, they commonly have a bottom built into them and generally have more strength than the plastic versions but also tend to be more expensive than plastic. Pipe penetrations are accomplished in a similar fashion to that of the plastic manholes.<\/p>\n<h1>Manhole covers<\/h1>\n<p>Manholes have lids that normally have a smaller opening built into them for access to the manhole. If the lid is flat, the smaller opening is cast eccentrically into the lid, allowing the lid to be rotated to align the smaller opening with the self-contained ladder below it. Tapered precast sections are also available for the same purpose, as seen below.<\/p>\n<figure id=\"attachment_59\" aria-describedby=\"caption-attachment-59\" style=\"width: 576px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-53\" src=\"https:\/\/opentextbc.ca\/plumbing3e\/wp-content\/uploads\/sites\/408\/2022\/06\/Tapered-precast-concrete-barrel-sections.jpg\" alt=\"\" width=\"576\" height=\"581\" srcset=\"https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/06\/Tapered-precast-concrete-barrel-sections.jpg 576w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/06\/Tapered-precast-concrete-barrel-sections-297x300.jpg 297w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/06\/Tapered-precast-concrete-barrel-sections-150x150.jpg 150w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/06\/Tapered-precast-concrete-barrel-sections-65x66.jpg 65w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/06\/Tapered-precast-concrete-barrel-sections-225x227.jpg 225w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/06\/Tapered-precast-concrete-barrel-sections-350x353.jpg 350w\" sizes=\"auto, (max-width: 576px) 100vw, 576px\" \/><figcaption id=\"caption-attachment-59\" class=\"wp-caption-text\">Figure 1 Tapered precast concrete barrel sections<\/figcaption><\/figure>\n<p>Traditionally, manhole covers are constructed of cast iron, concrete, or even a combination of the two. These materials are preferred due to specific qualities like durability, cost, and being heavy enough to stay in place without needing a locking mechanism. However, technology has led to various alternative manhole cover materials like composites, fiberglass, and plastic. Recessed type covers are used for residential projects and service industry projects like hospitals, hotels, malls, etc. Ductile iron covers are often used for airports, docks, roads, and pedestrian walkways where long lifespans in heavy traffic areas is required. Solid top covers are preferred in industrial areas and heavy-duty manufacturing workshops.<\/p>\n<figure id=\"attachment_59\" aria-describedby=\"caption-attachment-59\" style=\"width: 500px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-54\" src=\"https:\/\/opentextbc.ca\/plumbing3e\/wp-content\/uploads\/sites\/408\/2022\/08\/Manhole-lid-and-cover.jpg\" alt=\"\" width=\"500\" height=\"375\" srcset=\"https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Manhole-lid-and-cover.jpg 640w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Manhole-lid-and-cover-300x225.jpg 300w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Manhole-lid-and-cover-65x49.jpg 65w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Manhole-lid-and-cover-225x169.jpg 225w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Manhole-lid-and-cover-350x263.jpg 350w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><figcaption id=\"caption-attachment-59\" class=\"wp-caption-text\">Figure 2 Manhole lid and cover<\/figcaption><\/figure>\n<figure id=\"attachment_59\" aria-describedby=\"caption-attachment-59\" style=\"width: 400px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-91\" src=\"https:\/\/opentextbc.ca\/plumbing3e\/wp-content\/uploads\/sites\/408\/2022\/08\/Plstic-manhole-lid-1-scaled-1.jpg\" alt=\"\" width=\"400\" height=\"300\" \/><figcaption id=\"caption-attachment-59\" class=\"wp-caption-text\">Figure 3 Plastic manhole cover<\/figcaption><\/figure>\n<h1>Applications<\/h1>\n<p>While manholes were initially meant to provide workers with access to pipes and other underground utilities, they are often used for equipment access as well. They can be an access point for an underground public utility such as an underground storm reservoir or lift station, allowing inspection, maintenance, and system upgrades. Most underground services utilize manholes, including water, sewers, telephone, electricity, storm drains, district heating, and gas. Work crews can lower inspection cameras into manholes to gather CCTV footage to assist in determining the need for cleaning and routine maintenance. Manholes also allow the placement and use of remotely controlled equipment. This keeps people above ground and immune from the possible safety and cost implications of entering a confined space that may contain fumes, bacteria, debris, and sewage flows.<\/p>\n<h1>Manhole Locations<\/h1>\n<h2>Indoor Manholes<\/h2>\n<p>Although mainly used outdoors, manholes are sometimes installed inside commercial buildings to allow access to services such as underground electrical cables. Using this type of manhole, sometimes referred to as a work chamber, cable chamber or vault, an electrician can enter it to inspect and service existing circuits or to add more cables to service new equipment.<\/p>\n<figure id=\"attachment_59\" aria-describedby=\"caption-attachment-59\" style=\"width: 500px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-56\" src=\"https:\/\/opentextbc.ca\/plumbing3e\/wp-content\/uploads\/sites\/408\/2022\/08\/Triple-sealed-access-cover-for-interior-manhole-1.jpg\" alt=\"\" width=\"500\" height=\"457\" srcset=\"https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Triple-sealed-access-cover-for-interior-manhole-1.jpg 940w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Triple-sealed-access-cover-for-interior-manhole-1-300x274.jpg 300w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Triple-sealed-access-cover-for-interior-manhole-1-768x703.jpg 768w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Triple-sealed-access-cover-for-interior-manhole-1-65x59.jpg 65w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Triple-sealed-access-cover-for-interior-manhole-1-225x206.jpg 225w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Triple-sealed-access-cover-for-interior-manhole-1-350x320.jpg 350w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><figcaption id=\"caption-attachment-59\" class=\"wp-caption-text\">Figure 4 Triple-sealed access cover for interior manhole<\/figcaption><\/figure>\n<p>Clause 2.4.7.3. (1) (c) of the NPC requires that a manhole installed inside a building needs a vent to the exterior, with Sentence 2.5.7.6. (1) stating that the vent must be a minimum size of 2 inches. The codes don\u2019t specify what the manhole is used for, only that a vent is required if it is indoors.<\/p>\n<h1>Storm Manholes<\/h1>\n<p>Storm manholes are used in conjunction with catch basins to move untreated stormwater\u00a0to disposal areas such as ditches or larger bodies of water. \u00a0Storm manholes can have multiple inlet pipes at varying elevations and usually have only one outlet pipe. Because storm manholes are usually installed with a sealed bottom, there will be a standing water level within it. At the outlet, a hood or a downturned 90-degree elbow with its inlet below the standing water level prevents floating material from entering the outlet pipe. A backwater valve is sometimes installed at the outlet as well. The backwater valve prevents reverse flow back into the manhole caused by downstream drainage issues such as overloading.<\/p>\n<figure id=\"attachment_59\" aria-describedby=\"caption-attachment-59\" style=\"width: 702px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-57\" src=\"https:\/\/opentextbc.ca\/plumbing3e\/wp-content\/uploads\/sites\/408\/2022\/08\/Storm-manhole.jpg\" alt=\"\" width=\"702\" height=\"446\" srcset=\"https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Storm-manhole.jpg 702w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Storm-manhole-300x191.jpg 300w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Storm-manhole-65x41.jpg 65w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Storm-manhole-225x143.jpg 225w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Storm-manhole-350x222.jpg 350w\" sizes=\"auto, (max-width: 702px) 100vw, 702px\" \/><figcaption id=\"caption-attachment-59\" class=\"wp-caption-text\">Figure 5 Storm manhole<\/figcaption><\/figure>\n<h1>Sanitary Manholes<\/h1>\n<p>Sanitary manholes are used in conjunction with gravity or pressure fed piping systems\u00a0engineered\u00a0to move raw sewage\u00a0to treatment plants. Manholes are commonly placed every 100 \u2013 120m (300-400 ft) in sewer collecting lines, but this may vary depending on municipalities, engineers, codes, and design standards. Sanitary sewer manholes are most commonly made of precast concrete. They have concrete bottoms into which are sculpted channels for moving raw sewage, containing solids, from multiple inlets into a single outlet. The inlets and outlet are at elevations that differ only by the amount of grade required to allow flow by gravity between them.<\/p>\n<figure id=\"attachment_59\" aria-describedby=\"caption-attachment-59\" style=\"width: 651px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-58\" src=\"https:\/\/opentextbc.ca\/plumbing3e\/wp-content\/uploads\/sites\/408\/2022\/08\/Sanitary-manhole.jpg\" alt=\"\" width=\"651\" height=\"582\" srcset=\"https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Sanitary-manhole.jpg 651w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Sanitary-manhole-300x268.jpg 300w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Sanitary-manhole-65x58.jpg 65w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Sanitary-manhole-225x201.jpg 225w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Sanitary-manhole-350x313.jpg 350w\" sizes=\"auto, (max-width: 651px) 100vw, 651px\" \/><figcaption id=\"caption-attachment-59\" class=\"wp-caption-text\">Figure 6 Sanitary manhole<\/figcaption><\/figure>\n<h1>Specialty Manhole Types<\/h1>\n<h2>Drop Manhole<\/h2>\n<p>As previously stated, the flow through a sanitary manhole must be channeled, which means the entry and exit pipe elevations must be almost the same. \u00a0A drop manhole describes the piping arrangement sometimes provided at the junction point of a high-level sewer inlet and a low-level main sewer outlet. The use of a drop manhole avoids an unnecessary steep gradient of the sewer piping feeding into it and thus reduces the quantity of earthwork required, while it also negates the possibilities of sewage being thrown onto personnel entering the\u00a0working chamber of the manhole.<\/p>\n<figure id=\"attachment_59\" aria-describedby=\"caption-attachment-59\" style=\"width: 400px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-27 size-full\" src=\"https:\/\/opentextbc.ca\/plumbing3e\/wp-content\/uploads\/sites\/408\/2022\/08\/Manhole-components.png\" alt=\"\" width=\"400\" height=\"640\" srcset=\"https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Manhole-components.png 400w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Manhole-components-188x300.png 188w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Manhole-components-65x104.png 65w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Manhole-components-225x360.png 225w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Manhole-components-350x560.png 350w\" sizes=\"auto, (max-width: 400px) 100vw, 400px\" \/><figcaption id=\"caption-attachment-59\" class=\"wp-caption-text\">Figure 7 Manhole components<\/figcaption><\/figure>\n<h2>Lamp Manhole<\/h2>\n<p>A lamp manhole is a small opening on a sewer that is extended vertically to the ground\u2019s surface for the purpose of lowering a lamp or light inside it. The lamp holes were provided at places where inspection of the flow through the sewer was necessary due to bends in the sewer or where there was greater length between manholes than desired due to difficulty in installing or locating a \u201cstandard\u201d manhole. A lamp hole could also be used as a flushing point if needed, and if its top cover was perforated, it could assist in the ventilation of the sewer.<\/p>\n<p>Although existing lamp manholes can be found in some jurisdictions, they are not referenced in either the NPC nor the BCPC as such and their allowable use is debatable. Sentence 2.2.6.2. (1) of the NPC alludes to the existence of \u201cmaintenance holes\u201d and if a lamp manhole could be categorized as such, it might be allowable by code.<\/p>\n<figure id=\"attachment_59\" aria-describedby=\"caption-attachment-59\" style=\"width: 386px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-59\" src=\"https:\/\/opentextbc.ca\/plumbing3e\/wp-content\/uploads\/sites\/408\/2022\/08\/Lamp-manhole.jpg\" alt=\"\" width=\"386\" height=\"290\" srcset=\"https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Lamp-manhole.jpg 386w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Lamp-manhole-300x225.jpg 300w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Lamp-manhole-65x49.jpg 65w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Lamp-manhole-225x169.jpg 225w, https:\/\/opentextbc.ca\/plumbing3a\/wp-content\/uploads\/sites\/408\/2022\/08\/Lamp-manhole-350x263.jpg 350w\" sizes=\"auto, (max-width: 386px) 100vw, 386px\" \/><figcaption id=\"caption-attachment-59\" class=\"wp-caption-text\">Figure 8 Lamp manhole<\/figcaption><\/figure>\n<h3>Media Attributions<\/h3>\n<ul>\n<li>Figure 1 <a href=\"https:\/\/kohnenconcrete.com\/wp-content\/uploads\/2020\/03\/2-MH-Cones_Feature.jpg\">Tapered precast concrete barrel sections<\/a> \u00a9 <a href=\"https:\/\/kohnenconcrete.com\/\">Kohnen Concrete Products, Inc<\/a>. Used with permission.<\/li>\n<li>Figure 2 <a href=\"https:\/\/www.flickr.com\/photos\/gtzecosan\/4427168758\/in\/photostream\/\">Manhole lid and cover<\/a> by <a href=\"https:\/\/www.flickr.com\/photos\/gtzecosan\/\">SuSanA Secretariat<\/a> is licensed under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">CC BY 2.0 licence<\/a>.<\/li>\n<li>Figure 3 Plastic manhole cover by Greg Wirachowsky\u00a0is licensed under a\u00a0<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA licence<\/a>.<\/li>\n<li>Figure 4 <a href=\"https:\/\/kentstainless1.b-cdn.net\/wp-content\/uploads\/2020\/09\/STAINL2-2.jpg\">Triple-sealed access cover for interior manhole<\/a> \u00a9 <a href=\"https:\/\/kentstainless1.b-cdn.net\/\">Kent Stainless<\/a>. Used with permission.<\/li>\n<li>Figure 5 Storm manhole by ITA\u00a0is licensed under a\u00a0<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA licence<\/a>.<\/li>\n<li>Figure 6 Sanitary manhole\u00a0by ITA\u00a0is licensed under a\u00a0<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA licence<\/a>.<\/li>\n<li>Figure 7\u00a0<a href=\"https:\/\/reliner.com\/\">Manhole components<\/a>\u00a0\u00a9\u00a0<a href=\"https:\/\/reliner.com\/\">Reliner<\/a>, used with permission.<\/li>\n<li>Figure 8 Lamp manhole by Greg Wirachowsky\u00a0is licensed under a\u00a0<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA licence<\/a>.<\/li>\n<\/ul>\n","protected":false},"author":123,"menu_order":1,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"Describe Manholes","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-60","chapter","type-chapter","status-publish","hentry"],"part":52,"_links":{"self":[{"href":"https:\/\/opentextbc.ca\/plumbing3a\/wp-json\/pressbooks\/v2\/chapters\/60","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/opentextbc.ca\/plumbing3a\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/opentextbc.ca\/plumbing3a\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/opentextbc.ca\/plumbing3a\/wp-json\/wp\/v2\/users\/123"}],"version-history":[{"count":2,"href":"https:\/\/opentextbc.ca\/plumbing3a\/wp-json\/pressbooks\/v2\/chapters\/60\/revisions"}],"predecessor-version":[{"id":87,"href":"https:\/\/opentextbc.ca\/plumbing3a\/wp-json\/pressbooks\/v2\/chapters\/60\/revisions\/87"}],"part":[{"href":"https:\/\/opentextbc.ca\/plumbing3a\/wp-json\/pressbooks\/v2\/parts\/52"}],"metadata":[{"href":"https:\/\/opentextbc.ca\/plumbing3a\/wp-json\/pressbooks\/v2\/chapters\/60\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/opentextbc.ca\/plumbing3a\/wp-json\/wp\/v2\/media?parent=60"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/opentextbc.ca\/plumbing3a\/wp-json\/pressbooks\/v2\/chapter-type?post=60"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/opentextbc.ca\/plumbing3a\/wp-json\/wp\/v2\/contributor?post=60"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/opentextbc.ca\/plumbing3a\/wp-json\/wp\/v2\/license?post=60"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}